Known as Salt, this is one of the older encryption sites on the Internet. It features public-key cryptography, secret key cryptography, and low-level functions such as hashing and string comparison.
"The AES algorithm is a symmetric block cipher that can encrypt (encipher) and decrypt (decipher) information. Encryption converts data to an unintelligible form called ciphertext; decrypting the ciphertext converts the data back into its original form, called plaintext."
"A robust, commercial-grade, and full-featured toolkit for the Transport Layer Security (TLS) and Secure Sockets Layer (SSL) protocols. It is also a general-purpose cryptography library."