Key validation: use WebCrypto API when available for curve25519

For Ed25519/Ed25519Legacy native validation code does a sign-verify check over random data.
This is faster than re-deriving the public point using tweetnacl.
If the native implementation is not available, we fall back to re-deriving
the public point only.

For X25519/Curve25519Legacy, both the native and fallback flows do an ecdh exchange;
in the fallback case, this results in slower performance compared to the existing check,
but encryption subkeys are hardly ever validated directly (only in case of gnu-dummy keys),
and this solution keeps the code simpler.

Separately, all validation tests have been updated to use valid params from a different
key, rather than corrupted parameters.
This commit is contained in:
larabr 2025-07-25 18:54:25 +02:00
parent c30404c143
commit 721b918296
No known key found for this signature in database
GPG Key ID: 2A4BEC40729185DD
5 changed files with 79 additions and 56 deletions

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@ -82,14 +82,19 @@ export async function generate(algo) {
*/
export async function validateParams(algo, A, k) {
switch (algo) {
case enums.publicKey.x25519: {
/**
* Derive public point A' from private key
* and expect A == A'
*/
const { publicKey } = x25519.box.keyPair.fromSecretKey(k);
return util.equalsUint8Array(A, publicKey);
}
case enums.publicKey.x25519:
// Validation is typically not run for ECDH, since encryption subkeys are only validated
// for gnu-dummy keys.
// So, for simplicity, we do an encrypt-decrypt round even if WebCrypto support is not available
try {
const { ephemeralPublicKey, sharedSecret } = await generateEphemeralEncryptionMaterial(algo, A);
const recomputedSharedSecret = await recomputeSharedSecret(algo, ephemeralPublicKey, A, k);
return util.equalsUint8Array(sharedSecret, recomputedSharedSecret);
} catch (_) {
return false;
}
case enums.publicKey.x448: {
const x448 = await util.getNobleCurve(enums.publicKey.x448);
/**

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@ -23,7 +23,7 @@
import ed25519 from '@openpgp/tweetnacl';
import util from '../../../util';
import enums from '../../../enums';
import { getHashByteLength } from '../../hash';
import { computeDigest, getHashByteLength } from '../../hash';
import { getRandomBytes } from '../../random';
import { b64ToUint8Array, uint8ArrayToB64 } from '../../../encoding/base64';
@ -179,15 +179,34 @@ export async function verify(algo, hashAlgo, { RS }, m, publicKey, hashed) {
*/
export async function validateParams(algo, A, seed) {
switch (algo) {
case enums.publicKey.ed25519: {
/**
* Derive public point A' from private key
* and expect A == A'
* TODO: move to sign-verify using WebCrypto (same as ECDSA) when curve is more widely implemented
*/
const { publicKey } = ed25519.sign.keyPair.fromSeed(seed);
return util.equalsUint8Array(A, publicKey);
}
case enums.publicKey.ed25519:
// If webcrypto support is available, we sign-verify random data, as the import-export
// functions might not implement validity checks.
// If we need to fallback to JS, we instead only re-derive the public key,
// as this is much faster than sign-verify.
try {
const webCrypto = util.getWebCrypto();
const jwkPrivate = privateKeyToJWK(algo, A, seed);
const jwkPublic = publicKeyToJWK(algo, A);
const privateCryptoKey = await webCrypto.importKey('jwk', jwkPrivate, 'Ed25519', false, ['sign']);
const publicCryptoKey = await webCrypto.importKey('jwk', jwkPublic, 'Ed25519', false, ['verify']);
const randomData = getRandomBytes(8);
const signature = new Uint8Array(
await webCrypto.sign('Ed25519', privateCryptoKey, randomData)
);
const verified = await webCrypto.verify('Ed25519', publicCryptoKey, signature, randomData);
return verified;
} catch (err) {
if (err.name !== 'NotSupportedError') {
return false;
}
const { publicKey } = ed25519.sign.keyPair.fromSeed(seed);
return util.equalsUint8Array(A, publicKey);
}
case enums.publicKey.ed448: {
const ed448 = await util.getNobleCurve(enums.publicKey.ed448);

