DES:
Monolithic key code system: Encryption decrypts the same key; less than the management and transmission of the key
SHA and MD5
Message Abstract: Data block generates a digital fingerprint, regardless of the size length of the data block.
RSA
Public key password: The disclosed encryption key, the un disclosed decryption key.
Digital signature DSA
RSA encryption is performed on digital fingerprints. Two advantages, senders can't be reliable (how to guarantee?), The recipient can verify the correctness because the encryption key is open.
Digital signatures are signed with a private key.
