private static BCryptAlgorithmHandle GetEncryptionAlgorithmHandleAndCheckKeySize(string encryptionAlgorithm, string encryptionAlgorithmProvider, uint keyLengthInBits)
{
BCryptAlgorithmHandle algorithmHandle = null;
// Special-case cached providers
if (encryptionAlgorithmProvider == null)
{
if (encryptionAlgorithm == Constants.BCRYPT_AES_ALGORITHM)
{
algorithmHandle = CachedAlgorithmHandles.AES_GCM;
}
}
// Look up the provider dynamically if we couldn't fetch a cached instance
if (algorithmHandle == null)
{
algorithmHandle = BCryptAlgorithmHandle.OpenAlgorithmHandle(encryptionAlgorithm, encryptionAlgorithmProvider);
algorithmHandle.SetChainingMode(Constants.BCRYPT_CHAIN_MODE_GCM);
}
// make sure we're using a block cipher with an appropriate block size
uint cipherBlockSizeInBytes = algorithmHandle.GetCipherBlockLength();
CryptoUtil.Assert(cipherBlockSizeInBytes == 128 / 8, "cipherBlockSizeInBytes == 128 / 8");
// make sure the provided key length is valid
algorithmHandle.GetSupportedKeyLengths().EnsureValidKeyLength(keyLengthInBits);
// all good!
return(algorithmHandle);
}
public CbcAuthenticatedEncryptor(ProtectedMemoryBlob keyDerivationKey, BCryptAlgorithmHandle symmetricAlgorithmHandle, uint symmetricAlgorithmKeySizeInBytes, BCryptAlgorithmHandle hmacAlgorithmHandle, IBCryptGenRandom genRandom = null)
{
CryptoUtil.Assert(KEY_MODIFIER_SIZE_IN_BYTES <= symmetricAlgorithmKeySizeInBytes && symmetricAlgorithmKeySizeInBytes <= Constants.MAX_STACKALLOC_BYTES,
"KEY_MODIFIER_SIZE_IN_BYTES <= symmetricAlgorithmKeySizeInBytes && symmetricAlgorithmKeySizeInBytes <= Constants.MAX_STACKALLOC_BYTES");
_genRandom = genRandom ?? BCryptGenRandomImpl.Instance;
_sp800_108_ctr_hmac_provider = SP800_108_CTR_HMACSHA512Util.CreateProvider(keyDerivationKey);
_symmetricAlgorithmHandle = symmetricAlgorithmHandle;
_symmetricAlgorithmBlockSizeInBytes = symmetricAlgorithmHandle.GetCipherBlockLength();
_symmetricAlgorithmSubkeyLengthInBytes = symmetricAlgorithmKeySizeInBytes;
_hmacAlgorithmHandle = hmacAlgorithmHandle;
_hmacAlgorithmDigestLengthInBytes = hmacAlgorithmHandle.GetHashDigestLength();
_hmacAlgorithmSubkeyLengthInBytes = _hmacAlgorithmDigestLengthInBytes; // for simplicity we'll generate HMAC subkeys with a length equal to the digest length
CryptoUtil.Assert(SYMMETRIC_ALG_MIN_BLOCK_SIZE_IN_BYTES <= _symmetricAlgorithmBlockSizeInBytes && _symmetricAlgorithmBlockSizeInBytes <= Constants.MAX_STACKALLOC_BYTES,
"SYMMETRIC_ALG_MIN_BLOCK_SIZE_IN_BYTES <= _symmetricAlgorithmBlockSizeInBytes && _symmetricAlgorithmBlockSizeInBytes <= Constants.MAX_STACKALLOC_BYTES");
CryptoUtil.Assert(HASH_ALG_MIN_DIGEST_LENGTH_IN_BYTES <= _hmacAlgorithmDigestLengthInBytes,
"HASH_ALG_MIN_DIGEST_LENGTH_IN_BYTES <= _hmacAlgorithmDigestLengthInBytes");
CryptoUtil.Assert(KEY_MODIFIER_SIZE_IN_BYTES <= _hmacAlgorithmSubkeyLengthInBytes && _hmacAlgorithmSubkeyLengthInBytes <= Constants.MAX_STACKALLOC_BYTES,
"KEY_MODIFIER_SIZE_IN_BYTES <= _hmacAlgorithmSubkeyLengthInBytes && _hmacAlgorithmSubkeyLengthInBytes <= Constants.MAX_STACKALLOC_BYTES");
_contextHeader = CreateContextHeader();
}
public CngGcmAuthenticatedEncryptor(Secret keyDerivationKey, BCryptAlgorithmHandle symmetricAlgorithmHandle, uint symmetricAlgorithmKeySizeInBytes, IBCryptGenRandom?genRandom = null)
{
// Is the key size appropriate?
