Implement P256 verification via RIP-7212 precompile with Solidity fallback (#4881)

Co-authored-by: Ernesto García <ernestognw@gmail.com>
Co-authored-by: cairo <cairoeth@protonmail.com>
Co-authored-by: sudo rm -rf --no-preserve-root / <pcaversaccio@users.noreply.github.com>

test/utils/cryptography/P256.test.js

@@ -0,0 +1,156 @@
+const { ethers } = require('hardhat');
+const { expect } = require('chai');
+const { secp256r1 } = require('@noble/curves/p256');
+const { loadFixture } = require('@nomicfoundation/hardhat-network-helpers');
+
+const N = 0xffffffff00000000ffffffffffffffffbce6faada7179e84f3b9cac2fc632551n;
+
+// As in ECDSA, signatures are malleable and the tooling produce both high and low S values.
+// We need to ensure that the s value is in the lower half of the order of the curve.
+const ensureLowerOrderS = ({ s, recovery, ...rest }) => {
+  if (s > N / 2n) {
+    s = N - s;
+    recovery = 1 - recovery;
+  }
+  return { s, recovery, ...rest };
+};
+
+const prepareSignature = (
+  privateKey = secp256r1.utils.randomPrivateKey(),
+  messageHash = ethers.hexlify(ethers.randomBytes(0x20)),
+) => {
+  const publicKey = [
+    secp256r1.getPublicKey(privateKey, false).slice(0x01, 0x21),
+    secp256r1.getPublicKey(privateKey, false).slice(0x21, 0x41),
+  ].map(ethers.hexlify);
+  const { r, s, recovery } = ensureLowerOrderS(secp256r1.sign(messageHash.replace(/0x/, ''), privateKey));
+  const signature = [r, s].map(v => ethers.toBeHex(v, 0x20));
+
+  return { privateKey, publicKey, signature, recovery, messageHash };
+};
+
+describe('P256', function () {
+  async function fixture() {
+    return { mock: await ethers.deployContract('$P256') };
+  }
+
+  beforeEach(async function () {
+    Object.assign(this, await loadFixture(fixture));
+  });
+
+  describe('with signature', function () {
+    beforeEach(async function () {
+      Object.assign(this, prepareSignature());
+    });
+
+    it('verify valid signature', async function () {
+      expect(await this.mock.$verify(this.messageHash, ...this.signature, ...this.publicKey)).to.be.true;
+      expect(await this.mock.$verifySolidity(this.messageHash, ...this.signature, ...this.publicKey)).to.be.true;
+      await expect(this.mock.$verifyNative(this.messageHash, ...this.signature, ...this.publicKey))
+        .to.be.revertedWithCustomError(this.mock, 'MissingPrecompile')
+        .withArgs('0x0000000000000000000000000000000000000100');
+    });
+
+    it('recover public key', async function () {
+      expect(await this.mock.$recovery(this.messageHash, this.recovery, ...this.signature)).to.deep.equal(
+        this.publicKey,
+      );
+    });
+
+    it('reject signature with flipped public key coordinates ([x,y] >> [y,x])', async function () {
+      // flip public key
+      this.publicKey.reverse();
+
+      expect(await this.mock.$verify(this.messageHash, ...this.signature, ...this.publicKey)).to.be.false;
+      expect(await this.mock.$verifySolidity(this.messageHash, ...this.signature, ...this.publicKey)).to.be.false;
+      expect(await this.mock.$verifyNative(this.messageHash, ...this.signature, ...this.publicKey)).to.be.false; // Flipped public key is not in the curve
+    });
+
+    it('reject signature with flipped signature values ([r,s] >> [s,r])', async function () {
+      // Preselected signature where `r < N/2` and `s < N/2`
+      this.signature = [
+        '0x45350225bad31e89db662fcc4fb2f79f349adbb952b3f652eed1f2aa72fb0356',
+        '0x513eb68424c42630012309eee4a3b43e0bdc019d179ef0e0c461800845e237ee',
+      ];
+
+      // Corresponding hash and public key
