aes-cbc-mac

Node implementation for aes cbc mac.

Security Considerations

A number of attacks exist against Cipher Block Chaining Message Authentication Code (CBC-MAC) that need to be considered.

• A single key must only be used for messages of a fixed and known length. If this is not the case, an attacker will be able to generate a message with a valid tag given two message and tag pairs. This can be addressed by using different keys for messages of different lengths. The current structure mitigates this problem, as a specific encoding structure that includes lengths is built and signed. (CMAC also addresses this issue.)
• Cipher Block Chaining (CBC) mode, if the same key is used for both encryption and authentication operations, an attacker can produce messages with a valid authentication code.
• If the IV can be modified, then messages can be forged. This is addressed by fixing the IV to all zeros.

Installation

npm install aes-cbc-mac --save

Testing

npm run test

Usage

const aesCbcMac = require('aes-cbc-mac');

const message = 'Important message';
const key = Buffer.from('849B57219DAE48DE646D07DBB533566E', 'hex');
const hashLen = 8; // bytes, 64 bits
const hash = aesCbcMac.create(message, key, hashLen);

console.log(hash);