The foundation of good security methods begins with cryptography. Cryptography keeps your data and communications secure using techniques such as encryption, authentication, and data integrity. Encryption services protect sensitive data from being read by other than the intended receiver. Cryptographic authentication and data integrity services allow communicating hosts to detect if data is altered in transit. Public key cryptography can identify and authenticate hosts or users. Public key cryptography can also be used in the secure creation of symmetric session keys for both security endpoints. After a secure session is created, successful data authentication and decryption occur only if both hosts have the correct session keys.