341 lines
12 KiB
Rust
341 lines
12 KiB
Rust
// Written in 2014 by Andrew Poelstra <apoelstra@wpsoftware.net>
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// SPDX-License-Identifier: CC0-1.0
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//! Base58 encoder and decoder.
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//!
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//! This module provides functions for encoding and decoding base58 slices and
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//! strings respectively.
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//!
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use core::convert::TryInto;
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use core::{fmt, iter, slice, str};
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use crate::hashes::{sha256d, Hash};
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use crate::prelude::*;
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static BASE58_CHARS: &[u8] = b"123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
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#[rustfmt::skip]
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static BASE58_DIGITS: [Option<u8>; 128] = [
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None, None, None, None, None, None, None, None, // 0-7
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None, None, None, None, None, None, None, None, // 8-15
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None, None, None, None, None, None, None, None, // 16-23
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None, None, None, None, None, None, None, None, // 24-31
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None, None, None, None, None, None, None, None, // 32-39
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None, None, None, None, None, None, None, None, // 40-47
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None, Some(0), Some(1), Some(2), Some(3), Some(4), Some(5), Some(6), // 48-55
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Some(7), Some(8), None, None, None, None, None, None, // 56-63
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None, Some(9), Some(10), Some(11), Some(12), Some(13), Some(14), Some(15), // 64-71
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Some(16), None, Some(17), Some(18), Some(19), Some(20), Some(21), None, // 72-79
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Some(22), Some(23), Some(24), Some(25), Some(26), Some(27), Some(28), Some(29), // 80-87
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Some(30), Some(31), Some(32), None, None, None, None, None, // 88-95
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None, Some(33), Some(34), Some(35), Some(36), Some(37), Some(38), Some(39), // 96-103
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Some(40), Some(41), Some(42), Some(43), None, Some(44), Some(45), Some(46), // 104-111
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Some(47), Some(48), Some(49), Some(50), Some(51), Some(52), Some(53), Some(54), // 112-119
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Some(55), Some(56), Some(57), None, None, None, None, None, // 120-127
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];
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/// Decodes a base58-encoded string into a byte vector.
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#[deprecated(since = "0.30.0", note = "Use base58::decode() instead")]
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pub fn from(data: &str) -> Result<Vec<u8>, Error> { decode(data) }
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/// Decodes a base58-encoded string into a byte vector.
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pub fn decode(data: &str) -> Result<Vec<u8>, Error> {
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// 11/15 is just over log_256(58)
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let mut scratch = vec![0u8; 1 + data.len() * 11 / 15];
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// Build in base 256
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for d58 in data.bytes() {
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// Compute "X = X * 58 + next_digit" in base 256
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if d58 as usize >= BASE58_DIGITS.len() {
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return Err(Error::BadByte(d58));
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}
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let mut carry = match BASE58_DIGITS[d58 as usize] {
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Some(d58) => d58 as u32,
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None => {
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return Err(Error::BadByte(d58));
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}
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};
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for d256 in scratch.iter_mut().rev() {
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carry += *d256 as u32 * 58;
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*d256 = carry as u8;
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carry /= 256;
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}
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assert_eq!(carry, 0);
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}
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// Copy leading zeroes directly
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let mut ret: Vec<u8> = data.bytes().take_while(|&x| x == BASE58_CHARS[0]).map(|_| 0).collect();
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// Copy rest of string
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ret.extend(scratch.into_iter().skip_while(|&x| x == 0));
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Ok(ret)
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}
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/// Decodes a base58check-encoded string into a byte vector verifying the checksum.
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#[deprecated(since = "0.30.0", note = "Use base58::decode_check() instead")]
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pub fn from_check(data: &str) -> Result<Vec<u8>, Error> { decode_check(data) }
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/// Decodes a base58check-encoded string into a byte vector verifying the checksum.
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pub fn decode_check(data: &str) -> Result<Vec<u8>, Error> {
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let mut ret: Vec<u8> = decode(data)?;
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if ret.len() < 4 {
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return Err(Error::TooShort(ret.len()));
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}
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let check_start = ret.len() - 4;
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let hash_check =
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sha256d::Hash::hash(&ret[..check_start])[..4].try_into().expect("4 byte slice");
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let data_check = ret[check_start..].try_into().expect("4 byte slice");
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let expected = u32::from_le_bytes(hash_check);
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let actual = u32::from_le_bytes(data_check);
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if expected != actual {
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return Err(Error::BadChecksum(expected, actual));
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}
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ret.truncate(check_start);
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Ok(ret)
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}
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/// Encodes `data` as a base58 string.
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#[deprecated(since = "0.30.0", note = "Use base58::encode() instead")]
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pub fn encode_slice(data: &[u8]) -> String { encode(data) }
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/// Encodes `data` as a base58 string (see also `base58::encode_check()`).
