diff --git a/src/tls/asn1.c b/src/tls/asn1.c
index 2da7b4a..04d5320 100644
--- a/src/tls/asn1.c
+++ b/src/tls/asn1.c
@@ -129,6 +129,41 @@
 		return 1;
 	if (hdr->tag == ASN1_TAG_BOOLEAN && !asn1_valid_der_boolean(hdr))
 		return 0;
+	if (hdr->tag == ASN1_TAG_NULL && hdr->length != 0)
+		return 0;
+
+	/* Check for allowed primitive/constructed values */
+	if (hdr->constructed &&
+	    (hdr->tag == ASN1_TAG_BOOLEAN ||
+	     hdr->tag == ASN1_TAG_INTEGER ||
+	     hdr->tag == ASN1_TAG_NULL ||
+	     hdr->tag == ASN1_TAG_OID ||
+	     hdr->tag == ANS1_TAG_RELATIVE_OID ||
+	     hdr->tag == ASN1_TAG_REAL ||
+	     hdr->tag == ASN1_TAG_ENUMERATED ||
+	     hdr->tag == ASN1_TAG_BITSTRING ||
+	     hdr->tag == ASN1_TAG_OCTETSTRING ||
+	     hdr->tag == ASN1_TAG_NUMERICSTRING ||
+	     hdr->tag == ASN1_TAG_PRINTABLESTRING ||
+	     hdr->tag == ASN1_TAG_T61STRING ||
+	     hdr->tag == ASN1_TAG_VIDEOTEXSTRING ||
+	     hdr->tag == ASN1_TAG_VISIBLESTRING ||
+	     hdr->tag == ASN1_TAG_IA5STRING ||
+	     hdr->tag == ASN1_TAG_GRAPHICSTRING ||
+	     hdr->tag == ASN1_TAG_GENERALSTRING ||
+	     hdr->tag == ASN1_TAG_UNIVERSALSTRING ||
+	     hdr->tag == ASN1_TAG_UTF8STRING ||
+	     hdr->tag == ASN1_TAG_BMPSTRING ||
+	     hdr->tag == ASN1_TAG_CHARACTERSTRING ||
+	     hdr->tag == ASN1_TAG_UTCTIME ||
+	     hdr->tag == ASN1_TAG_GENERALIZEDTIME ||
+	     hdr->tag == ASN1_TAG_TIME))
+		return 0;
+	if (!hdr->constructed &&
+	    (hdr->tag == ASN1_TAG_SEQUENCE ||
+	     hdr->tag == ASN1_TAG_SET))
+		return 0;
+
 	return 1;
 }
 
@@ -151,18 +186,35 @@
 	hdr->constructed = !!(hdr->identifier & (1 << 5));
 
 	if ((hdr->identifier & 0x1f) == 0x1f) {
+		size_t ext_len = 0;
+
 		hdr->tag = 0;
+		if (pos == end || (*pos & 0x7f) == 0) {
+			wpa_printf(MSG_DEBUG,
+				   "ASN.1: Invalid extended tag (first octet has to be included with at least one nonzero bit for the tag value)");
+			return -1;
+		}
 		do {
 			if (pos >= end) {
 				wpa_printf(MSG_DEBUG, "ASN.1: Identifier "
 					   "underflow");
 				return -1;
 			}
+			ext_len++;
 			tmp = *pos++;
 			wpa_printf(MSG_MSGDUMP, "ASN.1: Extended tag data: "
 				   "0x%02x", tmp);
 			hdr->tag = (hdr->tag << 7) | (tmp & 0x7f);
 		} while (tmp & 0x80);
+		wpa_printf(MSG_MSGDUMP, "ASN.1: Extended Tag: 0x%x (len=%zu)",
+			   hdr->tag, ext_len);
+		if ((hdr->class != ASN1_CLASS_PRIVATE && hdr->tag < 31) ||
+		    ext_len * 7 > sizeof(hdr->tag) * 8) {
+			wpa_printf(MSG_DEBUG,
+				   "ASN.1: Invalid or unsupported (too large) extended Tag: 0x%x (len=%zu)",
+				   hdr->tag, ext_len);
+			return -1;
+		}
 	} else
 		hdr->tag = hdr->identifier & 0x1f;
 
@@ -179,6 +231,11 @@
 		}
 		tmp &= 0x7f; /* number of subsequent octets */
 		hdr->length = 0;
+		if (tmp == 0 || pos == end || *pos == 0) {
+			wpa_printf(MSG_DEBUG,
+				   "ASN.1: Definite long form of the length does not start with a nonzero value");
+			return -1;
+		}
 		if (tmp > 4) {
 			wpa_printf(MSG_DEBUG, "ASN.1: Too long length field");
 			return -1;
@@ -191,6 +248,11 @@
 			}
 			hdr->length = (hdr->length << 8) | *pos++;
 		}
+		if (hdr->length < 128) {
+			wpa_printf(MSG_DEBUG,
+				   "ASN.1: Definite long form of the length used with too short length");
+			return -1;
+		}
 	} else {
 		/* Short form - length 0..127 in one octet */
 		hdr->length = tmp;
@@ -203,7 +265,25 @@
 
 	hdr->payload = pos;
 
-	return asn1_valid_der(hdr) ? 0 : -1;
+	if (!asn1_valid_der(hdr)) {
+		asn1_print_hdr(hdr, "ASN.1: Invalid DER encoding: ");
+		return -1;
+	}
+	return 0;
+}
+
+
+void asn1_print_hdr(const struct asn1_hdr *hdr, const char *title)
+{
+	wpa_printf(MSG_DEBUG, "%sclass %d constructed %d tag 0x%x",
+		   title, hdr->class, hdr->constructed, hdr->tag);
+}
+
+
+void asn1_unexpected(const struct asn1_hdr *hdr, const char *title)
+{
+	wpa_printf(MSG_DEBUG, "%s - found class %d constructed %d tag 0x%x",
+		   title, hdr->class, hdr->constructed, hdr->tag);
 }
 
 
@@ -256,12 +336,9 @@
 {
 	struct asn1_hdr hdr;
 
-	if (asn1_get_next(buf, len, &hdr) < 0 || hdr.length == 0)
-		return -1;
-
-	if (hdr.class != ASN1_CLASS_UNIVERSAL || hdr.tag != ASN1_TAG_OID) {
-		wpa_printf(MSG_DEBUG, "ASN.1: Expected OID - found class %d "
-			   "tag 0x%x", hdr.class, hdr.tag);
+	if (asn1_get_next(buf, len, &hdr) < 0 || hdr.length == 0 ||
+	    !asn1_is_oid(&hdr)) {
+		asn1_unexpected(&hdr, "ASN.1: Expected OID");
 		return -1;
 	}
 
@@ -360,13 +437,9 @@
 	const u8 *pos;
 	int value;
 
-	if (asn1_get_next(buf, len, &hdr) < 0 || hdr.length == 0)
-		return -1;
-
-	if (hdr.class != ASN1_CLASS_UNIVERSAL || hdr.tag != ASN1_TAG_INTEGER) {
-		wpa_printf(MSG_DEBUG,
-			   "ASN.1: Expected INTEGER - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(buf, len, &hdr) < 0 || hdr.length == 0 ||
+	    !asn1_is_integer(&hdr)) {
+		asn1_unexpected(&hdr, "ASN.1: Expected INTEGER");
 		return -1;
 	}
 
@@ -393,12 +466,8 @@
 int asn1_get_sequence(const u8 *buf, size_t len, struct asn1_hdr *hdr,
 		      const u8 **next)
 {
-	if (asn1_get_next(buf, len, hdr) < 0 ||
-	    hdr->class != ASN1_CLASS_UNIVERSAL ||
-	    hdr->tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "ASN.1: Expected SEQUENCE - found class %d tag 0x%x",
-			   hdr->class, hdr->tag);
+	if (asn1_get_next(buf, len, hdr) < 0 || !asn1_is_sequence(hdr)) {
+		asn1_unexpected(hdr, "ASN.1: Expected SEQUENCE");
 		return -1;
 	}
 
diff --git a/src/tls/asn1.h b/src/tls/asn1.h
index 6878a4f..a4d1be4 100644
--- a/src/tls/asn1.h
+++ b/src/tls/asn1.h
@@ -23,11 +23,12 @@
 #define ASN1_TAG_EMBEDDED_PDV	0x0B /* not yet parsed */
 #define ASN1_TAG_UTF8STRING	0x0C /* not yet parsed */
 #define ANS1_TAG_RELATIVE_OID	0x0D
+#define ASN1_TAG_TIME		0x0E
 #define ASN1_TAG_SEQUENCE	0x10 /* shall be constructed */
 #define ASN1_TAG_SET		0x11
 #define ASN1_TAG_NUMERICSTRING	0x12 /* not yet parsed */
 #define ASN1_TAG_PRINTABLESTRING	0x13
-#define ASN1_TAG_TG1STRING	0x14 /* not yet parsed */
+#define ASN1_TAG_T61STRING	0x14 /* not yet parsed */
 #define ASN1_TAG_VIDEOTEXSTRING	0x15 /* not yet parsed */
 #define ASN1_TAG_IA5STRING	0x16
 #define ASN1_TAG_UTCTIME	0x17
@@ -59,6 +60,8 @@
 
 
 int asn1_get_next(const u8 *buf, size_t len, struct asn1_hdr *hdr);
+void asn1_print_hdr(const struct asn1_hdr *hdr, const char *title);
+void asn1_unexpected(const struct asn1_hdr *hdr, const char *title);
 int asn1_parse_oid(const u8 *buf, size_t len, struct asn1_oid *oid);
 int asn1_get_oid(const u8 *buf, size_t len, struct asn1_oid *oid,
 		 const u8 **next);
@@ -82,6 +85,108 @@
 				  const struct wpabuf *params);
 struct wpabuf * asn1_encaps(struct wpabuf *buf, u8 class, u8 tag);
 
