blsful 4.0.0

BLS signature implementation according to the IETF spec on the BLS12-381 curve.
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

use crate::*;
use subtle::{Choice, ConditionallySelectable};

/// A proof of possession for either supported BLS12-381 signature group.
///
/// This is the dynamic counterpart to [`ProofOfPossession<C>`].
#[derive(Copy, Clone, Debug, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
pub enum ProofOfPossessionEnum {
    /// A proof for signatures in G1 and public keys in G2.
    G1(ProofOfPossession<Bls12381G1Impl>),
    /// A proof for signatures in G2 and public keys in G1.
    G2(ProofOfPossession<Bls12381G2Impl>),
}

impl Default for ProofOfPossessionEnum {
    fn default() -> Self {
        Self::G1(ProofOfPossession::default())
    }
}

impl From<&ProofOfPossessionEnum> for Vec<u8> {
    fn from(value: &ProofOfPossessionEnum) -> Self {
        let (t, output) = match value {
            ProofOfPossessionEnum::G1(pop) => (Bls12381::G1, Vec::from(pop)),
            ProofOfPossessionEnum::G2(pop) => (Bls12381::G2, Vec::from(pop)),
        };
        typed_bytes(t, output)
    }
}

impl TryFrom<&[u8]> for ProofOfPossessionEnum {
    type Error = BlsError;

    fn try_from(value: &[u8]) -> Result<Self, Self::Error> {
        let (t, value) = Bls12381::split_typed_bytes(value)?;
        match t {
            Bls12381::G1 => ProofOfPossession::<Bls12381G1Impl>::try_from(value).map(Self::G1),
            Bls12381::G2 => ProofOfPossession::<Bls12381G2Impl>::try_from(value).map(Self::G2),
        }
    }
}

impl_from_derivatives!(ProofOfPossessionEnum);

impl ProofOfPossessionEnum {
    /// Return the concrete BLS12-381 signature group for this proof.
    pub fn curve(&self) -> Bls12381 {
        match self {
            Self::G1(_) => Bls12381::G1,
            Self::G2(_) => Bls12381::G2,
        }
    }

    /// Verify this proof of possession with a matching dynamic public key.
    pub fn verify(&self, pk: &PublicKeyEnum) -> BlsResult<()> {
        match (self, pk) {
            (Self::G1(pop), PublicKeyEnum::G1(pk)) => pop.verify(pk),
            (Self::G2(pop), PublicKeyEnum::G2(pk)) => pop.verify(pk),
            _ => Err(BlsError::InvalidInputs(
                "proof and public key curve variants differ".to_string(),
            )),
        }
    }
}

/// A proof of possession of the secret key
#[derive(PartialEq, Eq, serde::Serialize, serde::Deserialize)]
pub struct ProofOfPossession<C: BlsSignatureImpl>(
    /// The BLS proof of possession raw value
    #[serde(serialize_with = "traits::signature::serialize::<C, _>")]
    #[serde(deserialize_with = "traits::signature::deserialize::<C, _>")]
    pub <C as Pairing>::Signature,
);

impl<C: BlsSignatureImpl> Default for ProofOfPossession<C> {
    fn default() -> Self {
        Self(<C as Pairing>::Signature::default())
    }
}

impl<C: BlsSignatureImpl> Display for ProofOfPossession<C> {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        write!(f, "{}", self.0)
    }
}

impl<C: BlsSignatureImpl> fmt::Debug for ProofOfPossession<C> {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        write!(f, "ProofOfPossession{{ {:?} }}", self.0)
    }
}

impl<C: BlsSignatureImpl> Copy for ProofOfPossession<C> {}

impl<C: BlsSignatureImpl> Clone for ProofOfPossession<C> {
    fn clone(&self) -> Self {
        *self
    }
}

impl<C: BlsSignatureImpl> ConditionallySelectable for ProofOfPossession<C> {
    fn conditional_select(a: &Self, b: &Self, choice: Choice) -> Self {
        Self(<C as Pairing>::Signature::conditional_select(
            &a.0, &b.0, choice,
        ))
    }
}

impl_from_derivatives_generic!(ProofOfPossession);

impl<C: BlsSignatureImpl> From<&ProofOfPossession<C>> for Vec<u8> {
    fn from(value: &ProofOfPossession<C>) -> Self {
        value.0.to_bytes().as_ref().to_vec()
    }
}

impl<C: BlsSignatureImpl> TryFrom<&[u8]> for ProofOfPossession<C> {
    type Error = BlsError;

    fn try_from(value: &[u8]) -> Result<Self, Self::Error> {
        let mut repr = C::Signature::default().to_bytes();
        let len = repr.as_ref().len();

        if len != value.len() {
            return Err(BlsError::InvalidInputs(format!(
                "Invalid length, expected {}, got {}",
                len,
                value.len()
            )));
        }

        repr.as_mut().copy_from_slice(value);
        let key: Option<C::Signature> = C::Signature::from_bytes(&repr).into();
        key.map(Self)
            .ok_or_else(|| BlsError::InvalidInputs("Invalid byte sequence".to_string()))
    }
}

impl<C: BlsSignatureImpl> ProofOfPossession<C> {
    /// Verify this proof of possession with a public key.
    pub fn verify(&self, pk: &PublicKey<C>) -> BlsResult<()> {
        <C as BlsSignaturePop>::pop_verify(pk.0, self.0)
    }
}