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ECIES without MAC (#1948) 

* Use random IV for ECIES AES

* ECIES encrypt/decrypt for a single message

* Derive IV from shared secret
This commit is contained in:
Arkadiy Paronyan 2016-08-18 18:08:02 +02:00 committed by Gav Wood
parent d279794c32
commit 8159d743ef
1 changed files with 71 additions and 1 deletions
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72
util/src/crypto.rs
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@ -311,6 +311,7 @@ pub mod ecies {
use hash::*;
use bytes::*;
use crypto::*;
use sha3::Hashable;
/// Encrypt a message with a public key
pub fn encrypt(public: &Public, shared_mac: &[u8], plain: &[u8]) -> Result<Bytes, CryptoError> {
@ -334,9 +335,11 @@ pub mod ecies {
{
let msgd = &mut msg[1..];
r.public().copy_to(&mut msgd[0..64]);
let iv = H128::random();
iv.copy_to(&mut msgd[64..(64+16)]);
{
let cipher = &mut msgd[(64 + 16)..(64 + 16 + plain.len())];
aes::encrypt(ekey, &H128::new(), plain, cipher);
aes::encrypt(ekey, &iv, plain, cipher);
}
let mut hmac = Hmac::new(Sha256::new(), &mkey);
{
@ -349,6 +352,33 @@ pub mod ecies {
Ok(msg)
}
/// Encrypt a message with a public key
pub fn encrypt_single_message(public: &Public, plain: &[u8]) -> Result<Bytes, CryptoError> {
use ::rcrypto::digest::Digest;
use ::rcrypto::sha2::Sha256;
let r = try!(KeyPair::create());
let z = try!(ecdh::agree(r.secret(), public));
let mut key = [0u8; 32];
let mut mkey = [0u8; 32];
kdf(&z, &[0u8; 0], &mut key);
let mut hasher = Sha256::new();
let mkey_material = &key[16..32];
hasher.input(mkey_material);
hasher.result(&mut mkey);
let ekey = &key[0..16];
let mut msgd = vec![0u8; (64 + plain.len())];
{
r.public().copy_to(&mut msgd[0..64]);
let iv = H128::from_slice(&z.sha3()[0..16]);
{
let cipher = &mut msgd[64..(64 + plain.len())];
aes::encrypt(ekey, &iv, plain, cipher);
}
}
Ok(msgd)
}
/// Decrypt a message with a secret key
pub fn decrypt(secret: &Secret, shared_mac: &[u8], encrypted: &[u8]) -> Result<Bytes, CryptoError> {
use ::rcrypto::digest::Digest;
@ -394,6 +424,36 @@ pub mod ecies {
Ok(msg)
}
/// Decrypt single message with a secret key
pub fn decrypt_single_message(secret: &Secret, encrypted: &[u8]) -> Result<Bytes, CryptoError> {
use ::rcrypto::digest::Digest;
use ::rcrypto::sha2::Sha256;
let meta_len = 64;
if encrypted.len() < meta_len {
return Err(CryptoError::InvalidMessage); //invalid message: publickey
}
let e = encrypted;
let p = Public::from_slice(&e[0..64]);
let z = try!(ecdh::agree(secret, &p));
let mut key = [0u8; 32];
kdf(&z, &[0u8; 0], &mut key);
let ekey = &key[0..16];
let mkey_material = &key[16..32];
let mut hasher = Sha256::new();
let mut mkey = [0u8; 32];
hasher.input(mkey_material);
hasher.result(&mut mkey);
let clen = encrypted.len() - meta_len;
let cipher = &e[64..(64+clen)];
let mut msg = vec![0u8; clen];
let iv = H128::from_slice(&z.sha3()[0..16]);
aes::decrypt(ekey, &iv, cipher, &mut msg[..]);
Ok(msg)
}
fn kdf(secret: &Secret, s1: &[u8], dest: &mut [u8]) {
use ::rcrypto::digest::Digest;
use ::rcrypto::sha2::Sha256;
@ -487,4 +547,14 @@ mod tests {
let decrypted = ecies::decrypt(kp.secret(), shared, &encrypted).unwrap();
assert_eq!(decrypted[..message.len()], message[..]);
}
#[test]
fn ecies_shared_single() {
let kp = KeyPair::create().unwrap();
let message = b"So many books, so little time";
let encrypted = ecies::encrypt_single_message(kp.public(), message).unwrap();
assert!(encrypted[..] != message[..]);
let decrypted = ecies::decrypt_single_message(kp.secret(), &encrypted).unwrap();
assert_eq!(decrypted[..message.len()], message[..]);
}
}