+static inline bool asn1_is_oid(const struct asn1_hdr *hdr)
+{
+	return hdr->class == ASN1_CLASS_UNIVERSAL &&
+		hdr->tag == ASN1_TAG_OID;
+}
+
+static inline bool asn1_is_boolean(const struct asn1_hdr *hdr)
+{
+	return hdr->class == ASN1_CLASS_UNIVERSAL &&
+		hdr->tag == ASN1_TAG_BOOLEAN;
+}
+
+static inline bool asn1_is_integer(const struct asn1_hdr *hdr)
+{
+	return hdr->class == ASN1_CLASS_UNIVERSAL &&
+		hdr->tag == ASN1_TAG_INTEGER;
+}
+
+static inline bool asn1_is_enumerated(const struct asn1_hdr *hdr)
+{
+	return hdr->class == ASN1_CLASS_UNIVERSAL &&
+		hdr->tag == ASN1_TAG_ENUMERATED;
+}
+
+static inline bool asn1_is_sequence(const struct asn1_hdr *hdr)
+{
+	return hdr->class == ASN1_CLASS_UNIVERSAL &&
+		hdr->tag == ASN1_TAG_SEQUENCE;
+}
+
+static inline bool asn1_is_set(const struct asn1_hdr *hdr)
+{
+	return hdr->class == ASN1_CLASS_UNIVERSAL &&
+		hdr->tag == ASN1_TAG_SET;
+}
+
+static inline bool asn1_is_octetstring(const struct asn1_hdr *hdr)
+{
+	return hdr->class == ASN1_CLASS_UNIVERSAL &&
+		hdr->tag == ASN1_TAG_OCTETSTRING;
+}
+
+static inline bool asn1_is_bitstring(const struct asn1_hdr *hdr)
+{
+	return hdr->class == ASN1_CLASS_UNIVERSAL &&
+		hdr->tag == ASN1_TAG_BITSTRING;
+}
+
+static inline bool asn1_is_utctime(const struct asn1_hdr *hdr)
+{
+	return hdr->class == ASN1_CLASS_UNIVERSAL &&
+		hdr->tag == ASN1_TAG_UTCTIME;
+}
+
+static inline bool asn1_is_generalizedtime(const struct asn1_hdr *hdr)
+{
+	return hdr->class == ASN1_CLASS_UNIVERSAL &&
+		hdr->tag == ASN1_TAG_GENERALIZEDTIME;
+}
+
+static inline bool asn1_is_string_type(const struct asn1_hdr *hdr)
+{
+	if (hdr->class != ASN1_CLASS_UNIVERSAL || hdr->constructed)
+		return false;
+	return hdr->tag == ASN1_TAG_UTF8STRING ||
+		hdr->tag == ASN1_TAG_NUMERICSTRING ||
+		hdr->tag == ASN1_TAG_PRINTABLESTRING ||
+		hdr->tag == ASN1_TAG_T61STRING ||
+		hdr->tag == ASN1_TAG_VIDEOTEXSTRING ||
+		hdr->tag == ASN1_TAG_IA5STRING ||
+		hdr->tag == ASN1_TAG_GRAPHICSTRING ||
+		hdr->tag == ASN1_TAG_VISIBLESTRING ||
+		hdr->tag == ASN1_TAG_GENERALSTRING ||
+		hdr->tag == ASN1_TAG_UNIVERSALSTRING ||
+		hdr->tag == ASN1_TAG_CHARACTERSTRING ||
+		hdr->tag == ASN1_TAG_BMPSTRING;
+}
+
+static inline bool asn1_is_bmpstring(const struct asn1_hdr *hdr)
+{
+	return hdr->class == ASN1_CLASS_UNIVERSAL &&
+		hdr->tag == ASN1_TAG_BMPSTRING;
+}
+
+static inline bool asn1_is_utf8string(const struct asn1_hdr *hdr)
+{
+	return hdr->class == ASN1_CLASS_UNIVERSAL &&
+		hdr->tag == ASN1_TAG_UTF8STRING;
+}
+
+static inline bool asn1_is_null(const struct asn1_hdr *hdr)
+{
+	return hdr->class == ASN1_CLASS_UNIVERSAL &&
+		hdr->tag == ASN1_TAG_NULL;
+}
+
+static inline bool asn1_is_cs_tag(const struct asn1_hdr *hdr, unsigned int tag)
+{
+	return hdr->class == ASN1_CLASS_CONTEXT_SPECIFIC &&
+		hdr->tag == tag;
+}
+
 extern const struct asn1_oid asn1_sha1_oid;
 extern const struct asn1_oid asn1_sha256_oid;
 extern const struct asn1_oid asn1_ec_public_key_oid;
diff --git a/src/tls/pkcs1.c b/src/tls/pkcs1.c
index 654c01b..49e439d 100644
--- a/src/tls/pkcs1.c
+++ b/src/tls/pkcs1.c
@@ -236,14 +236,14 @@
 	 *
 	 */
 	if (asn1_get_next(decrypted, decrypted_len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #1: Expected SEQUENCE (DigestInfo) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #1: Expected SEQUENCE (DigestInfo)");
 		os_free(decrypted);
 		return -1;
 	}
+	wpa_hexdump(MSG_MSGDUMP, "PKCS #1: DigestInfo",
+		    hdr.payload, hdr.length);
 
 	pos = hdr.payload;
 	end = pos + hdr.length;
@@ -257,14 +257,14 @@
 	 */
 
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #1: Expected SEQUENCE (AlgorithmIdentifier) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #1: Expected SEQUENCE (AlgorithmIdentifier)");
 		os_free(decrypted);
 		return -1;
 	}
+	wpa_hexdump(MSG_MSGDUMP, "PKCS #1: DigestAlgorithmIdentifier",
+		    hdr.payload, hdr.length);
 	da_end = hdr.payload + hdr.length;
 
 	if (asn1_get_oid(hdr.payload, hdr.length, &oid, &next)) {
@@ -273,6 +273,23 @@
 		os_free(decrypted);
 		return -1;
 	}
+	wpa_hexdump(MSG_MSGDUMP, "PKCS #1: Digest algorithm parameters",
+		    next, da_end - next);
+
+	/*
+	 * RFC 5754: The correct encoding for the SHA2 algorithms would be to
+	 * omit the parameters, but there are implementation that encode these
+	 * as a NULL element. Allow these two cases and reject anything else.
+	 */
+	if (da_end > next &&
+	    (asn1_get_next(next, da_end - next, &hdr) < 0 ||
+	     !asn1_is_null(&hdr) ||
+	     hdr.payload + hdr.length != da_end)) {
+		wpa_printf(MSG_DEBUG,
+			   "PKCS #1: Unexpected digest algorithm parameters");
+		os_free(decrypted);
+		return -1;
+	}
 
 	if (!asn1_oid_equal(&oid, hash_alg)) {
 		char txt[100], txt2[100];
@@ -287,14 +304,11 @@
 
 	/* Digest ::= OCTET STRING */
 	pos = da_end;
-	end = decrypted + decrypted_len;
 
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_OCTETSTRING) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #1: Expected OCTETSTRING (Digest) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_octetstring(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #1: Expected OCTETSTRING (Digest)");
 		os_free(decrypted);
 		return -1;
 	}
@@ -310,13 +324,14 @@
 
 	os_free(decrypted);
 
-	if (hdr.payload + hdr.length != end) {
+	if (hdr.payload + hdr.length != decrypted + decrypted_len) {
 		wpa_printf(MSG_INFO,
 			   "PKCS #1: Extra data after signature - reject");
 
 		wpa_hexdump(MSG_DEBUG, "PKCS #1: Extra data",
 			    hdr.payload + hdr.length,
-			    end - hdr.payload - hdr.length);
+			    decrypted + decrypted_len - hdr.payload -
+			    hdr.length);
 		return -1;
 	}
 
diff --git a/src/tls/pkcs5.c b/src/tls/pkcs5.c
index a2ad83b..7bef89b 100644
--- a/src/tls/pkcs5.c
+++ b/src/tls/pkcs5.c
@@ -107,22 +107,18 @@
 	 */
 
 	if (asn1_get_next(pos, enc_alg_end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #5: Expected SEQUENCE (PBES2-params) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #5: Expected SEQUENCE (PBES2-params)");
 		return -1;
 	}
 	pos = hdr.payload;
 	end = hdr.payload + hdr.length;
 
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #5: Expected SEQUENCE (keyDerivationFunc) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #5: Expected SEQUENCE (keyDerivationFunc)");
 		return -1;
 	}
 
@@ -161,11 +157,9 @@
 	 */
 
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #5: Expected SEQUENCE (PBKDF2-params) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #5: Expected SEQUENCE (PBKDF2-params)");
 		return -1;
 	}
 
@@ -174,12 +168,10 @@
 
 	/* For now, only support the salt CHOICE specified (OCTET STRING) */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_OCTETSTRING ||
+	    !asn1_is_octetstring(&hdr) ||
 	    hdr.length > sizeof(params->salt)) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #5: Expected OCTET STRING (salt.specified) - found class %d tag 0x%x size %d",
-			   hdr.class, hdr.tag, hdr.length);
+		asn1_unexpected(&hdr,
+				"PKCS #5: Expected OCTET STRING (salt.specified)");
 		return -1;
 	}
 	pos = hdr.payload + hdr.length;
@@ -188,11 +180,8 @@
 	wpa_hexdump(MSG_DEBUG, "PKCS #5: salt", params->salt, params->salt_len);
 
