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
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188

use crate::constants::{CurveOrder, GroupG2_SIZE};
use crate::errors::{SerzDeserzError, ValueError};
use crate::field_elem::{FieldElement, FieldElementVector};
use crate::group_elem::{GroupElement, GroupElementVector};
use crate::types::{GroupG2, FP2};
use crate::utils::hash_msg;
use std::ops::{Add, AddAssign, Index, IndexMut, Mul, Neg, Sub};

use std::fmt;
use std::hash::{Hash, Hasher};
use std::slice::Iter;

use crate::group_elem_g1::parse_hex_as_FP;
use serde::de::{Deserialize, Deserializer, Error as DError, Visitor};
use serde::ser::{Error as SError, Serialize, Serializer};
use zeroize::Zeroize;

use std::str::SplitWhitespace;

#[derive(Clone, Debug)]
pub struct G2 {
    value: GroupG2,
}

impl GroupElement for G2 {
    fn new() -> Self {
        Self {
            value: GroupG2::new(),
        }
    }

    fn identity() -> Self {
        let mut v = GroupG2::new();
        v.inf();
        Self { value: v }
    }

    fn generator() -> Self {
        GroupG2::generator().into()
    }

    fn is_identity(&self) -> bool {
        self.value.is_infinity()
    }

    fn set_to_identity(&mut self) {
        self.value.inf()
    }

    fn from_msg_hash(msg: &[u8]) -> Self {
        GroupG2::mapit(&hash_msg(msg)).into()
    }

    fn to_bytes(&self) -> Vec<u8> {
        let mut temp = GroupG2::new();
        temp.copy(&self.value);
        let mut bytes: [u8; GroupG2_SIZE] = [0; GroupG2_SIZE];
        temp.tobytes(&mut bytes);
        bytes.to_vec()
    }

    fn from_bytes(bytes: &[u8]) -> Result<Self, SerzDeserzError> {
        if bytes.len() != GroupG2_SIZE {
            return Err(SerzDeserzError::G2BytesIncorrectSize(
                bytes.len(),
                GroupG2_SIZE,
            ));
        }
        Ok(GroupG2::frombytes(bytes).into())
    }

    fn add_assign_(&mut self, b: &Self) {
        self.value.add(&b.value);
    }

    fn sub_assign_(&mut self, b: &Self) {
        self.value.sub(&b.value);
    }

    fn plus(&self, b: &Self) -> Self {
        let mut sum = self.value.clone();
        sum.add(&b.value);
        sum.into()
    }

    fn minus(&self, b: &Self) -> Self {
        let mut diff = self.value.clone();
        diff.sub(&b.value);
        diff.into()
    }

    fn scalar_mul_const_time(&self, a: &FieldElement) -> Self {
        self.value.mul(&a.to_bignum()).into()
    }

    fn double(&self) -> Self {
        let mut d = self.value.clone();
        d.dbl();
        d.into()
    }

    fn double_mut(&mut self) {
        self.value.dbl();
    }

    fn to_hex(&self) -> String {
        self.value.to_hex()
    }

    fn from_hex(s: String) -> Result<Self, SerzDeserzError> {
        let mut iter = s.split_whitespace();
        let x = parse_hex_as_FP2(&mut iter)?;
        let y = parse_hex_as_FP2(&mut iter)?;
        let z = parse_hex_as_FP2(&mut iter)?;
        let mut value = GroupG2::new();
        value.setpx(x);
        value.setpy(y);
        value.setpz(z);
        Ok(Self { value })
    }

    fn negation(&self) -> Self {
        let mut n = self.to_ecp();
        n.neg();
        n.into()
    }

    fn is_extension() -> bool {
        return true;
    }

    fn has_correct_order(&self) -> bool {
        return self.value.mul(&CurveOrder).is_infinity();
    }
}

/// Parse given hex string as FP2
pub fn parse_hex_as_FP2(iter: &mut SplitWhitespace) -> Result<FP2, SerzDeserzError> {
    // Logic almost copied from AMCL but with error handling and constant time execution.
    // Constant time is important as hex is used during serialization and deserialization.
    // A seemingly effortless solution is to filter string for errors and pad with 0s before
    // passing to AMCL but that would be expensive as the string is scanned twice
    let a = parse_hex_as_FP(iter)?;
    let b = parse_hex_as_FP(iter)?;
    let mut fp2 = FP2::new();
    fp2.seta(a);
    fp2.setb(b);
    Ok(fp2)
}

impl_group_elem_traits!(G2, GroupG2);

impl_group_elem_conversions!(G2, GroupG2, GroupG2_SIZE);

impl_group_elem_ops!(G2);

impl_scalar_mul_ops!(G2);

impl_group_element_lookup_table!(G2, G2LookupTable);

/// Represents an element of the sub-group of the elliptic curve over prime the extension field
impl_optmz_scalar_mul_ops!(G2, GroupG2, G2LookupTable);

#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct G2Vector {
    elems: Vec<G2>,
}

impl_group_elem_vec_ops!(G2, G2Vector);

impl_group_elem_vec_product_ops!(G2, G2Vector, G2LookupTable);

impl_group_elem_vec_conversions!(G2, G2Vector);

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn test_parse_hex_for_FP2() {
        // TODO:
    }

    #[test]
    fn test_parse_bad_hex_for_FP2() {
        // TODO:
    }
}