penis 0.1.1

A Rust implementation of the Penis Protocol
Documentation 
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

use crate::consts::SCHEDULE_SEED;
use crate::primitivefns::*;
use crate::structs::{NRound, PartialSchedArray, PrivateBlock, RawBlockRef, SchedArray, State};

pub(crate) const fn execute_until_rounds(
    block: RawBlockRef,
    previous_state: &State,
    n: NRound,
) -> PrivateBlock {
    let mut schedule_array: SchedArray = [0; 64];

    let mut i = 0;
    while i < 16 {
        schedule_array[i] = u32::from_be_bytes([
            block[i * 4],
            block[i * 4 + 1],
            block[i * 4 + 2],
            block[i * 4 + 3],
        ]);
        i += 1;
    }

    while i < n + 16 {
        schedule_array[i] = lsigma1(schedule_array[i - 2])
            .wrapping_add(schedule_array[i - 7])
            .wrapping_add(lsigma0(schedule_array[i - 15]))
            .wrapping_add(schedule_array[i - 16]);
        i += 1;
    }

    let mut a = previous_state.a;
    let mut b = previous_state.b;
    let mut c = previous_state.c;
    let mut d = previous_state.d;
    let mut e = previous_state.e;
    let mut f = previous_state.f;
    let mut g = previous_state.g;
    let mut h = previous_state.h;

    let mut i = 0;
    while i < n {
        let t1 = h
            .wrapping_add(sigma1(e))
            .wrapping_add(ch(e, f, g))
            .wrapping_add(SCHEDULE_SEED[i])
            .wrapping_add(schedule_array[i]);
        let t2 = sigma0(a).wrapping_add(maj(a, b, c));
        h = g;
        g = f;
        f = e;
        e = d.wrapping_add(t1);
        d = c;
        c = b;
        b = a;
        a = t1.wrapping_add(t2);
        i += 1;
    }

    // copy the array, equivalent to
    // psa.copy_from_slice(&schedule_array[n..(n + 16)]);
    // but it can't be const, so we do it manually
    // Additionally, we can avoid the mut variable
    let psa: PartialSchedArray = [
        schedule_array[n],
        schedule_array[n + 1],
        schedule_array[n + 2],
        schedule_array[n + 3],
        schedule_array[n + 4],
        schedule_array[n + 5],
        schedule_array[n + 6],
        schedule_array[n + 7],
        schedule_array[n + 8],
        schedule_array[n + 9],
        schedule_array[n + 10],
        schedule_array[n + 11],
        schedule_array[n + 12],
        schedule_array[n + 13],
        schedule_array[n + 14],
        schedule_array[n + 15],
    ];

    let state = State {
        a,
        b,
        c,
        d,
        e,
        f,
        g,
        h,
    };
    PrivateBlock { state, psa }
}

pub(crate) const fn execute_from_rounds(
    pb: &PrivateBlock,
    previous_state: State,
    n: NRound,
) -> State {
    let partial_state = &pb.state;
    let psa = &pb.psa;
    let mut rsa: SchedArray = [0u32; 64];

    let mut i = 0;
    while i < 16 {
        rsa[i] = psa[i];
        i += 1;
    }
    while i < 64 - n {
        rsa[i] = lsigma1(rsa[i - 2])
            .wrapping_add(rsa[i - 7])
            .wrapping_add(lsigma0(rsa[i - 15]))
            .wrapping_add(rsa[i - 16]);
        i += 1;
    }

    let mut a = partial_state.a;
    let mut b = partial_state.b;
    let mut c = partial_state.c;
    let mut d = partial_state.d;
    let mut e = partial_state.e;
    let mut f = partial_state.f;
    let mut g = partial_state.g;
    let mut h = partial_state.h;

    let mut i = 0;
    while i < 64 - n {
        let t1 = h
            .wrapping_add(sigma1(e))
            .wrapping_add(ch(e, f, g))
            .wrapping_add(SCHEDULE_SEED[i + n])
            .wrapping_add(rsa[i]);
        let t2 = sigma0(a).wrapping_add(maj(a, b, c));
        h = g;
        g = f;
        f = e;
        e = d.wrapping_add(t1);
        d = c;
        c = b;
        b = a;
        a = t1.wrapping_add(t2);
        i += 1;
    }

    State {
        a: a.wrapping_add(previous_state.a),
        b: b.wrapping_add(previous_state.b),
        c: c.wrapping_add(previous_state.c),
        d: d.wrapping_add(previous_state.d),
        e: e.wrapping_add(previous_state.e),
        f: f.wrapping_add(previous_state.f),
        g: g.wrapping_add(previous_state.g),
        h: h.wrapping_add(previous_state.h),
    }
}