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::SHA256;
   5 use openssl::crypto::hmac::HMAC;
   6 use openssl::crypto::symm;
   7
   8 // These aren't the keys you're looking for.
   9 static 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];
  10 static 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];
  11
  12 /// Only returns the first ten bytes.
  13 pub fn compute_mac(data: &[u8]) -> [u8, ..10] {
  14    let mut hmac = HMAC(SHA256, KEY_A);
  15    hmac.update(data);
  16    let mut result = [0u8, ..10];
  17    copy_memory(&mut result, hmac.finalize().slice(0, 10));
  18    result
  19 }
  20
  21 /// Encrypt may fail if the provided data size isn't a multiple of 16.
  22 pub fn encrypt(plaindata: &[u8], iv: &[u8]) -> Option<Vec<u8>> {
  23    let c = symm::Crypter::new(symm::AES_256_CBC);
  24    c.init(symm::Encrypt, KEY_C, iv.to_vec());
  25    c.pad(false); // Padding disabled!
  26    let r = c.update(plaindata);
  27    let rest = c.finalize();
  28    if rest.is_empty() {
  29       Some(r)
  30    } else {
  31       None
  32    }
  33 }
  34
  35 /// Decrypt may fail if the provided data size isn't a multiple of 16.
  36 pub fn decrypt(cypherdata: &[u8], iv: &[u8]) -> Option<Vec<u8>> {
  37    let c = symm::Crypter::new(symm::AES_256_CBC);
  38    c.init(symm::Decrypt, KEY_C, iv.to_vec());
  39    c.pad(false); // Padding disabled!
  40    let r = c.update(cypherdata);
  41    let rest = c.finalize();
  42    if rest.is_empty() {
  43       Some(r)
  44    } else {
  45       None
  46    }
  47 }
  48
  49 pub fn generate_key(size_byte: uint) -> IoResult<Vec<u8>>  {
  50    let mut bytes = Vec::from_elem(size_byte, 0u8);
  51    let mut generator = try!(OsRng::new()); // Uses '/dev/urandom' on Unix-like systems.
  52    generator.fill_bytes(bytes.as_mut_slice_());
  53    Ok(bytes)
  54 }