AlgorithmAssert.IsAllowableSymmetricAlgorithmKeySize(checked (symmetricAlgorithmKeySizeInBytes * 8));
CryptoUtil.Assert(symmetricAlgorithmHandle.GetCipherBlockLength() == 128 / 8, "GCM requires a block cipher algorithm with a 128-bit block size.");
_genRandom = genRandom ?? BCryptGenRandomImpl.Instance;
_sp800_108_ctr_hmac_provider = SP800_108_CTR_HMACSHA512Util.CreateProvider(keyDerivationKey);
_symmetricAlgorithmHandle = symmetricAlgorithmHandle;
_symmetricAlgorithmSubkeyLengthInBytes = symmetricAlgorithmKeySizeInBytes;
_contextHeader = CreateContextHeader();
}
private BCryptAlgorithmHandle GetSymmetricBlockCipherAlgorithmHandle(ILogger logger)
{
// basic argument checking
if (String.IsNullOrEmpty(EncryptionAlgorithm))
{
throw Error.Common_PropertyCannotBeNullOrEmpty(nameof(EncryptionAlgorithm));
}
if (EncryptionAlgorithmKeySize < 0)
{
throw Error.Common_PropertyMustBeNonNegative(nameof(EncryptionAlgorithmKeySize));
}
BCryptAlgorithmHandle algorithmHandle = null;
if (logger.IsVerboseLevelEnabled())
{
logger.LogVerboseF($"Opening CNG algorithm '{EncryptionAlgorithm}' from provider '{EncryptionAlgorithmProvider}' with chaining mode GCM.");
}
// Special-case cached providers
if (EncryptionAlgorithmProvider == null)
{
if (EncryptionAlgorithm == Constants.BCRYPT_AES_ALGORITHM)
{
algorithmHandle = CachedAlgorithmHandles.AES_GCM;
}
}
// Look up the provider dynamically if we couldn't fetch a cached instance
if (algorithmHandle == null)
{
algorithmHandle = BCryptAlgorithmHandle.OpenAlgorithmHandle(EncryptionAlgorithm, EncryptionAlgorithmProvider);
algorithmHandle.SetChainingMode(Constants.BCRYPT_CHAIN_MODE_GCM);
}
// make sure we're using a block cipher with an appropriate key size & block size
CryptoUtil.Assert(algorithmHandle.GetCipherBlockLength() == 128 / 8, "GCM requires a block cipher algorithm with a 128-bit block size.");
AlgorithmAssert.IsAllowableSymmetricAlgorithmKeySize(checked ((uint)EncryptionAlgorithmKeySize));
// make sure the provided key length is valid
algorithmHandle.GetSupportedKeyLengths().EnsureValidKeyLength((uint)EncryptionAlgorithmKeySize);
// all good!
return(algorithmHandle);
}
public CbcAuthenticatedEncryptor(Secret keyDerivationKey, BCryptAlgorithmHandle symmetricAlgorithmHandle, uint symmetricAlgorithmKeySizeInBytes, BCryptAlgorithmHandle hmacAlgorithmHandle, IBCryptGenRandom?genRandom = null)
{
_genRandom = genRandom ?? BCryptGenRandomImpl.Instance;
_sp800_108_ctr_hmac_provider = SP800_108_CTR_HMACSHA512Util.CreateProvider(keyDerivationKey);
_symmetricAlgorithmHandle = symmetricAlgorithmHandle;
_symmetricAlgorithmBlockSizeInBytes = symmetricAlgorithmHandle.GetCipherBlockLength();
_symmetricAlgorithmSubkeyLengthInBytes = symmetricAlgorithmKeySizeInBytes;
_hmacAlgorithmHandle = hmacAlgorithmHandle;
_hmacAlgorithmDigestLengthInBytes = hmacAlgorithmHandle.GetHashDigestLength();
_hmacAlgorithmSubkeyLengthInBytes = _hmacAlgorithmDigestLengthInBytes; // for simplicity we'll generate HMAC subkeys with a length equal to the digest length
// Argument checking on the algorithms and lengths passed in to us
AlgorithmAssert.IsAllowableSymmetricAlgorithmBlockSize(checked (_symmetricAlgorithmBlockSizeInBytes * 8));
AlgorithmAssert.IsAllowableSymmetricAlgorithmKeySize(checked (_symmetricAlgorithmSubkeyLengthInBytes * 8));
AlgorithmAssert.IsAllowableValidationAlgorithmDigestSize(checked (_hmacAlgorithmDigestLengthInBytes * 8));
_contextHeader = CreateContextHeader();
}
private BCryptAlgorithmHandle GetSymmetricBlockCipherAlgorithmHandle(ILogger logger)
{
// basic argument checking
if (String.IsNullOrEmpty(EncryptionAlgorithm))
{
throw Error.Common_PropertyCannotBeNullOrEmpty(nameof(EncryptionAlgorithm));
}
if (EncryptionAlgorithmKeySize < 0)
{
throw Error.Common_PropertyMustBeNonNegative(nameof(EncryptionAlgorithmKeySize));
}
logger?.OpeningCNGAlgorithmFromProviderWithChainingModeCBC(EncryptionAlgorithm, EncryptionAlgorithmProvider);
BCryptAlgorithmHandle algorithmHandle = null;
// Special-case cached providers
if (EncryptionAlgorithmProvider == null)
{
if (EncryptionAlgorithm == Constants.BCRYPT_AES_ALGORITHM)
{
algorithmHandle = CachedAlgorithmHandles.AES_CBC;
}
}
// Look up the provider dynamically if we couldn't fetch a cached instance
if (algorithmHandle == null)
{
algorithmHandle = BCryptAlgorithmHandle.OpenAlgorithmHandle(EncryptionAlgorithm, EncryptionAlgorithmProvider);
algorithmHandle.SetChainingMode(Constants.BCRYPT_CHAIN_MODE_CBC);
}
// make sure we're using a block cipher with an appropriate key size & block size
AlgorithmAssert.IsAllowableSymmetricAlgorithmBlockSize(checked (algorithmHandle.GetCipherBlockLength() * 8));
AlgorithmAssert.IsAllowableSymmetricAlgorithmKeySize(checked ((uint)EncryptionAlgorithmKeySize));
// make sure the provided key length is valid
algorithmHandle.GetSupportedKeyLengths().EnsureValidKeyLength((uint)EncryptionAlgorithmKeySize);
// all good!
return(algorithmHandle);
}
