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Identity: Update for changes to ISO 18013-5.

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Key derivation for session encryption and MACing now involves mixing
in SessionTranscriptBytes. Update docs, default implementation, and
VTS tests to reflect this.

Also, the standard changed such that instead of DeviceAuthentication
being MACed or signed, it's instead DeviceAuthenticationBytes which is
defined as #6.24(bstr .cbor DeviceAuthentication). The same also for
ReaderAuthentication, now ReaderAuthenticationBytes is the CBOR which
is signed by the reader.

Also update the URL for CDDL since it's now a published RFC.

Bug: 159482543
Test: atest VtsHalIdentityTargetTest
Test: atest android.security.identity.cts
Change-Id: I73fc7eb48ffb71e00a8b54849266ed814295fa39
This commit is contained in:
David Zeuthen 2020-06-20 17:04:41 -04:00
parent 780f8c860d
commit 2e4533e5c1
5 changed files with 79 additions and 44 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

10
identity/aidl/android/hardware/identity/IIdentityCredential.aidl
View file

@ -151,8 +151,8 @@ interface IIdentityCredential {
* IntentToRetain = bool
*
* For the readerSignature parameter, this can either be empty or if non-empty it
* must be a COSE_Sign1 structure with an ECDSA signature over the content of the
* CBOR conforming to the following CDDL:
* must be a COSE_Sign1 where the payload is the bytes of the
* ReaderAuthenticationBytes CBOR defined below:
*
* ReaderAuthentication = [
* "ReaderAuthentication",
@ -164,6 +164,8 @@ interface IIdentityCredential {
*
* ItemsRequestBytes = #6.24(bstr .cbor ItemsRequest)
*
* ReaderAuthenticationBytes = #6.24(bstr .cbor ReaderAuthentication)
*
* The public key corresponding to the key used to made signature, can be found in the
* 'x5chain' unprotected header element of the COSE_Sign1 structure (as as described
* in 'draft-ietf-cose-x509-04'). There will be at least one certificate in said element
@ -278,7 +280,7 @@ interface IIdentityCredential {
*
* @param out mac is empty if signingKeyBlob or the sessionTranscript passed to
* startRetrieval() is empty. Otherwise it is a COSE_Mac0 with empty payload
* and the detached content is set to DeviceAuthentication as defined below.
* and the detached content is set to DeviceAuthenticationBytes as defined below.
* This code is produced by using the key agreement and key derivation function
* from the ciphersuite with the authentication private key and the reader
* ephemeral public key to compute a shared message authentication code (MAC)
@ -299,6 +301,8 @@ interface IIdentityCredential {
*
* DeviceNameSpacesBytes = #6.24(bstr .cbor DeviceNameSpaces)
*
* DeviceAuthenticationBytes = #6.24(bstr .cbor DeviceAuthentication)
*
* where
*
* DeviceNameSpaces = {

2
identity/aidl/android/hardware/identity/IIdentityCredentialStore.aidl
View file

@ -99,7 +99,7 @@ import android.hardware.identity.CipherSuite;
* Various fields need to be encoded as precisely-specified byte arrays. Where existing standards
* define appropriate encodings, those are used. For example, X.509 certificates. Where new
* encodings are needed, CBOR is used. CBOR maps are described in CDDL notation
* (https://tools.ietf.org/html/draft-ietf-cbor-cddl-06).
* (https://tools.ietf.org/html/rfc8610).
*
* All binder calls in the HAL may return a ServiceSpecificException with statuses from the
* STATUS_* integers defined in this interface. Each method states which status can be returned