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@ -21,12 +21,11 @@
* @module crypto/public_key/elliptic/eddsa_legacy
*/
import nacl from '@openpgp/tweetnacl';
import util from '../../../util';
import enums from '../../../enums';
import { getHashByteLength } from '../../hash';
import { CurveWithOID, checkPublicPointEnconding } from './oid_curves';
import { sign as eddsaSign, verify as eddsaVerify } from './eddsa';
import { sign as eddsaSign, verify as eddsaVerify, validateParams as eddsaValidateParams } from './eddsa';
/**
* Sign a message using the provided legacy EdDSA key
@ -97,12 +96,9 @@ export async function validateParams(oid, Q, k) {
return false;
}
/**
* Derive public point Q' = dG from private key
* and expect Q == Q'
*/
const { publicKey } = nacl.sign.keyPair.fromSeed(k);
const dG = new Uint8Array([0x40, ...publicKey]); // Add public key prefix
return util.equalsUint8Array(Q, dG);
// First byte is relevant for encoding purposes only
if (Q.length < 1 || Q[0] !== 0x40) {
return false;
}
return eddsaValidateParams(enums.publicKey.ed25519, Q.subarray(1), k);
}

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@ -26,7 +26,7 @@ import { uint8ArrayToB64, b64ToUint8Array } from '../../../encoding/base64';
import OID from '../../../type/oid';
import { UnsupportedError } from '../../../packet/packet';
import { generate as eddsaGenerate } from './eddsa';
import { generate as ecdhXGenerate } from './ecdh_x';
import { generate as ecdhXGenerate, validateParams as ecdhXValidateParams } from './ecdh_x';
const webCrypto = util.getWebCrypto();
const nodeCrypto = util.getNodeCrypto();
@ -252,17 +252,12 @@ async function validateStandardParams(algo, oid, Q, d) {
}
if (curveName === enums.curve.curve25519Legacy) {
d = d.slice().reverse();
// Re-derive public point Q'
const { publicKey } = nacl.box.keyPair.fromSecretKey(d);
Q = new Uint8Array(Q);
const dG = new Uint8Array([0x40, ...publicKey]); // Add public key prefix
if (!util.equalsUint8Array(dG, Q)) {
const dLittleEndian = d.slice().reverse();
// First byte is relevant for encoding purposes only
if (Q.length < 1 || Q[0] !== 0x40) {
return false;
}
return true;
return ecdhXValidateParams(enums.publicKey.x25519, Q.subarray(1), dLittleEndian);
}
const nobleCurve = await util.getNobleCurve(enums.publicKey.ecdsa, curveName); // excluding curve25519Legacy, ecdh and ecdsa use the same curves

