(ext/crypto) imported raw/spki compressed EC public keys should be uncompressed when exported

[panva]

The following export routines should account for the key material to be using compressed point format and uncompress it before exporting as per the WebCryptoAPI spec.

deno/ext/crypto/shared.rs

Lines 92 to 96 in eea742e

	RawKeyData::Public(data) => {
	// public_key is a serialized EncodedPoint
	p256::EncodedPoint::from_bytes(data)
	.map_err(|_| type_error("expected valid public EC key"))
	}

deno/ext/crypto/shared.rs

Lines 109 to 113 in eea742e

	RawKeyData::Public(data) => {
	// public_key is a serialized EncodedPoint
	p384::EncodedPoint::from_bytes(data)
	.map_err(|_| type_error("expected valid public EC key"))
	}

The following script demonstrates the issue

import * as assert from 'node:assert';
import { Buffer } from 'node:buffer';

const { subtle } = globalThis.crypto;

const keyData = {
  'P-256': {
    uncompressed: Buffer.from([
      48, 89, 48, 19, 6, 7, 42, 134, 72, 206, 61, 2, 1, 6, 8, 42, 134, 72, 206, 61, 3, 1, 7, 3, 66, 0, 4, 210, 16, 176, 166, 249, 217, 240, 18, 134, 128, 88, 180, 63, 164, 244, 113, 1, 133, 67, 187, 160, 12, 146, 80, 223, 146, 87, 194, 172, 174, 93, 209, 206, 3, 117, 82, 212, 129, 69, 12, 227, 155, 77, 16, 149, 112, 27, 23, 91, 250, 179, 75, 142, 108, 9, 158, 24, 241, 193, 152, 53, 131, 97, 232,
    ]),
    compressed: Buffer.from([
      48, 57, 48, 19, 6, 7, 42, 134, 72, 206, 61, 2, 1, 6, 8, 42, 134, 72, 206, 61, 3, 1, 7, 3, 34, 0, 2, 210, 16, 176, 166, 249, 217, 240, 18, 134, 128, 88, 180, 63, 164, 244, 113, 1, 133, 67, 187, 160, 12, 146, 80, 223, 146, 87, 194, 172, 174, 93, 209,
    ]),
  },

  'P-384': {
    uncompressed: Buffer.from([
      48, 118, 48, 16, 6, 7, 42, 134, 72, 206, 61, 2, 1, 6, 5, 43, 129, 4, 0, 34, 3, 98, 0, 4, 33, 156, 20, 214, 102, 23, 179, 110, 198, 216, 133, 107, 56, 91, 115, 167, 77, 52, 79, 216, 174, 117, 239, 4, 100, 53, 221, 165, 78, 59, 68, 189, 95, 189, 235, 209, 208, 141, 214, 158, 45, 125, 193, 220, 33, 140, 180, 53, 189, 40, 19, 140, 199, 120, 51, 122, 132, 47, 107, 214, 27, 36, 14, 116, 36, 159, 36, 102, 124, 42, 88, 16, 167, 107, 252, 40, 224, 51, 95, 136, 166, 80, 29, 236, 1, 151, 109, 168, 90, 251, 0, 134, 156, 182, 172, 232,
    ]),
    compressed: Buffer.from([
      48, 70, 48, 16, 6, 7, 42, 134, 72, 206, 61, 2, 1, 6, 5, 43, 129, 4, 0, 34, 3, 50, 0, 2, 33, 156, 20, 214, 102, 23, 179, 110, 198, 216, 133, 107, 56, 91, 115, 167, 77, 52, 79, 216, 174, 117, 239, 4, 100, 53, 221, 165, 78, 59, 68, 189, 95, 189, 235, 209, 208, 141, 214, 158, 45, 125, 193, 220, 33, 140, 180, 53,
    ]),
  },
};

const curves = Object.keys(keyData);
const testVectors = [
  {
    name: 'ECDSA',
    privateUsages: ['sign'],
    publicUsages: ['verify'],
  },
  {
    name: 'ECDH',
    privateUsages: ['deriveKey', 'deriveBits'],
    publicUsages: [],
  },
];

async function testRoundTripSpki({ name, publicUsages }, namedCurve) {
  const { compressed, uncompressed } = keyData[namedCurve];

  const key = await subtle.importKey(
    'spki',
    compressed,
    { name, namedCurve },
    true,
    publicUsages
  );

  const spki = await subtle.exportKey('spki', key);
  assert.deepStrictEqual(
    Buffer.from(spki).toString('hex'),
    uncompressed.toString('hex')
  );
}

async function testRoundTripRaw({ name, publicUsages }, namedCurve) {
  let { compressed, uncompressed } = keyData[namedCurve];
  let i = uncompressed.indexOf(Buffer.from([0x00, 0x04])) + 1;
  uncompressed = uncompressed.subarray(i);

  i =
    compressed.indexOf(Buffer.from([0x00, 0x02])) + 1 ||
    compressed.indexOf(Buffer.from([0x00, 0x03])) + 1;

  compressed = compressed.subarray(i);

  const key = await subtle.importKey(
    'raw',
    compressed,
    { name, namedCurve },
    true,
    publicUsages
  );

  const raw = await subtle.exportKey('raw', key);

  assert.strictEqual(
    Buffer.from(raw).toString('hex'),
    uncompressed.toString('hex')
  );
}

for (const namedCurve of curves) {
  for (const vector of testVectors) {
    await testRoundTripSpki(vector, namedCurve).then(
      () =>
        console.log(namedCurve, 'spki'.padEnd(4), vector.name.padEnd(5), '✅'),
      (e) => {
        console.log(namedCurve, 'spki'.padEnd(4), vector.name.padEnd(5), '❌', e.message)
      }
    );
    await testRoundTripRaw(vector, namedCurve).then(
      () =>
        console.log(namedCurve, 'raw'.padEnd(4), vector.name.padEnd(5), '✅'),
      (e) => {
        console.log(namedCurve, 'raw'.padEnd(4), vector.name.padEnd(5), '❌', e.message)
      }
    );
    console.log('\n');
  }
}