wolf550e

>> The password will be hashed with the SHA256 algorithm, the mode for encryption is 256 Bit Rijndael/AES

SHA256 is not a KDF, AES-256 is not a block cipher mode. Where is the source code?

pjc50

What's the standard for this kind of thing, PBKDF2 / AES-CBC / HMAC-256?

(I went and checked NaCl and it has its own primitives, http://nacl.cr.yp.to/secretbox.html)

jedisct1
Scrypt for key derivation, chacha20+poly1305 for authenticated secret-key encryption. In Javascript, https://github.com/jedisct1/libsodium.js provides them.