+      this.messageHash = '0x2ad1f900fe63745deeaedfdf396cb6f0f991c4338a9edf114d52f7d1812040a0';
+      this.publicKey = [
+        '0x9e30de165e521257996425d9bf12a7d366925614bf204eabbb78172b48e52e59',
+        '0x94bf0fe72f99654d7beae4780a520848e306d46a1275b965c4f4c2b8e9a2c08d',
+      ];
+
+      // Make sure it works
+      expect(await this.mock.$verify(this.messageHash, ...this.signature, ...this.publicKey)).to.be.true;
+
+      // Flip signature
+      this.signature.reverse();
+
+      expect(await this.mock.$verify(this.messageHash, ...this.signature, ...this.publicKey)).to.be.false;
+      expect(await this.mock.$verifySolidity(this.messageHash, ...this.signature, ...this.publicKey)).to.be.false;
+      await expect(this.mock.$verifyNative(this.messageHash, ...this.signature, ...this.publicKey))
+        .to.be.revertedWithCustomError(this.mock, 'MissingPrecompile')
+        .withArgs('0x0000000000000000000000000000000000000100');
+      expect(await this.mock.$recovery(this.messageHash, this.recovery, ...this.signature)).to.not.deep.equal(
+        this.publicKey,
+      );
+    });
+
+    it('reject signature with invalid message hash', async function () {
+      // random message hash
+      this.messageHash = ethers.hexlify(ethers.randomBytes(32));
+
+      expect(await this.mock.$verify(this.messageHash, ...this.signature, ...this.publicKey)).to.be.false;
+      expect(await this.mock.$verifySolidity(this.messageHash, ...this.signature, ...this.publicKey)).to.be.false;
+      await expect(this.mock.$verifyNative(this.messageHash, ...this.signature, ...this.publicKey))
+        .to.be.revertedWithCustomError(this.mock, 'MissingPrecompile')
+        .withArgs('0x0000000000000000000000000000000000000100');
+      expect(await this.mock.$recovery(this.messageHash, this.recovery, ...this.signature)).to.not.deep.equal(
+        this.publicKey,
+      );
+    });
+
+    it('fail to recover signature with invalid recovery bit', async function () {
+      // flip recovery bit
+      this.recovery = 1 - this.recovery;
+
+      expect(await this.mock.$recovery(this.messageHash, this.recovery, ...this.signature)).to.not.deep.equal(
+        this.publicKey,
+      );
+    });
+  });
+
+  // test cases for https://github.com/C2SP/wycheproof/blob/4672ff74d68766e7785c2cac4c597effccef2c5c/testvectors/ecdsa_secp256r1_sha256_p1363_test.json
+  describe('wycheproof tests', function () {
+    for (const { key, tests } of require('./ecdsa_secp256r1_sha256_p1363_test.json').testGroups) {
+      // parse public key
+      let [x, y] = [key.wx, key.wy].map(v => ethers.stripZerosLeft('0x' + v, 32));
+      if (x.length > 66 || y.length > 66) continue;
+      x = ethers.zeroPadValue(x, 32);
+      y = ethers.zeroPadValue(y, 32);
+
+      // run all tests for this key
+      for (const { tcId, comment, msg, sig, result } of tests) {
+        // only keep properly formatted signatures
+        if (sig.length != 128) continue;
+
+        it(`${tcId}: ${comment}`, async function () {
+          // split signature, and reduce modulo N
+          let [r, s] = Array(2)
+            .fill()
+            .map((_, i) => ethers.toBigInt('0x' + sig.substring(64 * i, 64 * (i + 1))));
+          // move s to lower part of the curve if needed
+          if (s <= N && s > N / 2n) s = N - s;
+          // prepare signature
+          r = ethers.toBeHex(r, 32);
+          s = ethers.toBeHex(s, 32);
+          // hash
+          const messageHash = ethers.sha256('0x' + msg);
+
+          // check verify
+          expect(await this.mock.$verify(messageHash, r, s, x, y)).to.equal(result == 'valid');
+        });
+      }
+    }
+  });
+});