private byte[]? ChangeKeyImpl(ReadOnlySpan <byte> key)
{
byte[]? modifiedKey = null;
// If _blockSize is -1 the key isn't going to be extractable by the object holder,
// so there's no point in recalculating it in managed code.
if (key.Length > _blockSize && _blockSize > 0)
{
// Perform RFC 2104, section 2 key adjustment.
if (_lazyHashProvider == null)
{
_lazyHashProvider = HashProviderDispenser.CreateHashProvider(_hashAlgorithmId);
}
_lazyHashProvider.AppendHashData(key);
modifiedKey = _lazyHashProvider.FinalizeHashAndReset();
}
HashProvider?oldHashProvider = _hMacProvider;
_hMacProvider = null !;
oldHashProvider?.Dispose(true);
_hMacProvider = HashProviderDispenser.CreateMacProvider(_hashAlgorithmId, key);
return(modifiedKey);
}
private IncrementalHash(HashAlgorithmName name, HashProvider hash)
{
Debug.Assert(!string.IsNullOrEmpty(name.Name));
Debug.Assert(hash != null);
_algorithmName = name;
_hash = hash;
}
/// <summary>
/// Saves a stream to a file returns a new HashableFile
/// </summary>
/// <param name="StreamToSave">A stream to save to a file</param>
/// <param name="Provider">If specified computes the hash after writing the file</param>
/// <param name="SigningCert">If specified with a valid Provider, computes the signature after writing the file</param>
public HashableFile(Stream StreamToSave, HashProvider?Provider = null, Cert SigningCert = null)
{
_filePath = FilePath;
using (var fileStream = File.Create(_filePath)) {
StreamToSave.Seek(0, SeekOrigin.Begin);
StreamToSave.CopyTo(fileStream);
}
if (Provider.HasValue)
{
this.ComputeHash(Provider.Value, SigningCert);
}
}
/// <summary>
/// Release all resources used by the current instance of the
/// <see cref="IncrementalHash"/> class.
/// </summary>
public void Dispose()
{
_disposed = true;
if (_hash != null)
{
_hash.Dispose();
_hash = null;
}
if (_hmac != null)
{
_hmac.Dispose(true);
_hmac = null;
}
}