323 lines
9.2 KiB
Rust
323 lines
9.2 KiB
Rust
// Copyright 2015-2020 Parity Technologies (UK) Ltd.
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// This file is part of OpenEthereum.
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// OpenEthereum is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// OpenEthereum is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with OpenEthereum. If not, see <http://www.gnu.org/licenses/>.
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use ethereum_types::H256;
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use memzero::Memzero;
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use rustc_hex::ToHex;
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use secp256k1::{constants::SECRET_KEY_SIZE as SECP256K1_SECRET_KEY_SIZE, key};
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use std::{fmt, ops::Deref, str::FromStr};
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use Error;
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use SECP256K1;
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#[derive(Clone, PartialEq, Eq)]
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pub struct Secret {
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inner: Memzero<H256>,
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}
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impl ToHex for Secret {
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fn to_hex(&self) -> String {
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format!("{:x}", *self.inner)
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}
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}
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impl fmt::LowerHex for Secret {
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fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
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self.inner.fmt(fmt)
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}
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}
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impl fmt::Debug for Secret {
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fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
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self.inner.fmt(fmt)
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}
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}
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impl fmt::Display for Secret {
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fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
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write!(
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fmt,
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"Secret: 0x{:x}{:x}..{:x}{:x}",
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self.inner[0], self.inner[1], self.inner[30], self.inner[31]
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)
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}
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}
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impl Secret {
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/// Creates a `Secret` from the given slice, returning `None` if the slice length != 32.
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pub fn from_slice(key: &[u8]) -> Option<Self> {
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if key.len() != 32 {
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return None;
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}
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let mut h = H256::default();
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h.copy_from_slice(&key[0..32]);
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Some(Secret {
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inner: Memzero::from(h),
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})
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}
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/// Creates zero key, which is invalid for crypto operations, but valid for math operation.
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pub fn zero() -> Self {
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Secret {
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inner: Memzero::from(H256::default()),
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}
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}
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/// Imports and validates the key.
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pub fn from_unsafe_slice(key: &[u8]) -> Result<Self, Error> {
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let secret = key::SecretKey::from_slice(&super::SECP256K1, key)?;
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Ok(secret.into())
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}
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/// Checks validity of this key.
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pub fn check_validity(&self) -> Result<(), Error> {
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self.to_secp256k1_secret().map(|_| ())
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}
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/// Inplace add one secret key to another (scalar + scalar)
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pub fn add(&mut self, other: &Secret) -> Result<(), Error> {
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match (self.is_zero(), other.is_zero()) {
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(true, true) | (false, true) => Ok(()),
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(true, false) => {
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*self = other.clone();
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Ok(())
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}
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(false, false) => {
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let mut key_secret = self.to_secp256k1_secret()?;
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let other_secret = other.to_secp256k1_secret()?;
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key_secret.add_assign(&SECP256K1, &other_secret)?;
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*self = key_secret.into();
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Ok(())
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}
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}
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}
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/// Inplace subtract one secret key from another (scalar - scalar)
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pub fn sub(&mut self, other: &Secret) -> Result<(), Error> {
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match (self.is_zero(), other.is_zero()) {
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(true, true) | (false, true) => Ok(()),
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(true, false) => {
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*self = other.clone();
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self.neg()
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}
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(false, false) => {
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let mut key_secret = self.to_secp256k1_secret()?;
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let mut other_secret = other.to_secp256k1_secret()?;
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other_secret.mul_assign(&SECP256K1, &key::MINUS_ONE_KEY)?;
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key_secret.add_assign(&SECP256K1, &other_secret)?;
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*self = key_secret.into();
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Ok(())
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}
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}
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}
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/// Inplace decrease secret key (scalar - 1)
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pub fn dec(&mut self) -> Result<(), Error> {
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match self.is_zero() {
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true => {
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*self = key::MINUS_ONE_KEY.into();
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Ok(())
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}
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false => {
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let mut key_secret = self.to_secp256k1_secret()?;
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key_secret.add_assign(&SECP256K1, &key::MINUS_ONE_KEY)?;
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*self = key_secret.into();
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Ok(())
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}
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}
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}
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/// Inplace multiply one secret key to another (scalar * scalar)
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pub fn mul(&mut self, other: &Secret) -> Result<(), Error> {
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match (self.is_zero(), other.is_zero()) {
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(true, true) | (true, false) => Ok(()),
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(false, true) => {
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*self = Self::zero();
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Ok(())
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}
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(false, false) => {
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let mut key_secret = self.to_secp256k1_secret()?;
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let other_secret = other.to_secp256k1_secret()?;
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key_secret.mul_assign(&SECP256K1, &other_secret)?;
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*self = key_secret.into();
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Ok(())
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}
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}
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}
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/// Inplace negate secret key (-scalar)
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pub fn neg(&mut self) -> Result<(), Error> {
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match self.is_zero() {
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true => Ok(()),
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false => {
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let mut key_secret = self.to_secp256k1_secret()?;
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key_secret.mul_assign(&SECP256K1, &key::MINUS_ONE_KEY)?;
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*self = key_secret.into();
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Ok(())
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}
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}
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}
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/// Inplace inverse secret key (1 / scalar)
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pub fn inv(&mut self) -> Result<(), Error> {
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let mut key_secret = self.to_secp256k1_secret()?;
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key_secret.inv_assign(&SECP256K1)?;
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*self = key_secret.into();
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Ok(())
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}
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/// Compute power of secret key inplace (secret ^ pow).
