Question

For aes with a 128-bit block length and a 128-bit key length, what is the output of the first round of aes if the plaintext consists of 128 zeros and the first subkey consists of 128 zeros?

Answer 1

The answer is 66e94bd4ef8a2c3b884cfa59ca342b2e.

You can check it with the following node.js program:

const crypto = require('crypto');
const zeros = Buffer.alloc(16);
var cipher = crypto.createCipheriv('aes-128-cbc', zeros, zeros);
var encrypted = Buffer.concat([cipher.update(zeros), cipher.final()]);
console.log(encrypted.toString('hex'));

Note that the output will contain 2 blocks of 128 bit, this is due to the padding algorithm. For this question you can ignore the second block.