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pub fn encode(data: &[u8]) -> String { encode_iter(data.iter().cloned()) }
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/// Encodes `data` as a base58 string including the checksum.
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///
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/// The checksum is the first four bytes of the sha256d of the data, concatenated onto the end.
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#[deprecated(since = "0.30.0", note = "Use base58::encode_check() instead")]
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pub fn check_encode_slice(data: &[u8]) -> String { encode_check(data) }
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/// Encodes `data` as a base58 string including the checksum.
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///
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/// The checksum is the first four bytes of the sha256d of the data, concatenated onto the end.
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pub fn encode_check(data: &[u8]) -> String {
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let checksum = sha256d::Hash::hash(data);
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encode_iter(data.iter().cloned().chain(checksum[0..4].iter().cloned()))
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}
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/// Encodes `data` as base58, including the checksum, into a formatter.
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///
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/// The checksum is the first four bytes of the sha256d of the data, concatenated onto the end.
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#[deprecated(since = "0.30.0", note = "Use base58::encode_check_to_fmt() instead")]
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pub fn check_encode_slice_to_fmt(fmt: &mut fmt::Formatter, data: &[u8]) -> fmt::Result {
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encode_check_to_fmt(fmt, data)
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}
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/// Encodes a slice as base58, including the checksum, into a formatter.
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///
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/// The checksum is the first four bytes of the sha256d of the data, concatenated onto the end.
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pub fn encode_check_to_fmt(fmt: &mut fmt::Formatter, data: &[u8]) -> fmt::Result {
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let checksum = sha256d::Hash::hash(data);
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let iter = data.iter().cloned().chain(checksum[0..4].iter().cloned());
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format_iter(fmt, iter)
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}
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fn encode_iter<I>(data: I) -> String
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where
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I: Iterator<Item = u8> + Clone,
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{
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let mut ret = String::new();
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format_iter(&mut ret, data).expect("writing into string shouldn't fail");
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ret
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}
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fn format_iter<I, W>(writer: &mut W, data: I) -> Result<(), fmt::Error>
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where
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I: Iterator<Item = u8> + Clone,
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W: fmt::Write,
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{
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let mut ret = SmallVec::new();
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let mut leading_zero_count = 0;
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let mut leading_zeroes = true;
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// Build string in little endian with 0-58 in place of characters...
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for d256 in data {
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let mut carry = d256 as usize;
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if leading_zeroes && carry == 0 {
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leading_zero_count += 1;
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} else {
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leading_zeroes = false;
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}
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for ch in ret.iter_mut() {
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let new_ch = *ch as usize * 256 + carry;
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*ch = (new_ch % 58) as u8;
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carry = new_ch / 58;
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}
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while carry > 0 {
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ret.push((carry % 58) as u8);
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carry /= 58;
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}
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}
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// ... then reverse it and convert to chars
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for _ in 0..leading_zero_count {
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ret.push(0);
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}
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for ch in ret.iter().rev() {
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writer.write_char(BASE58_CHARS[*ch as usize] as char)?;
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}
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Ok(())
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}
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/// Vector-like object that holds the first 100 elements on the stack. If more space is needed it
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/// will be allocated on the heap.
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struct SmallVec<T> {
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len: usize,
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stack: [T; 100],
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heap: Vec<T>,
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}
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impl<T: Default + Copy> SmallVec<T> {
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fn new() -> SmallVec<T> { SmallVec { len: 0, stack: [T::default(); 100], heap: Vec::new() } }
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fn push(&mut self, val: T) {
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if self.len < 100 {
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self.stack[self.len] = val;
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self.len += 1;
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} else {
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self.heap.push(val);
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}
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}
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fn iter(&self) -> iter::Chain<slice::Iter<T>, slice::Iter<T>> {
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// If len<100 then we just append an empty vec
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self.stack[0..self.len].iter().chain(self.heap.iter())
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}
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fn iter_mut(&mut self) -> iter::Chain<slice::IterMut<T>, slice::IterMut<T>> {
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// If len<100 then we just append an empty vec
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self.stack[0..self.len].iter_mut().chain(self.heap.iter_mut())
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}
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}
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/// An error that might occur during base58 decoding.
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#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Clone)]
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#[non_exhaustive]
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pub enum Error {
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/// Invalid character encountered.
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BadByte(u8),
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/// Checksum was not correct (expected, actual).
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BadChecksum(u32, u32),
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/// The length (in bytes) of the object was not correct.
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///
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/// Note that if the length is excessively long the provided length may be an estimate (and the
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/// checksum step may be skipped).
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InvalidLength(usize),
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/// Extended Key version byte(s) were not recognized.
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InvalidExtendedKeyVersion([u8; 4]),
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/// Address version byte were not recognized.
