From 14e1cd6072f3502f83c98206b66d13170bdc39db Mon Sep 17 00:00:00 2001
From: akwizgran <akwizgran@users.sourceforge.net>
Date: Thu, 16 Jan 2014 15:35:25 +0000
Subject: [PATCH] Normalise elliptic curve points.
---
briar-core/src/org/briarproject/crypto/Sec1KeyParser.java | 8 +++++---
briar-core/src/org/briarproject/crypto/Sec1PublicKey.java | 7 ++++---
2 files changed, 9 insertions(+), 6 deletions(-)
diff --git a/briar-core/src/org/briarproject/crypto/Sec1KeyParser.java b/briar-core/src/org/briarproject/crypto/Sec1KeyParser.java
index e64de28aaa..0446c6a523 100644
--- a/briar-core/src/org/briarproject/crypto/Sec1KeyParser.java
+++ b/briar-core/src/org/briarproject/crypto/Sec1KeyParser.java
@@ -9,6 +9,7 @@ import org.briarproject.api.crypto.PublicKey;
import org.spongycastle.crypto.params.ECDomainParameters;
import org.spongycastle.crypto.params.ECPrivateKeyParameters;
import org.spongycastle.crypto.params.ECPublicKeyParameters;
+import org.spongycastle.math.ec.ECCurve;
import org.spongycastle.math.ec.ECPoint;
/**
@@ -50,13 +51,14 @@ class Sec1KeyParser implements KeyParser {
BigInteger y = new BigInteger(1, yBytes); // Positive signum
if(y.compareTo(modulus) >= 0) throw new GeneralSecurityException();
// Verify that y^2 == x^3 + ax + b (mod p)
- BigInteger a = params.getCurve().getA().toBigInteger();
- BigInteger b = params.getCurve().getB().toBigInteger();
+ ECCurve curve = params.getCurve();
+ BigInteger a = curve.getA().toBigInteger();
+ BigInteger b = curve.getB().toBigInteger();
BigInteger lhs = y.multiply(y).mod(modulus);
BigInteger rhs = x.multiply(x).add(a).multiply(x).add(b).mod(modulus);
if(!lhs.equals(rhs)) throw new GeneralSecurityException();
// We know the point (x, y) is on the curve, so we can create the point
- ECPoint pub = params.getCurve().createPoint(x, y);
+ ECPoint pub = curve.createPoint(x, y).normalize();
// Verify that the point (x, y) is not the point at infinity
if(pub.isInfinity()) throw new GeneralSecurityException();
// Verify that the point (x, y) times n is the point at infinity
diff --git a/briar-core/src/org/briarproject/crypto/Sec1PublicKey.java b/briar-core/src/org/briarproject/crypto/Sec1PublicKey.java
index 290f35ce19..95523c79b8 100644
--- a/briar-core/src/org/briarproject/crypto/Sec1PublicKey.java
+++ b/briar-core/src/org/briarproject/crypto/Sec1PublicKey.java
@@ -1,8 +1,8 @@
package org.briarproject.crypto;
import org.briarproject.api.crypto.PublicKey;
-
import org.spongycastle.crypto.params.ECPublicKeyParameters;
+import org.spongycastle.math.ec.ECPoint;
/**
* An elliptic curve public key that uses the encoding defined in "SEC 1:
@@ -23,9 +23,10 @@ class Sec1PublicKey implements PublicKey {
public byte[] getEncoded() {
byte[] encodedKey = new byte[publicKeyBytes];
encodedKey[0] = 4;
- byte[] x = key.getQ().getAffineXCoord().toBigInteger().toByteArray();
+ ECPoint pub = key.getQ().normalize();
+ byte[] x = pub.getAffineXCoord().toBigInteger().toByteArray();
Sec1Utils.convertToFixedLength(x, encodedKey, 1, bytesPerInt);
- byte[] y = key.getQ().getAffineYCoord().toBigInteger().toByteArray();
+ byte[] y = pub.getAffineYCoord().toBigInteger().toByteArray();
Sec1Utils.convertToFixedLength(y, encodedKey, 1 + bytesPerInt,
bytesPerInt);
return encodedKey;
--
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