re: Possible namespaces. Why not use boost::digest? "Cryptographic hashes" are more pedantically known as one-way digests of blobs of data. A "hash," as hijacked by perl (or dictionary, or unordered_map), is an ADT comprised of a digest of a key and a value. crc's a digest as well, but for legacy reasons already has a top-level namespace. Some digests are crypto grade, some aren't, but they all fall in to the digest category. $0.02. -sc -- Sean Chittenden sean@chittenden.org