DIGEST

Added May 2013

xcall DIGEST, digtype, srcdata, bytes, digest, status

DIGEST.SBR returns various cryptographic digests of strings or files.

Parameters

digtype (Num) [in]

indicates the type of digest desired:

Value	Type	Digest Length in Bits
3	MD5	128
4	SHA 1	160
5	SHA 256	256

Note that the digtype values start at 3 rather than 1 to avoid possible conflict/confusion with the very similar HASH.SBR. See comments below.

srcdata (String or Raw) [in]

data to get the digest of. If bytes=-1, then this is interpreted as the filespec (AMOS or native) containing the data.

bytes (Num) [in]

number of bytes to process. If srcdata is type S, bytes may be set to 0 to mean the logical string length. If -1, srcdata is interpreted as the name of the file to process.

digest (String or Raw) [out]

returned digest. If X, the digest is returned in raw binary form. If S, it is returned in hex representation. Minimum sizes depend on the digtype:

Value	Type
MD5	X,16 or S,32
SHA-1	X,20 or S,40
SHA-256	X,32 or S,64

Note: for applications requiring the digest encoded in base64, you can use CRYPTO.SBR to perform the conversion.

status (Signed Num) [out]

returns status indicator:

Value	Meaning
>=0	# of bytes processed; should match bytes
-1	bad data type for srcdata
-2	bad digtype
-3	bad digest type or size
-4	file not found

Comments

DIGEST.SBR and HASH.SBR are very similar and may eventually be merged, although at present only DIGEST supports the file option. HASH is more oriented towards maximum performance with relatively small keys, as might be useful in a hash table alternative to a traditional index. DIGEST is more oriented towards security applications and large keys (or files) where computational performance and compactness are less important than minimizing the possibility of different keys having the same digest.