34
identity/aidl/default/IdentityCredential.cpp
View file

@ -39,6 +39,10 @@ using ::std::optional;
using namespace ::android::hardware::identity;
int IdentityCredential::initialize() {
if (credentialData_.size() == 0) {
LOG(ERROR) << "CredentialData is empty";
return IIdentityCredentialStore::STATUS_INVALID_DATA;
}
auto [item, _, message] = cppbor::parse(credentialData_);
if (item == nullptr) {
LOG(ERROR) << "CredentialData is not valid CBOR: " << message;
@ -312,13 +316,16 @@ ndk::ScopedAStatus IdentityCredential::startRetrieval(
}
const vector<uint8_t>& itemsRequestBytes = itemsRequest;
vector<uint8_t> dataThatWasSigned = cppbor::Array()
.add("ReaderAuthentication")
.add(sessionTranscriptItem_->clone())
.add(cppbor::Semantic(24, itemsRequestBytes))
.encode();
vector<uint8_t> encodedReaderAuthentication =
cppbor::Array()
.add("ReaderAuthentication")
.add(sessionTranscriptItem_->clone())
.add(cppbor::Semantic(24, itemsRequestBytes))
.encode();
vector<uint8_t> encodedReaderAuthenticationBytes =
cppbor::Semantic(24, encodedReaderAuthentication).encode();
if (!support::coseCheckEcDsaSignature(readerSignature,
dataThatWasSigned, // detached content
encodedReaderAuthenticationBytes, // detached content
readerPublicKey.value())) {
return ndk::ScopedAStatus(AStatus_fromServiceSpecificErrorWithMessage(
IIdentityCredentialStore::STATUS_READER_SIGNATURE_CHECK_FAILED,
@ -774,7 +781,7 @@ ndk::ScopedAStatus IdentityCredential::finishRetrieval(vector<uint8_t>* outMac,
array.add(sessionTranscriptItem_->clone());
array.add(docType_);
array.add(cppbor::Semantic(24, encodedDeviceNameSpaces));
vector<uint8_t> encodedDeviceAuthentication = array.encode();
vector<uint8_t> deviceAuthenticationBytes = cppbor::Semantic(24, array.encode()).encode();
vector<uint8_t> docTypeAsBlob(docType_.begin(), docType_.end());
optional<vector<uint8_t>> signingKey =
@ -792,17 +799,24 @@ ndk::ScopedAStatus IdentityCredential::finishRetrieval(vector<uint8_t>* outMac,
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(sharedSecret.value(), salt, info, 32);
optional<vector<uint8_t>> derivedKey =
support::hkdf(sharedSecretWithSessionTranscriptBytes, salt, info, 32);
if (!derivedKey) {
return ndk::ScopedAStatus(AStatus_fromServiceSpecificErrorWithMessage(
IIdentityCredentialStore::STATUS_FAILED,
"Error deriving key from shared secret"));
}
mac = support::coseMac0(derivedKey.value(), {}, // payload
encodedDeviceAuthentication); // additionalData
mac = support::coseMac0(derivedKey.value(), {}, // payload
deviceAuthenticationBytes); // detached content
if (!mac) {
return ndk::ScopedAStatus(AStatus_fromServiceSpecificErrorWithMessage(
IIdentityCredentialStore::STATUS_FAILED, "Error MACing data"));

38
identity/aidl/vts/ReaderAuthTests.cpp
View file

@ -289,16 +289,19 @@ void ReaderAuthTests::retrieveData(const vector<uint8_t>& readerPrivateKey,
.add("Accessible by None", false)))
.encode();
}
vector<uint8_t> dataToSign = cppbor::Array()
.add("ReaderAuthentication")
.add(sessionTranscript.clone())
.add(cppbor::Semantic(24, itemsRequestBytes))
.encode();
vector<uint8_t> encodedReaderAuthentication =
cppbor::Array()
.add("ReaderAuthentication")
.add(sessionTranscript.clone())
.add(cppbor::Semantic(24, itemsRequestBytes))
.encode();
vector<uint8_t> encodedReaderAuthenticationBytes =
cppbor::Semantic(24, encodedReaderAuthentication).encode();
optional<vector<uint8_t>> readerSignature =
support::coseSignEcDsa(readerPrivateKey, // private key for reader
{}, // content
dataToSign, // detached content
support::coseSignEcDsa(readerPrivateKey, // private key for reader
{}, // content
encodedReaderAuthenticationBytes, // detached content
support::certificateChainJoin(readerCertChain));
ASSERT_TRUE(readerSignature);
@ -528,17 +531,20 @@ TEST_P(ReaderAuthTests, ephemeralKeyNotInSessionTranscript) {
.add("Accessible by C", false)
.add("Accessible by None", false)))
.encode();
vector<uint8_t> dataToSign = cppbor::Array()
.add("ReaderAuthentication")
.add(sessionTranscript.clone())
.add(cppbor::Semantic(24, itemsRequestBytes))
.encode();
vector<uint8_t> encodedReaderAuthentication =
cppbor::Array()
.add("ReaderAuthentication")
.add(sessionTranscript.clone())
.add(cppbor::Semantic(24, itemsRequestBytes))
.encode();
vector<uint8_t> encodedReaderAuthenticationBytes =
cppbor::Semantic(24, encodedReaderAuthentication).encode();
vector<vector<uint8_t>> readerCertChain = {cert_reader_SelfSigned_};
optional<vector<uint8_t>> readerSignature =
support::coseSignEcDsa(readerPrivateKey_, // private key for reader
{}, // content
dataToSign, // detached content
support::coseSignEcDsa(readerPrivateKey_, // private key for reader
{}, // content
encodedReaderAuthenticationBytes, // detached content
support::certificateChainJoin(readerCertChain));
ASSERT_TRUE(readerSignature);

