1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
//! Base58-to-text encoding
//!
//! Based on https://github.com/trezor/trezor-crypto/blob/master/base58.c
//! commit hash: c6e7d37
//! works only up to 128 bytes
#![no_std]

#[macro_use]
extern crate alloc;

use alloc::vec::Vec;
use alloc::string::String;

const ALPHABET: &'static [u8] = b"123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";

const B58_DIGITS_MAP: &'static [i8] = &[
	-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
	-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
	-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
	-1, 0, 1, 2, 3, 4, 5, 6, 7, 8,-1,-1,-1,-1,-1,-1,
	-1, 9,10,11,12,13,14,15,16,-1,17,18,19,20,21,-1,
	22,23,24,25,26,27,28,29,30,31,32,-1,-1,-1,-1,-1,
	-1,33,34,35,36,37,38,39,40,41,42,43,-1,44,45,46,
	47,48,49,50,51,52,53,54,55,56,57,-1,-1,-1,-1,-1,
];

/// Errors that can occur when decoding base58 encoded string.
#[derive(Debug, PartialEq)]
pub enum FromBase58Error {
	/// The input contained a character which is not a part of the base58 format.
	InvalidBase58Character(char, usize),
	/// The input had invalid length.
	InvalidBase58Length,
}

/// A trait for converting a value to base58 encoded string.
pub trait ToBase58 {
	/// Converts a value of `self` to a base58 value, returning the owned string.
	fn to_base58(&self) -> String;
}

/// A trait for converting base58 encoded values.
pub trait FromBase58 {
	/// Convert a value of `self`, interpreted as base58 encoded data, into an owned vector of bytes, returning a vector.
	fn from_base58(&self) -> Result<Vec<u8>, FromBase58Error>;
}

impl ToBase58 for [u8] {
	fn to_base58(&self) -> String {
		let zcount = self.iter().take_while(|x| **x == 0).count();
		let size = (self.len() - zcount) * 138 / 100 + 1;
		let mut buffer = vec![0u8; size];

		let mut i = zcount;
		let mut high = size - 1;

		while i < self.len() {
			let mut carry = self[i] as u32;
			let mut j = size - 1;

			while j > high || carry != 0 {
				carry += 256 * buffer[j] as u32;
				buffer[j] = (carry % 58) as u8;
				carry /= 58;

				// in original trezor implementation it was underflowing
				if j  > 0 {
					j -= 1;
				}
			}

			i += 1;
			high = j;
		}

		let mut j = buffer.iter().take_while(|x| **x == 0).count();

		let mut result = String::new();
		for _ in 0..zcount {
			result.push('1');
		}

		while j < size {
			result.push(ALPHABET[buffer[j] as usize] as char);
			j += 1;
		}

		result
	}
}

impl FromBase58 for str {
	fn from_base58(&self) -> Result<Vec<u8>, FromBase58Error> {
		let mut bin = [0u8; 132];
		let mut out = [0u32; (132 + 3) / 4];
		let bytesleft = (bin.len() % 4) as u8;
		let zeromask = match bytesleft {
			0 => 0u32,
			_ => 0xffffffff << (bytesleft * 8),
		};

		let zcount = self.chars().take_while(|x| *x == '1').count();
		let mut i = zcount;
		let b58: Vec<u8> = self.bytes().collect();

		while i < self.len() {
			if (b58[i] & 0x80) != 0 {
				// High-bit set on invalid digit
				return Err(FromBase58Error::InvalidBase58Character(b58[i] as char, i));
			}

			if B58_DIGITS_MAP[b58[i] as usize] == -1 {
				// // Invalid base58 digit
				return Err(FromBase58Error::InvalidBase58Character(b58[i] as char, i));
			}

			let mut c = B58_DIGITS_MAP[b58[i] as usize] as u64;
			let mut j = out.len();
			while j != 0 {
				j -= 1;
				let t = out[j] as u64 * 58 + c;
				c = (t & 0x3f00000000) >> 32;
				out[j] = (t & 0xffffffff) as u32;
			}

			if c != 0 {
				// Output number too big (carry to the next int32)
				return Err(FromBase58Error::InvalidBase58Length);
			}

			if (out[0] & zeromask) != 0 {
				// Output number too big (last int32 filled too far)
				return Err(FromBase58Error::InvalidBase58Length);
			}

