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Commit 87cb07bd authored by David Zeuthen's avatar David Zeuthen
Browse files

Identity Credential: Require passing applicationId when generating attestation. 

Since the attestation format includes the applicationId, we need this
to be passed from credstore. Also clarify other requirements about
what needs to be in the attestation data.

Bug: 111446262
Test: atest android.security.identity.cts
Test: VtsHalIdentityCredentialTargetTest
Test: android.hardware.identity-support-lib-test
Change-Id: I623849bd61e55752a573002dc7a97c6658d94c91
parent 7b37dc5d

current.txt

+1 −1
Original line number Diff line number Diff line
@@ -618,7 +618,7 @@ db47f4ceceb1f06c656f39caa70c557b0f8471ef59fd58611bea667ffca20101 android.hardwar 
0589e410f519e36514e7ece18f283f022df0f70efd2c12821d822f67f74aba98 android.hardware.identity@1.0::types

bbeee9604128ede83ee755b67e73b5ad29e6e1dbac9ec41fea6ffe2745b0c50a android.hardware.identity@1.0::IIdentityCredential

96ce8aad80f4c476f25261f790d357c117e79e18474c7dadd850dac704bbe65e android.hardware.identity@1.0::IIdentityCredentialStore

6e1e28a96c90ba78d47257faea3f3bb4e6360affbbfa5822f0dc31211f9266ff android.hardware.identity@1.0::IWritableIdentityCredential

8da9c938e58f7d636ddd2f92c646f99d9a9e79612e6441b6380ab12744251873 android.hardware.identity@1.0::IWritableIdentityCredential

27ae3724053940462114228872b3ffaf0b8e6177d5ba97f5a76339d12b8a99dd android.hardware.keymaster@4.1::IKeymasterDevice

adb0efdf1462e9b2e742c0dcadd598666aac551f178be06e755bfcdf5797abd0 android.hardware.keymaster@4.1::IOperation

ac429fca0da4ce91218768ec31b64ded88251f8a26d8c4f27c06abdc5b1926d9 android.hardware.keymaster@4.1::types

identity/1.0/IWritableIdentityCredential.hal

+44 −8
Original line number Diff line number Diff line
@@ -26,20 +26,56 @@ interface IWritableIdentityCredential { 
     * characteristics to an issuing authority.  Must not be called more than once.

     *

     * The certificate chain must be generated using Keymaster Attestation

     * (see https://source.android.com/security/keystore/attestation) and must also

     * have the Tag::IDENTITY_CREDENTIAL_KEY tag from KeyMaster 4.1 set. This tag indicates

     * that this key is an Identity Credential key (which can only sign/MAC very

     * specific messages) and not an Android Keystore key (which can be used to sign/MAC

     * anything).

     * (see https://source.android.com/security/keystore/attestation) with the

     * following additional requirements:

     *

     *  - The attestationVersion field in the attestation extension must be at least 3.

     *

     *  - The attestationSecurityLevel field must be set to either Software (0),

     *    TrustedEnvironment (1), or StrongBox (2) depending on how attestation is

     *    implemented. Only the default AOSP implementation of this HAL may use

     *    value 0 (additionally, this implementation must not be used on production

     *    devices).

     *

     *  - The keymasterVersion field in the attestation extension must be set to (10*major + minor)

     *    where major and minor are the Identity Credential interface major and minor versions.

     *    Specifically for this version of the interface (1.0) this value is 10.

     *

     *  - The keymasterSecurityLevel field in the attestation extension must be set to

     *    either Software (0), TrustedEnvironment (1), or StrongBox (2) depending on how

     *    the Trusted Application backing the HAL implementation is implemented. Only

     *    the default AOSP implementation of this HAL may use value 0 (additionally, this

     *    implementation must not be used on production devices)

     *

     *  - The attestationChallenge field must be set to the passed-in challenge.

     *

     *  - The uniqueId field must be empty.

     *

     *  - The softwareEnforced field in the attestation extension must include

     *    Tag::ATTESTATION_APPLICATION_ID which must be set to the bytes of the passed-in

     *    attestationApplicationId.

     *

     *  - The teeEnforced field in the attestation extension must include

     *    Tag::IDENTITY_CREDENTIAL_KEY. This tag indicates that the key is an Identity

     *    Credential key (which can only sign/MAC very specific messages) and not an Android

     *    Keystore key (which can be used to sign/MAC anything).

     *

     * Additional authorizations may be needed in the softwareEnforced and teeEnforced

     * fields - the above is not an exhaustive list.

