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6a91f88030
Add deps/dleq.py (Adapted from bip-0374/reference.py) Extract pubkey from PSBT inputs - PSBT_IN_BIP32_DERIVATION - PSBT_IN_WITNESS_UTXO for P2TR Add script type helpers - bip352 input eligibility helpers
87 lines
2.2 KiB
Python
87 lines
2.2 KiB
Python
#!/usr/bin/env python3
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"""
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Handle DLEQ proof generation and verification
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Adapted from bip-0374 reference.py
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"""
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from secp256k1lab.secp256k1 import G, GE
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from secp256k1lab.util import tagged_hash, xor_bytes
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DLEQ_TAG_AUX = "BIP0374/aux"
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DLEQ_TAG_NONCE = "BIP0374/nonce"
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DLEQ_TAG_CHALLENGE = "BIP0374/challenge"
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def dleq_challenge(
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A: GE, B: GE, C: GE, R1: GE, R2: GE, m: bytes | None, G: GE,
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) -> int:
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if m is not None:
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assert len(m) == 32
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m = bytes([]) if m is None else m
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return int.from_bytes(
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tagged_hash(
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DLEQ_TAG_CHALLENGE,
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A.to_bytes_compressed()
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+ B.to_bytes_compressed()
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+ C.to_bytes_compressed()
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+ G.to_bytes_compressed()
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+ R1.to_bytes_compressed()
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+ R2.to_bytes_compressed()
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+ m,
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),
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"big",
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)
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def dleq_generate_proof(
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a: int, B: GE, r: bytes, G: GE = G, m: bytes | None = None
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) -> bytes | None:
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assert len(r) == 32
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if not (0 < a < GE.ORDER):
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return None
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if B.infinity:
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return None
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if m is not None:
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assert len(m) == 32
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A = a * G
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C = a * B
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t = xor_bytes(a.to_bytes(32, "big"), tagged_hash(DLEQ_TAG_AUX, r))
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m_prime = bytes([]) if m is None else m
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rand = tagged_hash(
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DLEQ_TAG_NONCE, t + A.to_bytes_compressed() + C.to_bytes_compressed() + m_prime
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)
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k = int.from_bytes(rand, "big") % GE.ORDER
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if k == 0:
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return None
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R1 = k * G
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R2 = k * B
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e = dleq_challenge(A, B, C, R1, R2, m, G)
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s = (k + e * a) % GE.ORDER
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proof = e.to_bytes(32, "big") + s.to_bytes(32, "big")
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if not dleq_verify_proof(A, B, C, proof, G=G, m=m):
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return None
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return proof
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def dleq_verify_proof(
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A: GE, B: GE, C: GE, proof: bytes, G: GE = G, m: bytes | None = None
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) -> bool:
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if A.infinity or B.infinity or C.infinity or G.infinity:
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return False
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assert len(proof) == 64
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e = int.from_bytes(proof[:32], "big")
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s = int.from_bytes(proof[32:], "big")
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if s >= GE.ORDER:
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return False
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R1 = s * G - e * A
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if R1.infinity:
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return False
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R2 = s * B - e * C
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if R2.infinity:
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return False
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if e != dleq_challenge(A, B, C, R1, R2, m, G):
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return False
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return True
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