public ManagedAuthenticatedEncryptor(Secret keyDerivationKey, Func <SymmetricAlgorithm> symmetricAlgorithmFactory, int symmetricAlgorithmKeySizeInBytes, Func <KeyedHashAlgorithm> validationAlgorithmFactory, IManagedGenRandom genRandom = null)
{
_genRandom = genRandom ?? ManagedGenRandomImpl.Instance;
_keyDerivationKey = keyDerivationKey;
// Validate that the symmetric algorithm has the properties we require
using (var symmetricAlgorithm = symmetricAlgorithmFactory())
{
_symmetricAlgorithmFactory = symmetricAlgorithmFactory;
_symmetricAlgorithmBlockSizeInBytes = symmetricAlgorithm.GetBlockSizeInBytes();
_symmetricAlgorithmSubkeyLengthInBytes = symmetricAlgorithmKeySizeInBytes;
}
// Validate that the MAC algorithm has the properties we require
using (var validationAlgorithm = validationAlgorithmFactory())
{
_validationAlgorithmFactory = validationAlgorithmFactory;
_validationAlgorithmDigestLengthInBytes = validationAlgorithm.GetDigestSizeInBytes();
_validationAlgorithmSubkeyLengthInBytes = _validationAlgorithmDigestLengthInBytes; // for simplicity we'll generate MAC subkeys with a length equal to the digest length
}
// Argument checking on the algorithms and lengths passed in to us
AlgorithmAssert.IsAllowableSymmetricAlgorithmBlockSize(checked ((uint)_symmetricAlgorithmBlockSizeInBytes * 8));
AlgorithmAssert.IsAllowableSymmetricAlgorithmKeySize(checked ((uint)_symmetricAlgorithmSubkeyLengthInBytes * 8));
AlgorithmAssert.IsAllowableValidationAlgorithmDigestSize(checked ((uint)_validationAlgorithmDigestLengthInBytes * 8));
_contextHeader = CreateContextHeader();
}
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 GetHmacAlgorithmHandle(CngCbcAuthenticatedEncryptorConfiguration configuration)
{
// basic argument checking
if (String.IsNullOrEmpty(configuration.HashAlgorithm))
{
throw Error.Common_PropertyCannotBeNullOrEmpty(nameof(configuration.HashAlgorithm));
}
_logger.OpeningCNGAlgorithmFromProviderWithHMAC(configuration.HashAlgorithm, configuration.HashAlgorithmProvider);
BCryptAlgorithmHandle?algorithmHandle = null;
// Special-case cached providers
if (configuration.HashAlgorithmProvider == null)
{
if (configuration.HashAlgorithm == Constants.BCRYPT_SHA1_ALGORITHM)
{
algorithmHandle = CachedAlgorithmHandles.HMAC_SHA1;
}
else if (configuration.HashAlgorithm == Constants.BCRYPT_SHA256_ALGORITHM)
{
algorithmHandle = CachedAlgorithmHandles.HMAC_SHA256;
}
else if (configuration.HashAlgorithm == Constants.BCRYPT_SHA512_ALGORITHM)
{
algorithmHandle = CachedAlgorithmHandles.HMAC_SHA512;
}
}
// Look up the provider dynamically if we couldn't fetch a cached instance
if (algorithmHandle == null)
{
algorithmHandle = BCryptAlgorithmHandle.OpenAlgorithmHandle(configuration.HashAlgorithm, configuration.HashAlgorithmProvider, hmac: true);
}
// Make sure we're using a hash algorithm. We require a minimum 128-bit digest.
uint digestSize = algorithmHandle.GetHashDigestLength();
AlgorithmAssert.IsAllowableValidationAlgorithmDigestSize(checked (digestSize * 8));
// all good!
return(algorithmHandle);
}
