Example of PyCrypto AES decryption

decrypt.py

import base64
import hashlib
import hmac
from Crypto.Cipher import AES


key = base64.decodebytes(b'v4QC6l4ttEogiBYvjLyvbA==')
nonce = base64.decodebytes(b'3iNVHJXuCfYoU9QP49DGqw==')
ct = base64.decodebytes(b'x9WM3Qy15Xw/2Z6pGVKXVA==')

cipher = AES.new(key, mode=AES.MODE_CTR, counter=lambda: nonce)
print(cipher.decrypt(ct))

key = base64.decodebytes(b'esU5jdGCbM7E/ME5WBECJ+BdX3kt7bcQ3HkeEK+W6ZQ=')
message = b'Ceterum censeo Carthaginem esse delendam'
expected = 'b3240371a17e1e9755b89b23449f0d85c4c361e94e081c7adbe5a89c2d901aaa'
h = hmac.new(key, message, hashlib.sha256)
print(hmac.compare_digest(h.hexdigest(), expected))

gen.rs

extern crate crypto;
extern crate rustc_serialize as serialize;
extern crate rand;

use crypto::digest::Digest;
use crypto::sha2::Sha256;
use crypto::aes::{self, KeySize};
use crypto::symmetriccipher::SynchronousStreamCipher;
use crypto::hmac::Hmac;
use crypto::mac::Mac;

use serialize::hex::ToHex;
use serialize::base64::{STANDARD, ToBase64};

use std::iter::repeat;

use rand::{OsRng, Rng};

fn main() {
    let input = "Hello world";
    let mut sha = Sha256::new();
    sha.input_str(input);
    println!("{}", sha.result_str());
    println!("");

    let mut bytes: Vec<u8> = repeat(0u8).take(sha.output_bytes()).collect();
    sha.result(&mut bytes[..]);
    println!("{}", bytes.to_base64(STANDARD));
    println!("");

    /* =========================== */

    let mut gen = OsRng::new().ok().expect("Failed to get OS random generator");

    let mut key: Vec<u8> = repeat(0u8).take(16).collect();
    gen.fill_bytes(&mut key);

    let mut nonce: Vec<u8> = repeat(0u8).take(16).collect();
    gen.fill_bytes(&mut nonce);

    println!("Key: {}", key.to_base64(STANDARD));
    println!("Nonce: {}", nonce.to_base64(STANDARD));

    let mut cipher = aes::ctr(KeySize::KeySize128, &key, &nonce);
    let secret = "I like Nicelback";
    let mut output: Vec<u8> = repeat(0u8).take(secret.len()).collect();
    cipher.process(secret.as_bytes(), &mut output);
    println!("Ciphertext: {}", output.to_base64(STANDARD));
    println!("");

    /* =========================== */

    let mut hmac_key: Vec<u8> = repeat(0u8).take(32).collect();
    gen.fill_bytes(&mut hmac_key);

    let message = "Ceterum censeo Carthaginem esse delendam";
    println!("Message: {}", message);
    println!("HMAC key: {}", hmac_key.to_base64(STANDARD));

    let mut hmac = Hmac::new(Sha256::new(), &hmac_key);
    hmac.input(message.as_bytes());
    println!("HMAC digest: {}", hmac.result().code().to_hex());
}