The "get challenge" apdu, 0x84, normally returns a random number. I once
collected 1600000 bytes from a Payflex P1 card and ran some simple tests. I
don't know how the rng is implemented in Payflex, and it's probably a highly
guarded secret.
If anyone wants to run some tests, the bits are here:
http://www.citi.umich.edu/projects/smartcard/mc1-noise-200k.bin
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Linux Smart Card Developers - M.U.S.C.L.E.
(Movement for the Use of Smart Cards in a Linux Environment)
http://www.linuxnet.com/smartcard/index.html
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