 	/* iterationCount INTEGER */
-	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL || hdr.tag != ASN1_TAG_INTEGER) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #5: Expected INTEGER - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, end - pos, &hdr) < 0 || !asn1_is_integer(&hdr)) {
+		asn1_unexpected(&hdr, "PKCS #5: Expected INTEGER");
 		return -1;
 	}
 	if (hdr.length == 1) {
@@ -222,11 +211,9 @@
 	/* encryptionScheme AlgorithmIdentifier {{PBES2-Encs}} */
 
 	if (asn1_get_next(pos, enc_alg_end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #5: Expected SEQUENCE (encryptionScheme) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #5: Expected SEQUENCE (encryptionScheme)");
 		return -1;
 	}
 
@@ -258,12 +245,9 @@
 	 * specifying the initialization vector for CBC mode.
 	 */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_OCTETSTRING ||
-	    hdr.length != 8) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #5: Expected OCTET STRING (SIZE(8)) (IV) - found class %d tag 0x%x size %d",
-			   hdr.class, hdr.tag, hdr.length);
+	    !asn1_is_octetstring(&hdr) || hdr.length != 8) {
+		asn1_unexpected(&hdr,
+				"PKCS #5: Expected OCTET STRING (SIZE(8)) (IV)");
 		return -1;
 	}
 	os_memcpy(params->iv, hdr.payload, hdr.length);
@@ -323,11 +307,9 @@
 	 */
 
 	if (asn1_get_next(pos, enc_alg_end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "PKCS #5: Expected SEQUENCE "
-			   "(PBEParameter) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #5: Expected SEQUENCE (PBEParameter)");
 		return -1;
 	}
 	pos = hdr.payload;
@@ -335,12 +317,9 @@
 
 	/* salt OCTET STRING SIZE(8) (PKCS #5) or OCTET STRING (PKCS #12) */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_OCTETSTRING ||
-	    hdr.length > sizeof(params->salt)) {
-		wpa_printf(MSG_DEBUG, "PKCS #5: Expected OCTETSTRING SIZE(8) "
-			   "(salt) - found class %d tag 0x%x size %d",
-			   hdr.class, hdr.tag, hdr.length);
+	    !asn1_is_octetstring(&hdr) || hdr.length > sizeof(params->salt)) {
+		asn1_unexpected(&hdr,
+				"PKCS #5: Expected OCTETSTRING SIZE(8) (salt)");
 		return -1;
 	}
 	pos = hdr.payload + hdr.length;
@@ -351,9 +330,8 @@
 
 	/* iterationCount INTEGER */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL || hdr.tag != ASN1_TAG_INTEGER) {
-		wpa_printf(MSG_DEBUG, "PKCS #5: Expected INTEGER - found "
-			   "class %d tag 0x%x", hdr.class, hdr.tag);
+	    !asn1_is_integer(&hdr)) {
+		asn1_unexpected(&hdr, "PKCS #5: Expected INTEGER");
 		return -1;
 	}
 	if (hdr.length == 1)
diff --git a/src/tls/pkcs8.c b/src/tls/pkcs8.c
index 52e43a4..75bbd12 100644
--- a/src/tls/pkcs8.c
+++ b/src/tls/pkcs8.c
@@ -27,22 +27,17 @@
 	/* PKCS #8, Chapter 6 */
 
 	/* PrivateKeyInfo ::= SEQUENCE */
-	if (asn1_get_next(buf, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "PKCS #8: Does not start with PKCS #8 "
-			   "header (SEQUENCE); assume PKCS #8 not used");
+	if (asn1_get_next(buf, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #8: Does not start with PKCS #8 header (SEQUENCE)");
 		return NULL;
 	}
 	pos = hdr.payload;
 	end = pos + hdr.length;
 
 	/* version Version (Version ::= INTEGER) */
-	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL || hdr.tag != ASN1_TAG_INTEGER) {
-		wpa_printf(MSG_DEBUG, "PKCS #8: Expected INTEGER - found "
-			   "class %d tag 0x%x; assume PKCS #8 not used",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, end - pos, &hdr) < 0 || !asn1_is_integer(&hdr)) {
+		asn1_unexpected(&hdr, "PKCS #8: Expected INTEGER");
 		return NULL;
 	}
 
@@ -68,13 +63,9 @@
 
 	/* privateKeyAlgorithm PrivateKeyAlgorithmIdentifier
 	 * (PrivateKeyAlgorithmIdentifier ::= AlgorithmIdentifier) */
-	if (asn1_get_next(pos, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "PKCS #8: Expected SEQUENCE "
-			   "(AlgorithmIdentifier) - found class %d tag 0x%x; "
-			   "assume PKCS #8 not used",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #8: Expected SEQUENCE (AlgorithmIdentifier); assume PKCS #8 not used");
 		return NULL;
 	}
 
@@ -104,11 +95,9 @@
 
 	/* privateKey PrivateKey (PrivateKey ::= OCTET STRING) */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_OCTETSTRING) {
-		wpa_printf(MSG_DEBUG, "PKCS #8: Expected OCTETSTRING "
-			   "(privateKey) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_octetstring(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #8: Expected OCTETSTRING (privateKey)");
 		return NULL;
 	}
 	wpa_printf(MSG_DEBUG, "PKCS #8: Try to parse RSAPrivateKey");
@@ -139,12 +128,9 @@
 	 * EncryptedData ::= OCTET STRING
 	 */
 
-	if (asn1_get_next(buf, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "PKCS #8: Does not start with PKCS #8 "
-			   "header (SEQUENCE); assume encrypted PKCS #8 not "
-			   "used");
+	if (asn1_get_next(buf, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #8: Does not start with PKCS #8 header (SEQUENCE); assume encrypted PKCS #8 not used");
 		return NULL;
 	}
 	pos = hdr.payload;
@@ -152,12 +138,9 @@
 
 	/* encryptionAlgorithm EncryptionAlgorithmIdentifier */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "PKCS #8: Expected SEQUENCE "
-			   "(AlgorithmIdentifier) - found class %d tag 0x%x; "
-			   "assume encrypted PKCS #8 not used",
-			   hdr.class, hdr.tag);
+	    !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #8: Expected SEQUENCE (AlgorithmIdentifier); assume encrypted PKCS #8 not used");
 		return NULL;
 	}
 	enc_alg = hdr.payload;
@@ -166,11 +149,9 @@
 
 	/* encryptedData EncryptedData */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_OCTETSTRING) {
-		wpa_printf(MSG_DEBUG, "PKCS #8: Expected OCTETSTRING "
-			   "(encryptedData) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_octetstring(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #8: Expected OCTETSTRING (encryptedData)");
 		return NULL;
 	}
 
diff --git a/src/tls/rsa.c b/src/tls/rsa.c
index 1b01f58..56ae7d7 100644
--- a/src/tls/rsa.c
+++ b/src/tls/rsa.c
@@ -37,9 +37,8 @@
 		return NULL;
 
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL || hdr.tag != ASN1_TAG_INTEGER) {
-		wpa_printf(MSG_DEBUG, "RSA: Expected INTEGER - found class %d "
-			   "tag 0x%x", hdr.class, hdr.tag);
+	    !asn1_is_integer(&hdr)) {
+		asn1_unexpected(&hdr, "RSA: Expected INTEGER");
 		return NULL;
 	}
 
@@ -84,12 +83,8 @@
 	 * }
 	 */
 
-	if (asn1_get_next(buf, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "RSA: Expected SEQUENCE "
-			   "(public key) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(buf, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr, "RSA: Expected SEQUENCE (public key)");
 		goto error;
 	}
 	pos = hdr.payload;
@@ -191,12 +186,8 @@
 	 *
 	 * Version ::= INTEGER -- shall be 0 for this version of the standard
 	 */
-	if (asn1_get_next(buf, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "RSA: Expected SEQUENCE "
-			   "(public key) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(buf, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr, "RSA: Expected SEQUENCE (public key)");
 		goto error;
 	}
 	pos = hdr.payload;
diff --git a/src/tls/tlsv1_client.c b/src/tls/tlsv1_client.c
index a147a54..486da16 100644
--- a/src/tls/tlsv1_client.c
+++ b/src/tls/tlsv1_client.c
@@ -38,9 +38,33 @@
 }
 
 
-int tls_derive_pre_master_secret(u8 *pre_master_secret)
+u16 tls_client_highest_ver(struct tlsv1_client *conn)
 {
-	WPA_PUT_BE16(pre_master_secret, TLS_VERSION);
+	u16 tls_version = TLS_VERSION;
+
+	/* Pick the highest locally enabled TLS version */
+#ifdef CONFIG_TLSV12
+	if ((conn->flags & TLS_CONN_DISABLE_TLSv1_2) &&
+	    tls_version == TLS_VERSION_1_2)
+		tls_version = TLS_VERSION_1_1;
+#endif /* CONFIG_TLSV12 */
+#ifdef CONFIG_TLSV11
+	if ((conn->flags & TLS_CONN_DISABLE_TLSv1_1) &&
+	    tls_version == TLS_VERSION_1_1)
+		tls_version = TLS_VERSION_1;
+#endif /* CONFIG_TLSV11 */
+	if ((conn->flags & TLS_CONN_DISABLE_TLSv1_0) &&
+	    tls_version == TLS_VERSION_1)
+		return 0;
+
+	return tls_version;
+}
+
+
+int tls_derive_pre_master_secret(struct tlsv1_client *conn,
+				 u8 *pre_master_secret)
+{
+	WPA_PUT_BE16(pre_master_secret, tls_client_highest_ver(conn));
 	if (os_get_random(pre_master_secret + 2,
 			  TLS_PRE_MASTER_SECRET_LEN - 2))
 		return -1;
@@ -844,6 +868,7 @@
 void tlsv1_client_set_flags(struct tlsv1_client *conn, unsigned int flags)
 {
 	conn->flags = flags;
+	conn->rl.tls_version = tls_client_highest_ver(conn);
 }
 
 
diff --git a/src/tls/tlsv1_client_i.h b/src/tls/tlsv1_client_i.h
index 12ec8df..ccb2e15 100644
--- a/src/tls/tlsv1_client_i.h
+++ b/src/tls/tlsv1_client_i.h
@@ -78,7 +78,9 @@
 
 void tls_alert(struct tlsv1_client *conn, u8 level, u8 description);
 void tlsv1_client_free_dh(struct tlsv1_client *conn);
-int tls_derive_pre_master_secret(u8 *pre_master_secret);
+u16 tls_client_highest_ver(struct tlsv1_client *conn);
+int tls_derive_pre_master_secret(struct tlsv1_client *conn,
+				 u8 *pre_master_secret);
 int tls_derive_keys(struct tlsv1_client *conn,
 		    const u8 *pre_master_secret, size_t pre_master_secret_len);
 u8 * tls_send_client_hello(struct tlsv1_client *conn, size_t *out_len);
diff --git a/src/tls/tlsv1_client_ocsp.c b/src/tls/tlsv1_client_ocsp.c
index 1d7b68c..128f4b5 100644
--- a/src/tls/tlsv1_client_ocsp.c
+++ b/src/tls/tlsv1_client_ocsp.c
@@ -138,12 +138,8 @@
 	 */
 