			i += 1;
		}

		let mut i = 1;
		let mut j = 0;

		bin[0] = match bytesleft {
			3 => ((out[0] & 0xff0000) >> 16) as u8,
			2 => ((out[0] & 0xff00) >> 8) as u8,
			1 => {
				j = 1;
				(out[0] & 0xff) as u8
			},
			_ => {
				i = 0;
				bin[0]
			}
		};

		while j < out.len() {
			bin[i] = ((out[j] >> 0x18) & 0xff) as u8;
			bin[i + 1] = ((out[j] >> 0x10) & 0xff) as u8;
			bin[i + 2] = ((out[j] >> 8) & 0xff) as u8;
			bin[i + 3] = ((out[j] >> 0) & 0xff) as u8;
			i += 4;
			j += 1;
		}

		let leading_zeros = bin.iter().take_while(|x| **x == 0).count();
		Ok(bin[leading_zeros - zcount..].to_vec())
	}
}

#[cfg(test)]
mod tests {
	use super::{ToBase58, FromBase58};

	#[test]
	fn test_from_base58_basic() {
		assert_eq!("".from_base58().unwrap(), b"");
		assert_eq!("Z".from_base58().unwrap(), &[32]);
		assert_eq!("n".from_base58().unwrap(), &[45]);
		assert_eq!("q".from_base58().unwrap(), &[48]);
		assert_eq!("r".from_base58().unwrap(), &[49]);
		assert_eq!("z".from_base58().unwrap(), &[57]);
		assert_eq!("4SU".from_base58().unwrap(), &[45, 49]);
		assert_eq!("4k8".from_base58().unwrap(), &[49, 49]);
		assert_eq!("ZiCa".from_base58().unwrap(), &[97, 98, 99]);
		assert_eq!("3mJr7AoUXx2Wqd".from_base58().unwrap(), b"1234598760");
		assert_eq!("3yxU3u1igY8WkgtjK92fbJQCd4BZiiT1v25f".from_base58().unwrap(), b"abcdefghijklmnopqrstuvwxyz");
	}

	#[test]
	fn test_from_base58_invalid_char() {
		assert!("0".from_base58().is_err());
		assert!("O".from_base58().is_err());
		assert!("I".from_base58().is_err());
		assert!("l".from_base58().is_err());
		assert!("3mJr0".from_base58().is_err());
		assert!("O3yxU".from_base58().is_err());
		assert!("3sNI".from_base58().is_err());
		assert!("4kl8".from_base58().is_err());
		assert!("s!5<".from_base58().is_err());
		assert!("t$@mX<*".from_base58().is_err());
	}

	#[test]
	fn test_from_base58_initial_zeros() {
		assert_eq!("1ZiCa".from_base58().unwrap(), b"\0abc");
		assert_eq!("11ZiCa".from_base58().unwrap(), b"\0\0abc");
		assert_eq!("111ZiCa".from_base58().unwrap(), b"\0\0\0abc");
		assert_eq!("1111ZiCa".from_base58().unwrap(), b"\0\0\0\0abc");
	}

	#[test]
	fn test_to_base58_basic() {
		assert_eq!(b"".to_base58(), "");
		assert_eq!(&[32].to_base58(), "Z");
		assert_eq!(&[45].to_base58(), "n");
		assert_eq!(&[48].to_base58(), "q");
		assert_eq!(&[49].to_base58(), "r");
		assert_eq!(&[57].to_base58(), "z");
		assert_eq!(&[45, 49].to_base58(), "4SU");
		assert_eq!(&[49, 49].to_base58(), "4k8");
		assert_eq!(b"abc".to_base58(), "ZiCa");
		assert_eq!(b"1234598760".to_base58(), "3mJr7AoUXx2Wqd");
		assert_eq!(b"abcdefghijklmnopqrstuvwxyz".to_base58(), "3yxU3u1igY8WkgtjK92fbJQCd4BZiiT1v25f");
	}

	#[test]
	fn test_to_base58_initial_zeros() {
		assert_eq!(b"\0abc".to_base58(), "1ZiCa");
		assert_eq!(b"\0\0abc".to_base58(), "11ZiCa");
		assert_eq!(b"\0\0\0abc".to_base58(), "111ZiCa");
		assert_eq!(b"\0\0\0\0abc".to_base58(), "1111ZiCa");
	}
}