public static DocumentHashAlgorithm ToHashAlgorithm(this Guid guid)
{
if (guid == hash_md5)
return DocumentHashAlgorithm.MD5;
if (guid == hash_sha1)
return DocumentHashAlgorithm.SHA1;
if (guid == hash_sha256)
return DocumentHashAlgorithm.SHA256;
return DocumentHashAlgorithm.None;
}