openethereum/util/src/crypto.rs
Robert Habermeier ea08dd76a5 remove all possible unsafe code in crypto (#1168)
* use #[repr(C)] for all hash types

* use a zeroed buffer in crypto::ec::sign

* eliminate most usages of unsafe in crypto::ecdh::agree

* eliminate all possible unsafety in crypto module
2016-05-28 21:48:42 +02:00

462 lines
14 KiB
Rust

// Copyright 2015, 2016 Ethcore (UK) Ltd.
// This file is part of Parity.
// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Parity. If not, see <http://www.gnu.org/licenses/>.
//! Ethcore crypto.
use numbers::*;
use bytes::*;
use secp256k1::{key, Secp256k1};
use rand::os::OsRng;
use sha3::Hashable;
use std::fmt;
/// Secret key for secp256k1 EC operations. 256 bit generic "hash" data.
pub type Secret = H256;
/// Public key for secp256k1 EC operations. 512 bit generic "hash" data.
pub type Public = H512;
/// Signature for secp256k1 EC operations; encodes two 256-bit curve points
/// and a third sign bit. 520 bit generic "hash" data.
pub type Signature = H520;
lazy_static! {
static ref SECP256K1: Secp256k1 = Secp256k1::new();
}
impl Signature {
/// Create a new signature from the R, S and V componenets.
pub fn from_rsv(r: &H256, s: &H256, v: u8) -> Signature {
let mut ret: Signature = Signature::new();
(&mut ret[0..32]).copy_from_slice(r);
(&mut ret[32..64]).copy_from_slice(s);
ret[64] = v;
ret
}
/// Convert transaction to R, S and V components.
pub fn to_rsv(&self) -> (U256, U256, u8) {
(U256::from(&self.as_slice()[0..32]), U256::from(&self.as_slice()[32..64]), self[64])
}
}
#[derive(Debug)]
/// Crypto error
pub enum CryptoError {
/// Invalid secret key
InvalidSecret,
/// Invalid public key
InvalidPublic,
/// Invalid EC signature
InvalidSignature,
/// Invalid AES message
InvalidMessage,
/// IO Error
Io(::std::io::Error),
}
impl fmt::Display for CryptoError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
let msg = match *self {
CryptoError::InvalidSecret => "Invalid secret key".into(),
CryptoError::InvalidPublic => "Invalid public key".into(),
CryptoError::InvalidSignature => "Invalid EC signature".into(),
CryptoError::InvalidMessage => "Invalid AES message".into(),
CryptoError::Io(ref err) => format!("I/O error: {}", err),
};
f.write_fmt(format_args!("Crypto error ({})", msg))
}
}
impl From<::secp256k1::Error> for CryptoError {
fn from(e: ::secp256k1::Error) -> CryptoError {
match e {
::secp256k1::Error::InvalidMessage => CryptoError::InvalidMessage,
::secp256k1::Error::InvalidPublicKey => CryptoError::InvalidPublic,
::secp256k1::Error::InvalidSecretKey => CryptoError::InvalidSecret,
_ => CryptoError::InvalidSignature,
}
}
}
impl From<::std::io::Error> for CryptoError {
fn from(err: ::std::io::Error) -> CryptoError {
CryptoError::Io(err)
}
}
#[derive(Debug, PartialEq, Eq)]
/// secp256k1 Key pair
///
/// Use `create()` to create a new random key pair.
