1 files changed, 81 insertions, 0 deletions

diff --git a/src/main/java/org/uic/barcode/utils/SecurityUtils.java b/src/main/java/org/uic/barcode/utils/SecurityUtils.java
index 5fdbda7..29a2346 100644
--- a/src/main/java/org/uic/barcode/utils/SecurityUtils.java
+++ b/src/main/java/org/uic/barcode/utils/SecurityUtils.java
@@ -1,5 +1,8 @@
 package org.uic.barcode.utils;

 

+import java.io.ByteArrayOutputStream;

+import java.io.IOException;

+import java.math.BigInteger;

 import java.security.KeyFactory;

 import java.security.NoSuchAlgorithmException;

 import java.security.PrivateKey;

@@ -10,6 +13,7 @@ import java.security.Security;
 import java.security.spec.InvalidKeySpecException;

 import java.security.spec.PKCS8EncodedKeySpec;

 import java.security.spec.X509EncodedKeySpec;

+import java.util.Arrays;

 

 /**

  * The Class SecurityUtils.

@@ -182,4 +186,81 @@ public class SecurityUtils {
 		

 		return null;

 	}

+	

+	/**

+	 * Decode signature integer sequence.

+	 * 

+	 * Support function to decode a DSA signature

+	 * Provides the two DSA signature parameter encoded in a DSA signature

+	 *

+	 * @param bytes the bytes

+	 * @return the big integer[]

+	 * @throws Exception the exception

+	 */

+	public static BigInteger[] decodeSignatureIntegerSequence(byte[] bytes) throws Exception {

+

+		int sequenceTag = (int) bytes[0];

+		

+		if (sequenceTag != 48) throw new Exception("signature is not a sequence");

+		

+		int sequenceLength = (int) bytes[1];

+		

+		if (sequenceLength < 6) throw new Exception("signature sequence too short");

+		

+		BigInteger[] result = new BigInteger[2];

+		

+		int offset = 2;

+		int i = 0;

+		while (offset < bytes.length && i < 2) {

+			int integerTag = (int) bytes[offset];

+			if (integerTag != 2) throw new Exception("signature is not an integer sequence");

+			int integerLength = (int) bytes[offset + 1];

+			byte[] value = Arrays.copyOfRange(bytes, offset + 2, offset + 2 + integerLength);		

+			result[i] = new BigInteger(+1, value);

+			offset = offset + integerLength + 2;

+			i++;

+		}

+

+		return result;

+	}

+	

+	/**

+	 * Encode signature integer sequence.

+	 *  

+	 *  Support function to format two parameters as DER encoded integer list 

+	 *  to get a valid formated DSA signature from the signature parameter

+	 *

+	 * @param i1 the i 1

+	 * @param i2 the i 2

+	 * @return the byte[]

+	 * @throws IOException Signals that an I/O exception has occurred.

+	 */

+	public static byte[] encodeSignatureIntegerSequence(BigInteger i1, BigInteger i2) throws IOException {

+		

+		//SEQUENCE OF --> tag 16

+		int sequenceTag = 16 + 32;  // (bits 6 = 1 constructed)

+		//INTEGER     --> tag 2

+		int integerTag = 2;

+			

+		byte[] b1 = i1.toByteArray();

+        int lb1 = b1.length;

+		byte[] b2 = i2.toByteArray();

+        int lb2 = b2.length;		

+        

+        int sequenceLength = lb1 + lb2 + 4;

+		

+		ByteArrayOutputStream out = new ByteArrayOutputStream();

+		

+		out.write((byte) sequenceTag);

+		out.write((byte) sequenceLength);   

+		out.write((byte) integerTag);  

+		out.write((byte) lb1);  

+		out.write(b1);   

+		out.write((byte) integerTag);  

+		out.write((byte) lb2);  

+		out.write(b2);   

+

+		return out.toByteArray();

+	}

+

 }