Merge "identity: Fix attestation and documentation problems." am: d47c62b62a (e727d997) · Commits · e / os / android_hardware_interfaces

identity/aidl/android/hardware/identity/IIdentityCredential.aidl

+10 −9

Original line number	Diff line number	Diff line
		@@ -55,7 +55,7 @@ interface IIdentityCredential {
		* This method may only be called once per instance. If called more than once, STATUS_FAILED
		* will be returned.
		*
		* @return the unencrypted key-pair in PKCS#8 format.
		* @return the private key, in DER format as specified in RFC 5915.
		*/
		byte[] createEphemeralKeyPair();

		@@ -88,10 +88,10 @@ interface IIdentityCredential {
		* The setRequestedNamespaces() and setVerificationToken() methods will be called before
		* this method is called.
		*
		* This method be called after createEphemeralKeyPair(), setReaderEphemeralPublicKey(),
		* createAuthChallenge() and before startRetrieveEntry(). This method call is followed by
		* multiple calls of startRetrieveEntryValue(), retrieveEntryValue(), and finally
		* finishRetrieval().
		* This method is called after createEphemeralKeyPair(), setReaderEphemeralPublicKey(),
		* createAuthChallenge() (note that those calls are optional) and before startRetrieveEntry().
		* This method call is followed by multiple calls of startRetrieveEntryValue(),
		* retrieveEntryValue(), and finally finishRetrieval().
		*
		* It is permissible to perform data retrievals multiple times using the same instance (e.g.
		* startRetrieval(), then multiple calls of startRetrieveEntryValue(), retrieveEntryValue(),
		@@ -343,12 +343,13 @@ interface IIdentityCredential {
		*
		* - signature: must be set to ECDSA.
		*
		* - subject: CN shall be set to "Android Identity Credential Authentication Key".
		* - subject: CN shall be set to "Android Identity Credential Authentication Key". (fixed
		* value: same on all certs)
		*
		* - issuer: shall be set to "credentialStoreName (credentialStoreAuthorName)" using the
		* values returned in HardwareInformation.
		* - issuer: CN shall be set to "Android Identity Credential Key". (fixed value:
		* same on all certs)
		*
		* - validity: should be from current time and one year in the future.
		* - validity: should be from current time and one year in the future (365 days).
		*
		* - subjectPublicKeyInfo: must contain attested public key.
		*

identity/aidl/android/hardware/identity/IWritableIdentityCredential.aidl

+19 −20

Original line number	Diff line number	Diff line
		@@ -37,12 +37,12 @@ interface IWritableIdentityCredential {
		*
		* - signature: must be set to ECDSA.
		*
		* - subject: CN shall be set to "Android Identity Credential Key".
		* - subject: CN shall be set to "Android Identity Credential Key". (fixed value:
		* same on all certs)
		*
		* - issuer: shall be set to "credentialStoreName (credentialStoreAuthorName)" using the
		* values returned in HardwareInformation.
		* - issuer: Same as the subject field of the batch attestation key.
		*
		* - validity: should be from current time and expire at the same time as the
		* - validity: Should be set to current time and expire at the same time as the
		* attestation batch certificate used.
		*
		* - subjectPublicKeyInfo: must contain attested public key.
		@@ -55,19 +55,14 @@ interface IWritableIdentityCredential {
		*
		* - 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).
		* implemented.
		*
		* - 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 keymasterVersion field in the attestation extension must be set to the.
		* same value as used for Android Keystore keys.
		*
		* - 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 Trusted Application backing the HAL implementation is implemented.
		*
		* - The attestationChallenge field must be set to the passed-in challenge.
		*
		@@ -81,7 +76,8 @@ interface IWritableIdentityCredential {
		*
		* - Tag::IDENTITY_CREDENTIAL_KEY which 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).
		* Keystore key (which can be used to sign/MAC anything). This must not be set
		* for test credentials.
		*
		* - Tag::PURPOSE must be set to SIGN
		*
		@@ -95,10 +91,13 @@ interface IWritableIdentityCredential {
		*
		* - Tag::EC_CURVE must be set to P_256
		*
		* Additional authorizations may be needed in the softwareEnforced and teeEnforced
		* fields - the above is not an exhaustive list. Specifically, authorizations containing
		* information about the root of trust, OS version, verified boot state, and so on should
		* be included.
		* - Tag::ROOT_OF_TRUST must be set
		*
		* - Tag::OS_VERSION and Tag::OS_PATCHLEVEL must be set
		*
		* Additional authorizations may be appear in the softwareEnforced and teeEnforced
		* fields. For example if the device has a boot or vendor partitions, then BOOT_PATCHLEVEL
		* and VENDOR_PATCHLEVEL should be set.
		*
		* Since the chain is required to be generated using Keymaster Attestation, the returned
		* certificate chain has the following properties:
		@@ -112,8 +111,8 @@ interface IWritableIdentityCredential {
		* As with any user of attestation, the Issuing Authority (as a relying party) wishing
		* to issue a credential to a device using these APIs, must carefully examine the
		* returned certificate chain for all of the above (and more). In particular, the Issuing
		* Authority should check the root of trust, verified boot state, patch level,
		* application id, etc.
		* Authority should check the root of trust (which include verified boot state), patch level,
		* attestation application id, etc.
		*
		* This all depends on the needs of the Issuing Authority and the kind of credential but
		* in general an Issuing Authority should never issue a credential to a device without

