Public key cryptography theory is difficult. ItÕs based on number theory, one of the finer branches of mathematics.
See e.g. http://www.ssh.fi/tech/crypto/algorithms.html for some introduction text.

Bruce Schneier: Applied Cryptography, 2nd edition. John Wiley & Sons, 1995 is a seminal work in the field.








Only for those who want to go into the details, search for these documents:
¥ DNSSEC signatures see RFC 2536 (DSA) and RFC 2537 (RSA).
¥ The digital signature standard  (DSS) that is used in combination with DSA is described in: Federal information Processing Standards Publication 186 (FIPS 186).