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schnorr: remove packSig

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This commit is contained in:
Paul Miller 2023-01-25 06:54:00 +00:00
parent cffea91061
commit f2ee24bee4
No known key found for this signature in database
GPG Key ID: 697079DA6878B89B
1 changed files with 7 additions and 15 deletions
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22
src/secp256k1.ts
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@ -149,19 +149,6 @@ function lift_x(x: bigint) {
p.assertValidity();
return p;
}
function packSig(r: bigint, s: bigint): Uint8Array {
validateRS(r, s);
const sig = new Uint8Array(64);
sig.set(numTo32b(r), 0);
sig.set(numTo32b(s), 32);
return sig;
}
function unpackSig(sig: Uint8Array): { r: bigint; s: bigint } {
const r = b2num(sig.subarray(0, 32)); // Let r = int(sig[0:32]); fail if r ≥ p.
const s = b2num(sig.subarray(32, 64)); // Let s = int(sig[32:64]); fail if s ≥ n.
validateRS(r, s);
return { r, s };
}
/**
* Synchronously creates Schnorr signature. Improved security: verifies itself before
* producing an output.
@ -182,7 +169,9 @@ function schnorrSign(message: Hex, privateKey: Hex, auxRand: Hex = randomBytes(3
if (k_ === _0n) throw new Error('sign failed: k is zero'); // Fail if k' = 0.
const { point: R, x: rx, scalar: k } = schnorrGetScalar(k_);
const e = modN(b2num(tag(TAGS.challenge, rx, px, m)));
const sig = packSig(R.px, modN(k + e * d));
const sig = new Uint8Array(64); // Let sig = bytes(R) || bytes((k + ed) mod n).
sig.set(numTo32b(R.px), 0);
sig.set(numTo32b(modN(k + e * d)), 32);
if (!schnorrVerify(sig, m, px)) throw new Error('sign: Invalid signature produced');
return sig;
}
@ -193,7 +182,10 @@ function schnorrSign(message: Hex, privateKey: Hex, auxRand: Hex = randomBytes(3
function schnorrVerify(signature: Hex, message: Hex, publicKey: Hex): boolean {
try {
const P = lift_x(b2num(ensureBytes(publicKey, 32))); // P = lift_x(int(pk)); fail if that fails
const { r, s } = unpackSig(ensureBytes(signature, 64));
const sig = ensureBytes(signature, 64);
const r = b2num(sig.subarray(0, 32)); // Let r = int(sig[0:32]); fail if r ≥ p.
const s = b2num(sig.subarray(32, 64)); // Let s = int(sig[32:64]); fail if s ≥ n.
validateRS(r, s);
const m = ensureBytes(message);
const e = modN(b2num(tag(TAGS.challenge, numTo32b(r), toRawX(P), m)));
const R = PPoint.BASE.multiplyAndAddUnsafe(P, s, modN(-e)); // R = s⋅G - e⋅P