1 // This is a modification of base32 encoding to support the zbase32 alphabet.
2 // The original piece of software can be found at https://github.com/andreasots/base32
5 Copyright (c) 2015 The base32 Developers
7 Permission is hereby granted, free of charge, to any person obtaining a copy
8 of this software and associated documentation files (the "Software"), to deal
9 in the Software without restriction, including without limitation the rights
10 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 copies of the Software, and to permit persons to whom the Software is
12 furnished to do so, subject to the following conditions:
14 The above copyright notice and this permission notice shall be included in all
15 copies or substantial portions of the Software.
17 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
26 const ALPHABET: &'static [u8] = b"ybndrfg8ejkmcpqxot1uwisza345h769";
28 /// Encodes some bytes as a zbase32 string
29 pub fn encode(data: &[u8]) -> String {
30 let mut ret = Vec::with_capacity((data.len() + 4) / 5 * 8);
32 for chunk in data.chunks(5) {
34 let mut buf = [0u8; 5];
35 for (i, &b) in chunk.iter().enumerate() {
41 ret.push(ALPHABET[((buf[0] & 0xF8) >> 3) as usize]);
42 ret.push(ALPHABET[(((buf[0] & 0x07) << 2) | ((buf[1] & 0xC0) >> 6)) as usize]);
43 ret.push(ALPHABET[((buf[1] & 0x3E) >> 1) as usize]);
44 ret.push(ALPHABET[(((buf[1] & 0x01) << 4) | ((buf[2] & 0xF0) >> 4)) as usize]);
45 ret.push(ALPHABET[(((buf[2] & 0x0F) << 1) | (buf[3] >> 7)) as usize]);
46 ret.push(ALPHABET[((buf[3] & 0x7C) >> 2) as usize]);
47 ret.push(ALPHABET[(((buf[3] & 0x03) << 3) | ((buf[4] & 0xE0) >> 5)) as usize]);
48 ret.push(ALPHABET[(buf[4] & 0x1F) as usize]);
51 ret.truncate((data.len() * 8 + 4) / 5);
53 // Check that our capacity calculation doesn't under-shoot in fuzzing
55 assert_eq!(ret.capacity(), (data.len() + 4) / 5 * 8);
57 String::from_utf8(ret).unwrap()
61 const INV_ALPHABET: [i8; 43] = [
62 -1, 18, -1, 25, 26, 27, 30, 29, 7, 31, -1, -1, -1, -1, -1, -1, -1, 24, 1, 12, 3, 8, 5, 6, 28,
63 21, 9, 10, -1, 11, 2, 16, 13, 14, 4, 22, 17, 19, -1, 20, 15, 0, 23,
66 /// Decodes a zbase32 string to the original bytes, failing if the string was not encoded by a
67 /// proper zbase32 encoder.
68 pub fn decode(data: &str) -> Result<Vec<u8>, ()> {
73 let data = data.as_bytes();
74 let output_length = data.len() * 5 / 8;
75 if data.len() > (output_length * 8 + 4) / 5 {
76 // If the string has more charachters than are required to encode the number of bytes
77 // decodable, treat the string as invalid.
81 let mut ret = Vec::with_capacity((data.len() + 7) / 8 * 5);
83 for chunk in data.chunks(8) {
85 let mut buf = [0u8; 8];
86 for (i, &c) in chunk.iter().enumerate() {
87 match INV_ALPHABET.get(c.to_ascii_uppercase().wrapping_sub(b'0') as usize) {
88 Some(&-1) | None => return Err(()),
89 Some(&value) => buf[i] = value as u8,
94 ret.push((buf[0] << 3) | (buf[1] >> 2));
95 ret.push((buf[1] << 6) | (buf[2] << 1) | (buf[3] >> 4));
96 ret.push((buf[3] << 4) | (buf[4] >> 1));
97 ret.push((buf[4] << 7) | (buf[5] << 2) | (buf[6] >> 3));
98 ret.push((buf[6] << 5) | buf[7]);
100 for c in ret.drain(output_length..) {
102 // If the original string had any bits set at positions outside of the encoded data,
103 // treat the string as invalid.
108 // Check that our capacity calculation doesn't under-shoot in fuzzing
110 assert_eq!(ret.capacity(), (data.len() + 7) / 8 * 5);
119 const TEST_DATA: &[(&str, &[u8])] = &[
123 ("tqrey", &[0x8b, 0x88, 0x80]),
124 ("6n9hq", &[0xf0, 0xbf, 0xc7]),
125 ("4t7ye", &[0xd4, 0x7a, 0x04]),
126 ("6im5sdy", &[0xf5, 0x57, 0xbb, 0x0c]),
127 ("ybndrfg8ejkmcpqxot1uwisza345h769", &[0x00, 0x44, 0x32, 0x14, 0xc7, 0x42, 0x54, 0xb6,
128 0x35, 0xcf, 0x84, 0x65, 0x3a, 0x56, 0xd7, 0xc6,
129 0x75, 0xbe, 0x77, 0xdf])
135 for &(zbase32, data) in TEST_DATA {
136 assert_eq!(encode(data), zbase32);
142 for &(zbase32, data) in TEST_DATA {
143 assert_eq!(decode(zbase32).unwrap(), data);
148 fn test_decode_wrong() {
149 const WRONG_DATA: &[&str] = &["00", "l1", "?", "="];
151 for &data in WRONG_DATA {
153 Ok(_) => assert!(false, "Data shouldn't be decodable"),
154 Err(_) => assert!(true),