internal static byte[] GetHashParameter(SafeCapiHashHandle hashHandle, CapiNative.HashParameter parameter)
{
Contract.Requires(hashHandle != null);
Contract.Requires(CapiNative.HashParameter.AlgorithmId <= parameter && parameter <= CapiNative.HashParameter.HashSize);
//
// Determine the maximum size of the parameter and retrieve it
//
int parameterSize = 0;
if (!CapiNative.UnsafeNativeMethods.CryptGetHashParam(hashHandle, parameter, null, ref parameterSize, 0))
{
throw new CryptographicException(Marshal.GetLastWin32Error());
}
Debug.Assert(0 < parameterSize, "Invalid parameter size returned");
byte[] parameterValue = new byte[parameterSize];
if (!CapiNative.UnsafeNativeMethods.CryptGetHashParam(hashHandle, parameter, parameterValue, ref parameterSize, 0))
{
throw new CryptographicException(Marshal.GetLastWin32Error());
}
// CAPI may have asked for a larger buffer than it used, so only copy the used bytes
if (parameterSize != parameterValue.Length)
{
byte[] realValue = new byte[parameterSize];
Buffer.BlockCopy(parameterValue, 0, realValue, 0, parameterSize);
parameterValue = realValue;
}
return(parameterValue);
}
/// <summary>
/// Reset the hash algorithm to begin hashing a new set of data
/// </summary>
public SafeCapiHashHandle Initialize()
{
Contract.Ensures(m_hashHandle != null && !m_hashHandle.IsInvalid && !m_hashHandle.IsClosed);
Contract.Assert(m_cspHandle != null);
// Try to create a new hash algorithm to use
SafeCapiHashHandle?newHashAlgorithm = null;
#if !NET_COREAPP_50
RuntimeHelpers.PrepareConstrainedRegions();
#endif
try
{
if (!CapiNative.UnsafeNativeMethods.CryptCreateHash(m_cspHandle,
m_algorithmId,
SafeCapiKeyHandle.InvalidHandle,
0,
out newHashAlgorithm))
{
// BadAlgorithmId means that this CSP does not support the specified algorithm, which means
// that we're on a platform that does not support the given hash function.
int error = Marshal.GetLastWin32Error();
if (error == (int)CapiNative.ErrorCode.BadAlgorithmId)
{
throw new PlatformNotSupportedException(SR.Cryptography_PlatformNotSupported);
}
else
{
throw new CryptographicException(error);
}
}
}
finally
{
if (newHashAlgorithm != null && !newHashAlgorithm.IsInvalid)
{
newHashAlgorithm.SetParentCsp(m_cspHandle);
}
}
// If we created a new algorithm, dispose of the old one and use the new one
Contract.Assert(newHashAlgorithm != null, "newHashAlgorithm != null");
if (m_hashHandle != null)
{
m_hashHandle.Dispose();
}
m_hashHandle = newHashAlgorithm;
return(m_hashHandle);
}
/*
* SafeCritical - we're not exposing out anything that we want to prevent untrusted code from getting at
*/
public CapiHashAlgorithm(
string provider,
CapiNative.ProviderType providerType,
CapiNative.AlgorithmId algorithm)
{
Contract.Requires(!string.IsNullOrEmpty(provider));
Contract.Requires((CapiNative.AlgorithmClass)((uint)algorithm & (uint)CapiNative.AlgorithmClass.Hash) == CapiNative.AlgorithmClass.Hash);
m_algorithmId = algorithm;
m_cspHandle = CapiNative.AcquireCsp(null,
provider,
providerType,
CapiNative.CryptAcquireContextFlags.VerifyContext,
true);
m_hashHandle = Initialize();
}
public static extern unsafe bool CryptHashData(SafeCapiHashHandle hHash,
byte *pbData,
int dwDataLen,
int dwFlags);
public static extern bool CryptCreateHash(SafeCspHandle hProv,
AlgorithmId Algid,
SafeCapiKeyHandle hKey,
int dwFlags,
[Out] out SafeCapiHashHandle phHash);
public static extern bool CryptGetHashParam(SafeCapiHashHandle hHash,
HashParameter dwParam,
[Out, MarshalAs(UnmanagedType.LPArray)] byte[]?pbData,
[In, Out] ref int pdwDataLen,
int dwFlags);
