diff --git a/keystore2/include/certificate_utils.h b/keystore2/include/certificate_utils.h
new file mode 100644
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+++ b/keystore2/include/certificate_utils.h
@@ -0,0 +1,167 @@
+/*
+ * Copyright 2020, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <openssl/err.h>
+#include <openssl/x509.h>
+#include <stdint.h>
+
+#include <memory>
+#include <optional>
+#include <variant>
+
+namespace keystore {
+// We use boringssl error codes. Error codes that we add are folded into LIB_USER.
+// The CertificateUtilsInternallErrorCodes enum should not be used by callers, instead use the
+// BoringSslError constant definitions below for error codes.
+using BoringSslError = unsigned long;
+
+#define DEFINE_OPENSSL_OBJECT_POINTER(name) using name##_Ptr = bssl::UniquePtr<name>
+
+DEFINE_OPENSSL_OBJECT_POINTER(ASN1_BIT_STRING);
+DEFINE_OPENSSL_OBJECT_POINTER(ASN1_STRING);
+DEFINE_OPENSSL_OBJECT_POINTER(ASN1_INTEGER);
+DEFINE_OPENSSL_OBJECT_POINTER(ASN1_OCTET_STRING);
+DEFINE_OPENSSL_OBJECT_POINTER(ASN1_TIME);
+DEFINE_OPENSSL_OBJECT_POINTER(EVP_PKEY);
+DEFINE_OPENSSL_OBJECT_POINTER(X509);
+DEFINE_OPENSSL_OBJECT_POINTER(X509_EXTENSION);
+DEFINE_OPENSSL_OBJECT_POINTER(X509_NAME);
+DEFINE_OPENSSL_OBJECT_POINTER(EVP_PKEY_CTX);
+
+class CertUtilsError {
+  public:
+    enum Error {
+        Ok = 0,
+        BoringSsl,
+        Encoding,
+        MemoryAllocation,
+        InvalidArgument,
+        UnexpectedNullPointer,
+    };
+
+  private:
+    Error e_;
+
+  public:
+    constexpr CertUtilsError(Error e) : e_(e) {}
+    explicit constexpr operator bool() const { return e_ != Ok; }
+};
+
+struct KeyUsageExtension {
+    bool isSigningKey;
+    bool isEncryptionKey;
+    bool isCertificationKey;
+};
+
+struct BasicConstraintsExtension {
+    bool isCa;
+    std::optional<int> pathLength;
+};
+
+/**
+ * This function allocates and prepares an X509 certificate structure with all of the information
+ * given. Next steps would be to set an Issuer with `setIssuer` and sign it with either
+ * `signCert` or `signCertWith`.
+ * @param evp_pkey The public key that the certificate is issued for.
+ * @param serial The certificate serial number.
+ * @param subject The subject common name.
+ * @param activeDateTimeMilliSeconds The not before date in epoch milliseconds.
+ * @param usageExpireDateTimeMilliSeconds The not after date in epoch milliseconds.
+ * @param addSubjectKeyIdEx If true, adds the subject key id extension.
+ * @param keyUsageEx If given adds, the key usage extension with the given flags.
+ * @param basicConstraints If given, adds the basic constraints extension with the given data.
+ * @return CertUtilsError::Ok on success.
+ */
+std::variant<CertUtilsError, X509_Ptr>
+makeCert(const EVP_PKEY* evp_pkey,                                    //
+         const uint32_t serial,                                       //
+         const char subject[],                                        //
+         const uint64_t activeDateTimeMilliSeconds,                   //
+         const uint64_t usageExpireDateTimeMilliSeconds,              //
+         bool addSubjectKeyIdEx,                                      //
+         std::optional<KeyUsageExtension> keyUsageEx,                 //
+         std::optional<BasicConstraintsExtension> basicConstraints);  //
+
+/**
+ * Takes the subject name from `signingCert` and sets it as issuer name in `cert`.
+ * if `addAuthKeyExt` is true it also generates the digest of the signing certificates's public key
+ * and sets it as authority key id extension in `cert`.
+ * For self signed certificates pass the same pointer to both `cert` and `signingCert`.
+ *
+ * @param cert
+ * @param signingCert
+ * @param addAuthKeyExt
+ * @return CertUtilsError::Ok on success.
+ */
+CertUtilsError setIssuer(X509* cert, const X509* signingCert, bool addAuthKeyExt);
+
+/**
+ * Takes a certificate, and private signing_key.
+ * Signs the certificate with the latter.
+ */
+CertUtilsError signCert(X509* certificate, EVP_PKEY* signing_key);
+
+enum class Digest {
+    SHA1,
+    SHA224,
+    SHA256,
+    SHA384,
+    SHA512,
+};
+
+enum class Algo {
+    ECDSA,
+    RSA,
+};
+
+enum class Padding {
+    Ignored,
+    PKCS1_5,
+    PSS,
+};
+
+/**
+ * Sets the signature specifier of the certificate and the signature according to the parameters
+ * c. Then it signs the certificate with the `sign` callback.
+ * IMPORTANT: The parameters `algo`, `padding`, and `digest` do not control the actual signing
+ * algorithm. The caller is responsible to provide a callback that actually performs the signature
+ * as described by this triplet.
+ * The `padding` argument is ignored if `algo` is Algo::EC.
+ * The `digest` field controls the message digest used, and, in case of RSA with PSS padding,
+ *              also the MGF1 digest.
+ *
+ * @param certificate X509 certificate structure to be signed.
+ * @param sign Callback function used to digest and sign the DER encoded to-be-signed certificate.
+ * @param algo Algorithm specifier used to encode the signing algorithm id of the X509 certificate.
+ * @param padding Padding specifier used to encode the signing algorithm id of the X509 certificate.
+ * @param digest Digest specifier used to encode the signing algorithm id of the X509 certificate.
+ * @return CertUtilsError::Ok on success.
+ */
+CertUtilsError signCertWith(X509* certificate,
+                            std::function<std::vector<uint8_t>(const uint8_t*, size_t)> sign,
+                            Algo algo, Padding padding, Digest digest);
+
+/**
+ * Generates the DER representation of the given signed X509 certificate structure.
+ * @param certificate
+ * @return std::vector<uint8_t> with the DER encoded certificate on success. An error code
+ *         otherwise.
+ */
+std::variant<CertUtilsError, std::vector<uint8_t>> encodeCert(X509* certificate);
+
+}  // namespace keystore