identity/aidl/default/IdentityCredential.cpp

+12 −34

Original line number	Diff line number	Diff line
		@@ -272,6 +272,7 @@ ndk::ScopedAStatus IdentityCredential::startRetrieval(
		const HardwareAuthToken& authToken, const vector<uint8_t>& itemsRequest,
		const vector<uint8_t>& signingKeyBlob, const vector<uint8_t>& sessionTranscript,
		const vector<uint8_t>& readerSignature, const vector<int32_t>& requestCounts) {
		std::unique_ptr<cppbor::Item> sessionTranscriptItem;
		if (sessionTranscript.size() > 0) {
		auto [item, _, message] = cppbor::parse(sessionTranscript);
		if (item == nullptr) {
		@@ -279,7 +280,7 @@ ndk::ScopedAStatus IdentityCredential::startRetrieval(
		IIdentityCredentialStore::STATUS_INVALID_DATA,
		"SessionTranscript contains invalid CBOR"));
		}
		sessionTranscriptItem_ = std::move(item);
		sessionTranscriptItem = std::move(item);
		}
		if (numStartRetrievalCalls_ > 0) {
		if (sessionTranscript_ != sessionTranscript) {
		@@ -319,7 +320,7 @@ ndk::ScopedAStatus IdentityCredential::startRetrieval(
		vector<uint8_t> encodedReaderAuthentication =
		cppbor::Array()
		.add("ReaderAuthentication")
		.add(sessionTranscriptItem_->clone())
		.add(std::move(sessionTranscriptItem))
		.add(cppbor::Semantic(24, itemsRequestBytes))
		.encode();
		vector<uint8_t> encodedReaderAuthenticationBytes =
		@@ -776,13 +777,6 @@ ndk::ScopedAStatus IdentityCredential::finishRetrieval(vector<uint8_t>* outMac,
		optional<vector<uint8_t>> mac;
		if (signingKeyBlob_.size() > 0 && sessionTranscript_.size() > 0 &&
		readerPublicKey_.size() > 0) {
		cppbor::Array array;
		array.add("DeviceAuthentication");
		array.add(sessionTranscriptItem_->clone());
		array.add(docType_);
		array.add(cppbor::Semantic(24, encodedDeviceNameSpaces));
		vector<uint8_t> deviceAuthenticationBytes = cppbor::Semantic(24, array.encode()).encode();

		vector<uint8_t> docTypeAsBlob(docType_.begin(), docType_.end());
		optional<vector<uint8_t>> signingKey =
		support::decryptAes128Gcm(storageKey_, signingKeyBlob_, docTypeAsBlob);
		@@ -792,31 +786,15 @@ ndk::ScopedAStatus IdentityCredential::finishRetrieval(vector<uint8_t>* outMac,
		"Error decrypting signingKeyBlob"));
		}

		optional<vector<uint8_t>> sharedSecret =
		support::ecdh(readerPublicKey_, signingKey.value());
		if (!sharedSecret) {
		return ndk::ScopedAStatus(AStatus_fromServiceSpecificErrorWithMessage(
		IIdentityCredentialStore::STATUS_FAILED, "Error doing ECDH"));
		}

