Plug.Crypto.MessageEncryptor

Plug.Crypto.MessageEncryptor

MessageEncryptor is a simple way to encrypt values which get stored somewhere you don’t trust.

The encrypted key, initialization vector, cipher text, and cipher tag are base64url 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)

data = "José"
encrypted = MessageEncryptor.encrypt(data, secret, sign_secret)
decrypted = MessageEncryptor.decrypt(encrypted, secret, sign_secret)
decrypted # => {:ok, "José"}

Summary

Functions

decrypt(encrypted, secret, sign_secret)

Decrypts a message using authenticated encryption

encrypt(message, secret, sign_secret)

Encrypts a message using authenticated encryption

encrypt_and_sign(message, secret, sign_secret, cipher \\ nil)

WARNING: This function is deprecated in favor of encrypt/3. Encrypts and signs a message

verify_and_decrypt(encrypted, secret, sign_secret, cipher \\ nil)

WARNING: This function is deprecated in favor of decrypt/3. Decrypts and verifies a message

Functions

decrypt(encrypted, secret, sign_secret)

Decrypts a message using authenticated encryption.

encrypt(message, secret, sign_secret)

Encrypts a message using authenticated encryption.

encrypt_and_sign(message, secret, sign_secret, cipher \\ nil)

WARNING: This function is deprecated in favor of encrypt/3. Encrypts and signs a message.

verify_and_decrypt(encrypted, secret, sign_secret, cipher \\ nil)

WARNING: This function is deprecated in favor of decrypt/3. 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