status-im/status-keycard
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constant time comparison

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This commit is contained in:
Michele Balistreri 2022-11-25 10:03:55 +01:00
parent 4956fcc1ee
commit a2595b35e7
3 changed files with 19 additions and 21 deletions
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2
build.gradle
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@ -59,7 +59,7 @@ dependencies {
testCompile(files("../jcardsim/jcardsim-3.0.5-SNAPSHOT.jar"))
testCompile('org.web3j:core:2.3.1')
testCompile('org.bitcoinj:bitcoinj-core:0.14.5')
testCompile('com.github.status-im.status-keycard-java:desktop:64aece4')
testCompile('com.github.status-im.status-keycard-java:desktop:15a61e1')
testCompile('org.bouncycastle:bcprov-jdk15on:1.65')
testCompile("org.junit.jupiter:junit-jupiter-api:5.1.1")
testRuntime("org.junit.jupiter:junit-jupiter-engine:5.1.1")

2
buildSrc/build.gradle
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@ -4,5 +4,5 @@ repositories {
}
dependencies {
compile 'com.github.status-im.status-keycard-java:desktop:64aece4'
compile 'com.github.status-im.status-keycard-java:desktop:15a61e1'
}

36
src/main/java/im/status/keycard/Crypto.java
View File

@ -89,11 +89,7 @@ public class Crypto {
addm256(output, outOff, data, dataOff, SECP256k1.SECP256K1_R, (short) 0, output, outOff);
if (isZero256(output, outOff)) {
return false;
}
return true;
return !isZero256(output, outOff);
}
/**
@ -202,17 +198,22 @@ public class Crypto {
* @return the comparison result
*/
private short ucmp256(byte[] a, short aOff, byte[] b, short bOff) {
short ai, bi;
short gt = 0;
short eq = 1;
for (short i = 0 ; i < 32; i++) {
ai = (short)(a[(short)(aOff + i)] & 0x00ff);
bi = (short)(b[(short)(bOff + i)] & 0x00ff);
short l = (short)(a[(short)(aOff + i)] & 0x00ff);
short r = (short)(b[(short)(bOff + i)] & 0x00ff);
short d = (short)(r - l);
short l_xor_r = (short)(l ^ r);
short l_xor_d = (short)(l ^ d);
short d_xored = (short)(d ^ (short)(l_xor_r & l_xor_d));
if (ai != bi) {
return (short)(ai - bi);
}
gt |= (d_xored >>> 15) & eq;
eq &= ((short)(l_xor_r - 1) >>> 15);
}
return 0;
return (short) ((gt + gt + eq) - 1);
}
/**
@ -223,16 +224,13 @@ public class Crypto {
* @return true if a is 0, false otherwise
*/
private boolean isZero256(byte[] a, short aOff) {
boolean isZero = true;
byte acc = 0;
for (short i = 0; i < (byte) 32; i++) {
if (a[(short)(aOff + i)] != 0) {
isZero = false;
break;
}
for (short i = 0; i < 32; i++) {
acc |= a[(short)(aOff + i)];
}
return isZero;
return acc == 0;
}
/**