peter at cadcamlab.org
Wed Jan 24 16:15:14 GMT 2001
> > Use all 8 bits of each character to derive two 56-bit keys.
> > DES-encrypt two known strings with the two keys.
> take first 7 upper-case ascii chars, use as key to DES-encrypt the
> string "!"£$%KGS". take 2nd 7 upper-case, do same. concatenate
> results to produce 128-bit result.
OK, s/two known strings/one string used twice/ . I was close. (:
> significant diff. between nt-auth and unix auth is that the nt-auth
> uses the hashes as cleartext-equivalent.
Yes, that is true. That's the problem with challenge-response, it's
trivial to implement if you have a plaintext-equivalent stored, and
much more complex if you don't. Then again, it's not like this is a
new problem -- algorithms *do* exist in the literature (Diffie-Hellman,
etc) and Microsoft could have used them. Maybe it had something to do
with US export licensing. Or was it just the old security-by-obscurity
("nobody will ever reverse-engineer this stuff") sloppiness?
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