Browse Source

Allowing to encode and decode hex signatures

pull/2/head
Jør∂¡ 3 years ago
parent
commit
b9978cef75
2 changed files with 67 additions and 1 deletions
  1. +27
    -0
      src/index.ts
  2. +40
    -1
      test/index.test.ts

+ 27
- 0
src/index.ts

@ -121,3 +121,30 @@ export function verify(m: BigNumber, s: UnblindedSignature, q: Point) {
} }
return false return false
} }
export function signatureToHex(signature: UnblindedSignature): string {
if (!signature || !signature.f || !signature.s) throw new Error("The signature is empty")
const { f, s } = signature
// hex(swapEndiannes(s) ) + hex(f)
const hexPaddedS = zeroPad(s.toBuffer().toString("hex"), 32)
const flippedHexS = Buffer.from(hexPaddedS, "hex").reverse().toString("hex")
return zeroPad(flippedHexS, 32) + zeroPad(f.encode("hex", false).substr(2), 64) // strip 04
}
export function signatureFromHex(hexSignature: string): UnblindedSignature {
if (!hexSignature || hexSignature.length != 192) throw new Error("Invalid hex signature (96 bytes expected)")
const s = new BigNumber(Buffer.from(hexSignature.substr(0, 64), "hex").reverse())
const f = decodePoint("04" + hexSignature.substr(64))
return { s, f }
}
function zeroPad(hexString: string, byteLength: number) {
if (hexString.length > (byteLength * 2)) throw new Error("Out of bounds")
while (hexString.length < (byteLength * 2)) {
hexString = "0" + hexString
}
return hexString
}

+ 40
- 1
test/index.test.ts

@ -13,7 +13,9 @@ import {
verify, verify,
hashBigNumber, hashBigNumber,
Point, Point,
BigNumber
BigNumber,
signatureToHex,
signatureFromHex
} from "../src/index" } from "../src/index"
describe("keccak256", function () { describe("keccak256", function () {
@ -53,3 +55,40 @@ describe("blind signatures", function () {
assert(verified) assert(verified)
}) })
}) })
describe("encoding", () => {
it("should encode and decode signatures", () => {
const { sk } = newKeyPair()
const { k, signerR } = newRequestParameters()
const msg = messageToBigNumber("test")
const { mBlinded, userSecretData } = blind(msg, signerR)
const sBlind = blindSign(sk, mBlinded, k)
const sig = unblind(sBlind, userSecretData)
const hexSignature = signatureToHex(sig)
assert.strictEqual(hexSignature.length, 192)
const decodedSig = signatureFromHex(hexSignature)
assert.strictEqual(decodedSig.f.encode("hex", false).length, 130)
assert.strictEqual(signatureToHex(signatureFromHex(hexSignature)), hexSignature)
// explicit values
const hexSignature2 = "089a89f07bd41560454b1640fd30e51ee088d1be8355275a88e38a38f2e7a3af9e80fcc14af9c47c8066c6726e7d3cac9370494d5c67936b2978d6cecf5a4d21bf3ef00b060c47ba874c0764d662eff2d0e9daa8ba766f4aa6a2be8ec3d37523"
const decodedSig2 = signatureFromHex(hexSignature2)
assert.strictEqual(decodedSig2.s.toString("hex"), "afa3e7f2388ae3885a275583bed188e01ee530fd40164b456015d47bf0899a08")
assert.strictEqual(decodedSig2.f.encode("hex", false).substr(2), "9e80fcc14af9c47c8066c6726e7d3cac9370494d5c67936b2978d6cecf5a4d21bf3ef00b060c47ba874c0764d662eff2d0e9daa8ba766f4aa6a2be8ec3d37523")
assert.strictEqual(signatureToHex(signatureFromHex(hexSignature2)), hexSignature2)
// swapEndianness(s) starting with 0
const hexSignature3 = "089a89f07bd41560454b1640fd30e51ee088d1be8355275a88e38a38f2e7a30f9e80fcc14af9c47c8066c6726e7d3cac9370494d5c67936b2978d6cecf5a4d21bf3ef00b060c47ba874c0764d662eff2d0e9daa8ba766f4aa6a2be8ec3d37523"
const decodedSig3 = signatureFromHex(hexSignature3)
assert.strictEqual(decodedSig3.s.toString("hex"), /* 0 */ "fa3e7f2388ae3885a275583bed188e01ee530fd40164b456015d47bf0899a08")
assert.strictEqual(decodedSig3.f.encode("hex", false).substr(2), "9e80fcc14af9c47c8066c6726e7d3cac9370494d5c67936b2978d6cecf5a4d21bf3ef00b060c47ba874c0764d662eff2d0e9daa8ba766f4aa6a2be8ec3d37523")
assert.strictEqual(signatureToHex(signatureFromHex(hexSignature3)), hexSignature3)
})
})

Loading…
Cancel
Save