 	/* CertID ::= SEQUENCE */
-	if (asn1_get_next(resp, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "OCSP: Expected SEQUENCE (CertID) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(resp, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr, "OCSP: Expected SEQUENCE (CertID)");
 		return -1;
 	}
 	pos = hdr.payload;
@@ -163,11 +159,9 @@
 
 	/* issuerNameHash  OCTET STRING */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_OCTETSTRING) {
-		wpa_printf(MSG_DEBUG,
-			   "OCSP: Expected OCTET STRING (issuerNameHash) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_octetstring(&hdr)) {
+		asn1_unexpected(&hdr,
+				"OCSP: Expected OCTET STRING (issuerNameHash)");
 		return -1;
 	}
 	name_hash = hdr.payload;
@@ -190,11 +184,9 @@
 
 	/* issuerKeyHash  OCTET STRING */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_OCTETSTRING) {
-		wpa_printf(MSG_DEBUG,
-			   "OCSP: Expected OCTET STRING (issuerKeyHash) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_octetstring(&hdr)) {
+		asn1_unexpected(&hdr,
+				"OCSP: Expected OCTET STRING (issuerKeyHash)");
 		return -1;
 	}
 	key_hash = hdr.payload;
@@ -214,11 +206,10 @@
 
 	/* serialNumber CertificateSerialNumber ::= INTEGER */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_INTEGER ||
+	    !asn1_is_integer(&hdr) ||
 	    hdr.length < 1 || hdr.length > X509_MAX_SERIAL_NUM_LEN) {
-		wpa_printf(MSG_DEBUG, "OCSP: No INTEGER tag found for serialNumber; class=%d tag=0x%x length=%u",
-			   hdr.class, hdr.tag, hdr.length);
+		asn1_unexpected(&hdr,
+				"OCSP: No INTEGER tag found for serialNumber");
 		return -1;
 	}
 	serial_number = hdr.payload;
@@ -240,12 +231,16 @@
 	pos = end;
 	end = resp + len;
 
-	/* certStatus CertStatus ::= CHOICE */
+	/* certStatus CertStatus ::= CHOICE
+	 *
+	 * CertStatus ::= CHOICE {
+	 *     good        [0]     IMPLICIT NULL,
+	 *     revoked     [1]     IMPLICIT RevokedInfo,
+	 *     unknown     [2]     IMPLICIT UnknownInfo }
+	 */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
 	    hdr.class != ASN1_CLASS_CONTEXT_SPECIFIC) {
-		wpa_printf(MSG_DEBUG,
-			   "OCSP: Expected CHOICE (CertStatus) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+		asn1_unexpected(&hdr, "OCSP: Expected CHOICE (CertStatus)");
 		return -1;
 	}
 	cert_status = hdr.tag;
@@ -257,8 +252,7 @@
 	os_get_time(&now);
 	/* thisUpdate  GeneralizedTime */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_GENERALIZEDTIME ||
+	    !asn1_is_generalizedtime(&hdr) ||
 	    x509_parse_time(hdr.payload, hdr.length, hdr.tag, &update) < 0) {
 		wpa_printf(MSG_DEBUG, "OCSP: Failed to parse thisUpdate");
 		return -1;
@@ -275,12 +269,11 @@
 	if (pos < end) {
 		if (asn1_get_next(pos, end - pos, &hdr) < 0)
 			return -1;
-		if (hdr.class == ASN1_CLASS_CONTEXT_SPECIFIC && hdr.tag == 0) {
+		if (asn1_is_cs_tag(&hdr, 0) && hdr.constructed) {
 			const u8 *next = hdr.payload + hdr.length;
 
 			if (asn1_get_next(hdr.payload, hdr.length, &hdr) < 0 ||
-			    hdr.class != ASN1_CLASS_UNIVERSAL ||
-			    hdr.tag != ASN1_TAG_GENERALIZEDTIME ||
+			    !asn1_is_generalizedtime(&hdr) ||
 			    x509_parse_time(hdr.payload, hdr.length, hdr.tag,
 					    &update) < 0) {
 				wpa_printf(MSG_DEBUG,
@@ -329,11 +322,9 @@
 	while (pos < end) {
 		/* SingleResponse ::= SEQUENCE */
 		if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-		    hdr.class != ASN1_CLASS_UNIVERSAL ||
-		    hdr.tag != ASN1_TAG_SEQUENCE) {
-			wpa_printf(MSG_DEBUG,
-				   "OCSP: Expected SEQUENCE (SingleResponse) - found class %d tag 0x%x",
-				   hdr.class, hdr.tag);
+		    !asn1_is_sequence(&hdr)) {
+			asn1_unexpected(&hdr,
+					"OCSP: Expected SEQUENCE (SingleResponse)");
 			return TLS_OCSP_INVALID;
 		}
 		if (tls_process_ocsp_single_response(conn, cert, issuer,
@@ -381,12 +372,9 @@
 	 *    certs            [0] EXPLICIT SEQUENCE OF Certificate OPTIONAL }
 	 */
 
-	if (asn1_get_next(resp, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "OCSP: Expected SEQUENCE (BasicOCSPResponse) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(resp, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"OCSP: Expected SEQUENCE (BasicOCSPResponse)");
 		return TLS_OCSP_INVALID;
 	}
 	pos = hdr.payload;
@@ -394,11 +382,9 @@
 
 	/* ResponseData ::= SEQUENCE */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "OCSP: Expected SEQUENCE (ResponseData) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"OCSP: Expected SEQUENCE (ResponseData)");
 		return TLS_OCSP_INVALID;
 	}
 	resp_data = hdr.payload;
@@ -413,11 +399,9 @@
 
 	/* signature  BIT STRING */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_BITSTRING) {
-		wpa_printf(MSG_DEBUG,
-			   "OCSP: Expected BITSTRING (signature) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_bitstring(&hdr)) {
+		asn1_unexpected(&hdr,
+				"OCSP: Expected BITSTRING (signature)");
 		return TLS_OCSP_INVALID;
 	}
 	if (hdr.length < 1)
@@ -439,11 +423,9 @@
 	/* certs  [0] EXPLICIT SEQUENCE OF Certificate OPTIONAL */
 	if (pos < end) {
 		if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-		    hdr.class != ASN1_CLASS_CONTEXT_SPECIFIC ||
-		    hdr.tag != 0) {
-			wpa_printf(MSG_DEBUG,
-				   "OCSP: Expected [0] EXPLICIT (certs) - found class %d tag 0x%x",
-				   hdr.class, hdr.tag);
+		    !hdr.constructed || !asn1_is_cs_tag(&hdr, 0)) {
+			asn1_unexpected(&hdr,
+					"OCSP: Expected [0] EXPLICIT (certs)");
 			return TLS_OCSP_INVALID;
 		}
 		wpa_hexdump(MSG_MSGDUMP, "OCSP: certs",
@@ -454,11 +436,9 @@
 			struct x509_certificate *cert;
 
 			if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-			    hdr.class != ASN1_CLASS_UNIVERSAL ||
-			    hdr.tag != ASN1_TAG_SEQUENCE) {
-				wpa_printf(MSG_DEBUG,
-					   "OCSP: Expected SEQUENCE (Certificate) - found class %d tag 0x%x",
-					   hdr.class, hdr.tag);
+			    !asn1_is_sequence(&hdr)) {
+				asn1_unexpected(&hdr,
+						"OCSP: Expected SEQUENCE (Certificate)");
 				goto fail;
 			}
 
@@ -491,16 +471,12 @@
 	 * version [0] EXPLICIT Version DEFAULT v1
 	 * Version ::= INTEGER { v1(0) }
 	 */
-	if (asn1_get_next(pos, end - pos, &hdr) < 0 &&
-	    hdr.class == ASN1_CLASS_CONTEXT_SPECIFIC &&
-	    hdr.tag == 0) {
+	if (asn1_get_next(pos, end - pos, &hdr) == 0 && hdr.constructed &&
+	    asn1_is_cs_tag(&hdr, 0)) {
 		if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-		    hdr.class != ASN1_CLASS_UNIVERSAL ||
-		    hdr.tag != ASN1_TAG_INTEGER ||
-		    hdr.length != 1) {
-			wpa_printf(MSG_DEBUG,
-				   "OCSP: No INTEGER (len=1) tag found for version field - found class %d tag 0x%x length %d",
-				   hdr.class, hdr.tag, hdr.length);
+		    !asn1_is_integer(&hdr) || hdr.length != 1) {
+			asn1_unexpected(&hdr,
+					"OCSP: No INTEGER (len=1) tag found for version field");
 			goto fail;
 		}
 		wpa_printf(MSG_DEBUG, "OCSP: ResponseData version %u",
@@ -524,9 +500,7 @@
 	 */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
 	    hdr.class != ASN1_CLASS_CONTEXT_SPECIFIC) {
-		wpa_printf(MSG_DEBUG,
-			   "OCSP: Expected CHOICE (ResponderID) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+		asn1_unexpected(&hdr, "OCSP: Expected CHOICE (ResponderID)");
 		goto fail;
 	}
 
