blsful 4.0.0-rc2

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

use crate::impls::inner_types::*;
use crate::*;

/// Represents a BLS signature for multiple signatures that signed different messages
#[derive(PartialEq, Eq, serde::Serialize, serde::Deserialize)]
pub enum MultiSignature<C: BlsSignatureImpl> {
    /// The basic signature scheme
    Basic(
        #[serde(serialize_with = "traits::signature::serialize::<C, _>")]
        #[serde(deserialize_with = "traits::signature::deserialize::<C, _>")]
        <C as Pairing>::Signature,
    ),
    /// The message augmentation signature scheme
    MessageAugmentation(
        #[serde(serialize_with = "traits::signature::serialize::<C, _>")]
        #[serde(deserialize_with = "traits::signature::deserialize::<C, _>")]
        <C as Pairing>::Signature,
    ),
    /// The proof of possession scheme
    ProofOfPossession(
        #[serde(serialize_with = "traits::signature::serialize::<C, _>")]
        #[serde(deserialize_with = "traits::signature::deserialize::<C, _>")]
        <C as Pairing>::Signature,
    ),
}

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

impl_signature_enum_traits!(
    MultiSignature,
    <C as Pairing>::Signature,
    "Signature::conditional_select: mismatched variants"
);

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

    fn try_from(sigs: &[Signature<C>]) -> Result<Self, Self::Error> {
        if sigs.len() < 2 {
            return Err(BlsError::InvalidSignature);
        }
        let mut g = <C as Pairing>::Signature::identity();
        for s in &sigs[1..] {
            if !s.same_scheme(&sigs[0]) {
                return Err(BlsError::InvalidSignatureScheme);
            }
            let ss = match s {
                Signature::Basic(sig) => sig,
                Signature::MessageAugmentation(_) => {
                    return Err(BlsError::InvalidSignatureScheme);
                }
                Signature::ProofOfPossession(sig) => sig,
            };
            g += ss;
        }
        match sigs[0] {
            Signature::Basic(s) => Ok(Self::Basic(g + s)),
            Signature::MessageAugmentation(s) => Ok(Self::MessageAugmentation(g + s)),
            Signature::ProofOfPossession(s) => Ok(Self::ProofOfPossession(g + s)),
        }
    }
}

impl_from_derivatives_generic!(MultiSignature);

impl<C: BlsSignatureImpl> TryFrom<&MultiSignature<C>> for Vec<u8> {
    type Error = BlsError;

    fn try_from(value: &MultiSignature<C>) -> BlsResult<Self> {
        serde_bare::to_vec(value).map_err(|e| BlsError::SerializationError(e.to_string()))
    }
}

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

    fn try_from(value: &[u8]) -> Result<Self, Self::Error> {
        serde_bare::from_slice(value).map_err(|_| BlsError::InvalidSignature)
    }
}

impl<C: BlsSignatureImpl> MultiSignature<C> {
    /// Verify the multi-signature using the multi-public key
    pub fn verify<B: AsRef<[u8]>>(&self, pk: MultiPublicKey<C>, msg: B) -> BlsResult<()> {
        match self {
            Self::Basic(sig) => <C as BlsSignatureBasic>::verify(pk.0, *sig, msg),
            Self::MessageAugmentation(sig) => {
                <C as BlsSignatureMessageAugmentation>::verify(pk.0, *sig, msg)
            }
            Self::ProofOfPossession(sig) => <C as BlsSignaturePop>::verify(pk.0, *sig, msg),
        }
    }

    /// Extract the inner raw representation
    pub fn as_raw_value(&self) -> &<C as Pairing>::Signature {
        match self {
            Self::Basic(s) => s,
            Self::MessageAugmentation(s) => s,
            Self::ProofOfPossession(s) => s,
        }
    }

    /// Accumulate multiple signatures into a single signature
    pub fn from_signatures<B: AsRef<[Signature<C>]>>(signatures: B) -> BlsResult<Self> {
        Self::try_from(signatures.as_ref())
    }
}