diff --git a/security/keymint/aidl/android/hardware/security/keymint/IKeyMintDevice.aidl b/security/keymint/aidl/android/hardware/security/keymint/IKeyMintDevice.aidl
index 1c503c2..ddbeafc 100644
--- a/security/keymint/aidl/android/hardware/security/keymint/IKeyMintDevice.aidl
+++ b/security/keymint/aidl/android/hardware/security/keymint/IKeyMintDevice.aidl
@@ -325,6 +325,10 @@
      *        return ErrorCode::INCOMPATIBLE_PURPOSE.  If the provided AttestationKey has an empty
      *        issuer subject name, the IKeyMintDevice must return ErrorCode::INVALID_ARGUMENT.
      *
+     *        If `attestationKey` is null and `keyParams` contains Tag::ATTESTATION_CHALLENGE but
+     *        the KeyMint implementation does not have factory-provisioned attestation keys, it must
+     *        return ErrorCode::ATTESTATION_KEYS_NOT_PROVISIONED.
+     *
      * @return The result of key creation.  See KeyCreationResult.aidl.
      */
     KeyCreationResult generateKey(
@@ -364,6 +368,10 @@
      *        return ErrorCode::INCOMPATIBLE_PURPOSE.  If the provided AttestationKey has an empty
      *        issuer subject name, the IKeyMintDevice must return ErrorCode::INVALID_ARGUMENT.
      *
+     *        If `attestationKey` is null and `keyParams` contains Tag::ATTESTATION_CHALLENGE but
+     *        the KeyMint implementation does not have factory-provisioned attestation keys, it must
+     *        return ErrorCode::ATTESTATION_KEYS_NOT_PROVISIONED.
+     *
      * @return The result of key creation.  See KeyCreationResult.aidl.
      */
     KeyCreationResult importKey(in KeyParameter[] keyParams, in KeyFormat keyFormat,
diff --git a/security/keymint/aidl/android/hardware/security/keymint/KeyCreationResult.aidl b/security/keymint/aidl/android/hardware/security/keymint/KeyCreationResult.aidl
index c2e21b6..972a6a5 100644
--- a/security/keymint/aidl/android/hardware/security/keymint/KeyCreationResult.aidl
+++ b/security/keymint/aidl/android/hardware/security/keymint/KeyCreationResult.aidl
@@ -66,7 +66,8 @@
      *     provisioned attestation key, and the full certificate chain for that factory-provisioned
      *     attestation key.  Tag::ATTESTATION_APPLICATION_ID must also be provided when the
      *     ATTESTATION_CHALLENGE is provided, otherwise ATTESTATION_APPLICATION_ID_MISSING will be
-     *     returned.
+     *     returned.  KeyMint implementations are not required to support factory-provisioned
+     *     attestation keys.
      *
      * 2.  Asymmetric key attestation with caller-provided key.  If Tag::ATTESTATION_CHALLENGE is
      *     provided and the `attestationKey` parameter on the generat/import call is non-null and
@@ -90,6 +91,110 @@
      * 5.  Symmetric key.  If the generated/imported key is symmetric, the certificate chain must
      *     return empty, any Tag::ATTESTATION_CHALLENGE or Tag::ATTESTATION_APPLICATION_ID inputs,
      *     if provided, are ignored.
+     *
+     * In all cases except the symmetric key, the contents of certificate chain must be DER-encoded
+     * X.509 certificates ordered such that each certificate is signed by the subsequent one, up to
+     * the root which must be self-signed (or contain a fake signature in the case of case 4 above).
+     * The first certificate in the chain signs the public key info of the newly-generated or
+     * newly-imported key pair.  In the attestation cases (1 and 2 above), the first certificate
+     * must also satisfy some other requirements:
+     *
+     * o It must have the serial number provided in Tag::CERTIFICATE_SERIAL, or default to 1 if the
+     *   tag is not provided.
+     *
+     * o It must have the subject provided in Tag::CERTIFICATE_SUBJECT, or default to CN="Android
+     *   Keystore Key", if the tag is not provided.
+     *
+     * o It must contain the notBefore and notAfter date-times specified in
+     *   Tag::CERTIFICATE_NOT_BEFORE and Tag::CERTIFICATE_NOT_AFTER, respectively.
+     *
+     * o It must contain a Key Usage extension with:
+     *
+     *    - the digitalSignature bit set iff the attested key has KeyPurpose::SIGN,
+     *    - the dataEncipherment bit set iff the attested key has KeyPurpose::DECRYPT,
+     *    - the keyEncipherment bit set iff the attested key has KeyPurpose::WRAP_KEY,
+     *    - the keyAgreement bit set iff the attested key has KeyPurpose::AGREE_KEY, and
+     *    - the keyCertSignBit set iff the attested key has KeyPurpose::ATTEST_KEY.
+     *
+     * o it must contain a KeyDescription attestation extension with OID 1.3.6.1.4.1.11129.2.1.17.
+     *
+     * The KeyDescription content is defined by the following ASN.1 schema, which is mostly a
+     * straightforward translation of the KeyMint tag/value parameter lists to ASN.1.
+     *
+     * KeyDescription ::= SEQUENCE {