@@ -539,11 +513,9 @@
 	} else if (hdr.tag == 2) {
 		/* KeyHash ::= OCTET STRING */
 		if (asn1_get_next(hdr.payload, hdr.length, &hdr) < 0 ||
-		    hdr.class != ASN1_CLASS_UNIVERSAL ||
-		    hdr.tag != ASN1_TAG_OCTETSTRING) {
-			wpa_printf(MSG_DEBUG,
-				   "OCSP: Expected OCTET STRING (KeyHash) - found class %d tag 0x%x",
-				   hdr.class, hdr.tag);
+		    !asn1_is_octetstring(&hdr)) {
+			asn1_unexpected(&hdr,
+					"OCSP: Expected OCTET STRING (KeyHash)");
 			goto fail;
 		}
 		key_hash = hdr.payload;
@@ -564,8 +536,7 @@
 
 	/* producedAt  GeneralizedTime */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_GENERALIZEDTIME ||
+	    !asn1_is_generalizedtime(&hdr) ||
 	    x509_parse_time(hdr.payload, hdr.length, hdr.tag,
 			    &produced_at) < 0) {
 		wpa_printf(MSG_DEBUG, "OCSP: Failed to parse producedAt");
@@ -577,11 +548,9 @@
 
 	/* responses  SEQUENCE OF SingleResponse */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "OCSP: Expected SEQUENCE (responses) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"OCSP: Expected SEQUENCE (responses)");
 		goto fail;
 	}
 	responses = hdr.payload;
@@ -697,12 +666,9 @@
 	 *    responseBytes   [0] EXPLICIT ResponseBytes OPTIONAL }
 	 */
 
-	if (asn1_get_next(resp, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "OCSP: Expected SEQUENCE (OCSPResponse) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(resp, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"OCSP: Expected SEQUENCE (OCSPResponse)");
 		return TLS_OCSP_INVALID;
 	}
 	pos = hdr.payload;
@@ -710,12 +676,9 @@
 
 	/* OCSPResponseStatus ::= ENUMERATED */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_ENUMERATED ||
-	    hdr.length != 1) {
-		wpa_printf(MSG_DEBUG,
-			   "OCSP: Expected ENUMERATED (responseStatus) - found class %d tag 0x%x length %u",
-			   hdr.class, hdr.tag, hdr.length);
+	    !asn1_is_enumerated(&hdr) || hdr.length != 1) {
+		asn1_unexpected(&hdr,
+				"OCSP: Expected ENUMERATED (responseStatus)");
 		return TLS_OCSP_INVALID;
 	}
 	resp_status = hdr.payload[0];
@@ -730,12 +693,10 @@
 	if (pos == end)
 		return TLS_OCSP_NO_RESPONSE;
 
-	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_CONTEXT_SPECIFIC ||
-	    hdr.tag != 0) {
-		wpa_printf(MSG_DEBUG,
-			   "OCSP: Expected [0] EXPLICIT (responseBytes) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, end - pos, &hdr) < 0 || !hdr.constructed ||
+	    !asn1_is_cs_tag(&hdr, 0)) {
+		asn1_unexpected(&hdr,
+				"OCSP: Expected [0] EXPLICIT (responseBytes)");
 		return TLS_OCSP_INVALID;
 	}
 
@@ -746,11 +707,9 @@
 	 */
 
 	if (asn1_get_next(hdr.payload, hdr.length, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "OCSP: Expected SEQUENCE (ResponseBytes) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"OCSP: Expected SEQUENCE (ResponseBytes)");
 		return TLS_OCSP_INVALID;
 	}
 	pos = hdr.payload;
@@ -771,11 +730,8 @@
 
 	/* response       OCTET STRING */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_OCTETSTRING) {
-		wpa_printf(MSG_DEBUG,
-			   "OCSP: Expected OCTET STRING (response) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_octetstring(&hdr)) {
+		asn1_unexpected(&hdr, "OCSP: Expected OCTET STRING (response)");
 		return TLS_OCSP_INVALID;
 	}
 
diff --git a/src/tls/tlsv1_client_write.c b/src/tls/tlsv1_client_write.c
index 4a1147b..9b12618 100644
--- a/src/tls/tlsv1_client_write.c
+++ b/src/tls/tlsv1_client_write.c
@@ -48,21 +48,9 @@
 	struct os_time now;
 	size_t len, i;
 	u8 *ext_start;
-	u16 tls_version = TLS_VERSION;
+	u16 tls_version = tls_client_highest_ver(conn);
 
-	/* Pick the highest locally enabled TLS version */
-#ifdef CONFIG_TLSV12
-	if ((conn->flags & TLS_CONN_DISABLE_TLSv1_2) &&
-	    tls_version == TLS_VERSION_1_2)
-		tls_version = TLS_VERSION_1_1;
-#endif /* CONFIG_TLSV12 */
-#ifdef CONFIG_TLSV11
-	if ((conn->flags & TLS_CONN_DISABLE_TLSv1_1) &&
-	    tls_version == TLS_VERSION_1_1)
-		tls_version = TLS_VERSION_1;
-#endif /* CONFIG_TLSV11 */
-	if ((conn->flags & TLS_CONN_DISABLE_TLSv1_0) &&
-	    tls_version == TLS_VERSION_1) {
+	if (!tls_version) {
 		wpa_printf(MSG_INFO, "TLSv1: No TLS version allowed");
 		return NULL;
 	}
@@ -474,7 +462,7 @@
 	size_t clen;
 	int res;
 
-	if (tls_derive_pre_master_secret(pre_master_secret) < 0 ||
+	if (tls_derive_pre_master_secret(conn, pre_master_secret) < 0 ||
 	    tls_derive_keys(conn, pre_master_secret,
 			    TLS_PRE_MASTER_SECRET_LEN)) {
 		wpa_printf(MSG_DEBUG, "TLSv1: Failed to derive keys");
diff --git a/src/tls/tlsv1_cred.c b/src/tls/tlsv1_cred.c
index 01b2f83..1310f4e 100644
--- a/src/tls/tlsv1_cred.c
+++ b/src/tls/tlsv1_cred.c
@@ -455,12 +455,8 @@
 	 * }
 	 */
 
-	if (asn1_get_next(buf, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: Expected SEQUENCE (CertBag) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(buf, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr, "PKCS #12: Expected SEQUENCE (CertBag)");
 		return -1;
 	}
 
@@ -482,21 +478,17 @@
 			   obuf);
 	}
 
-	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_CONTEXT_SPECIFIC ||
-	    hdr.tag != 0) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: Expected [0] EXPLICIT (certValue) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, end - pos, &hdr) < 0 || !hdr.constructed ||
+	    !asn1_is_cs_tag(&hdr, 0)) {
+		asn1_unexpected(&hdr,
+				"PKCS #12: Expected [0] EXPLICIT (certValue)");
 		return -1;
 	}
 
 	if (asn1_get_next(hdr.payload, hdr.length, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_OCTETSTRING) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: Expected OCTET STRING (x509Certificate) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_octetstring(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #12: Expected OCTET STRING (x509Certificate)");
 		return -1;
 	}
 
@@ -534,11 +526,9 @@
 	 * }
 	 */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_BMPSTRING) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: Expected BMPSTRING (friendlyName) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_bmpstring(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #12: Expected BMPSTRING (friendlyName)");
 		return 0;
 	}
 	wpa_hexdump_ascii(MSG_DEBUG, "PKCS #12: friendlyName",
@@ -561,11 +551,9 @@
 	 * }
 	 */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_OCTETSTRING) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: Expected OCTET STRING (localKeyID) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_octetstring(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #12: Expected OCTET STRING (localKeyID)");
 		return -1;
 	}
 	wpa_hexdump_key(MSG_DEBUG, "PKCS #12: localKeyID",
@@ -596,12 +584,8 @@
 	asn1_oid_to_str(&a_oid, obuf, sizeof(obuf));
 	wpa_printf(MSG_DEBUG, "PKCS #12: attrId %s", obuf);
 
-	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SET) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: Expected SET (attrValues) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, end - pos, &hdr) < 0 || !asn1_is_set(&hdr)) {
+		asn1_unexpected(&hdr, "PKCS #12: Expected SET (attrValues)");
 		return -1;
 	}
 	wpa_hexdump_key(MSG_MSGDUMP, "PKCS #12: attrValues",
@@ -641,12 +625,10 @@
 	asn1_oid_to_str(&oid, obuf, sizeof(obuf));
 	wpa_printf(MSG_DEBUG, "PKCS #12: BAG-TYPE %s", obuf);
 
-	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_CONTEXT_SPECIFIC ||
-	    hdr.tag != 0) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: Expected [0] EXPLICIT (bagValue) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, end - pos, &hdr) < 0 || !hdr.constructed ||
+	    !asn1_is_cs_tag(&hdr, 0)) {
+		asn1_unexpected(&hdr,
+				"PKCS #12: Expected [0] EXPLICIT (bagValue)");
 		return 0;
 	}
 	value = hdr.payload;
@@ -657,11 +639,9 @@
 	if (pos < end) {
 		/* bagAttributes  SET OF PKCS12Attribute OPTIONAL */
 		if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-		    hdr.class != ASN1_CLASS_UNIVERSAL ||
-		    hdr.tag != ASN1_TAG_SET) {
-			wpa_printf(MSG_DEBUG,
-				   "PKCS #12: Expected SET (bagAttributes) - found class %d tag 0x%x",
-				   hdr.class, hdr.tag);
+		    !asn1_is_set(&hdr)) {
+			asn1_unexpected(&hdr,
+					"PKCS #12: Expected SET (bagAttributes)");
 			return -1;
 		}
 		wpa_hexdump_key(MSG_MSGDUMP, "PKCS #12: bagAttributes",
@@ -672,11 +652,9 @@
 		while (pos < end) {
 			/* PKCS12Attribute ::= SEQUENCE */
 			if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-			    hdr.class != ASN1_CLASS_UNIVERSAL ||
-			    hdr.tag != ASN1_TAG_SEQUENCE) {
-				wpa_printf(MSG_DEBUG,
-					   "PKCS #12: Expected SEQUENCE (PKCS12Attribute) - found class %d tag 0x%x",
-					   hdr.class, hdr.tag);
+			    !asn1_is_sequence(&hdr)) {
+				asn1_unexpected(&hdr,
+						"PKCS #12: Expected SEQUENCE (PKCS12Attribute)");
 				return -1;
 			}
 			if (pkcs12_parse_attr(hdr.payload, hdr.length) < 0)
@@ -705,12 +683,9 @@
 	const u8 *pos, *end;
 
