How to securly encrypt and decrypt data with JavaScript.

Stanford University has released a secure, powerful, fast, small, easy-to-use, cross-browser library for cryptography in Javascript.
It is very easy to use, to encrypt data you just call sjcl.encrypt(“password”, “data”) and you can decrypt it by calling sjcl.decrypt(“password”, “encrypted-data”)

SJCL is secure. It uses the industry-standard AES algorithm at 128, 192 or 256 bits; the SHA256 hash function; the HMAC authentication code; the PBKDF2 password strengthener; and the CCM and OCB authenticated-encryption modes.