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use std::ops::{Deref, DerefMut};
use std::cmp::PartialEq;
use std::fmt;
use std::str::FromStr;
use std::hash::{Hash, Hasher};
use secp256k1::{Message as SecpMessage, RecoverableSignature, RecoveryId, Error as SecpError};
use secp256k1::key::{SecretKey, PublicKey};
use rustc_hex::{ToHex, FromHex};
use ethereum_types::{H520, H256};
use {Secret, Public, SECP256K1, Error, Message, public_to_address, Address};
#[repr(C)]
pub struct Signature([u8; 65]);
impl Signature {
pub fn r(&self) -> &[u8] {
&self.0[0..32]
}
pub fn s(&self) -> &[u8] {
&self.0[32..64]
}
pub fn v(&self) -> u8 {
self.0[64]
}
pub fn into_electrum(mut self) -> [u8; 65] {
self.0[64] += 27;
self.0
}
pub fn from_electrum(data: &[u8]) -> Self {
if data.len() != 65 || data[64] < 27 {
return Signature::default();
}
let mut sig = [0u8; 65];
sig.copy_from_slice(data);
sig[64] -= 27;
Signature(sig)
}
pub fn from_rsv(r: &H256, s: &H256, v: u8) -> Self {
let mut sig = [0u8; 65];
sig[0..32].copy_from_slice(&r);
sig[32..64].copy_from_slice(&s);
sig[64] = v;
Signature(sig)
}
pub fn is_low_s(&self) -> bool {
H256::from_slice(self.s()) <= "7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0".into()
}
pub fn is_valid(&self) -> bool {
self.v() <= 1 &&
H256::from_slice(self.r()) < "fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141".into() &&
H256::from_slice(self.r()) >= 1.into() &&
H256::from_slice(self.s()) < "fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141".into() &&
H256::from_slice(self.s()) >= 1.into()
}
}
impl PartialEq for Signature {
fn eq(&self, other: &Self) -> bool {
&self.0[..] == &other.0[..]
}
}
impl Eq for Signature { }
impl fmt::Debug for Signature {
fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
f.debug_struct("Signature")
.field("r", &self.0[0..32].to_hex())
.field("s", &self.0[32..64].to_hex())
.field("v", &self.0[64..65].to_hex())
.finish()
}
}
impl fmt::Display for Signature {
fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
write!(f, "{}", self.to_hex())
}
}
impl FromStr for Signature {
type Err = Error;
fn from_str(s: &str) -> Result<Self, Self::Err> {
match s.from_hex() {
Ok(ref hex) if hex.len() == 65 => {
let mut data = [0; 65];
data.copy_from_slice(&hex[0..65]);
Ok(Signature(data))
},
_ => Err(Error::InvalidSignature)
}
}
}
impl Default for Signature {
fn default() -> Self {
Signature([0; 65])
}
}
impl Hash for Signature {
fn hash<H: Hasher>(&self, state: &mut H) {
H520::from(self.0).hash(state);
}
}
impl Clone for Signature {
fn clone(&self) -> Self {
Signature(self.0)
}
}
impl From<[u8; 65]> for Signature {
fn from(s: [u8; 65]) -> Self {
Signature(s)
}
}
impl Into<[u8; 65]> for Signature {
fn into(self) -> [u8; 65] {
self.0
}
}
impl From<Signature> for H520 {
fn from(s: Signature) -> Self {
H520::from(s.0)
}
}
impl From<H520> for Signature {
fn from(bytes: H520) -> Self {
Signature(bytes.into())
}
}
impl Deref for Signature {
type Target = [u8; 65];
fn deref(&self) -> &Self::Target {
&self.0
}
}
impl DerefMut for Signature {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.0
}
}
pub fn sign(secret: &Secret, message: &Message) -> Result<Signature, Error> {
let context = &SECP256K1;
let sec = SecretKey::from_slice(context, &secret)?;
let s = context.sign_recoverable(&SecpMessage::from_slice(&message[..])?, &sec)?;
let (rec_id, data) = s.serialize_compact(context);
let mut data_arr = [0; 65];
data_arr[0..64].copy_from_slice(&data[0..64]);
data_arr[64] = rec_id.to_i32() as u8;
Ok(Signature(data_arr))
}
pub fn verify_public(public: &Public, signature: &Signature, message: &Message) -> Result<bool, Error> {
let context = &SECP256K1;
let rsig = RecoverableSignature::from_compact(context, &signature[0..64], RecoveryId::from_i32(signature[64] as i32)?)?;
let sig = rsig.to_standard(context);
let pdata: [u8; 65] = {
let mut temp = [4u8; 65];
temp[1..65].copy_from_slice(&**public);
temp
};
let publ = PublicKey::from_slice(context, &pdata)?;
match context.verify(&SecpMessage::from_slice(&message[..])?, &sig, &publ) {
Ok(_) => Ok(true),
Err(SecpError::IncorrectSignature) => Ok(false),
Err(x) => Err(Error::from(x))
}
}
pub fn verify_address(address: &Address, signature: &Signature, message: &Message) -> Result<bool, Error> {
let public = recover(signature, message)?;
let recovered_address = public_to_address(&public);
Ok(address == &recovered_address)
}
pub fn recover(signature: &Signature, message: &Message) -> Result<Public, Error> {
let context = &SECP256K1;
let rsig = RecoverableSignature::from_compact(context, &signature[0..64], RecoveryId::from_i32(signature[64] as i32)?)?;
let pubkey = context.recover(&SecpMessage::from_slice(&message[..])?, &rsig)?;
let serialized = pubkey.serialize_vec(context, false);
let mut public = Public::default();
public.copy_from_slice(&serialized[1..65]);
Ok(public)
}
#[cfg(test)]
mod tests {
use std::str::FromStr;
use {Generator, Random, Message};
use super::{sign, verify_public, verify_address, recover, Signature};
#[test]
fn vrs_conversion() {
let keypair = Random.generate().unwrap();
let message = Message::default();
let signature = sign(keypair.secret(), &message).unwrap();
let vrs = signature.clone().into_electrum();
let from_vrs = Signature::from_electrum(&vrs);
assert_eq!(signature, from_vrs);
}
#[test]
fn signature_to_and_from_str() {
let keypair = Random.generate().unwrap();
let message = Message::default();
let signature = sign(keypair.secret(), &message).unwrap();
let string = format!("{}", signature);
let deserialized = Signature::from_str(&string).unwrap();
assert_eq!(signature, deserialized);
}
#[test]
fn sign_and_recover_public() {
let keypair = Random.generate().unwrap();
let message = Message::default();
let signature = sign(keypair.secret(), &message).unwrap();
assert_eq!(keypair.public(), &recover(&signature, &message).unwrap());
}
#[test]
fn sign_and_verify_public() {
let keypair = Random.generate().unwrap();
let message = Message::default();
let signature = sign(keypair.secret(), &message).unwrap();
assert!(verify_public(keypair.public(), &signature, &message).unwrap());
}
#[test]
fn sign_and_verify_address() {
let keypair = Random.generate().unwrap();
let message = Message::default();
let signature = sign(keypair.secret(), &message).unwrap();
assert!(verify_address(&keypair.address(), &signature, &message).unwrap());
}
}