lab1_rust/src/crypto.rs

   1 use std::rand::{ OsRng, Rng };
   2 use std::io::IoResult;
   3 use std::slice::bytes::copy_memory;
   4 use openssl::crypto::hash::HashType::SHA256;
   5 use openssl::crypto::hmac::HMAC;
   6 use openssl::crypto::symm;
   7 use utils::from_elem;
   8
   9 // These aren't the keys you're looking for.
  10 const KEY_A: &'static [u8] = &[125, 31, 131, 118, 143, 180, 252, 53, 211, 217, 79, 240, 128, 91, 252, 87, 104, 236, 145, 198, 163, 203, 161, 12, 53, 56, 218, 40, 221, 95, 171, 140];
  11 const KEY_C: &'static [u8] = &[75, 226, 88, 31, 223, 216, 182, 216, 178, 58, 59, 193, 245, 80, 254, 128, 125, 246, 246, 224, 194, 190, 123, 123, 10, 131, 217, 183, 112, 157, 166, 102];
  12
  13 /// Only returns the first ten bytes from HMAC-SHA256.
  14 pub fn compute_mac(data: &[u8]) -> [u8; 10] {
  15    let mut hmac = HMAC(SHA256, KEY_A);
  16    hmac.update(data);
  17    let mut result = [0u8; 10];
  18    copy_memory(&mut result, hmac.finalize().slice(0, 10));
  19    result
  20 }
  21
  22 /// Encrypt may fail if the provided data size isn't a multiple of 16, no padding will be automatically added.
  23 pub fn encrypt(plaindata: &[u8], iv: &[u8]) -> Option<Vec<u8>> {
  24    let c = symm::Crypter::new(symm::Type::AES_256_CBC);
  25    c.init(symm::Mode::Encrypt, KEY_C, iv.to_vec());
  26    c.pad(false); // Padding disabled!
  27    let r = c.update(plaindata);
  28    let rest = c.finalize();
  29    if rest.is_empty() {
  30       Some(r)
  31    } else {
  32       None
  33    }
  34 }
  35
  36 /// Decrypt may fail if the provided data size isn't a multiple of 16, no padding will be automatically added.
  37 pub fn decrypt(cipherdata: &[u8], iv: &[u8]) -> Option<Vec<u8>> {
  38    let c = symm::Crypter::new(symm::Type::AES_256_CBC);
  39    c.init(symm::Mode::Decrypt, KEY_C, iv.to_vec());
  40    c.pad(false); // Padding disabled!
  41    let r = c.update(cipherdata);
  42    let rest = c.finalize();
  43    if rest.is_empty() {
  44       Some(r)
  45    } else {
  46       None
  47    }
  48 }
  49
  50 pub fn generate_key(size_byte: uint) -> IoResult<Vec<u8>>  {
  51    let mut bytes = from_elem(size_byte, 0u8);
  52    let mut generator = try!(OsRng::new()); // Uses '/dev/urandom' on Unix-like systems.
  53    generator.fill_bytes(bytes.as_mut_slice());
  54    Ok(bytes)
  55 }