//
// - "hashAlgId" must be a name recognized by BCryptOpenAlgorithmProvider(). Examples: MD5, SHA1, SHA256.
//
// - "key" activates MAC hashing if present. If null, this HashProvider performs a regular old hash.
//
public HashProviderCng(String hashAlgId, byte[] key)
{
Cng.OpenAlgorithmProviderFlags dwFlags = Cng.OpenAlgorithmProviderFlags.NONE;
if (key != null)
{
_key = key.CloneByteArray();
dwFlags |= Cng.OpenAlgorithmProviderFlags.BCRYPT_ALG_HANDLE_HMAC_FLAG;
}
_hAlgorithm = Cng.BCryptOpenAlgorithmProvider(hashAlgId, null, dwFlags);
_hHash = _hAlgorithm.BCryptTryCreateReusableHash(_key);
if (_hHash == null)
{
// If we got here, we're running on a downlevel OS that doesn't support reusable CNG hash objects. Fall back to creating a
// new HASH object each time.
ResetHashObject();
}
else
{
_reusable = true;
}
_hashSize = _hHash.GetHashSizeInBytes();
return;
}
private static Lazy <SafeAlgorithmHandle> Open3DesAlgorithm(string cipherMode, int feedback = 0)
{
return(new Lazy <SafeAlgorithmHandle>(() =>
{
SafeAlgorithmHandle hAlg = Cng.BCryptOpenAlgorithmProvider(Cng.BCRYPT_3DES_ALGORITHM, null,
Cng.OpenAlgorithmProviderFlags.NONE);
hAlg.SetCipherMode(cipherMode);
// The default feedback size is 1 (CFB8) on Windows. Do not set the CNG property
// if we would be setting it to the default. Windows 7 only supports CFB8 and
// does not permit setting the feedback size, so we don't call the property
// setter at all in that case.
if (feedback > 0 && feedback != 1)
{
try
{
hAlg.SetFeedbackSize(feedback);
}
catch (CryptographicException ex)
{
throw new CryptographicException(SR.Cryptography_FeedbackSizeNotSupported, ex);
}
}
return hAlg;
}));
}
private static SafeAlgorithmHandle GetCachedAlgorithmHandle(ref SafeAlgorithmHandle?handle, string algId, string?chainingMode = null)
{
// Do we already have a handle to this algorithm?
SafeAlgorithmHandle?existingHandle = Volatile.Read(ref handle);
if (existingHandle != null)
{
return(existingHandle);
}
// No cached handle exists; create a new handle. It's ok if multiple threads call
// this concurrently. Only one handle will "win" and the rest will be destroyed.
SafeAlgorithmHandle newHandle = Cng.BCryptOpenAlgorithmProvider(algId, null, Cng.OpenAlgorithmProviderFlags.NONE);
if (chainingMode != null)
{
newHandle.SetCipherMode(chainingMode);
}
existingHandle = Interlocked.CompareExchange(ref handle, newHandle, null);
if (existingHandle != null)
{
newHandle.Dispose();
return(existingHandle);
}
else
{
return(newHandle);
}
}
private static SafeAlgorithmHandle Open3DesAlgorithm(string cipherMode)
{
SafeAlgorithmHandle hAlg = Cng.BCryptOpenAlgorithmProvider(Cng.BCRYPT_3DES_ALGORITHM, null, Cng.OpenAlgorithmProviderFlags.NONE);
hAlg.SetCipherMode(cipherMode);
return(hAlg);
}
protected override string FormatNative(Oid oid, byte[] rawData, bool multiLine)
{
// If OID is not present, then we can force CryptFormatObject
// to use hex formatting by providing an empty OID string.
string oidValue = string.Empty;
if (oid != null && oid.Value != null)
{
oidValue = oid.Value;
}
return(Cng.CryptFormatObject(oidValue, rawData, multiLine));
}
private static Lazy <SafeAlgorithmHandle> OpenDesAlgorithm(string cipherMode)
{
return(new Lazy <SafeAlgorithmHandle>(() =>
{
SafeAlgorithmHandle hAlg = Cng.BCryptOpenAlgorithmProvider(
Cng.BCRYPT_DES_ALGORITHM,
null,
Cng.OpenAlgorithmProviderFlags.NONE);
hAlg.SetCipherMode(cipherMode);
return hAlg;
}));
}
private static SafeAlgorithmHandle OpenRC2Algorithm(string cipherMode, int effectiveKeyLength)
{
SafeAlgorithmHandle hAlg = Cng.BCryptOpenAlgorithmProvider(Cng.BCRYPT_RC2_ALGORITHM, null, Cng.OpenAlgorithmProviderFlags.NONE);
hAlg.SetCipherMode(cipherMode);
if (effectiveKeyLength != 0)
{
Cng.SetEffectiveKeyLength(hAlg, effectiveKeyLength);
}
return(hAlg);
}
private static Lazy <SafeAlgorithmHandle> Open3DesAlgorithm(string cipherMode, int feedback = 0)
{
return(new Lazy <SafeAlgorithmHandle>(() =>
{
SafeAlgorithmHandle hAlg = Cng.BCryptOpenAlgorithmProvider(Cng.BCRYPT_3DES_ALGORITHM, null,
Cng.OpenAlgorithmProviderFlags.NONE);
hAlg.SetCipherMode(cipherMode);
if (feedback > 0)
{
// feedback is in bytes!
hAlg.SetFeedbackSize(feedback);
}
return hAlg;
}));
}
private byte[] _currentIv; // CNG mutates this with the updated IV for the next stage on each Encrypt/Decrypt call.
// The base IV holds a copy of the original IV for Reset(), until it is cleared by Dispose().
public BasicSymmetricCipherBCrypt(SafeAlgorithmHandle algorithm, CipherMode cipherMode, int blockSizeInBytes, byte[] key, int effectiveKeyLength, byte[] iv, bool encrypting)
: base(cipherMode.GetCipherIv(iv), blockSizeInBytes)
{
Debug.Assert(algorithm != null);
_encrypting = encrypting;
if (IV != null)
{
_currentIv = new byte[IV.Length];
}
_hKey = algorithm.BCryptImportKey(key);
if (effectiveKeyLength != 0)
{
Cng.SetEffectiveKeyLength(_hKey, effectiveKeyLength);
}
Reset();
}
private static int DecryptInPlace(SafeKeyHandle hKey, byte[] currentIv, byte[] inOutBuffer, int offset, int count)
{
int numBytesWritten = Cng.BCryptDecrypt(hKey, inOutBuffer, offset, count, currentIv, inOutBuffer, offset, inOutBuffer.Length - offset);
return(numBytesWritten);
}