39
identity/aidl/vts/VtsHalIdentityEndToEndTest.cpp
View file

@ -319,7 +319,7 @@ TEST_P(IdentityAidl, createAndRetrieveCredential) {
cppbor::Array sessionTranscript = cppbor::Array()
.add(cppbor::Semantic(24, deviceEngagementBytes))
.add(cppbor::Semantic(24, eReaderPubBytes));
vector<uint8_t> sessionTranscriptBytes = sessionTranscript.encode();
vector<uint8_t> sessionTranscriptEncoded = sessionTranscript.encode();
vector<uint8_t> itemsRequestBytes =
cppbor::Map("nameSpaces",
@ -347,14 +347,17 @@ TEST_P(IdentityAidl, createAndRetrieveCredential) {
" },\n"
"}",
cborPretty);
vector<uint8_t> dataToSign = cppbor::Array()
.add("ReaderAuthentication")
.add(sessionTranscript.clone())
.add(cppbor::Semantic(24, itemsRequestBytes))
.encode();
vector<uint8_t> encodedReaderAuthentication =
cppbor::Array()
.add("ReaderAuthentication")
.add(sessionTranscript.clone())
.add(cppbor::Semantic(24, itemsRequestBytes))
.encode();
vector<uint8_t> encodedReaderAuthenticationBytes =
cppbor::Semantic(24, encodedReaderAuthentication).encode();
optional<vector<uint8_t>> readerSignature =
support::coseSignEcDsa(readerKey, {}, // content
dataToSign, // detached content
support::coseSignEcDsa(readerKey, {}, // content
encodedReaderAuthenticationBytes, // detached content
readerCertificate.value());
ASSERT_TRUE(readerSignature);
@ -388,7 +391,7 @@ TEST_P(IdentityAidl, createAndRetrieveCredential) {
credential->setVerificationToken(verificationToken);
ASSERT_TRUE(credential
->startRetrieval(secureProfiles.value(), authToken, itemsRequestBytes,
signingKeyBlob, sessionTranscriptBytes,
signingKeyBlob, sessionTranscriptEncoded,
readerSignature.value(), testEntriesEntryCounts)
.isOk());
@ -432,7 +435,7 @@ TEST_P(IdentityAidl, createAndRetrieveCredential) {
" },\n"
"}",
cborPretty);
// The data that is MACed is ["DeviceAuthentication", sessionTranscriptBytes, docType,
// The data that is MACed is ["DeviceAuthentication", sessionTranscript, docType,
// deviceNameSpacesBytes] so build up that structure
cppbor::Array deviceAuthentication;
deviceAuthentication.add("DeviceAuthentication");
@ -441,7 +444,8 @@ TEST_P(IdentityAidl, createAndRetrieveCredential) {
string docType = "org.iso.18013-5.2019.mdl";
deviceAuthentication.add(docType);
deviceAuthentication.add(cppbor::Semantic(24, deviceNameSpacesBytes));
vector<uint8_t> encodedDeviceAuthentication = deviceAuthentication.encode();
vector<uint8_t> deviceAuthenticationBytes =
cppbor::Semantic(24, deviceAuthentication.encode()).encode();
// Derive the key used for MACing.
optional<vector<uint8_t>> readerEphemeralPrivateKey =
@ -449,13 +453,20 @@ TEST_P(IdentityAidl, createAndRetrieveCredential) {
optional<vector<uint8_t>> sharedSecret =
support::ecdh(signingPubKey.value(), readerEphemeralPrivateKey.value());
ASSERT_TRUE(sharedSecret);
// Mix-in SessionTranscriptBytes
vector<uint8_t> sessionTranscriptBytes =
cppbor::Semantic(24, sessionTranscript.encode()).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(sharedSecret.value(), salt, info, 32);
optional<vector<uint8_t>> derivedKey =
support::hkdf(sharedSecretWithSessionTranscriptBytes, salt, info, 32);
ASSERT_TRUE(derivedKey);
optional<vector<uint8_t>> calculatedMac =
support::coseMac0(derivedKey.value(), {}, // payload
encodedDeviceAuthentication); // detached content
support::coseMac0(derivedKey.value(), {}, // payload
deviceAuthenticationBytes); // detached content
ASSERT_TRUE(calculatedMac);
EXPECT_EQ(mac, calculatedMac);
}