PlugRailsCookieSessionStore.MessageEncryptor (plug_rails_cookie_session_store v2.0.0)

MessageEncryptor is a simple way to encrypt values which get stored somewhere you don't trust. The cipher text and initialization vector are base64 encoded and returned to you. This can be used in situations similar to the MessageVerifier, but where you don't want users to be able to determine the value of the payload.

Example

secret_key_base = "072d1e0157c008193fe48a670cce031faa4e..."
encrypted_cookie_salt = "encrypted cookie"
encrypted_signed_cookie_salt = "signed encrypted cookie"
secret = KeyGenerator.generate(secret_key_base, encrypted_cookie_salt)
sign_secret = KeyGenerator.generate(secret_key_base, encrypted_signed_cookie_salt)
encryptor = MessageEncryptor.new(secret, sign_secret)
data = %{current_user: %{name: "José"}}
encrypted = MessageEncryptor.encrypt_and_sign(encryptor, data)
decrypted = MessageEncryptor.verify_and_decrypt(encryptor, encrypted)
decrypted.current_user.name # => "José"

Link to this section Summary

Functions

Decrypts and verifies a message. We need to verify the message in order to avoid padding attacks. Reference: http://www.limited-entropy.com/padding-oracle-attacks

Link to this section Functions

Link to this function

encrypt_and_sign(message, secret, sign_secret, cipher \\ :aes_256_cbc)

Encrypts and signs a message.

Link to this function

verify_and_decrypt(encrypted, secret, sign_secret, cipher \\ :aes_256_cbc)

Decrypts and verifies a message. We need to verify the message in order to avoid padding attacks. Reference: http://www.limited-entropy.com/padding-oracle-attacks