Update SRP6Util.java

adds calculateM1, calculateM2, calculateKey

1 files changed, 59 insertions, 0 deletions

diff --git a/core/src/main/java/org/bouncycastle/crypto/agreement/srp/SRP6Util.java b/core/src/main/java/org/bouncycastle/crypto/agreement/srp/SRP6Util.java
index ad5ceac8..bf1b1377 100644
--- a/core/src/main/java/org/bouncycastle/crypto/agreement/srp/SRP6Util.java
+++ b/core/src/main/java/org/bouncycastle/crypto/agreement/srp/SRP6Util.java
@@ -60,6 +60,65 @@ public class SRP6Util
 
         return val;
     }
+    
+    /**
+	 * Computes the client evidence message (M1) according to the standard routine:
+	 * M1 = H( A | B | S )
+	 * @param digest The Digest used as the hashing function H
+	 * @param A The public client value
+	 * @param B The public server value
+	 * @param S The secret calculated by both sides
+	 * @return M1 The calculated client evidence message
+	 */
+	public static BigInteger calculateM1(Digest digest, BigInteger A, BigInteger B, BigInteger S) {
+		byte[] _output = new byte[digest.getDigestSize()];
+		byte[] _A = A.toByteArray();
+		byte[] _B = B.toByteArray();
+		byte[] _S = S.toByteArray();
+		digest.update(_A, 0, _A.length);
+		digest.update(_B, 0, _B.length);
+		digest.update(_S, 0, _S.length);
+		digest.doFinal(_output, 0);
+		BigInteger M1 = new BigInteger(1, _output);
+		return M1;
+	}
+
+	/**
+	 * Computes the server evidence message (M2) according to the standard routine:
+	 * M2 = H( A | M1 | S )
+	 * @param digest The Digest used as the hashing function H
+	 * @param A The public client value
+	 * @param M1 The client evidence message
+	 * @param S The secret calculated by both sides
+	 * @return M2 The calculated server evidence message
+	 */
+	public static BigInteger calculateM2(Digest digest, BigInteger A, BigInteger M1, BigInteger S){
+		byte[] _output = new byte[digest.getDigestSize()];
+		byte[] _A = A.toByteArray();
+		byte[] _M1 = M1.toByteArray();
+		byte[] _S = S.toByteArray();
+		digest.update(_A, 0, _A.length);
+		digest.update(_M1,0,_M1.length);
+		digest.update(_S, 0, _S.length);
+		digest.doFinal(_output, 0);
+		BigInteger M2 = new BigInteger(1, _output);
+		return M2;
+	}
+
+	/**
+	 * Computes the final Key according to the standard routine: Key = H(S)
+	 * @param digest The Digest used as the hashing function H
+	 * @param S The secret calculated by both sides
+	 * @return
+	 */
+	public static BigInteger calculateKey(Digest digest, BigInteger S) {
+		byte[] _output = new byte[digest.getDigestSize()];
+		byte[] _S = S.toByteArray();
+		digest.update(_S, 0, _S.length);
+		digest.doFinal(_output, 0);
+		BigInteger Key = new BigInteger(1, _output);
+		return Key;
+	}
 
     private static BigInteger hashPaddedPair(Digest digest, BigInteger N, BigInteger n1, BigInteger n2)
     {