1 files changed, 47 insertions, 0 deletions
diff --git a/core/src/main/java/org/spongycastle/crypto/agreement/srp/SRP6VerifierGenerator.java b/core/src/main/java/org/spongycastle/crypto/agreement/srp/SRP6VerifierGenerator.java
new file mode 100644
index 00000000..0324af18
--- /dev/null
+++ b/core/src/main/java/org/spongycastle/crypto/agreement/srp/SRP6VerifierGenerator.java
@@ -0,0 +1,47 @@
+package org.spongycastle.crypto.agreement.srp;
+
+import java.math.BigInteger;
+
+import org.spongycastle.crypto.Digest;
+
+/**
+ * Generates new SRP verifier for user
+ */
+public class SRP6VerifierGenerator
+{
+    protected BigInteger N;
+    protected BigInteger g;
+    protected Digest digest;
+
+    public SRP6VerifierGenerator()
+    {
+    }
+
+    /**
+     * Initialises generator to create new verifiers
+     * @param N The safe prime to use (see DHParametersGenerator)
+     * @param g The group parameter to use (see DHParametersGenerator)
+     * @param digest The digest to use. The same digest type will need to be used later for the actual authentication
+     * attempt. Also note that the final session key size is dependent on the chosen digest.
+     */
+    public void init(BigInteger N, BigInteger g, Digest digest)
+    {
+        this.N = N;
+        this.g = g;
+        this.digest = digest;
+    }
+
+    /**
+     * Creates a new SRP verifier
+     * @param salt The salt to use, generally should be large and random
+     * @param identity The user's identifying information (eg. username)
+     * @param password The user's password
+     * @return A new verifier for use in future SRP authentication
+     */
+    public BigInteger generateVerifier(byte[] salt, byte[] identity, byte[] password)
+    {
+        BigInteger x = SRP6Util.calculateX(digest, N, salt, identity, password);
+
+        return g.modPow(x, N);
+    }
+}