internal static SafeBCryptKeyHandle ImportKey(SafeBCryptAlgorithmHandle algorithm, byte[] key)
{
const int BCRYPT_KEY_DATA_BLOB_MAGIC = 0x4d42444b;
// Concatenate the BCRYPT_KEY_DATA_BLOB header and the raw key.
byte[] keyBlob = new byte[Marshal.SizeOf(typeof(BCRYPT_KEY_DATA_BLOB)) + key.Length];
unsafe
{
fixed(byte *pbKeyBlob = keyBlob)
{
BCRYPT_KEY_DATA_BLOB *pkeyDataBlob = (BCRYPT_KEY_DATA_BLOB *)pbKeyBlob;
pkeyDataBlob->dwMagic = BCRYPT_KEY_DATA_BLOB_MAGIC;
pkeyDataBlob->dwVersion = 1;
pkeyDataBlob->cbKeyData = key.Length;
}
}
Buffer.BlockCopy(key, 0, keyBlob, Marshal.SizeOf(typeof(BCRYPT_KEY_DATA_BLOB)), key.Length);
int cbKeyData = BitConverter.ToInt32(GetProperty(algorithm, "ObjectLength"), 0);
var pbKeyData = Marshal.AllocCoTaskMem(cbKeyData);
ErrorCode error = UnsafeNativeMethods.BCryptImportKey(algorithm, IntPtr.Zero, "KeyDataBlob", out var keyHandle, pbKeyData, cbKeyData, keyBlob, keyBlob.Length, 0);
if (error == ErrorCode.Success)
{
keyHandle.DataBuffer = pbKeyData;
return(keyHandle);
}
else
{
Marshal.FreeCoTaskMem(pbKeyData);
throw new CryptographicException("Failed to import key: error " + error);
}
}
public unsafe void SetKey(Span <byte> key)
{
var keyBlob = stackalloc byte[sizeof(BCRYPT_KEY_DATA_BLOB) + _keyLength];
BCRYPT_KEY_DATA_BLOB *pkeyDataBlob = (BCRYPT_KEY_DATA_BLOB *)keyBlob;
pkeyDataBlob->dwMagic = BCRYPT_KEY_DATA_BLOB_MAGIC;
pkeyDataBlob->dwVersion = BCRYPT_KEY_DATA_BLOB_VERSION1;
pkeyDataBlob->cbKeyData = _keyLength;
var keyBlobSpan = new Span <byte>(keyBlob + sizeof(BCRYPT_KEY_DATA_BLOB), _keyLength);
key.CopyTo(keyBlobSpan);
Interop.Windows.ExceptionHelper.CheckReturnCode(
BCryptImportKey(_algo, IntPtr.Zero, "KeyDataBlob", out _key, IntPtr.Zero, 0, (IntPtr)keyBlob, sizeof(BCRYPT_KEY_DATA_BLOB) + _keyLength, 0));
BCryptPropertiesHelper.SetBlockChainingMode(_key, _chainingMode);
_blockLength = BCryptPropertiesHelper.GetBlockLength(_key);
_maxTagLength = _blockLength;
}
internal static SafeBCryptKeyHandle ImportSymmetricKey(SafeBCryptAlgorithmHandle algorithm, byte[] key)
{
Debug.Assert(algorithm != null, "algorithm != null");
Debug.Assert(!algorithm.IsClosed && !algorithm.IsInvalid, "!algorithm.IsClosed && !algorithm.IsInvalid");
Debug.Assert(key != null, "buffer != null");
IntPtr keyDataBuffer = IntPtr.Zero;
SafeBCryptKeyHandle keyHandle = null;
RuntimeHelpers.PrepareConstrainedRegions();
try
{
// Build up the key blob structure in memory. BCryptImportKey requries a
// BCRYPT_KEY_DATA_BLOB header immediately followed by the raw key data.
byte[] keyBlob = new byte[Marshal.SizeOf(typeof(BCRYPT_KEY_DATA_BLOB)) + key.Length];
unsafe
{
fixed(byte *pbKeyBlob = keyBlob)
{
BCRYPT_KEY_DATA_BLOB *pkeyDataBlob = (BCRYPT_KEY_DATA_BLOB *)pbKeyBlob;
pkeyDataBlob->dwMagic = KeyBlobMagicNumber.KeyDataBlob;
pkeyDataBlob->dwVersion = 1;
pkeyDataBlob->cbKeyData = key.Length;
}
}
Buffer.BlockCopy(key, 0, keyBlob, Marshal.SizeOf(typeof(BCRYPT_KEY_DATA_BLOB)), key.Length);
// Figure out how big of a key data buffer we need and allocate space on the native heap for
// it. We cannot use a managed array here because the address needs to stay constant for
// the lifetime of the algorithm handle. Pinning for a potentially long lifetime is
// undesirable, so we use a native heap allocation instead.
int keyDataSize = GetInt32Property(algorithm, ObjectPropertyName.ObjectLength);
RuntimeHelpers.PrepareConstrainedRegions();
try { }
finally
{
keyDataBuffer = Marshal.AllocCoTaskMem(keyDataSize);
}
// Import the key
ErrorCode error = UnsafeNativeMethods.BCryptImportKey(algorithm,
IntPtr.Zero,
KeyBlobType.KeyDataBlob,
out keyHandle,
keyDataBuffer,
keyDataSize,
keyBlob,
keyBlob.Length,
0);
if (error != ErrorCode.Success)
{
throw new CryptographicException((int)error);
}
// Give the key ownership of the key data buffer
keyHandle.DataBuffer = keyDataBuffer;
return(keyHandle);
}
finally
{
// If we allocated a key data buffer, but never transfered ownership to the key handle, then
// we need to free it now otherwise it will leak.
if (keyDataBuffer != IntPtr.Zero)
{
if (keyHandle == null || keyHandle.DataBuffer == IntPtr.Zero)
{
Marshal.FreeCoTaskMem(keyDataBuffer);
}
}
}
}