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InvalidAddressVersion(u8),
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/// Checked data was less than 4 bytes.
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TooShort(usize),
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}
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impl fmt::Display for Error {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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match *self {
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Error::BadByte(b) => write!(f, "invalid base58 character {:#x}", b),
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Error::BadChecksum(exp, actual) =>
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write!(f, "base58ck checksum {:#x} does not match expected {:#x}", actual, exp),
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Error::InvalidLength(ell) => write!(f, "length {} invalid for this base58 type", ell),
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Error::InvalidExtendedKeyVersion(ref v) =>
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write!(f, "extended key version {:#04x?} is invalid for this base58 type", v),
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Error::InvalidAddressVersion(ref v) =>
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write!(f, "address version {} is invalid for this base58 type", v),
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Error::TooShort(_) => write!(f, "base58ck data not even long enough for a checksum"),
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}
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}
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}
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#[cfg(feature = "std")]
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#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
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impl std::error::Error for Error {
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fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
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use self::Error::*;
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match self {
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BadByte(_)
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| BadChecksum(_, _)
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| InvalidLength(_)
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| InvalidExtendedKeyVersion(_)
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| InvalidAddressVersion(_)
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| TooShort(_) => None,
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}
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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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use crate::internal_macros::hex;
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#[test]
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fn test_base58_encode() {
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// Basics
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assert_eq!(&encode(&[0][..]), "1");
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assert_eq!(&encode(&[1][..]), "2");
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assert_eq!(&encode(&[58][..]), "21");
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assert_eq!(&encode(&[13, 36][..]), "211");
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// Leading zeroes
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assert_eq!(&encode(&[0, 13, 36][..]), "1211");
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assert_eq!(&encode(&[0, 0, 0, 0, 13, 36][..]), "1111211");
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// Long input (>100 bytes => has to use heap)
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let res = encode(
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"BitcoinBitcoinBitcoinBitcoinBitcoinBitcoinBitcoinBitcoinBitcoinBit\
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coinBitcoinBitcoinBitcoinBitcoinBitcoinBitcoinBitcoinBitcoinBitcoinBitcoin"
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.as_bytes(),
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);
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let exp =
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"ZqC5ZdfpZRi7fjA8hbhX5pEE96MdH9hEaC1YouxscPtbJF16qVWksHWR4wwvx7MotFcs2ChbJqK8KJ9X\
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wZznwWn1JFDhhTmGo9v6GjAVikzCsBWZehu7bm22xL8b5zBR5AsBygYRwbFJsNwNkjpyFuDKwmsUTKvkULCvucPJrN5\
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QUdxpGakhqkZFL7RU4yT";
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assert_eq!(&res, exp);
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// Addresses
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let addr = hex!("00f8917303bfa8ef24f292e8fa1419b20460ba064d");
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assert_eq!(&encode_check(&addr[..]), "1PfJpZsjreyVrqeoAfabrRwwjQyoSQMmHH");
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}
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#[test]
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fn test_base58_decode() {
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// Basics
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assert_eq!(decode("1").ok(), Some(vec![0u8]));
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assert_eq!(decode("2").ok(), Some(vec![1u8]));
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assert_eq!(decode("21").ok(), Some(vec![58u8]));
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assert_eq!(decode("211").ok(), Some(vec![13u8, 36]));
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// Leading zeroes
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assert_eq!(decode("1211").ok(), Some(vec![0u8, 13, 36]));
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assert_eq!(decode("111211").ok(), Some(vec![0u8, 0, 0, 13, 36]));
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// Addresses
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assert_eq!(
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decode_check("1PfJpZsjreyVrqeoAfabrRwwjQyoSQMmHH").ok(),
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Some(hex!("00f8917303bfa8ef24f292e8fa1419b20460ba064d"))
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);
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// Non Base58 char.
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assert_eq!(decode("¢").unwrap_err(), Error::BadByte(194));
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}
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#[test]
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fn test_base58_roundtrip() {
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let s = "xprv9wTYmMFdV23N2TdNG573QoEsfRrWKQgWeibmLntzniatZvR9BmLnvSxqu53Kw1UmYPxLgboyZQaXwTCg8MSY3H2EU4pWcQDnRnrVA1xe8fs";
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let v: Vec<u8> = decode_check(s).unwrap();
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assert_eq!(encode_check(&v[..]), s);
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assert_eq!(decode_check(&encode_check(&v[..])).ok(), Some(v));
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// Check that empty slice passes roundtrip.
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assert_eq!(decode_check(&encode_check(&[])), Ok(vec![]));
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// Check that `len > 4` is enforced.
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assert_eq!(decode_check(&encode(&[1, 2, 3])), Err(Error::TooShort(3)));
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}
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}
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