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/// This function is not intended to be used with large powers.
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pub fn pow(&mut self, pow: usize) -> Result<(), Error> {
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if self.is_zero() {
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return Ok(());
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}
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match pow {
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0 => *self = key::ONE_KEY.into(),
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1 => (),
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_ => {
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let c = self.clone();
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for _ in 1..pow {
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self.mul(&c)?;
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}
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}
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}
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Ok(())
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}
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/// Create `secp256k1::key::SecretKey` based on this secret
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pub fn to_secp256k1_secret(&self) -> Result<key::SecretKey, Error> {
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Ok(key::SecretKey::from_slice(&SECP256K1, &self[..])?)
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}
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}
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impl FromStr for Secret {
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type Err = Error;
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fn from_str(s: &str) -> Result<Self, Self::Err> {
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Ok(H256::from_str(s)
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.map_err(|e| Error::Custom(format!("{:?}", e)))?
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.into())
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}
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}
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impl From<[u8; 32]> for Secret {
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fn from(k: [u8; 32]) -> Self {
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Secret {
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inner: Memzero::from(H256(k)),
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}
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}
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}
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impl From<H256> for Secret {
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fn from(s: H256) -> Self {
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s.0.into()
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}
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}
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impl From<&'static str> for Secret {
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fn from(s: &'static str) -> Self {
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s.parse().expect(&format!(
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"invalid string literal for {}: '{}'",
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stringify!(Self),
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s
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))
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}
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}
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impl From<key::SecretKey> for Secret {
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fn from(key: key::SecretKey) -> Self {
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let mut a = [0; SECP256K1_SECRET_KEY_SIZE];
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a.copy_from_slice(&key[0..SECP256K1_SECRET_KEY_SIZE]);
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a.into()
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}
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}
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impl Deref for Secret {
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type Target = H256;
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fn deref(&self) -> &Self::Target {
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&self.inner
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}
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}
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#[cfg(test)]
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mod tests {
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use super::{
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super::{Generator, Random},
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Secret,
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};
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use std::str::FromStr;
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#[test]
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fn multiplicating_secret_inversion_with_secret_gives_one() {
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let secret = Random.generate().unwrap().secret().clone();
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let mut inversion = secret.clone();
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inversion.inv().unwrap();
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inversion.mul(&secret).unwrap();
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assert_eq!(
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inversion,
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Secret::from_str("0000000000000000000000000000000000000000000000000000000000000001")
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.unwrap()
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);
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}
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#[test]
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fn secret_inversion_is_reversible_with_inversion() {
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let secret = Random.generate().unwrap().secret().clone();
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let mut inversion = secret.clone();
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inversion.inv().unwrap();
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inversion.inv().unwrap();
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assert_eq!(inversion, secret);
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}
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#[test]
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fn secret_pow() {
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let secret = Random.generate().unwrap().secret().clone();
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let mut pow0 = secret.clone();
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pow0.pow(0).unwrap();
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assert_eq!(
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pow0,
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Secret::from_str("0000000000000000000000000000000000000000000000000000000000000001")
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.unwrap()
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);
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let mut pow1 = secret.clone();
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pow1.pow(1).unwrap();
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assert_eq!(pow1, secret);
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let mut pow2 = secret.clone();
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pow2.pow(2).unwrap();
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let mut pow2_expected = secret.clone();
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pow2_expected.mul(&secret).unwrap();
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assert_eq!(pow2, pow2_expected);
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let mut pow3 = secret.clone();
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pow3.pow(3).unwrap();
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let mut pow3_expected = secret.clone();
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pow3_expected.mul(&secret).unwrap();
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pow3_expected.mul(&secret).unwrap();
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assert_eq!(pow3, pow3_expected);
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}
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}
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