///
/// # Example
/// ```rust
/// extern crate ethcore_util;
/// use ethcore_util::crypto::*;
/// use ethcore_util::hash::*;
/// fn main() {
/// let pair = KeyPair::create().unwrap();
/// let message = H256::random();
/// let signature = ec::sign(pair.secret(), &message).unwrap();
///
/// assert!(ec::verify(pair.public(), &signature, &message).unwrap());
/// assert_eq!(ec::recover(&signature, &message).unwrap(), *pair.public());
/// }
/// ```
pub struct KeyPair {
secret: Secret,
public: Public,
}
impl KeyPair {
/// Create a pair from secret key
pub fn from_secret(secret: Secret) -> Result<KeyPair, CryptoError> {
let context = &SECP256K1;
let s: key::SecretKey = try!(key::SecretKey::from_slice(context, &secret));
let pub_key = try!(key::PublicKey::from_secret_key(context, &s));
let serialized = pub_key.serialize_vec(context, false);
let p: Public = Public::from_slice(&serialized[1..65]);
Ok(KeyPair {
secret: secret,
public: p,
})
}
/// Create a new random key pair
pub fn create() -> Result<KeyPair, CryptoError> {
let context = &SECP256K1;
let mut rng = try!(OsRng::new());
let (sec, publ) = try!(context.generate_keypair(&mut rng));
let serialized = publ.serialize_vec(context, false);
let p: Public = Public::from_slice(&serialized[1..65]);
let mut s = Secret::new();
s.copy_from_slice(&sec[0..32]);
Ok(KeyPair {
secret: s,
public: p,
})
}
/// Returns public key
pub fn public(&self) -> &Public {
&self.public
}
/// Returns private key
pub fn secret(&self) -> &Secret {
&self.secret
}
/// Returns address.
pub fn address(&self) -> Address {
Address::from(self.public.sha3())
}
/// Sign a message with our secret key.
pub fn sign(&self, message: &H256) -> Result<Signature, CryptoError> { ec::sign(&self.secret, message) }
}
/// EC functions
#[cfg_attr(feature="dev", allow(similar_names))]
pub mod ec {
use numbers::*;
use standard::*;
use crypto::*;
use crypto::{self};
/// Recovers Public key from signed message hash.
pub fn recover(signature: &Signature, message: &H256) -> Result<Public, CryptoError> {
use secp256k1::*;
let context = &crypto::SECP256K1;
let rsig = try!(RecoverableSignature::from_compact(context, &signature[0..64], try!(RecoveryId::from_i32(signature[64] as i32))));
let publ = try!(context.recover(&try!(Message::from_slice(&message)), &rsig));
let serialized = publ.serialize_vec(context, false);
let p: Public = Public::from_slice(&serialized[1..65]);
//TODO: check if it's the zero key and fail if so.
Ok(p)
}
/// Returns siganture of message hash.
pub fn sign(secret: &Secret, message: &H256) -> Result<Signature, CryptoError> {
// TODO: allow creation of only low-s signatures.
use secp256k1::{Message, key};
let context = &crypto::SECP256K1;
// no way to create from raw byte array.
let sec: &key::SecretKey = unsafe { ::std::mem::transmute(secret) };
let s = try!(context.sign_recoverable(&try!(Message::from_slice(&message)), sec));
let (rec_id, data) = s.serialize_compact(context);
let mut signature = crypto::Signature::new();
signature.clone_from_slice(&data);
signature[64] = rec_id.to_i32() as u8;
let (_, s, v) = signature.to_rsv();
let secp256k1n = U256::from_str("fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141").unwrap();
if !is_low_s(&s) {
signature = super::Signature::from_rsv(&H256::from_slice(&signature[0..32]), &H256::from(secp256k1n - s), v ^ 1);
}
Ok(signature)
}
/// Verify signature.
pub fn verify(public: &Public, signature: &Signature, message: &H256) -> Result<bool, CryptoError> {
use secp256k1::*;
let context = &crypto::SECP256K1;
let rsig = try!(RecoverableSignature::from_compact(context, &signature[0..64], try!(RecoveryId::from_i32(signature[64] as i32))));
let sig = rsig.to_standard(context);
let pdata: [u8; 65] = {
let mut temp = [4u8; 65];
(&mut temp[1..65]).copy_from_slice(public);
temp
};
let publ = try!(key::PublicKey::from_slice(context, &pdata));
match context.verify(&try!(Message::from_slice(&message)), &sig, &publ) {
Ok(_) => Ok(true),
Err(Error::IncorrectSignature) => Ok(false),
Err(x) => Err(CryptoError::from(x))
}
}
/// Check if this is a "low" signature.
