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Merge pull request #288 from koto/dsafix

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Correctly check parameters range in DSA verify. Fixes #286
This commit is contained in:
Tankred Hase 2015-02-11 11:00:30 +01:00
commit 1728ad48bc
1 changed files with 8 additions and 4 deletions
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12
src/crypto/public_key/dsa.js
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@ -102,14 +102,18 @@ function DSA() {
function verify(hashalgo, s1, s2, m, p, q, g, y) {
var hashed_data = util.getLeftNBits(hashModule.digest(hashalgo, m), q.bitLength());
var hash = new BigInteger(util.hexstrdump(hashed_data), 16);
if (BigInteger.ZERO.compareTo(s1) > 0 ||
s1.compareTo(q) > 0 ||
BigInteger.ZERO.compareTo(s2) > 0 ||
s2.compareTo(q) > 0) {
if (BigInteger.ZERO.compareTo(s1) >= 0 ||
s1.compareTo(q) >= 0 ||
BigInteger.ZERO.compareTo(s2) >= 0 ||
s2.compareTo(q) >= 0) {
util.print_debug("invalid DSA Signature");
return null;
}
var w = s2.modInverse(q);
if (BigInteger.ZERO.compareTo(w) == 0) {
util.print_debug("invalid DSA Signature");
return null;
}
var u1 = hash.multiply(w).mod(q);
var u2 = s1.multiply(w).mod(q);
return g.modPow(u1, p).multiply(y.modPow(u2, p)).mod(p).mod(q);