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Validate coordinates when creating EC2 keys #25

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Merged
vikram-gaur merged 1 commit into from
Feb 24, 2024
Merged

Validate coordinates when creating EC2 keys #25

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10 changes: 9 additions & 1 deletion src/com/google/cose/utils/CoseUtils.java
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Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,7 @@
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.DERSequenceGenerator;
import org.bouncycastle.jce.ECNamedCurveTable;
import org.bouncycastle.jce.spec.ECNamedCurveParameterSpec;

public class CoseUtils {
private static final String EC_PARAMETER_SPEC = "EC";
Expand Down Expand Up @@ -148,8 +149,15 @@ public static ECPrivateKey getEc2PrivateKeyFromInteger(int curve, BigInteger s)
public static PublicKey getEc2PublicKeyFromCoordinates(int curve, BigInteger x, BigInteger y)
throws CoseException {
try {
final String curveName = getEc2CoseCurveName(curve);
final ECNamedCurveParameterSpec spec = ECNamedCurveTable.getParameterSpec(curveName);
if (spec == null) {
throw new IllegalStateException("Unsupported curve: " + curveName);
}
spec.getCurve().validatePoint(x, y);

final AlgorithmParameters params = AlgorithmParameters.getInstance(EC_PARAMETER_SPEC);
params.init(new ECGenParameterSpec(getEc2CoseCurveName(curve)));
params.init(new ECGenParameterSpec(curveName));
final ECParameterSpec ecParameters = params.getParameterSpec(ECParameterSpec.class);

final ECPoint ecPoint = new ECPoint(x, y);
Expand Down
33 changes: 22 additions & 11 deletions test/com/google/cose/Ec2SigningKeyTest.java
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Expand Up @@ -80,17 +80,28 @@ public void testRoundTrip() throws CborException, CoseException {
}

@Test
public void testConversion() throws CborException, CoseException {
final String cborString = "A4010220012158205A88D182BCE5F42EFA59943F33359D2E8A968FF289D93E5FA44"
+ "4B624343167FE225820B16E8CF858DDC7690407BA61D4C338237A8CFCF3DE6AA672FC60A557AA32FC67";
final ByteString x = new ByteString(X_BYTES);
final ByteString y = new ByteString(Y_BYTES);
final Ec2SigningKey sKey = Ec2SigningKey.parse(TestUtilities.hexStringToByteArray(cborString));
Assert.assertEquals(Headers.KEY_TYPE_EC2, sKey.getKeyType());
Assert.assertEquals(new UnsignedInteger(Headers.CURVE_EC2_P256),
sKey.getLabels().get(Headers.KEY_PARAMETER_CURVE));
Assert.assertEquals(x, sKey.getLabels().get(Headers.KEY_PARAMETER_X));
Assert.assertEquals(y, sKey.getLabels().get(Headers.KEY_PARAMETER_Y));
public void testCoordinatesNotOnCurve() {
final int[] allCurves = new int[]{
Headers.CURVE_EC2_P256,
Headers.CURVE_EC2_P384,
Headers.CURVE_EC2_P521
};

for (int curve: allCurves) {
final Map map = new Map();
map.put(new UnsignedInteger(Headers.KEY_PARAMETER_KEY_TYPE),
new UnsignedInteger(Headers.KEY_TYPE_EC2));
map.put(new NegativeInteger(Headers.KEY_PARAMETER_CURVE), new UnsignedInteger(curve));
map.put(new NegativeInteger(Headers.KEY_PARAMETER_X),
new ByteString(
TestUtilities.hexStringToByteArray(
"59cc8d401bbd23517c7b5e948d269190d2a897e9061d1af3bc0398d77edd1400")));
map.put(new NegativeInteger(Headers.KEY_PARAMETER_Y),
new ByteString(
TestUtilities.hexStringToByteArray(
"77550f5dbc8b3fbbb35c099961d51a956c7228c6e36aeccb4c95ac69cf27f7e6")));
assertThrows(IllegalArgumentException.class, () -> new Ec2SigningKey(map));
}
}

@Test
Expand Down