Public-key (or asymmetric) cryptography is a form of cryptography that does not require common secrets between the communicating partners.
Public-key cryptography or asymmetric cryptography is a form of cryptography that does not require common secrets between the communicating partners. It thus solves the problem of key-exchange. In many modern cryptosystems, public-key cryptography is used to establish a secret key, and the faster symmetric key crypto is used to actually encrypt and decrypt data.
Public-key cryptography is generally based on "one-way" mathematical functions - operations that are easy to perform, but difficult to undo. An example (on which RSA is based) is multiplication vs. factoring. Given two enormous primes p and q, it is simple (for a computer) to multiply them together to get p*q = n, but it turns out it is very difficult (even for a computer) to factor n in a reasonable amount of time.