     *

     * @param attestationApplicationId is the DER encoded value to be stored

     *     in Tag::ATTESTATION_APPLICATION_ID. This schema is described in

     *     https://developer.android.com/training/articles/security-key-attestation#certificate_schema_attestationid

     *

     * @param attestationChallenge a challenge set by the issuer to ensure freshness.

     *

     * @return result is OK on success, FAILED if an error occurred.

     *

     * @return certificate is the X.509 certificate chain for the credentialKey

     * @return certificateChain is the X.509 certificate chain for the credentialKey

     */

    getAttestationCertificate(vec<uint8_t> attestationChallenge)

        generates(Result result, vec<uint8_t> certificate);

    getAttestationCertificate(vec<uint8_t> attestationApplicationId,

                              vec<uint8_t> attestationChallenge)

        generates(Result result, vec<vec<uint8_t>> certificateChain);



    /**

     * Start the personalization process.

identity/1.0/default/WritableIdentityCredential.cpp

+15 −1
Original line number Diff line number Diff line
@@ -108,7 +108,12 @@ bool WritableIdentityCredential::initialize() { 
    return true;

}



// TODO: use |attestationApplicationId| and |attestationChallenge| and also

//       ensure the returned certificate chain satisfy the requirements listed in

//       the docs for IWritableIdentityCredential::getAttestationCertificate()

//

Return<void> WritableIdentityCredential::getAttestationCertificate(

        const hidl_vec<uint8_t>& /* attestationApplicationId */,

        const hidl_vec<uint8_t>& /* attestationChallenge */,

        getAttestationCertificate_cb _hidl_cb) {

    // For now, we dynamically generate an attestion key on each and every
@@ -181,7 +186,16 @@ Return<void> WritableIdentityCredential::getAttestationCertificate( 
    certificateChain.insert(certificateChain.end(), attestationKeyCertificate.value().begin(),

                            attestationKeyCertificate.value().end());



    _hidl_cb(support::resultOK(), certificateChain);

    optional<vector<vector<uint8_t>>> splitCertChain =

            support::certificateChainSplit(certificateChain);

    if (!splitCertChain) {

        _hidl_cb(support::result(ResultCode::FAILED, "Error splitting certificate chain"), {});

        return Void();

    }

    hidl_vec<hidl_vec<uint8_t>> ret;

    ret.resize(splitCertChain.value().size());

    std::copy(splitCertChain.value().begin(), splitCertChain.value().end(), ret.begin());

    _hidl_cb(support::resultOK(), ret);

    return Void();

}

identity/1.0/default/WritableIdentityCredential.h

+2 −1
Original line number Diff line number Diff line
@@ -51,7 +51,8 @@ class WritableIdentityCredential : public IWritableIdentityCredential { 


    // Methods from ::android::hardware::identity::IWritableIdentityCredential

    // follow.

    Return<void> getAttestationCertificate(const hidl_vec<uint8_t>& attestationChallenge,

    Return<void> getAttestationCertificate(const hidl_vec<uint8_t>& attestationApplicationId,

                                           const hidl_vec<uint8_t>& attestationChallenge,

                                           getAttestationCertificate_cb _hidl_cb) override;



    Return<void> startPersonalization(uint16_t accessControlProfileCount,

identity/1.0/vts/functional/VtsHalIdentityCredentialTargetTest.cpp

+8 −3
Original line number Diff line number Diff line
@@ -201,13 +201,18 @@ TEST_P(IdentityCredentialStoreHidlTest, createAndRetrieveCredential) { 
    ASSERT_NE(writableCredential, nullptr);



    string challenge = "attestationChallenge";

    // TODO: set it to something random and check it's in the cert chain

    vector<uint8_t> attestationApplicationId = {};

    vector<uint8_t> attestationChallenge(challenge.begin(), challenge.end());

    vector<uint8_t> attestationCertificate;

    writableCredential->getAttestationCertificate(

            attestationChallenge,

            [&](const Result& _result, const hidl_vec<uint8_t>& _attestationCertificate) {

            attestationApplicationId, attestationChallenge,

            [&](const Result& _result, const hidl_vec<hidl_vec<uint8_t>>& _splitCertChain) {

                result = _result;

                attestationCertificate = _attestationCertificate;

                vector<vector<uint8_t>> splitCerts;

                std::copy(_splitCertChain.begin(), _splitCertChain.end(),

                          std::back_inserter(splitCerts));

                attestationCertificate = support::certificateChainJoin(splitCerts);

            });

    EXPECT_EQ("", result.message);

    ASSERT_EQ(ResultCode::OK, result.code);