pub fn is_low(sig: &Signature) -> bool {
H256::from_slice(&sig[32..64]) <= h256_from_hex("7fffffffffffffffffffffffffffffff5d576e7357a4501ddfe92f46681b20a0")
}
/// Check if this is a "low" signature.
pub fn is_low_s(s: &U256) -> bool {
s <= &U256::from_str("7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0").unwrap()
}
/// Check if each component of the signature is in range.
pub fn is_valid(sig: &Signature) -> bool {
sig[64] <= 1 &&
H256::from_slice(&sig[0..32]) < h256_from_hex("fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141") &&
H256::from_slice(&sig[32..64]) < h256_from_hex("fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141") &&
H256::from_slice(&sig[32..64]) >= h256_from_u64(1) &&
H256::from_slice(&sig[0..32]) >= h256_from_u64(1)
}
}
/// ECDH functions
#[cfg_attr(feature="dev", allow(similar_names))]
pub mod ecdh {
use hash::FixedHash;
use crypto::{self, Secret, Public, CryptoError};
/// Agree on a shared secret
pub fn agree(secret: &Secret, public: &Public) -> Result<Secret, CryptoError> {
use secp256k1::{ecdh, key};
let context = &crypto::SECP256K1;
let pdata = {
let mut temp = [4u8; 65];
(&mut temp[1..65]).copy_from_slice(&public[0..64]);
temp
};
let publ = try!(key::PublicKey::from_slice(context, &pdata));
// no way to create SecretKey from raw byte array.
let sec: &key::SecretKey = unsafe { ::std::mem::transmute(secret) };
let shared = ecdh::SharedSecret::new_raw(context, &publ, &sec);
let mut s = crypto::Secret::new();
s.copy_from_slice(&shared[0..32]);
Ok(s)
}
}
/// ECIES function
#[cfg_attr(feature="dev", allow(similar_names))]
pub mod ecies {
use hash::*;
use bytes::*;
use crypto::*;
/// Encrypt a message with a public key
pub fn encrypt(public: &Public, shared_mac: &[u8], plain: &[u8]) -> Result<Bytes, CryptoError> {
use ::rcrypto::digest::Digest;
use ::rcrypto::sha2::Sha256;
use ::rcrypto::hmac::Hmac;
use ::rcrypto::mac::Mac;
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 msg = vec![0u8; (1 + 64 + 16 + plain.len() + 32)];
msg[0] = 0x04u8;
{
let msgd = &mut msg[1..];
r.public().copy_to(&mut msgd[0..64]);
{
let cipher = &mut msgd[(64 + 16)..(64 + 16 + plain.len())];
aes::encrypt(ekey, &H128::new(), plain, cipher);
}
let mut hmac = Hmac::new(Sha256::new(), &mkey);
{
let cipher_iv = &msgd[64..(64 + 16 + plain.len())];
hmac.input(cipher_iv);
}
hmac.input(shared_mac);
hmac.raw_result(&mut msgd[(64 + 16 + plain.len())..]);
}
Ok(msg)
}
/// Decrypt a message with a secret key
pub fn decrypt(secret: &Secret, shared_mac: &[u8], encrypted: &[u8]) -> Result<Bytes, CryptoError> {
use ::rcrypto::digest::Digest;
use ::rcrypto::sha2::Sha256;
use ::rcrypto::hmac::Hmac;
use ::rcrypto::mac::Mac;
let meta_len = 1 + 64 + 16 + 32;
if encrypted.len() < meta_len || encrypted[0] < 2 || encrypted[0] > 4 {
return Err(CryptoError::InvalidMessage); //invalid message: publickey
}
let e = &encrypted[1..];
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_with_iv = &e[64..(64+16+clen)];
let cipher_iv = &cipher_with_iv[0..16];
let cipher_no_iv = &cipher_with_iv[16..];
let msg_mac = &e[(64+16+clen)..];
// Verify tag
let mut hmac = Hmac::new(Sha256::new(), &mkey);
hmac.input(cipher_with_iv);
hmac.input(shared_mac);
let mut mac = H256::new();
hmac.raw_result(&mut mac);
if &mac[..] != msg_mac {
return Err(CryptoError::InvalidMessage);
}
let mut msg = vec![0u8; clen];
aes::decrypt(ekey, cipher_iv, cipher_no_iv, &mut msg[..]);
Ok(msg)
}
fn kdf(secret: &Secret, s1: &[u8], dest: &mut [u8]) {
use ::rcrypto::digest::Digest;
use ::rcrypto::sha2::Sha256;
let mut hasher = Sha256::new();
// SEC/ISO/Shoup specify counter size SHOULD be equivalent
// to size of hash output, however, it also notes that
// the 4 bytes is okay. NIST specifies 4 bytes.
