jwks endpoint for X/Y coordinates in EC keypair can return less bytes than expected (#14952)

Closes #14933
This commit is contained in:
rmartinc 2023-02-23 16:22:23 +01:00 committed by GitHub
parent f180115d27
commit c9fdaf572b
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
4 changed files with 160 additions and 39 deletions

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@ -124,8 +124,8 @@ public class JWKBuilder {
k.setAlgorithm(algorithm);
k.setPublicKeyUse(DEFAULT_PUBLIC_KEY_USE);
k.setCrv("P-" + fieldSize);
k.setX(Base64Url.encode(toIntegerBytes(ecKey.getW().getAffineX())));
k.setY(Base64Url.encode(toIntegerBytes(ecKey.getW().getAffineY())));
k.setX(Base64Url.encode(toIntegerBytes(ecKey.getW().getAffineX(), fieldSize)));
k.setY(Base64Url.encode(toIntegerBytes(ecKey.getW().getAffineY(), fieldSize)));
return k;
}

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@ -18,35 +18,46 @@
package org.keycloak.jose.jwk;
import java.math.BigInteger;
import java.util.Arrays;
public class JWKUtil {
/**
* Convert BigInteger to 64-byte integer array
* Coverts {@code BigInteger} to 64-byte array removing the sign byte if
* necessary.
*
* Copied from org.apache.commons.codec.binary.Base64
* @param bigInt {@code BigInteger} to be converted
* @return Byte array representation of the BigInteger parameter
*/
public static byte[] toIntegerBytes(final BigInteger bigInt) {
int bitlen = bigInt.bitLength();
// round bitlen
bitlen = ((bitlen + 7) >> 3) << 3;
final byte[] bigBytes = bigInt.toByteArray();
return toIntegerBytes(bigInt, bigInt.bitLength());
}
if (((bigInt.bitLength() % 8) != 0) && (((bigInt.bitLength() / 8) + 1) == (bitlen / 8))) {
return bigBytes;
/**
* Coverts {@code BigInteger} to 64-byte array but maintaining the length
* to bitlen as specified in rfc7518 for certain fields (X and Y parameter
* for EC keys).
*
* @param bigInt {@code BigInteger} to be converted
* @param bitlen The bit length size of the integer (for example 521 for EC P-521)
* @return Byte array representation of the BigInteger parameter with length (bitlen + 7) / 8
* @throws IllegalStateException if the big integer is longer than bitlen
*/
public static byte[] toIntegerBytes(final BigInteger bigInt, int bitlen) {
assert bigInt.bitLength() <= bitlen : "Incorrect big integer with bit length " + bigInt.bitLength() + " for " + bitlen;
final int bytelen = (bitlen + 7) / 8;
final byte[] array = bigInt.toByteArray();
if (array.length == bytelen) {
// expected number of bytes, return them
return array;
} else if (bytelen < array.length) {
// if array is greater is because the sign bit (it can be only 1 byte more), remove it
return Arrays.copyOfRange(array, array.length - bytelen, array.length);
} else {
// if array is smaller fill it with zeros
final byte[] resizedBytes = new byte[bytelen];
System.arraycopy(array, 0, resizedBytes, bytelen - array.length, array.length);
return resizedBytes;
}
// set up params for copying everything but sign bit
int startSrc = 0;
int len = bigBytes.length;
// if bigInt is exactly byte-aligned, just skip signbit in copy
if ((bigInt.bitLength() % 8) == 0) {
startSrc = 1;
len--;
}
final int startDst = bitlen / 8 - len; // to pad w/ nulls as per spec
final byte[] resizedBytes = new byte[bitlen / 8];
System.arraycopy(bigBytes, startSrc, resizedBytes, startDst, len);
return resizedBytes;
}
}

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@ -135,15 +135,14 @@ public abstract class JWKTest {
verify(data, sign, JavaAlgorithm.RS256, publicKeyFromJwk);
}
@Test
public void publicEs256() throws Exception {
private void testPublicEs256(String algorithm) throws Exception {
KeyPairGenerator keyGen = CryptoIntegration.getProvider().getKeyPairGen(KeyType.EC);
SecureRandom randomGen = new SecureRandom();
ECGenParameterSpec ecSpec = new ECGenParameterSpec("secp256r1");
ECGenParameterSpec ecSpec = new ECGenParameterSpec(algorithm);
keyGen.initialize(ecSpec, randomGen);
KeyPair keyPair = keyGen.generateKeyPair();
PublicKey publicKey = keyPair.getPublic();
ECPublicKey publicKey = (ECPublicKey) keyPair.getPublic();
JWK jwk = JWKBuilder.create().kid(KeyUtils.createKeyId(keyPair.getPublic())).algorithm("ES256").ec(publicKey);
@ -162,28 +161,36 @@ public abstract class JWKTest {
byte[] xBytes = Base64Url.decode(ecJwk.getX());
byte[] yBytes = Base64Url.decode(ecJwk.getY());
assertTrue(publicKey instanceof ECPublicKey);
ECPoint ecPoint = ((ECPublicKey) publicKey).getW();
assertNotNull(ecPoint);
int lengthAffineX = JWKUtil.toIntegerBytes(ecPoint.getAffineX()).length;
int lengthAffineY = JWKUtil.toIntegerBytes(ecPoint.getAffineY()).length;
assertEquals(lengthAffineX, xBytes.length);
assertEquals(lengthAffineY, yBytes.length);
final int expectedSize = (publicKey.getParams().getCurve().getField().getFieldSize() + 7) / 8;
assertEquals(expectedSize, xBytes.length);
assertEquals(expectedSize, yBytes.length);
String jwkJson = JsonSerialization.writeValueAsString(jwk);
JWKParser parser = JWKParser.create().parse(jwkJson);
PublicKey publicKeyFromJwk = parser.toPublicKey();
assertArrayEquals(publicKey.getEncoded(), publicKeyFromJwk.getEncoded());
ECPublicKey publicKeyFromJwk = (ECPublicKey) parser.toPublicKey();
assertEquals(publicKey.getW(), publicKeyFromJwk.getW());
byte[] data = "Some test string".getBytes(StandardCharsets.UTF_8);
byte[] sign = sign(data, JavaAlgorithm.ES256, keyPair.getPrivate());
verify(data, sign, JavaAlgorithm.ES256, publicKeyFromJwk);
}
@Test
public void publicEs256P256() throws Exception {
testPublicEs256("secp256r1");
}
@Test
public void publicEs256P521() throws Exception {
testPublicEs256("secp521r1");
}
@Test
public void publicEs256P384() throws Exception {
testPublicEs256("secp384r1");
}
@Test
public void parse() {
String jwkJson = "{" +

