Cryptography
Cryptography and the Electronic Signature
The electronic signature and cryptography are fundamental parts of any system that needs to comunicate or store data securely. It's the basic requisite for all healthcare, military and banking systems.
There are many cryptographic methods.
Symmetric cryptography assumes the acquitance of a common encryption key. Such cryptographic methods are usually very fast but need to ensure the key privacy (the usage usually include periodic key change and handover using assymetric methods).
Assymetric cryptography is usually based on two keys. One key is private (secret) and the only party that knows this key is it's owner. The second key is public (non-secret). Data are encrypted using the public key. Such data may be decrypted only using the private key because the public key holds only composite information needed to encrypt data (such information is insufficient for decryption). As a very usable side effect, the assymetric cryptography can be used as tool for sending party verification (electronic signature).