### Cryptographic Algorithms

Kanav Gupta | Saturday, December 26, 2009 |
Cryptography

Algorithms are primarily characterized as either symmetric or asymmetric.

Briefly, symmetric encryption uses a single key to encrypt and decrypt. Asymmetric uses two keys.

**Symmetric encryption:**

► Is about 1000 times faster than symmetric encryption.

► The key is commonly called a session key, a shared key, a pre-shared key, or a shared secret.

► The most popular encryption algorithm is AES which faster and more efficient than other encryption algorithms (such as DES and 3DES).

**Asymmetric encryption:**

► Is extremely slow compared to symmetric encryption so only used to encrypt/decrypt a very small amount of data.

► Is primarily used to privately share a symmetric key over a public network (such as the Internet). Once the key is exchanged using asymmetric encryption, symmetric encryption is used to encrypt session data.

► Uses two keys know as a public key and a private key (or public/private key pair). The public key is freely shared but the private key is kept private for a single entity (such as a single server).

► Requires a public key infrastructure (PKI) to publish certificates. Public keys are published in a certificate and the certificate is freely shared to others.

► If a public key encrypts data, only the private key can decrypt it.

► If a private key encrypts data, only the public key can decrypt it.

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