openssl (version 0.5)

aes_cbc: Symmetric AES encryption

Description

Low-level symmetric encryption/decryption using the AES block cipher in CBC mode. The key is a raw vector, for example a hash of some secret. When no shared secret is available, a random key can be used which is exchanged via an asymettric protocol such as RSA. See rsa_encrypt for a worked example or encrypt_envelope for a high-level wrapper combining AES and RSA.

Usage

aes_cbc_encrypt(data, key, iv = rand_bytes(16))

aes_cbc_decrypt(data, key, iv = attr(data, "iv"))

Arguments

data
raw vector or path to file with data to encrypt or decrypt
key
raw vector of length 16, 24 or 32, e.g. the hash of a shared secret
iv
raw vector of length 16 (aes block size) or NULL. The initialization vector is not secret but should be random

Examples

Run this code
# aes-256 requires 32 byte key
passphrase <- charToRaw("This is super secret")
key <- sha256(passphrase)

# symmetric encryption uses same key for decryption
x <- serialize(iris, NULL)
y <- aes_cbc_encrypt(x, key = key)
x2 <- aes_cbc_decrypt(y, key = key)
stopifnot(identical(x, x2))

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