		// Mix-in SessionTranscriptBytes
		vector<uint8_t> sessionTranscriptBytes = cppbor::Semantic(24, sessionTranscript_).encode();
		vector<uint8_t> sharedSecretWithSessionTranscriptBytes = sharedSecret.value();
		std::copy(sessionTranscriptBytes.begin(), sessionTranscriptBytes.end(),
		std::back_inserter(sharedSecretWithSessionTranscriptBytes));

		vector<uint8_t> salt = {0x00};
		vector<uint8_t> info = {};
		optional<vector<uint8_t>> derivedKey =
		support::hkdf(sharedSecretWithSessionTranscriptBytes, salt, info, 32);
		if (!derivedKey) {
		optional<vector<uint8_t>> eMacKey =
		support::calcEMacKey(signingKey.value(), readerPublicKey_, sessionTranscriptBytes);
		if (!eMacKey) {
		return ndk::ScopedAStatus(AStatus_fromServiceSpecificErrorWithMessage(
		IIdentityCredentialStore::STATUS_FAILED,
		"Error deriving key from shared secret"));
		IIdentityCredentialStore::STATUS_FAILED, "Error calculating EMacKey"));
		}

		mac = support::coseMac0(derivedKey.value(), {}, // payload
		deviceAuthenticationBytes); // detached content
		mac = support::calcMac(sessionTranscript_, docType_, encodedDeviceNameSpaces,
		eMacKey.value());
		if (!mac) {
		return ndk::ScopedAStatus(AStatus_fromServiceSpecificErrorWithMessage(
		IIdentityCredentialStore::STATUS_FAILED, "Error MACing data"));
		@@ -830,9 +808,9 @@ ndk::ScopedAStatus IdentityCredential::finishRetrieval(vector<uint8_t>* outMac,

		ndk::ScopedAStatus IdentityCredential::generateSigningKeyPair(
		vector<uint8_t>* outSigningKeyBlob, Certificate* outSigningKeyCertificate) {
		string serialDecimal = "0"; // TODO: set serial to something unique
		string issuer = "Android Open Source Project";
		string subject = "Android IdentityCredential Reference Implementation";
		string serialDecimal = "1";
		string issuer = "Android Identity Credential Key";
		string subject = "Android Identity Credential Authentication Key";
		time_t validityNotBefore = time(nullptr);
		time_t validityNotAfter = validityNotBefore + 365 * 24 * 3600;

identity/aidl/default/IdentityCredential.h

+0 −1

Original line number	Diff line number	Diff line
		@@ -103,7 +103,6 @@ class IdentityCredential : public BnIdentityCredential {
		map<int32_t, int> profileIdToAccessCheckResult_;
		vector<uint8_t> signingKeyBlob_;
		vector<uint8_t> sessionTranscript_;
		std::unique_ptr<cppbor::Item> sessionTranscriptItem_;
		vector<uint8_t> itemsRequest_;
		vector<int32_t> requestCountsRemaining_;
		map<string, set<string>> requestedNameSpacesAndNames_;

identity/aidl/default/WritableIdentityCredential.cpp

+1 −1

Original line number	Diff line number	Diff line
		@@ -74,7 +74,7 @@ ndk::ScopedAStatus WritableIdentityCredential::getAttestationCertificate(
		vector<uint8_t> appId(attestationApplicationId.begin(), attestationApplicationId.end());

		optional<std::pair<vector<uint8_t>, vector<vector<uint8_t>>>> keyAttestationPair =
		support::createEcKeyPairAndAttestation(challenge, appId);
		support::createEcKeyPairAndAttestation(challenge, appId, testCredential_);
		if (!keyAttestationPair) {
		LOG(ERROR) << "Error creating credentialKey and attestation";
		return ndk::ScopedAStatus(AStatus_fromServiceSpecificErrorWithMessage(