public async Task <byte[]> TransformData(byte[] originalData)
{
string hash;
using (var stream = new MemoryStream(originalData))
{
hash = await this.Hasher.ComputeHash(stream);
}
var hashBytes = Encoding.UTF8.GetBytes(hash);
var dataWithSignature = new DataWithSignature(originalData, hashBytes);
return(dataWithSignature.AsByteArray());
}
public async Task <IDecryptionResult> GetOriginalData(byte[] transformedData)
{
var dataWithSignature = DataWithSignature.FromByteArray(transformedData);
var expectedHash = Encoding.UTF8.GetString(dataWithSignature.Signature);
using (var stream = new MemoryStream(dataWithSignature.Data))
{
var actualHash = await this.Hasher.ComputeHash(stream);
if (expectedHash != actualHash)
{
return(new FailedDecryptionResult());
}
}
return(new SuccessfulDecryptionResult(dataWithSignature.Data));
}