 	/* SafeContents ::= SEQUENCE OF SafeBag */
-	if (asn1_get_next(buf, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: Expected SEQUENCE (SafeContents) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(buf, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #12: Expected SEQUENCE (SafeContents)");
 		return -1;
 	}
 	pos = hdr.payload;
@@ -726,11 +701,9 @@
 
 	while (pos < end) {
 		if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-		    hdr.class != ASN1_CLASS_UNIVERSAL ||
-		    hdr.tag != ASN1_TAG_SEQUENCE) {
-			wpa_printf(MSG_DEBUG,
-				   "PKCS #12: Expected SEQUENCE (SafeBag) - found class %d tag 0x%x",
-				   hdr.class, hdr.tag);
+		    !asn1_is_sequence(&hdr)) {
+			asn1_unexpected(&hdr,
+					"PKCS #12: Expected SEQUENCE (SafeBag)");
 			return -1;
 		}
 		if (pkcs12_safebag(cred, hdr.payload, hdr.length, passwd) < 0)
@@ -750,11 +723,8 @@
 
 	/* Data ::= OCTET STRING */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_OCTETSTRING) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: Expected OCTET STRING (Data) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_octetstring(&hdr)) {
+		asn1_unexpected(&hdr, "PKCS #12: Expected OCTET STRING (Data)");
 		return -1;
 	}
 
@@ -782,21 +752,17 @@
 	 *   encryptedContentInfo EncryptedContentInfo }
 	 */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: Expected SEQUENCE (EncryptedData) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #12: Expected SEQUENCE (EncryptedData)");
 		return 0;
 	}
 	pos = hdr.payload;
 
 	/* Version ::= INTEGER */
-	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL || hdr.tag != ASN1_TAG_INTEGER) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: No INTEGER tag found for version; class=%d tag=0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, end - pos, &hdr) < 0 || !asn1_is_integer(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #12: No INTEGER tag found for version");
 		return -1;
 	}
 	if (hdr.length != 1 || hdr.payload[0] != 0) {
@@ -815,11 +781,9 @@
 	 *   encryptedContent [0] IMPLICIT EncryptedContent OPTIONAL }
 	 */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: Expected SEQUENCE (EncryptedContentInfo) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #12: Expected SEQUENCE (EncryptedContentInfo)");
 		return -1;
 	}
 
@@ -845,22 +809,19 @@
 
 	/* ContentEncryptionAlgorithmIdentifier ::= AlgorithmIdentifier */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "PKCS #12: Expected SEQUENCE (ContentEncryptionAlgorithmIdentifier) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #12: Expected SEQUENCE (ContentEncryptionAlgorithmIdentifier)");
 		return -1;
 	}
 	enc_alg = hdr.payload;
 	enc_alg_len = hdr.length;
 	pos = hdr.payload + hdr.length;
 
-	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_CONTEXT_SPECIFIC ||
-	    hdr.tag != 0) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: Expected [0] IMPLICIT (encryptedContent) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, end - pos, &hdr) < 0 || hdr.constructed ||
+	    !asn1_is_cs_tag(&hdr, 0)) {
+		asn1_unexpected(&hdr,
+				"PKCS #12: Expected [0] IMPLICIT (encryptedContent)");
 		return -1;
 	}
 
@@ -900,12 +861,10 @@
 	asn1_oid_to_str(&oid, txt, sizeof(txt));
 	wpa_printf(MSG_DEBUG, "PKCS #12: contentType %s", txt);
 
-	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_CONTEXT_SPECIFIC ||
-	    hdr.tag != 0) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: Expected [0] EXPLICIT (content) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, end - pos, &hdr) < 0 || !hdr.constructed ||
+	    !asn1_is_cs_tag(&hdr, 0)) {
+		asn1_unexpected(&hdr,
+				"PKCS #12: Expected [0] EXPLICIT (content)");
 		return 0;
 	}
 	pos = hdr.payload;
@@ -938,23 +897,18 @@
 	 * }
 	 */
 
-	if (asn1_get_next(key, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: Expected SEQUENCE (PFX) - found class %d tag 0x%x; assume PKCS #12 not used",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(key, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #12: Expected SEQUENCE (PFX); assume PKCS #12 not used");
 		return -1;
 	}
 
 	pos = hdr.payload;
 	end = pos + hdr.length;
 
-	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL || hdr.tag != ASN1_TAG_INTEGER) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: No INTEGER tag found for version; class=%d tag=0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, end - pos, &hdr) < 0 || !asn1_is_integer(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #12: No INTEGER tag found for version");
 		return -1;
 	}
 	if (hdr.length != 1 || hdr.payload[0] != 3) {
@@ -970,11 +924,9 @@
 	 */
 
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: Expected SEQUENCE (authSafe) - found class %d tag 0x%x; assume PKCS #12 not used",
-			   hdr.class, hdr.tag);
+	    !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #12: Expected SEQUENCE (authSafe); assume PKCS #12 not used");
 		return -1;
 	}
 
@@ -995,12 +947,10 @@
 		return -1;
 	}
 
-	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_CONTEXT_SPECIFIC ||
-	    hdr.tag != 0) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: Expected [0] EXPLICIT (content) - found class %d tag 0x%x; assume PKCS #12 not used",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, end - pos, &hdr) < 0 || !hdr.constructed ||
+	    !asn1_is_cs_tag(&hdr, 0)) {
+		asn1_unexpected(&hdr,
+				"PKCS #12: Expected [0] EXPLICIT (content); assume PKCS #12 not used");
 		return -1;
 	}
 
@@ -1008,11 +958,9 @@
 
 	/* Data ::= OCTET STRING */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_OCTETSTRING) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: Expected OCTET STRING (Data) - found class %d tag 0x%x; assume PKCS #12 not used",
-			   hdr.class, hdr.tag);
+	    !asn1_is_octetstring(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #12: Expected OCTET STRING (Data); assume PKCS #12 not used");
 		return -1;
 	}
 
@@ -1026,11 +974,9 @@
 		    hdr.payload, hdr.length);
 
 	if (asn1_get_next(hdr.payload, hdr.length, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG,
-			   "PKCS #12: Expected SEQUENCE within Data content - found class %d tag 0x%x; assume PKCS #12 not used",
-			   hdr.class, hdr.tag);
+	    !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"PKCS #12: Expected SEQUENCE within Data content; assume PKCS #12 not used");
 		return -1;
 	}
 
@@ -1039,11 +985,9 @@
 
 	while (end > pos) {
 		if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-		    hdr.class != ASN1_CLASS_UNIVERSAL ||
-		    hdr.tag != ASN1_TAG_SEQUENCE) {
-			wpa_printf(MSG_DEBUG,
-				   "PKCS #12: Expected SEQUENCE (ContentInfo) - found class %d tag 0x%x; assume PKCS #12 not used",
-				   hdr.class, hdr.tag);
+		    !asn1_is_sequence(&hdr)) {
+			asn1_unexpected(&hdr,
+					"PKCS #12: Expected SEQUENCE (ContentInfo); assume PKCS #12 not used");
 			return -1;
 		}
 		if (pkcs12_parse_content(cred, hdr.payload, hdr.length,
@@ -1141,24 +1085,17 @@
 	 */
 
 	/* DHParamer ::= SEQUENCE */
-	if (asn1_get_next(pos, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "DH: DH parameters did not start with a "
-			   "valid SEQUENCE - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"DH: DH parameters did not start with a valid SEQUENCE");
 		return -1;
 	}
 	pos = hdr.payload;
 
 	/* prime INTEGER */
-	if (asn1_get_next(pos, end - pos, &hdr) < 0)
-		return -1;
-
-	if (hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_INTEGER) {
-		wpa_printf(MSG_DEBUG, "DH: No INTEGER tag found for p; "
-			   "class=%d tag=0x%x", hdr.class, hdr.tag);
+	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
+	    !asn1_is_integer(&hdr)) {
+		asn1_unexpected(&hdr, "DH: No INTEGER tag found for p");
 		return -1;
 	}
 
@@ -1173,13 +1110,9 @@
 	pos = hdr.payload + hdr.length;
 
 	/* base INTEGER */
-	if (asn1_get_next(pos, end - pos, &hdr) < 0)
-		return -1;
-
-	if (hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_INTEGER) {
-		wpa_printf(MSG_DEBUG, "DH: No INTEGER tag found for g; "
-			   "class=%d tag=0x%x", hdr.class, hdr.tag);
+	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
+	    !asn1_is_integer(&hdr)) {
+		asn1_unexpected(&hdr, "DH: No INTEGER tag found for g");
 		return -1;
 	}
 
diff --git a/src/tls/x509v3.c b/src/tls/x509v3.c
index d2e685c..b006e99 100644
--- a/src/tls/x509v3.c
+++ b/src/tls/x509v3.c
@@ -192,12 +192,9 @@
 	 * }
 	 */
 
