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Unit tests for forbidden RSA key usage

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This CL adds unit tests to verify that the following
forbidden uses of an RSA private key do not work:

- ForbidPrepAndSign -- A cast cert key cannot sign a license
  request.
- ForbidUseAsDRMCert -- A cast cert cannot be used with the
  DRM cert's padding scheme and it cannot be used to derive
  keys from a session key.
- *ForbidRSASignatureForDRMKey* -- A DRM cert key cannot be
  used with GenerateRSASignature.
- *OEMCertForbidGenerateRSASignature* -- An OEM cert key
  cannot be used with GenerateRSASignature.

Bug: 251875110
Change-Id: Ic2b23e3fd279e878c190a8294078a8d092126a29
This commit is contained in:
Fred Gylys-Colwell
2023-08-20 21:40:02 -07:00
committed by Robert Shih
parent 343324e97c
commit 8f3ee84c1b
4 changed files with 124 additions and 41 deletions
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72
libwvdrmengine/oemcrypto/test/oemcrypto_cast_test.cpp
View File

@@ -11,16 +11,32 @@ using ::testing::Range;
namespace wvoec {
// The alternate padding is only required for cast receivers, but if a device
// does load an alternate certificate, it should NOT use it for generating
// a license request signature.
/** If a device can load a private key with the alternate padding schemes, it
* should support signing with the alternate scheme. */
TEST_F(OEMCryptoLoadsCertificateAlternates, TestSignaturePKCS1) {
// TODO(b/197141970): Need to revisit OEMCryptoLoadsCert* tests for
// provisioning 4. Disabled here temporarily.
if (!global_features.loads_certificate ||
global_features.provisioning_method == OEMCrypto_BootCertificateChain) {
GTEST_SKIP() << "Test for non Prov 4.0 devices only.";
// Try to load an RSA key with alternative padding schemes. This signing
// scheme is used by cast receivers.
LoadCastCertificateKey(false);
// If the device is a cast receiver, then this scheme is required.
if (global_features.cast_receiver) {
ASSERT_TRUE(key_loaded_);
// A signature with a valid size should succeed.
TestSignature(kSign_PKCS1_Block1, 83);
TestSignature(kSign_PKCS1_Block1, 50);
}
// If the key loaded with no error, then we will verify that it is not used
// for forbidden padding schemes. This should be tested for both devices that
// are cast receivers and devices that are not.
if (key_loaded_) {
// A signature with padding that is too big should fail.
DisallowForbiddenPaddingDRMKey(kSign_PKCS1_Block1, 84); // too big.
}
}
/** The alternate padding is only required for cast receivers, but if a device
* does load an alternate certificate, it should NOT be used to as a DRM cert
* key. */
TEST_F(OEMCryptoLoadsCertificateAlternates, ForbidUseAsDRMCert) {
// Try to load an RSA key with alternative padding schemes. This signing
// scheme is used by cast receivers.
LoadCastCertificateKey(false);
@@ -34,13 +50,39 @@ TEST_F(OEMCryptoLoadsCertificateAlternates, TestSignaturePKCS1) {
// The other padding scheme should fail.
DisallowForbiddenPaddingDRMKey(kSign_RSASSA_PSS, 83);
DisallowDeriveKeys();
if (global_features.cast_receiver) {
// A signature with a valid size should succeed.
TestSignature(kSign_PKCS1_Block1, 83);
TestSignature(kSign_PKCS1_Block1, 50);
}
// A signature with padding that is too big should fail.
DisallowForbiddenPaddingDRMKey(kSign_PKCS1_Block1, 84); // too big.
}
}
/** A Cast receiver certificate private key cannot be used with the function
* PrepAndSignLicenseRequest.
*/
TEST_F(OEMCryptoLoadsCertificateAlternates, ForbidPrepAndSign) {
// Try to load an RSA key with alternative padding schemes. This signing
// scheme is used by cast receivers.
LoadCastCertificateKey(false);
// If the device is a cast receiver, then this scheme is required.
if (global_features.cast_receiver) {
ASSERT_TRUE(key_loaded_);
}
// If the key loaded with no error, then we will verify that it is not used
// for forbidden padding schemes.
if (key_loaded_) {
Session s;
ASSERT_NO_FATAL_FAILURE(s.open());
ASSERT_NO_FATAL_FAILURE(s.LoadWrappedRsaDrmKey(wrapped_drm_key_));
s.GenerateNonce();
size_t core_message_length = 100;
std::vector<uint8_t> message(128, 0);
std::vector<uint8_t> signature(256, 0);
size_t signature_length = signature.size();
OEMCryptoResult result = OEMCrypto_PrepAndSignLicenseRequest(
s.session_id(), message.data(), message.size(), &core_message_length,
signature.data(), &signature_length);
ASSERT_EQ(OEMCrypto_ERROR_INVALID_KEY, result);
const vector<uint8_t> zero(signature.size(), 0);
ASSERT_EQ(signature, zero); // Signature should not have been computed.
}
}