CAST key size

Peter Gutmann pgut001 at
Mon Aug 25 04:41:57 PDT 1997

>Just a quick question on the keysize of the CAST algorithm. According to
>the bible of Bruce,  CAST uses a 64 bit keysize, while  in the manual of
>PGP 5.0 (page 89), Phill states that CAST uses a 128 bit keysize...
>Am I missing something?
"CAST" isn't a particular algorithm, but a design process for creating 
algorithms.  The particular CAST instantiation used in PGP 5 is either 
CAST-128 or CAST5, depending on who you ask.  Other versions of CAST abound, 
including an earlier one used by MS for unknown purposes which had a 64-bit 
key, probably the one Bruce is referring to.

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