+     *     attestationVersion         INTEGER, # Value 100
+     *     attestationSecurityLevel   SecurityLevel, # See below
+     *     keyMintVersion             INTEGER, # Value 100
+     *     keymintSecurityLevel       SecurityLevel, # See below
+     *     attestationChallenge       OCTET_STRING, # Tag::ATTESTATION_CHALLENGE from attestParams
+     *     uniqueId                   OCTET_STRING, # Empty unless key has Tag::INCLUDE_UNIQUE_ID
+     *     softwareEnforced           AuthorizationList, # See below
+     *     hardwareEnforced           AuthorizationList, # See below
+     * }
+     *
+     * SecurityLevel ::= ENUMERATED {
+     *     Software                   (0),
+     *     TrustedEnvironment         (1),
+     *     StrongBox                  (2),
+     * }
+     *
+     * RootOfTrust ::= SEQUENCE {
+     *     verifiedBootKey            OCTET_STRING,
+     *     deviceLocked               BOOLEAN,
+     *     verifiedBootState          VerifiedBootState,
+     *     # verifiedBootHash must contain 32-byte value that represents the state of all binaries
+     *     # or other components validated by verified boot.  Updating any verified binary or
+     *     # component must cause this value to change.
+     *     verifiedBootHash           OCTET_STRING,
+     * }
+     *
+     * VerifiedBootState ::= ENUMERATED {
+     *     Verified                   (0),
+     *     SelfSigned                 (1),
+     *     Unverified                 (2),
+     *     Failed                     (3),
+     * }
+     *
+     * AuthorizationList ::= SEQUENCE {
+     *     purpose                    [1] EXPLICIT SET OF INTEGER OPTIONAL,
+     *     algorithm                  [2] EXPLICIT INTEGER OPTIONAL,
+     *     keySize                    [3] EXPLICIT INTEGER OPTIONAL,
+     *     blockMode                  [4] EXPLICIT SET OF INTEGER OPTIONAL,
+     *     digest                     [5] EXPLICIT SET OF INTEGER OPTIONAL,
+     *     padding                    [6] EXPLICIT SET OF INTEGER OPTIONAL,
+     *     callerNonce                [7] EXPLICIT NULL OPTIONAL,
+     *     minMacLength               [8] EXPLICIT INTEGER OPTIONAL,
+     *     ecCurve                    [10] EXPLICIT INTEGER OPTIONAL,
+     *     rsaPublicExponent          [200] EXPLICIT INTEGER OPTIONAL,
+     *     rollbackResistance         [303] EXPLICIT NULL OPTIONAL,
+     *     activeDateTime             [400] EXPLICIT INTEGER OPTIONAL,
+     *     originationExpireDateTime  [401] EXPLICIT INTEGER OPTIONAL,
+     *     usageExpireDateTime        [402] EXPLICIT INTEGER OPTIONAL,
+     *     userSecureId               [502] EXPLICIT INTEGER OPTIONAL,
+     *     noAuthRequired             [503] EXPLICIT NULL OPTIONAL,
+     *     userAuthType               [504] EXPLICIT INTEGER OPTIONAL,
+     *     authTimeout                [505] EXPLICIT INTEGER OPTIONAL,
+     *     allowWhileOnBody           [506] EXPLICIT NULL OPTIONAL,
+     *     trustedUserPresenceReq     [507] EXPLICIT NULL OPTIONAL,
+     *     trustedConfirmationReq     [508] EXPLICIT NULL OPTIONAL,
+     *     unlockedDeviceReq          [509] EXPLICIT NULL OPTIONAL,
+     *     creationDateTime           [701] EXPLICIT INTEGER OPTIONAL,
+     *     origin                     [702] EXPLICIT INTEGER OPTIONAL,
+     *     rootOfTrust                [704] EXPLICIT RootOfTrust OPTIONAL,
+     *     osVersion                  [705] EXPLICIT INTEGER OPTIONAL,
+     *     osPatchLevel               [706] EXPLICIT INTEGER OPTIONAL,
+     *     attestationApplicationId   [709] EXPLICIT OCTET_STRING OPTIONAL,
+     *     attestationIdBrand         [710] EXPLICIT OCTET_STRING OPTIONAL,
+     *     attestationIdDevice        [711] EXPLICIT OCTET_STRING OPTIONAL,
+     *     attestationIdProduct       [712] EXPLICIT OCTET_STRING OPTIONAL,
+     *     attestationIdSerial        [713] EXPLICIT OCTET_STRING OPTIONAL,
+     *     attestationIdImei          [714] EXPLICIT OCTET_STRING OPTIONAL,
+     *     attestationIdMeid          [715] EXPLICIT OCTET_STRING OPTIONAL,
+     *     attestationIdManufacturer  [716] EXPLICIT OCTET_STRING OPTIONAL,
+     *     attestationIdModel         [717] EXPLICIT OCTET_STRING OPTIONAL,
+     *     vendorPatchLevel           [718] EXPLICIT INTEGER OPTIONAL,
+     *     bootPatchLevel             [719] EXPLICIT INTEGER OPTIONAL,
+     * }
      */
     Certificate[] certificateChain;
 }
diff --git a/security/keymint/aidl/android/hardware/security/keymint/Tag.aidl b/security/keymint/aidl/android/hardware/security/keymint/Tag.aidl
index cde1fc0..2a1ec5c 100644
--- a/security/keymint/aidl/android/hardware/security/keymint/Tag.aidl
+++ b/security/keymint/aidl/android/hardware/security/keymint/Tag.aidl
@@ -935,33 +935,34 @@
     CONFIRMATION_TOKEN = (9 << 28) /* TagType:BYTES */ | 1005,
 
