# User:TomYu/PKINIT notes

From K5Wiki

## Diffie-Hellman

- Oakley MODP groups (used in PKINIT) have safe primes as moduli
- These primes don't satisfy the OpenSSL DH_check() tests, so there can be some confusion when debugging
- The generator generates the subgroup of order
*q*instead of the whole group. (OpenSSL wants it to generate the whole group -- the test is*p*= 11 mod 24, which includes the test*p*= 3 mod 8, which is false if 2 is a quadratic residue mod*p*.)

- Windows 7 clients omit the
*q*value in DomainParameters when sending PA-PK-AS-REQ [krbdev.mit.edu #7596] - Even after allowing the omission of the
*q*value, Windows 7 doesn't seem to deal with Diffie-Hellman group negotiation. (The KDC has to accept the 1024-bit modulus, because the counterproposal of the 2048-bit modulus fails on the client somehow.)