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Support 32 bytes session key

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[ Merge of http://go/wvgerrit/149849 ]

With ECC based DRM cert, the session key is expected to be 32, as
compared to 16 bytes in RSA case. This CL adds supports for 32 bytes
session key.

Bug: 236317198
Test: oemcrypto_test
Change-Id: I657fdd92d17736a23375ddcd457f83efa6ca6d1f
This commit is contained in:
Alex Dale
2022-06-21 16:01:20 -07:00
parent 02c7062349
commit d874fffaec
6 changed files with 63 additions and 21 deletions
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24
libwvdrmengine/oemcrypto/test/oec_key_deriver.cpp
View File

@@ -83,19 +83,23 @@ void Encryptor::PadAndEncryptProvisioningMessage(
// This generates the data for deriving one key. If there are failures in
// this function, then there is something wrong with the test program and its
// dependency on BoringSSL.
void KeyDeriver::DeriveKey(const uint8_t* key, const vector<uint8_t>& context,
int counter, vector<uint8_t>* out) {
void KeyDeriver::DeriveKey(const uint8_t* key, size_t master_key_size,
const vector<uint8_t>& context, int counter,
vector<uint8_t>* out) {
ASSERT_NE(key, nullptr);
ASSERT_FALSE(context.empty());
ASSERT_GE(4, counter);
ASSERT_LE(1, counter);
ASSERT_NE(out, nullptr);
// For RSA, the master key is expected to be 16 bytes; for EC key, 32 bytes.
ASSERT_TRUE(master_key_size == KEY_SIZE || master_key_size == 2 * KEY_SIZE);
const EVP_CIPHER* cipher = EVP_aes_128_cbc();
const EVP_CIPHER* cipher =
master_key_size == KEY_SIZE ? EVP_aes_128_cbc() : EVP_aes_256_cbc();
CMAC_CTX* cmac_ctx = CMAC_CTX_new();
ASSERT_NE(nullptr, cmac_ctx);
ASSERT_TRUE(CMAC_Init(cmac_ctx, key, KEY_SIZE, cipher, nullptr));
ASSERT_TRUE(CMAC_Init(cmac_ctx, key, master_key_size, cipher, nullptr));
std::vector<uint8_t> message;
message.push_back(static_cast<uint8_t>(counter));
@@ -114,24 +118,24 @@ void KeyDeriver::DeriveKey(const uint8_t* key, const vector<uint8_t>& context,
// This generates the data for deriving a set of keys. If there are failures in
// this function, then there is something wrong with the test program and its
// dependency on BoringSSL.
void KeyDeriver::DeriveKeys(const uint8_t* master_key,
void KeyDeriver::DeriveKeys(const uint8_t* master_key, size_t master_key_size,
const vector<uint8_t>& mac_key_context,
const vector<uint8_t>& enc_key_context) {
// Generate derived key for mac key
std::vector<uint8_t> mac_key_part2;
DeriveKey(master_key, mac_key_context, 1, &mac_key_server_);
DeriveKey(master_key, mac_key_context, 2, &mac_key_part2);
DeriveKey(master_key, master_key_size, mac_key_context, 1, &mac_key_server_);
DeriveKey(master_key, master_key_size, mac_key_context, 2, &mac_key_part2);
mac_key_server_.insert(mac_key_server_.end(), mac_key_part2.begin(),
mac_key_part2.end());
DeriveKey(master_key, mac_key_context, 3, &mac_key_client_);
DeriveKey(master_key, mac_key_context, 4, &mac_key_part2);
DeriveKey(master_key, master_key_size, mac_key_context, 3, &mac_key_client_);
DeriveKey(master_key, master_key_size, mac_key_context, 4, &mac_key_part2);
mac_key_client_.insert(mac_key_client_.end(), mac_key_part2.begin(),
mac_key_part2.end());
// Generate derived key for encryption key
std::vector<uint8_t> enc_key;
DeriveKey(master_key, enc_key_context, 1, &enc_key);
DeriveKey(master_key, master_key_size, enc_key_context, 1, &enc_key);
set_enc_key(enc_key);
}