let mut ctr = 1u32;
let mut written = 0usize;
while written < dest.len() {
let ctrs = [(ctr >> 24) as u8, (ctr >> 16) as u8, (ctr >> 8) as u8, ctr as u8];
hasher.input(&ctrs);
hasher.input(secret);
hasher.input(s1);
hasher.result(&mut dest[written..(written + 32)]);
hasher.reset();
written += 32;
ctr += 1;
}
}
}
/// AES encryption
pub mod aes {
use ::rcrypto::blockmodes::*;
use ::rcrypto::aessafe::*;
use ::rcrypto::symmetriccipher::*;
use ::rcrypto::buffer::*;
/// Encrypt a message
pub fn encrypt(k: &[u8], iv: &[u8], plain: &[u8], dest: &mut [u8]) {
let mut encryptor = CtrMode::new(AesSafe128Encryptor::new(k), iv.to_vec());
encryptor.encrypt(&mut RefReadBuffer::new(plain), &mut RefWriteBuffer::new(dest), true).expect("Invalid length or padding");
}
/// Decrypt a message
pub fn decrypt(k: &[u8], iv: &[u8], encrypted: &[u8], dest: &mut [u8]) {
let mut encryptor = CtrMode::new(AesSafe128Encryptor::new(k), iv.to_vec());
encryptor.decrypt(&mut RefReadBuffer::new(encrypted), &mut RefWriteBuffer::new(dest), true).expect("Invalid length or padding");
}
}
#[cfg(test)]
mod tests {
use hash::*;
use crypto::*;
// TODO: tests for sign/recover roundtrip, at least.
#[test]
fn test_signature() {
let pair = KeyPair::create().unwrap();
let message = H256::random();
let signature = ec::sign(pair.secret(), &message).unwrap();
assert!(ec::verify(pair.public(), &signature, &message).unwrap());
assert_eq!(ec::recover(&signature, &message).unwrap(), *pair.public());
}
#[test]
fn test_invalid_key() {
assert!(KeyPair::from_secret(h256_from_hex("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff")).is_err());
assert!(KeyPair::from_secret(h256_from_hex("0000000000000000000000000000000000000000000000000000000000000000")).is_err());
assert!(KeyPair::from_secret(h256_from_hex("fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141")).is_err());
}
#[test]
fn test_key() {
let pair = KeyPair::from_secret(h256_from_hex("6f7b0d801bc7b5ce7bbd930b84fd0369b3eb25d09be58d64ba811091046f3aa2")).unwrap();
assert_eq!(pair.public().hex(), "101b3ef5a4ea7a1c7928e24c4c75fd053c235d7b80c22ae5c03d145d0ac7396e2a4ffff9adee3133a7b05044a5cee08115fd65145e5165d646bde371010d803c");
}
#[test]
fn ecies_shared() {
let kp = KeyPair::create().unwrap();
let message = b"So many books, so little time";
let shared = b"shared";
let wrong_shared = b"incorrect";
let encrypted = ecies::encrypt(kp.public(), shared, message).unwrap();
assert!(encrypted[..] != message[..]);
assert_eq!(encrypted[0], 0x04);
assert!(ecies::decrypt(kp.secret(), wrong_shared, &encrypted).is_err());
let decrypted = ecies::decrypt(kp.secret(), shared, &encrypted).unwrap();
assert_eq!(decrypted[..message.len()], message[..]);
}
}