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
3 // The original portions of this software are Copyright (c) 2015 The base32 Developers
5 /* This file is licensed under either of
6 * Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0) or
7 * MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)
11 const ALPHABET: &'static [u8] = b"ybndrfg8ejkmcpqxot1uwisza345h769";
13 /// Encodes some bytes as a zbase32 string
14 pub fn encode(data: &[u8]) -> String {
15 let mut ret = Vec::with_capacity((data.len() + 4) / 5 * 8);
17 for chunk in data.chunks(5) {
19 let mut buf = [0u8; 5];
20 for (i, &b) in chunk.iter().enumerate() {
26 ret.push(ALPHABET[((buf[0] & 0xF8) >> 3) as usize]);
27 ret.push(ALPHABET[(((buf[0] & 0x07) << 2) | ((buf[1] & 0xC0) >> 6)) as usize]);
28 ret.push(ALPHABET[((buf[1] & 0x3E) >> 1) as usize]);
29 ret.push(ALPHABET[(((buf[1] & 0x01) << 4) | ((buf[2] & 0xF0) >> 4)) as usize]);
30 ret.push(ALPHABET[(((buf[2] & 0x0F) << 1) | (buf[3] >> 7)) as usize]);
31 ret.push(ALPHABET[((buf[3] & 0x7C) >> 2) as usize]);
32 ret.push(ALPHABET[(((buf[3] & 0x03) << 3) | ((buf[4] & 0xE0) >> 5)) as usize]);
33 ret.push(ALPHABET[(buf[4] & 0x1F) as usize]);
36 ret.truncate((data.len() * 8 + 4) / 5);
38 // Check that our capacity calculation doesn't under-shoot in fuzzing
40 assert_eq!(ret.capacity(), (data.len() + 4) / 5 * 8);
42 String::from_utf8(ret).unwrap()
46 const INV_ALPHABET: [i8; 43] = [
47 -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,
48 21, 9, 10, -1, 11, 2, 16, 13, 14, 4, 22, 17, 19, -1, 20, 15, 0, 23,
51 /// Decodes a zbase32 string to the original bytes, failing if the string was not encoded by a
52 /// proper zbase32 encoder.
53 pub fn decode(data: &str) -> Result<Vec<u8>, ()> {
58 let data = data.as_bytes();
59 let output_length = data.len() * 5 / 8;
60 if data.len() > (output_length * 8 + 4) / 5 {
61 // If the string has more charachters than are required to encode the number of bytes
62 // decodable, treat the string as invalid.
66 let mut ret = Vec::with_capacity((data.len() + 7) / 8 * 5);
68 for chunk in data.chunks(8) {
70 let mut buf = [0u8; 8];
71 for (i, &c) in chunk.iter().enumerate() {
72 match INV_ALPHABET.get(c.to_ascii_uppercase().wrapping_sub(b'0') as usize) {
73 Some(&-1) | None => return Err(()),
74 Some(&value) => buf[i] = value as u8,
79 ret.push((buf[0] << 3) | (buf[1] >> 2));
80 ret.push((buf[1] << 6) | (buf[2] << 1) | (buf[3] >> 4));
81 ret.push((buf[3] << 4) | (buf[4] >> 1));
82 ret.push((buf[4] << 7) | (buf[5] << 2) | (buf[6] >> 3));
83 ret.push((buf[6] << 5) | buf[7]);
85 for c in ret.drain(output_length..) {
87 // If the original string had any bits set at positions outside of the encoded data,
88 // treat the string as invalid.
93 // Check that our capacity calculation doesn't under-shoot in fuzzing
95 assert_eq!(ret.capacity(), (data.len() + 7) / 8 * 5);
104 const TEST_DATA: &[(&str, &[u8])] = &[
108 ("tqrey", &[0x8b, 0x88, 0x80]),
109 ("6n9hq", &[0xf0, 0xbf, 0xc7]),
110 ("4t7ye", &[0xd4, 0x7a, 0x04]),
111 ("6im5sdy", &[0xf5, 0x57, 0xbb, 0x0c]),
112 ("ybndrfg8ejkmcpqxot1uwisza345h769", &[0x00, 0x44, 0x32, 0x14, 0xc7, 0x42, 0x54, 0xb6,
113 0x35, 0xcf, 0x84, 0x65, 0x3a, 0x56, 0xd7, 0xc6,
114 0x75, 0xbe, 0x77, 0xdf])
119 for &(zbase32, data) in TEST_DATA {
120 assert_eq!(encode(data), zbase32);
126 for &(zbase32, data) in TEST_DATA {
127 assert_eq!(decode(zbase32).unwrap(), data);
132 fn test_decode_wrong() {
133 const WRONG_DATA: &[&str] = &["00", "l1", "?", "="];
135 for &data in WRONG_DATA {
137 Ok(_) => assert!(false, "Data shouldn't be decodable"),
138 Err(_) => assert!(true),