-	if (asn1_get_next(buf, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "X509: Expected SEQUENCE "
-			   "(AlgorithmIdentifier) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(buf, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"X509: Expected SEQUENCE (AlgorithmIdentifier)");
 		return -1;
 	}
 	if (hdr.length > buf + len - hdr.payload)
@@ -234,11 +231,9 @@
 	end = buf + len;
 
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "X509: Expected SEQUENCE "
-			   "(SubjectPublicKeyInfo) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"X509: Expected SEQUENCE (SubjectPublicKeyInfo)");
 		return -1;
 	}
 	pos = hdr.payload;
@@ -253,11 +248,9 @@
 		return -1;
 
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_BITSTRING) {
-		wpa_printf(MSG_DEBUG, "X509: Expected BITSTRING "
-			   "(subjectPublicKey) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_bitstring(&hdr)) {
+		asn1_unexpected(&hdr,
+				"X509: Expected BITSTRING (subjectPublicKey)");
 		return -1;
 	}
 	if (hdr.length < 1)
@@ -309,12 +302,9 @@
 	 * AttributeValue ::= ANY DEFINED BY AttributeType
 	 */
 
-	if (asn1_get_next(buf, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "X509: Expected SEQUENCE "
-			   "(Name / RDNSequencer) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(buf, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"X509: Expected SEQUENCE (Name / RDNSequencer)");
 		return -1;
 	}
 	pos = hdr.payload;
@@ -328,11 +318,9 @@
 		enum x509_name_attr_type type;
 
 		if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-		    hdr.class != ASN1_CLASS_UNIVERSAL ||
-		    hdr.tag != ASN1_TAG_SET) {
-			wpa_printf(MSG_DEBUG, "X509: Expected SET "
-				   "(RelativeDistinguishedName) - found class "
-				   "%d tag 0x%x", hdr.class, hdr.tag);
+		    !asn1_is_set(&hdr)) {
+			asn1_unexpected(&hdr,
+					"X509: Expected SET (RelativeDistinguishedName)");
 			x509_free_name(name);
 			return -1;
 		}
@@ -341,11 +329,9 @@
 		pos = set_end = hdr.payload + hdr.length;
 
 		if (asn1_get_next(set_pos, set_end - set_pos, &hdr) < 0 ||
-		    hdr.class != ASN1_CLASS_UNIVERSAL ||
-		    hdr.tag != ASN1_TAG_SEQUENCE) {
-			wpa_printf(MSG_DEBUG, "X509: Expected SEQUENCE "
-				   "(AttributeTypeAndValue) - found class %d "
-				   "tag 0x%x", hdr.class, hdr.tag);
+		    !asn1_is_sequence(&hdr)) {
+			asn1_unexpected(&hdr,
+					"X509: Expected SEQUENCE (AttributeTypeAndValue)");
 			x509_free_name(name);
 			return -1;
 		}
@@ -366,6 +352,13 @@
 			return -1;
 		}
 
+		if (!asn1_is_string_type(&hdr)) {
+			wpa_printf(MSG_DEBUG,
+				   "X509: Ignore non-string type attribute (tag 0x%x)",
+				   hdr.tag);
+			continue;
+		}
+
 		/* RFC 3280:
 		 * MUST: country, organization, organizational-unit,
 		 * distinguished name qualifier, state or province name,
@@ -709,12 +702,8 @@
 	 * validity dates in 2050 or later MUST be encoded as GeneralizedTime.
 	 */
 
-	if (asn1_get_next(buf, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "X509: Expected SEQUENCE "
-			   "(Validity) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(buf, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr, "X509: Expected SEQUENCE (Validity)");
 		return -1;
 	}
 	pos = hdr.payload;
@@ -726,7 +715,7 @@
 	*next = pos + plen;
 
 	if (asn1_get_next(pos, plen, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
+	    (!asn1_is_utctime(&hdr) && !asn1_is_generalizedtime(&hdr)) ||
 	    x509_parse_time(hdr.payload, hdr.length, hdr.tag,
 			    &cert->not_before) < 0) {
 		wpa_hexdump_ascii(MSG_DEBUG, "X509: Failed to parse notBefore "
@@ -738,7 +727,7 @@
 	plen = *next - pos;
 
 	if (asn1_get_next(pos, plen, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
+	    (!asn1_is_utctime(&hdr) && !asn1_is_generalizedtime(&hdr)) ||
 	    x509_parse_time(hdr.payload, hdr.length, hdr.tag,
 			    &cert->not_after) < 0) {
 		wpa_hexdump_ascii(MSG_DEBUG, "X509: Failed to parse notAfter "
@@ -791,13 +780,9 @@
 	 *     decipherOnly            (8) }
 	 */
 
-	if (asn1_get_next(pos, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_BITSTRING ||
+	if (asn1_get_next(pos, len, &hdr) < 0 || !asn1_is_bitstring(&hdr) ||
 	    hdr.length < 1) {
-		wpa_printf(MSG_DEBUG, "X509: Expected BIT STRING in "
-			   "KeyUsage; found %d tag 0x%x len %d",
-			   hdr.class, hdr.tag, hdr.length);
+		asn1_unexpected(&hdr, "X509: Expected BIT STRING in KeyUsage");
 		return -1;
 	}
 
@@ -824,12 +809,9 @@
 	 * pathLenConstraint       INTEGER (0..MAX) OPTIONAL }
 	 */
 
-	if (asn1_get_next(pos, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "X509: Expected SEQUENCE in "
-			   "BasicConstraints; found %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"X509: Expected SEQUENCE in BasicConstraints");
 		return -1;
 	}
 
@@ -839,14 +821,13 @@
 		return 0;
 
 	end_seq = hdr.payload + hdr.length;
-	if (asn1_get_next(hdr.payload, hdr.length, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL) {
+	if (asn1_get_next(hdr.payload, hdr.length, &hdr) < 0) {
 		wpa_printf(MSG_DEBUG, "X509: Failed to parse "
 			   "BasicConstraints");
 		return -1;
 	}
 
-	if (hdr.tag == ASN1_TAG_BOOLEAN) {
+	if (asn1_is_boolean(&hdr)) {
 		cert->ca = hdr.payload[0];
 
 		pos = hdr.payload + hdr.length;
@@ -856,18 +837,16 @@
 				   cert->ca);
 			return 0;
 		}
-		if (asn1_get_next(pos, end_seq - pos, &hdr) < 0 ||
-		    hdr.class != ASN1_CLASS_UNIVERSAL) {
+		if (asn1_get_next(pos, end_seq - pos, &hdr) < 0) {
 			wpa_printf(MSG_DEBUG, "X509: Failed to parse "
 				   "BasicConstraints");
 			return -1;
 		}
 	}
 
-	if (hdr.tag != ASN1_TAG_INTEGER) {
-		wpa_printf(MSG_DEBUG, "X509: Expected INTEGER in "
-			   "BasicConstraints; found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (!asn1_is_integer(&hdr)) {
+		asn1_unexpected(&hdr,
+				"X509: Expected INTEGER in BasicConstraints");
 		return -1;
 	}
 
@@ -1074,12 +1053,9 @@
 
 	/* SubjectAltName ::= GeneralNames */
 
-	if (asn1_get_next(pos, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "X509: Expected SEQUENCE in "
-			   "SubjectAltName; found %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"X509: Expected SEQUENCE in SubjectAltName");
 		return -1;
 	}
 
@@ -1101,12 +1077,9 @@
 
 	/* IssuerAltName ::= GeneralNames */
 
-	if (asn1_get_next(pos, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "X509: Expected SEQUENCE in "
-			   "IssuerAltName; found %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"X509: Expected SEQUENCE in IssuerAltName");
 		return -1;
 	}
 
@@ -1187,11 +1160,9 @@
 	 * CertPolicyId ::= OBJECT IDENTIFIER
 	 */
 
-	if (asn1_get_next(pos, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "X509: Expected SEQUENCE (certificatePolicies) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"X509: Expected SEQUENCE (certificatePolicies)");
 		return -1;
 	}
 	if (hdr.length > pos + len - hdr.payload)
@@ -1207,10 +1178,9 @@
 		char buf[80];
 
 		if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-		    hdr.class != ASN1_CLASS_UNIVERSAL ||
-		    hdr.tag != ASN1_TAG_SEQUENCE) {
-			wpa_printf(MSG_DEBUG, "X509: Expected SEQUENCE (PolicyInformation) - found class %d tag 0x%x",
-				   hdr.class, hdr.tag);
+		    !asn1_is_sequence(&hdr)) {
+			asn1_unexpected(&hdr,
+					"X509: Expected SEQUENCE (PolicyInformation)");
 			return -1;
 		}
 		if (hdr.length > end - hdr.payload)
@@ -1310,12 +1280,9 @@
 	 * KeyPurposeId ::= OBJECT IDENTIFIER
 	 */
 
-	if (asn1_get_next(pos, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "X509: Expected SEQUENCE "
-			   "(ExtKeyUsageSyntax) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"X509: Expected SEQUENCE (ExtKeyUsageSyntax)");
 		return -1;
 	}
 	if (hdr.length > pos + len - hdr.payload)
@@ -1402,12 +1369,8 @@
 	 * }
 	 */
 
-	if (asn1_get_next(pos, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "X509: Unexpected ASN.1 header in "
-			   "Extensions: class %d tag 0x%x; expected SEQUENCE",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr, "X509: Expected SEQUENCE in Extensions");
 		return -1;
 	}
 	pos = hdr.payload;
@@ -1420,26 +1383,27 @@
 	}
 
