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
#![deny(missing_docs)]
#![allow(warnings)]
pub use base64::DecodeError as Error;
use base64::{alphabet, engine, Engine};
pub struct Base64 {
engine: engine::GeneralPurpose,
}
impl Base64 {
pub fn new(key: &[u8]) -> Self {
let alphabet = alphabet::Alphabet::new(&Self::get_alphabet(key)).expect("alphabet");
let config = engine::GeneralPurposeConfig::new()
.with_decode_allow_trailing_bits(false)
.with_encode_padding(false)
.with_decode_padding_mode(engine::DecodePaddingMode::RequireNone);
Self {
engine: engine::GeneralPurpose::new(&alphabet, config),
}
}
fn get_alphabet(key: &[u8]) -> String {
let rev_key = key.iter().cloned().rev().collect::<Vec<_>>();
let hash = crc32fast::hash(key);
let rev_hash = crc32fast::hash(&rev_key);
let mut alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"
.chars()
.enumerate()
.map(|(i, c)| {
(
c,
crc32fast::hash(c.to_string().as_bytes())
% if i % 2 == 0 { hash } else { rev_hash },
)
})
.collect::<Vec<(char, u32)>>();
alphabet.sort_by(|a, b| b.1.cmp(&a.1));
alphabet.iter().map(|a| a.0).collect::<String>()
}
pub fn encode<T: AsRef<[u8]>>(&self, input: T) -> String {
self.engine.encode(input)
}
pub fn decode<T: AsRef<[u8]>>(&self, input: T) -> Result<Vec<u8>, Error> {
self.engine.decode(input)
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn encode_decode() {
let x = Base64::new(b"test");
let encoded = x.encode("test");
let decoded = x.decode(encoded.as_bytes()).expect("success");
assert_eq!("test".to_owned(), String::from_utf8_lossy(&decoded));
}
#[test]
fn incorrect_key() {
let x = Base64::new(b"test");
let y = Base64::new(b"test1");
let encoded = x.encode("test");
assert!(y.decode(encoded.as_bytes()).is_err());
assert!(x.decode(encoded.as_bytes()).is_ok());
}
#[test]
fn expected_data() {
let x = Base64::new(b"long and random key\0test\0");
let result = x.decode("t0mvt-").expect("decode");
assert_eq!("test".to_owned(), String::from_utf8_lossy(&result));
}
}