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@ -0,0 +1,103 @@
/*
* Copyright 2022 Red Hat, Inc. and/or its affiliates
* and other contributors as indicated by the @author tags.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.keycloak.jose.jwk;
import java.math.BigInteger;
import org.junit.Assert;
import org.junit.Test;
/**
* <p>Test class for <em>JWKUtil.toIntegerBytes</em> methods.</p>
*
* @author rmartinc
*/
public class JWKUtilTest {
@Test
public void testBigInteger256bit33bytes() {
// big integer that is 256b/32B (P-256) but positive sign adds one more byte
BigInteger bi = new BigInteger("106978455244904118504029146852168092303170743300495577837424194202315290288011");
Assert.assertEquals(256, bi.bitLength());
Assert.assertEquals(33, bi.toByteArray().length);
byte[] bytes = JWKUtil.toIntegerBytes(bi, 256);
Assert.assertEquals(32, bytes.length);
Assert.assertEquals(bi, new BigInteger(1, bytes));
}
@Test
public void testBigInteger521bit66bytes() {
// big integer that is 521b/66B (P-521)
BigInteger bi = new BigInteger("6734373674814691396115132088653791161514881890352734019594374673014557152383502505390504647094584246525242385854438954847939940255492102589858760446395824148");
Assert.assertEquals(521, bi.bitLength());
Assert.assertEquals(66, bi.toByteArray().length);
byte[] bytes = JWKUtil.toIntegerBytes(bi, 521);
Assert.assertEquals(66, bytes.length);
Assert.assertEquals(bi, new BigInteger(1, bytes));
}
@Test
public void testBigInteger519bit65bytes() {
// big integer is 519b/65B (P-521)
BigInteger bi = new BigInteger("1056406612537758216307284361941630998827278875643943164504783316640832530092186610655845467862847840003942818620330993843247554843391332954698064457598103921");
Assert.assertEquals(519, bi.bitLength());
Assert.assertEquals(65, bi.toByteArray().length);
byte[] bytes = JWKUtil.toIntegerBytes(bi, 521);
Assert.assertEquals(66, bytes.length);
Assert.assertEquals(bi, new BigInteger(1, bytes));
bytes = JWKUtil.toIntegerBytes(bi);
Assert.assertEquals(65, bytes.length);
Assert.assertEquals(bi, new BigInteger(1, bytes));
}
@Test
public void testBigInteger509bit65bytes() {
// big integer is 509b/64B (P-521)
BigInteger bi = new BigInteger("1020105336060806799317581876370378670178920448263046037385822665297838480884942245045412789346716977404456327079571798657084244307627713218035021026706753");
Assert.assertEquals(509, bi.bitLength());
Assert.assertEquals(64, bi.toByteArray().length);
byte[] bytes = JWKUtil.toIntegerBytes(bi, 521);
Assert.assertEquals(66, bytes.length);
Assert.assertEquals(bi, new BigInteger(1, bytes));
bytes = JWKUtil.toIntegerBytes(bi);
Assert.assertEquals(64, bytes.length);
Assert.assertEquals(bi, new BigInteger(1, bytes));
}
@Test
public void testBigInteger380bit48bytes() {
// big integer is 380b/48B (P-384)
BigInteger bi = new BigInteger("1318324198847573133767761135109898830134893480775680898178696604234765693579204018161102886445531980641666395659568");
Assert.assertEquals(380, bi.bitLength());
Assert.assertEquals(48, bi.toByteArray().length);
byte[] bytes = JWKUtil.toIntegerBytes(bi, 384);
Assert.assertEquals(48, bytes.length);
Assert.assertEquals(bi, new BigInteger(1, bytes));
bytes = JWKUtil.toIntegerBytes(bi);
Assert.assertEquals(48, bytes.length);
Assert.assertEquals(bi, new BigInteger(1, bytes));
}
@Test
public void testBigInteger380bit48bytesErrorFor256() {
// big integer is 380b/48B (P-384) not valid for 256b (P-256)
BigInteger bi = new BigInteger("1318324198847573133767761135109898830134893480775680898178696604234765693579204018161102886445531980641666395659568");
Assert.assertEquals(380, bi.bitLength());
Assert.assertEquals(48, bi.toByteArray().length);
AssertionError e = Assert.assertThrows(AssertionError.class, () -> JWKUtil.toIntegerBytes(bi, 256));
Assert.assertEquals("Incorrect big integer with bit length 380 for 256", e.getMessage());
}
}