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@ -90,8 +90,10 @@ async function generatePrivateKeyObject(options) {
export default () => {
describe('EdDSA parameter validation (legacy format)', function() {
let eddsaKey;
let anotherEddsaKey;
before(async () => {
eddsaKey = await generatePrivateKeyObject({ curve: 'ed25519Legacy' });
anotherEddsaKey = await generatePrivateKeyObject({ curve: 'ed25519Legacy' });
});
it('EdDSA params should be valid', async function() {
@ -100,11 +102,10 @@ export default () => {
it('detect invalid edDSA Q', async function() {
const eddsaKeyPacket = await cloneKeyPacket(eddsaKey);
const Q = eddsaKeyPacket.publicParams.Q;
Q[0]++;
eddsaKeyPacket.publicParams.Q = anotherEddsaKey.keyPacket.publicParams.Q;
await expect(eddsaKeyPacket.validate()).to.be.rejectedWith('Key is invalid');
const infQ = new Uint8Array(Q.length);
const infQ = new Uint8Array(eddsaKeyPacket.publicParams.Q.length);
eddsaKeyPacket.publicParams.Q = infQ;
await expect(eddsaKeyPacket.validate()).to.be.rejectedWith('Key is invalid');
});
@ -198,13 +199,19 @@ export default () => {
describe(`ECC ${curve} parameter validation`, () => {
let ecdsaKey;
let ecdhKey;
let anotherEcdsaKey;
let anotherEcdhKey;
before(async () => {
if (curve !== 'curve25519Legacy') {
ecdsaKey = await generatePrivateKeyObject({ curve });
ecdhKey = ecdsaKey.subkeys[0];
anotherEcdsaKey = await generatePrivateKeyObject({ curve });
anotherEcdhKey = anotherEcdsaKey.subkeys[0];
} else {
const eddsaKey = await generatePrivateKeyObject({ curve: 'ed25519Legacy' });
ecdhKey = eddsaKey.subkeys[0];
const anotherEddsaKey = await generatePrivateKeyObject({ curve: 'ed25519Legacy' });
anotherEcdhKey = anotherEddsaKey.subkeys[0];
}
});
@ -220,10 +227,9 @@ export default () => {
this.skip();
}
const keyPacket = await cloneKeyPacket(ecdsaKey);
const Q = keyPacket.publicParams.Q;
Q[16]++;
keyPacket.publicParams.Q = anotherEcdsaKey.keyPacket.publicParams.Q;
await expect(keyPacket.validate()).to.be.rejectedWith('Key is invalid');
const infQ = new Uint8Array(Q.length);
const infQ = new Uint8Array(anotherEcdsaKey.keyPacket.publicParams.Q.length);
infQ[0] = 4;
keyPacket.publicParams.Q = infQ;
await expect(keyPacket.validate()).to.be.rejectedWith('Key is invalid');
@ -235,11 +241,10 @@ export default () => {
it(`ECDH ${curve} - detect invalid Q`, async function() {
const keyPacket = await cloneKeyPacket(ecdhKey);
const Q = keyPacket.publicParams.Q;
Q[16]++;
keyPacket.publicParams.Q = anotherEcdhKey.keyPacket.publicParams.Q;
await expect(keyPacket.validate()).to.be.rejectedWith('Key is invalid');
const infQ = new Uint8Array(Q.length);
const infQ = new Uint8Array(keyPacket.publicParams.Q.length);
keyPacket.publicParams.Q = infQ;
infQ[0] = 4;
await expect(keyPacket.validate()).to.be.rejectedWith('Key is invalid');
@ -252,9 +257,13 @@ export default () => {
describe(`Ed${curveID}/X${curveID} parameter validation`, function() {
let eddsaKey;
let ecdhXKey;
let anotherEddsaKey;
let anotherEcdhXKey;
before(async () => {
eddsaKey = await generatePrivateKeyObject({ type: `curve${curveID}` });
ecdhXKey = eddsaKey.subkeys[0];
anotherEddsaKey = await generatePrivateKeyObject({ type: `curve${curveID}` });
anotherEcdhXKey = anotherEddsaKey.subkeys[0];
});
it(`Ed${curveID} params should be valid`, async function() {
@ -263,11 +272,10 @@ export default () => {
it(`detect invalid Ed${curveID} public point`, async function() {
const eddsaKeyPacket = await cloneKeyPacket(eddsaKey);
const A = eddsaKeyPacket.publicParams.A;
A[0]++;
eddsaKeyPacket.publicParams.A = anotherEddsaKey.keyPacket.publicParams.A;
await expect(eddsaKeyPacket.validate()).to.be.rejectedWith('Key is invalid');
const infA = new Uint8Array(A.length);
const infA = new Uint8Array(eddsaKeyPacket.publicParams.A.length);
eddsaKeyPacket.publicParams.A = infA;
await expect(eddsaKeyPacket.validate()).to.be.rejectedWith('Key is invalid');
});
@ -278,11 +286,10 @@ export default () => {
it(`detect invalid X${curveID} public point`, async function() {
const ecdhXKeyPacket = await cloneKeyPacket(ecdhXKey);
const A = ecdhXKeyPacket.publicParams.A;
A[0]++;
ecdhXKeyPacket.publicParams.A = anotherEcdhXKey.keyPacket.publicParams.A;
await expect(ecdhXKeyPacket.validate()).to.be.rejectedWith('Key is invalid');
const infA = new Uint8Array(A.length);
const infA = new Uint8Array(ecdhXKeyPacket.publicParams.A.length);
ecdhXKeyPacket.publicParams.A = infA;
await expect(ecdhXKeyPacket.validate()).to.be.rejectedWith('Key is invalid');
});
@ -291,8 +298,10 @@ export default () => {
describe('RSA parameter validation', function() {
let rsaKey;
let anotherRsaKey;
before(async () => {
rsaKey = await generatePrivateKeyObject({ type: 'rsa', rsaBits: 2048 });
anotherRsaKey = await generatePrivateKeyObject({ type: 'rsa', rsaBits: 2048 });
});
it('generated RSA params are valid', async function() {
@ -301,15 +310,14 @@ export default () => {
it('detect invalid RSA n', async function() {
const keyPacket = await cloneKeyPacket(rsaKey);
const n = keyPacket.publicParams.n;
n[0]++;
keyPacket.publicParams.n = anotherRsaKey.keyPacket.publicParams.n;
await expect(keyPacket.validate()).to.be.rejectedWith('Key is invalid');
});
it('detect invalid RSA e', async function() {
const keyPacket = await cloneKeyPacket(rsaKey);
const e = keyPacket.publicParams.e;
e[0]++;
e[0]++; // e is hard-coded so we don't take it from `anotherRsaKey`
await expect(keyPacket.validate()).to.be.rejectedWith('Key is invalid');
});
});