zbase32/
lib.rs

1#[cfg(feature = "python")]
2mod python;
3
4#[cfg(test)]
5#[macro_use]
6extern crate quickcheck;
7
8use std::{error::Error, fmt};
9
10const ALPHABET: &[u8] = b"ybndrfg8ejkmcpqxot1uwisza345h769";
11const INVERSE_ALPHABET: [i8; 123] = [
12    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
13    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
14    -1, 18, -1, 25, 26, 27, 30, 29, 7, 31, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
15    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
16    -1, 24, 1, 12, 3, 8, 5, 6, 28, 21, 9, 10, -1, 11, 2, 16, 13, 14, 4, 22, 17, 19, -1, 20, 15, 0,
17    23,
18];
19
20#[derive(Debug, PartialEq)]
21pub struct DecodeError;
22
23impl Error for DecodeError {}
24
25impl fmt::Display for DecodeError {
26    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
27        write!(f, "DecodeError: Non-zbase32 digit found")
28    }
29}
30
31pub fn encode(input: &[u8]) -> String {
32    let mut result = Vec::new();
33    let chunks = input.chunks(5);
34
35    for chunk in chunks {
36        let buf = {
37            let mut buf = [0u8; 5];
38            for (i, &b) in chunk.iter().enumerate() {
39                buf[i] = b;
40            }
41            buf
42        };
43        result.push(ALPHABET[((buf[0] & 0xF8) >> 3) as usize]);
44        result.push(ALPHABET[((buf[0] & 0x07) << 2 | (buf[1] & 0xC0) >> 6) as usize]);
45        result.push(ALPHABET[((buf[1] & 0x3E) >> 1) as usize]);
46        result.push(ALPHABET[((buf[1] & 0x01) << 4 | (buf[2] & 0xF0) >> 4) as usize]);
47        result.push(ALPHABET[((buf[2] & 0x0F) << 1 | (buf[3] & 0x80) >> 7) as usize]);
48        result.push(ALPHABET[((buf[3] & 0x7C) >> 2) as usize]);
49        result.push(ALPHABET[((buf[3] & 0x03) << 3 | (buf[4] & 0xE0) >> 5) as usize]);
50        result.push(ALPHABET[(buf[4] & 0x1F) as usize]);
51    }
52
53    let expected_len = (input.len() as f32 * 8.0 / 5.0).ceil() as usize;
54    for _ in 0..(result.len() - expected_len) {
55        result.pop();
56    }
57    unsafe { String::from_utf8_unchecked(result) }
58}
59
60pub fn decode(input: &str) -> Result<Vec<u8>, DecodeError> {
61    let mut result = Vec::new();
62    for chunk in input.as_bytes().chunks(8) {
63        let buf = {
64            let mut buf = [0u8; 8];
65            for (i, &ch) in chunk.iter().enumerate() {
66                match INVERSE_ALPHABET.get(ch as usize) {
67                    Some(-1) => return Err(DecodeError),
68                    Some(x) => buf[i] = *x as u8,
69                    None => return Err(DecodeError),
70                };
71            }
72            buf
73        };
74        result.push((buf[0] << 3) | (buf[1] >> 2));
75        result.push((buf[1] << 6) | (buf[2] << 1) | (buf[3] >> 4));
76        result.push((buf[3] << 4) | (buf[4] >> 1));
77        result.push((buf[4] << 7) | (buf[5] << 2) | (buf[6] >> 3));
78        result.push((buf[6] << 5) | buf[7]);
79    }
80
81    for _ in 0..(result.len() - input.len() * 5 / 8) {
82        result.pop();
83    }
84    Ok(result)
85}
86
87#[cfg(test)]
88mod tests {
89    use super::*;
90    #[test]
91    fn simple_encode() {
92        assert_eq!(encode(b"asdasd"), "cf3seamuco".to_string());
93    }
94
95    #[test]
96    fn simple_decode() {
97        assert_eq!(decode("cf3seamu"), Ok(b"asdas".to_vec()))
98    }
99
100    #[test]
101    fn encode_decode() {
102        assert_eq!(decode(&encode(b"foo")).unwrap(), b"foo")
103    }
104
105    #[test]
106    fn invalid_decode() {
107        assert_eq!(decode("bar#"), Err(DecodeError))
108    }
109
110    quickcheck! {
111        fn prop(input: Vec<u8>) -> bool {
112            decode(&encode(&input)).unwrap() == input
113
114        }
115    }
116
117    quickcheck! {
118        #[allow(unused_must_use)]
119        fn not_panic(input: String) -> bool {
120            decode(&input);
121            true
122        }
123    }
124}
zbase32/lib.rs

zbase32/
lib.rs