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    (hdr.tag != ASN1_TAG_BOOLEAN &&
-	     hdr.tag != ASN1_TAG_OCTETSTRING)) {
-		wpa_printf(MSG_DEBUG, "X509: Unexpected ASN.1 header in "
-			   "Extensions: class %d tag 0x%x; expected BOOLEAN "
-			   "or OCTET STRING", hdr.class, hdr.tag);
+	    (!asn1_is_boolean(&hdr) && !asn1_is_octetstring(&hdr))) {
+		asn1_unexpected(&hdr,
+				"X509: Expected BOOLEAN or OCTETSTRING in Extensions");
 		return -1;
 	}
 
 	if (hdr.tag == ASN1_TAG_BOOLEAN) {
 		critical_ext = hdr.payload[0];
 		pos = hdr.payload;
+		/*
+		 * Number of CA certificates seem to be using Private class in
+		 * one of the X.509v3 extensions, so let's accept that instead
+		 * of rejecting the certificate. asn1_is_octetstring() covers
+		 * the more common case.
+		 */
 		if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-		    (hdr.class != ASN1_CLASS_UNIVERSAL &&
-		     hdr.class != ASN1_CLASS_PRIVATE) ||
-		    hdr.tag != ASN1_TAG_OCTETSTRING) {
-			wpa_printf(MSG_DEBUG, "X509: Unexpected ASN.1 header "
-				   "in Extensions: class %d tag 0x%x; "
-				   "expected OCTET STRING",
-				   hdr.class, hdr.tag);
+		    (!asn1_is_octetstring(&hdr) &&
+		     !(hdr.class == ASN1_CLASS_PRIVATE &&
+		       hdr.tag == ASN1_TAG_OCTETSTRING))) {
+			asn1_unexpected(&hdr,
+					"X509: Expected OCTETSTRING in Extensions");
 			return -1;
 		}
 	}
@@ -1470,12 +1434,8 @@
 
 	/* Extensions  ::=  SEQUENCE SIZE (1..MAX) OF Extension */
 
-	if (asn1_get_next(pos, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "X509: Unexpected ASN.1 data "
-			   "for Extensions: class %d tag 0x%x; "
-			   "expected SEQUENCE", hdr.class, hdr.tag);
+	if (asn1_get_next(pos, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr, "X509: Expected SEQUENCE for Extensions");
 		return -1;
 	}
 
@@ -1504,12 +1464,9 @@
 	const u8 *subject_dn;
 
 	/* tbsCertificate TBSCertificate ::= SEQUENCE */
-	if (asn1_get_next(buf, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "X509: tbsCertificate did not start "
-			   "with a valid SEQUENCE - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(buf, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"X509: tbsCertificate did not start with a valid SEQUENCE");
 		return -1;
 	}
 	pos = hdr.payload;
@@ -1523,15 +1480,11 @@
 		return -1;
 	pos = hdr.payload;
 
-	if (hdr.class == ASN1_CLASS_CONTEXT_SPECIFIC) {
-		if (asn1_get_next(pos, end - pos, &hdr) < 0)
-			return -1;
-
-		if (hdr.class != ASN1_CLASS_UNIVERSAL ||
-		    hdr.tag != ASN1_TAG_INTEGER) {
-			wpa_printf(MSG_DEBUG, "X509: No INTEGER tag found for "
-				   "version field - found class %d tag 0x%x",
-				   hdr.class, hdr.tag);
+	if (asn1_is_cs_tag(&hdr, 0) && hdr.constructed) {
+		if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
+		    !asn1_is_integer(&hdr)) {
+			asn1_unexpected(&hdr,
+					"X509: No INTEGER tag found for version field");
 			return -1;
 		}
 		if (hdr.length != 1) {
@@ -1564,12 +1517,10 @@
 	wpa_printf(MSG_MSGDUMP, "X509: Version X.509v%d", cert->version + 1);
 
 	/* serialNumber CertificateSerialNumber ::= INTEGER */
-	if (hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_INTEGER ||
+	if (!asn1_is_integer(&hdr) ||
 	    hdr.length < 1 || hdr.length > X509_MAX_SERIAL_NUM_LEN) {
-		wpa_printf(MSG_DEBUG, "X509: No INTEGER tag found for "
-			   "serialNumber; class=%d tag=0x%x length=%u",
-			   hdr.class, hdr.tag, hdr.length);
+		asn1_unexpected(&hdr,
+				"X509: No INTEGER tag found for serialNumber");
 		return -1;
 	}
 
@@ -1622,10 +1573,8 @@
 
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
 	    hdr.class != ASN1_CLASS_CONTEXT_SPECIFIC) {
-		wpa_printf(MSG_DEBUG, "X509: Expected Context-Specific"
-			   " tag to parse optional tbsCertificate "
-			   "field(s); parsed class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+		asn1_unexpected(&hdr,
+				"X509: Expected Context-Specific tag to parse optional tbsCertificate field(s)");
 		return -1;
 	}
 
@@ -1640,10 +1589,8 @@
 
 		if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
 		    hdr.class != ASN1_CLASS_CONTEXT_SPECIFIC) {
-			wpa_printf(MSG_DEBUG, "X509: Expected Context-Specific"
-				   " tag to parse optional tbsCertificate "
-				   "field(s); parsed class %d tag 0x%x",
-				   hdr.class, hdr.tag);
+			asn1_unexpected(&hdr,
+					"X509: Expected Context-Specific tag to parse optional tbsCertificate field(s)");
 			return -1;
 		}
 	}
@@ -1659,18 +1606,16 @@
 
 		if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
 		    hdr.class != ASN1_CLASS_CONTEXT_SPECIFIC) {
-			wpa_printf(MSG_DEBUG, "X509: Expected Context-Specific"
-				   " tag to parse optional tbsCertificate "
-				   "field(s); parsed class %d tag 0x%x",
-				   hdr.class, hdr.tag);
+			asn1_unexpected(&hdr,
+					"X509: Expected Context-Specific tag to parse optional tbsCertificate field(s)");
 			return -1;
 		}
 	}
 
 	if (hdr.tag != 3) {
-		wpa_printf(MSG_DEBUG, "X509: Ignored unexpected "
-			   "Context-Specific tag %d in optional "
-			   "tbsCertificate fields", hdr.tag);
+		wpa_printf(MSG_DEBUG,
+			   "X509: Ignored unexpected Context-Specific constructed %d tag %d in optional tbsCertificate fields",
+			   hdr.constructed, hdr.tag);
 		return 0;
 	}
 
@@ -1798,12 +1743,9 @@
 	/* RFC 3280 - X.509 v3 certificate / ASN.1 DER */
 
 	/* Certificate ::= SEQUENCE */
-	if (asn1_get_next(pos, len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "X509: Certificate did not start with "
-			   "a valid SEQUENCE - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	if (asn1_get_next(pos, len, &hdr) < 0 || !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"X509: Certificate did not start with a valid SEQUENCE");
 		x509_certificate_free(cert);
 		return NULL;
 	}
@@ -1838,11 +1780,9 @@
 
 	/* signatureValue BIT STRING */
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_BITSTRING) {
-		wpa_printf(MSG_DEBUG, "X509: Expected BITSTRING "
-			   "(signatureValue) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_bitstring(&hdr)) {
+		asn1_unexpected(&hdr,
+				"X509: Expected BITSTRING (signatureValue)");
 		x509_certificate_free(cert);
 		return NULL;
 	}
@@ -1956,14 +1896,12 @@
 	 *
 	 */
 	if (asn1_get_next(data, data_len, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "X509: Expected SEQUENCE "
-			   "(DigestInfo) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr, "X509: Expected SEQUENCE (DigestInfo)");
 		os_free(data);
 		return -1;
 	}
+	wpa_hexdump(MSG_MSGDUMP, "X509: DigestInfo", hdr.payload, hdr.length);
 
 	pos = hdr.payload;
 	end = pos + hdr.length;
@@ -1977,14 +1915,14 @@
 	 */
 
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_SEQUENCE) {
-		wpa_printf(MSG_DEBUG, "X509: Expected SEQUENCE "
-			   "(AlgorithmIdentifier) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_sequence(&hdr)) {
+		asn1_unexpected(&hdr,
+				"X509: Expected SEQUENCE (AlgorithmIdentifier)");
 		os_free(data);
 		return -1;
 	}
+	wpa_hexdump(MSG_MSGDUMP, "X509: DigestAlgorithmIdentifier",
+		    hdr.payload, hdr.length);
 	da_end = hdr.payload + hdr.length;
 
 	if (asn1_get_oid(hdr.payload, hdr.length, &oid, &next)) {
@@ -1992,6 +1930,23 @@
 		os_free(data);
 		return -1;
 	}
+	wpa_hexdump(MSG_MSGDUMP, "X509: Digest algorithm parameters",
+		    next, da_end - next);
+
+	/*
+	 * RFC 5754: The correct encoding for the SHA2 algorithms would be to
+	 * omit the parameters, but there are implementation that encode these
+	 * as a NULL element. Allow these two cases and reject anything else.
+	 */
+	if (da_end > next &&
+	    (asn1_get_next(next, da_end - next, &hdr) < 0 ||
+	     !asn1_is_null(&hdr) ||
+	     hdr.payload + hdr.length != da_end)) {
+		wpa_printf(MSG_DEBUG,
+			   "X509: Unexpected digest algorithm parameters");
+		os_free(data);
+		return -1;
+	}
 
 	if (x509_sha1_oid(&oid)) {
 		if (signature->oid.oid[6] != 5 /* sha-1WithRSAEncryption */) {
@@ -2070,14 +2025,10 @@
 skip_digest_oid:
 	/* Digest ::= OCTET STRING */
 	pos = da_end;
-	end = data + data_len;
 
 	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
-	    hdr.class != ASN1_CLASS_UNIVERSAL ||
-	    hdr.tag != ASN1_TAG_OCTETSTRING) {
-		wpa_printf(MSG_DEBUG, "X509: Expected OCTETSTRING "
-			   "(Digest) - found class %d tag 0x%x",
-			   hdr.class, hdr.tag);
+	    !asn1_is_octetstring(&hdr)) {
+		asn1_unexpected(&hdr, "X509: Expected OCTETSTRING (Digest)");
 		os_free(data);
 		return -1;
 	}