Diffie-Hellman Key Generation

[Anonymous]

> Finally, I'm basing this on comments in 'Applied Cryptography' that D-H
> keys should be at least 512 bits and preferably 1024. How does the
> difficulty of breaking a D-H exchange with a 512 bit key compare to
> breaking a 512 bit RSA key ?

Calculating discrete logarithms is a bit more difficult than factoring.
So a 512-bit DH modulus will give you somewhat more security than a 512-bit
RSA key.  I'm not sure how much, probably not a lot.