ssi-bbs 0.1.1

The BBS Signature Scheme implementation for SSI
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

use ssi_claims_core::{InvalidProof, MessageSignatureError, ProofValidationError, ProofValidity};
use ssi_crypto::algorithm::BbsParameters;
pub use zkryptium::{
    bbsplus::keys::{BBSplusPublicKey, BBSplusSecretKey},
    errors::Error,
};
use zkryptium::{
    bbsplus::{
        ciphersuites::{BbsCiphersuite, Bls12381Sha256},
        commitment::BlindFactor,
    },
    keys::pair::KeyPair,
    schemes::{
        algorithms::BBSplus,
        generics::{BlindSignature, Signature},
    },
};

pub use ssi_crypto::algorithm::Bbs;

#[derive(Debug)]
pub struct ProofGenFailed;

pub fn proof_gen(
    pk: &BBSplusPublicKey,
    signature: &[u8],
    header: &[u8],
    ph: Option<&[u8]>,
    messages: &[Vec<u8>],
    disclosed_indexes: &[usize],
) -> Result<Vec<u8>, ProofGenFailed> {
    Ok(
        zkryptium::schemes::generics::PoKSignature::<BBSplus<Bls12381Sha256>>::proof_gen(
            pk,
            signature,
            Some(header),
            ph,
            Some(messages),
            Some(disclosed_indexes),
        )
        .map_err(|_| ProofGenFailed)?
        .to_bytes(),
    )
}

pub fn proof_verify(
    pk: &BBSplusPublicKey,
    signature: &[u8],
    header: &[u8],
    ph: Option<&[u8]>,
    disclosed_messages: &[Vec<u8>],
    disclosed_indexes: &[usize],
) -> Result<ProofValidity, ProofValidationError> {
    let signature =
        zkryptium::schemes::generics::PoKSignature::<BBSplus<Bls12381Sha256>>::from_bytes(
            signature,
        )
        .map_err(|_| ProofValidationError::InvalidSignature)?;

    Ok(signature
        .proof_verify(
            pk,
            Some(disclosed_messages),
            Some(disclosed_indexes),
            Some(header),
            ph,
        )
        .map_err(|_| InvalidProof::Signature))
}

pub fn sign(
    params: BbsParameters,
    sk: &BBSplusSecretKey,
    pk: &BBSplusPublicKey,
    messages: &[Vec<u8>],
) -> Result<Vec<u8>, MessageSignatureError> {
    match params {
        BbsParameters::Baseline { header } => {
            Ok(
                Signature::<BBSplus<Bls12381Sha256>>::sign(Some(messages), sk, pk, Some(&header))
                    .map_err(MessageSignatureError::signature_failed)?
                    .to_bytes()
                    .to_vec(),
            )
        }
        BbsParameters::Blind {
            header,
            commitment_with_proof,
            signer_blind,
        } => {
            let signer_blind = signer_blind.map(|b| BlindFactor::from_bytes(&b).unwrap());
            Ok(BlindSignature::<BBSplus<Bls12381Sha256>>::blind_sign(
                sk,
                pk,
                commitment_with_proof.as_deref(),
                Some(&header),
                Some(messages),
                signer_blind.as_ref(),
            )
            .map_err(MessageSignatureError::signature_failed)?
            .to_bytes()
            .to_vec())
        }
    }
}

pub fn generate_secret_key(rng: &mut impl rand::RngCore) -> BBSplusSecretKey {
    let mut key_material = [0; Bls12381Sha256::IKM_LEN];
    rng.fill_bytes(&mut key_material);
    let pair = KeyPair::<BBSplus<Bls12381Sha256>>::generate(&key_material, None, None).unwrap();
    pair.into_parts().0
}