From 1ece8a05fbf4caf4d7c9718798377a3a0dffdb5e Mon Sep 17 00:00:00 2001
From: akwizgran <michael@briarproject.org>
Date: Thu, 7 Mar 2013 21:01:44 +0000
Subject: [PATCH] Stricter verification of public keys.
---
briar-core/src/net/sf/briar/crypto/Sec1KeyParser.java | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/briar-core/src/net/sf/briar/crypto/Sec1KeyParser.java b/briar-core/src/net/sf/briar/crypto/Sec1KeyParser.java
index 87a3e7a6fa..a3014e95f9 100644
--- a/briar-core/src/net/sf/briar/crypto/Sec1KeyParser.java
+++ b/briar-core/src/net/sf/briar/crypto/Sec1KeyParser.java
@@ -47,7 +47,11 @@ class Sec1KeyParser implements KeyParser {
System.arraycopy(encodedKey, bytesPerInt + 1, yBytes, 0, bytesPerInt);
BigInteger y = new BigInteger(1, yBytes); // Positive signum
if(y.compareTo(modulus) >= 0) throw new InvalidKeySpecException();
- // FIXME: Verify that y^2 == x^3 + ax + b (mod q)
+ // Verify that y^2 == x^3 + ax + b (mod q)
+ BigInteger a = params.getCurve().getA(), b = params.getCurve().getB();
+ 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 InvalidKeySpecException();
// Construct a public key from the point (x, y) and the params
ECPoint pub = new ECPoint(x, y);
ECPublicKeySpec keySpec = new ECPublicKeySpec(pub, params);
--
GitLab