1 files changed, 52 insertions, 0 deletions
diff --git a/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/generators/DHParametersGenerator.java b/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/generators/DHParametersGenerator.java
new file mode 100644
index 000000000..894c3804b
--- /dev/null
+++ b/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/generators/DHParametersGenerator.java
@@ -0,0 +1,52 @@
+package org.spongycastle.crypto.generators;
+
+import org.spongycastle.crypto.params.DHParameters;
+
+import java.math.BigInteger;
+import java.security.SecureRandom;
+
+public class DHParametersGenerator
+{
+    private int             size;
+    private int             certainty;
+    private SecureRandom    random;
+
+    private static final BigInteger TWO = BigInteger.valueOf(2);
+
+    /**
+     * Initialise the parameters generator.
+     * 
+     * @param size bit length for the prime p
+     * @param certainty level of certainty for the prime number tests
+     * @param random  a source of randomness
+     */
+    public void init(
+        int             size,
+        int             certainty,
+        SecureRandom    random)
+    {
+        this.size = size;
+        this.certainty = certainty;
+        this.random = random;
+    }
+
+    /**
+     * which generates the p and g values from the given parameters,
+     * returning the DHParameters object.
+     * <p>
+     * Note: can take a while...
+     */
+    public DHParameters generateParameters()
+    {
+        //
+        // find a safe prime p where p = 2*q + 1, where p and q are prime.
+        //
+        BigInteger[] safePrimes = DHParametersHelper.generateSafePrimes(size, certainty, random);
+
+        BigInteger p = safePrimes[0];
+        BigInteger q = safePrimes[1];
+        BigInteger g = DHParametersHelper.selectGenerator(p, q, random);
+
+        return new DHParameters(p, g, q, TWO, null);
+    }
+}