/// <summary>
/// Computes the hash of a given InputStream. This is a wrapper over the HashAlgorithm crypto functions.
/// </summary>
/// <param name="stream">the source stream. Use a MemoryStream if uncertain.</param>
/// <param name="hashType">the Algorithm to use to compute the hash</param>
/// <returns>a byte[] representation of the hash. If the Stream is a null object
/// then null will be returned. If the Stream is empty an empty byte[] {} will be returned.</returns>
public static byte[] ComputeHash(this Stream stream, ChecksumAlgorithm hashType = ChecksumAlgorithm.SHA256, long?maxBodySize = null)
{
if (stream == null)
{
return(null);
}
using (var algorithm = HashTypeFactory.Create(hashType))
if (maxBodySize != null && maxBodySize > 0)
{
return(algorithm.ComputeHash(stream.ReadExactly((long)maxBodySize)));
}
else
{
return(algorithm.ComputeHash(stream));
}
}
/// <summary>
/// Computes the HMAC hash of a given byte[]. This is a wrapper over the Mac crypto functions.
/// </summary>
/// <param name="data">byte[] of content to hash</param>
/// <param name="key">secret key to salt the hash. This is assumed to be UTF-8 encoded</param>
/// <param name="hashType">determines which alogirthm to use. The recommendation is to use HMAC-SHA256</param>
/// <returns>a byte[] presenting the HMAC hash of the source data. If the data object is null, null will be returned</returns>
public static byte[] ComputeKeyedHash(this byte[] data, string key, KeyedHashAlgorithm hashType = KeyedHashAlgorithm.HMACSHA256)
{
if (data == null)
{
return(null);
}
if (string.IsNullOrEmpty(key))
{
throw new ArgumentNullException("key");
}
using (var algorithm = HashTypeFactory.Create(hashType))
{
algorithm.Key = key.ToByteArray();
return(algorithm.ComputeHash(data));
}
}