     /**
-     * Tag::CERTIFICATE_SERIAL specifies the serial number to be assigned to the
-     * attestation certificate to be generated for the given key.  This parameter should only
-     * be passed to keyMint in the attestation parameters during generateKey() and importKey().
+     * Tag::CERTIFICATE_SERIAL specifies the serial number to be assigned to the attestation
+     * certificate to be generated for the given key.  This parameter should only be passed to
+     * keyMint in the attestation parameters during generateKey() and importKey().  If not provided,
+     * the serial shall default to 1.
      */
     CERTIFICATE_SERIAL = (8 << 28) /* TagType:BIGNUM */ | 1006,
 
     /**
-     * Tag::CERTIFICATE_SUBJECT the certificate subject. The value is a DER encoded X509 NAME.
-     * This value is used when generating a self signed certificates. This tag may be specified
+     * Tag::CERTIFICATE_SUBJECT the certificate subject.  The value is a DER encoded X509 NAME.
+     * This value is used when generating a self signed certificates.  This tag may be specified
      * during generateKey and importKey. If not provided the subject name shall default to
-     * <TODO default subject here>.
+     * CN="Android Keystore Key".
      */
     CERTIFICATE_SUBJECT = (9 << 28) /* TagType:BYTES */ | 1007,
 
     /**
      * Tag::CERTIFICATE_NOT_BEFORE the beginning of the validity of the certificate in UNIX epoch
-     * time in seconds. This value is used when generating attestation or self signed certificates.
-     * ErrorCode::MISSING_NOT_BEFORE must be returned if this tag is not provided if this tag is
-     * not provided to generateKey or importKey.
+     * time in seconds.  This value is used when generating attestation or self signed certificates.
+     * ErrorCode::MISSING_NOT_BEFORE must be returned if this tag is not provided if this tag is not
+     * provided to generateKey or importKey.
      */
     CERTIFICATE_NOT_BEFORE = (6 << 28) /* TagType:DATE */ | 1008,
 
     /**
-     * Tag::CERTIFICATE_NOT_AFTER the end of the validity of the certificate in UNIX epoch
-     * time in seconds. This value is used when generating attestation or self signed certificates.
-     * ErrorCode::MISSING_NOT_AFTER must be returned if this tag is not provided to generateKey
-     * or importKey.
+     * Tag::CERTIFICATE_NOT_AFTER the end of the validity of the certificate in UNIX epoch time in
+     * seconds.  This value is used when generating attestation or self signed certificates.
+     * ErrorCode::MISSING_NOT_AFTER must be returned if this tag is not provided to generateKey or
+     * importKey.
      */
     CERTIFICATE_NOT_AFTER = (6 << 28) /* TagType:DATE */ | 1009,
 
diff --git a/security/keymint/aidl/vts/functional/KeyMintAidlTestBase.cpp b/security/keymint/aidl/vts/functional/KeyMintAidlTestBase.cpp
index 6202a8b..ce23f70 100644
--- a/security/keymint/aidl/vts/functional/KeyMintAidlTestBase.cpp
+++ b/security/keymint/aidl/vts/functional/KeyMintAidlTestBase.cpp
@@ -942,7 +942,7 @@
     EXPECT_EQ(ErrorCode::OK, error);
     if (error != ErrorCode::OK) return false;
 
-    EXPECT_GE(att_attestation_version, 3U);
+    EXPECT_EQ(att_attestation_version, 100U);
     vector<uint8_t> appId(app_id.begin(), app_id.end());
 
     // check challenge and app id only if we expects a non-fake certificate
@@ -953,7 +953,7 @@
         expected_sw_enforced.push_back(TAG_ATTESTATION_APPLICATION_ID, appId);
     }
 
-    EXPECT_GE(att_keymaster_version, 4U);
+    EXPECT_EQ(att_keymaster_version, 100U);
     EXPECT_EQ(security_level, att_keymaster_security_level);
     EXPECT_EQ(security_level, att_attestation_security_level);