add: public key check searching for small primes (less than 10k)

[gigi.git] / src / club / wpia / gigi / crypto / key / KeyCheckSmallFactors.java

diff --git a/src/club/wpia/gigi/crypto/key/KeyCheckSmallFactors.java b/src/club/wpia/gigi/crypto/key/KeyCheckSmallFactors.java
new file mode 100644 (file)
index 0000000..a096534
--- /dev/null
+++ b/src/club/wpia/gigi/crypto/key/KeyCheckSmallFactors.java
@@ -0,0 +1,52 @@
+package club.wpia.gigi.crypto.key;
+
+import java.math.BigInteger;
+import java.security.PublicKey;
+import java.security.interfaces.RSAPublicKey;
+import java.util.ArrayList;
+
+import club.wpia.gigi.GigiApiException;
+import club.wpia.gigi.output.template.SprintfCommand;
+
+public class KeyCheckSmallFactors extends KeyCheck {
+
+    private static final long MAX_CHECKED_SMALL_PRIME_BOUNDARY = 10000;
+
+    private static final BigInteger[] primes;
+
+    static {
+        ArrayList<BigInteger> prims = new ArrayList<>(1024);
+
+        NextPrime:
+        for (long i = 2; i < MAX_CHECKED_SMALL_PRIME_BOUNDARY; i++) {
+            for (BigInteger p : prims) {
+                if (BigInteger.ZERO.equals(BigInteger.valueOf(i).mod(p))) {
+                    continue NextPrime;
+                }
+            }
+
+            prims.add(BigInteger.valueOf(i));
+        }
+
+        primes = prims.toArray(new BigInteger[0]);
+
+        register(new KeyCheckSmallFactors());
+    }
+
+    @Override
+    public void check(PublicKey key) throws GigiApiException {
+        if ( !(key instanceof RSAPublicKey)) {
+            return;
+        }
+
+        BigInteger modulus = ((RSAPublicKey) key).getModulus();
+
+        // Check for small prime factors below 10000
+        for (BigInteger n : primes) {
+            if (BigInteger.ZERO.equals(modulus.mod(n))) {
+                throw new GigiApiException(SprintfCommand.createSimple("Small factors check of public key: Key is divisible by {0}.", n.toString()));
+            }
+        }
+    }
+
+}