-----BEGIN PGP SIGNED MESSAGE----- In pgp 2.6 UI When pgp is called with the -c switch, the routine idea_encryptfile in crypto.c is called from main in pgp.c.

status = idea_encryptfile( workfile, tempf, attempt_compression);

int idea_encryptfile(char *infile, char *outfile, boolean attempt_compression) { FILE *f; /* input file */ FILE *g; /* output file */ byte ideakey[16]; struct hashedpw *hpw;

Note that idea key is a 16 bytes. Now idea_encryptfile calls squish_and_idea_file in crypto.c with this 16 byte key.

/* Now compress the plaintext and encrypt it with IDEA... */ squish_and_idea_file( ideakey, f, g, attempt_compression );

Now squish_and_idea_file calls idea_file in the module crypto.c with the same 16 byte key.

static int squish_and_idea_file(byte *ideakey, FILE *f, FILE *g, boolean attempt_compression) {