Navigation: Subroutines

DIGEST

Reviewed and revised April 2024

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

DIGEST returns various cryptographic digests of strings or files.

Parameters

digtype  (Num)  [in]

indicates the type of digest desired:

 

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

srcdata (String or BLOB)  [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 BLOB)  [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:

 

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

 

status  (Signed Num)  [out]

returns status indicator:

 

Comments

DIGEST and HASH 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.

See Also

History

2013 May, A-Shell 6.1.1353:  Routine added to A-Shell