added padding option to CryptogramDataBuilder + tests

jpos · Dec 21, 2023 · 0a9f0a4 · 0a9f0a4
1 parent cbc2668
commit 0a9f0a4
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Showing 7 changed files with 159 additions and 7 deletions.
diff --git a/jpos/src/main/java/org/jpos/emv/cryptogram/CVN10DataBuilder.java b/jpos/src/main/java/org/jpos/emv/cryptogram/CVN10DataBuilder.java
@@ -30,7 +30,7 @@
  * @author Rainer Reyes
  */
 public class CVN10DataBuilder implements CryptogramDataBuilder {
-    
+
     @Override
     public String getDefaultARPCRequest(boolean approved) {
         return approved ? "0000" : "9900";
@@ -44,4 +44,9 @@ public String buildARQCRequest(TLVList data, IssuerApplicationData iad) {
         sb.append(iad.getCardVerificationResults());
         return sb.toString();
     }
+
+    @Override
+    public String buildARQCRequest_padded(TLVList data, IssuerApplicationData iad, PaddingMethod paddingMethod){
+        return paddingMethod.apply(buildARQCRequest(data, iad));
+    }
 }
diff --git a/jpos/src/main/java/org/jpos/emv/cryptogram/CVN18DataBuilder.java b/jpos/src/main/java/org/jpos/emv/cryptogram/CVN18DataBuilder.java
@@ -28,7 +28,7 @@
  * @author Rainer Reyes
  */
 public class CVN18DataBuilder implements CryptogramDataBuilder {
-    
+
     @Override
     public String getDefaultARPCRequest(boolean approved) {
         /* for success:
@@ -47,4 +47,9 @@ public String buildARQCRequest(TLVList data, IssuerApplicationData iad) {
         sb.append(iad.toString());
         return sb.toString();
     }
+
+    @Override
+    public String buildARQCRequest_padded(TLVList data, IssuerApplicationData iad, PaddingMethod paddingMethod) {
+        return paddingMethod.apply(buildARQCRequest(data, iad));
+    }
 }
diff --git a/jpos/src/main/java/org/jpos/emv/cryptogram/CVNMCDataBuilder.java b/jpos/src/main/java/org/jpos/emv/cryptogram/CVNMCDataBuilder.java
@@ -48,9 +48,14 @@ public String buildARQCRequest(TLVList data, IssuerApplicationData iad) {
         return sb.toString();
     }
 
+    @Override
+    public String buildARQCRequest_padded(TLVList data, IssuerApplicationData iad, PaddingMethod paddingMethod) {
+        return paddingMethod.apply(buildARQCRequest(data, iad));
+    }
+
     @Override
     public String getDefaultARPCRequest(boolean approved) {
         return approved ? "0012" : "9900";
     }
-    
+
 }
diff --git a/jpos/src/main/java/org/jpos/emv/cryptogram/CryptogramDataBuilder.java b/jpos/src/main/java/org/jpos/emv/cryptogram/CryptogramDataBuilder.java
@@ -20,11 +20,10 @@
 
 import org.jpos.emv.EMVStandardTagType;
 import org.jpos.emv.IssuerApplicationData;
+import org.jpos.iso.ISOUtil;
 import org.jpos.tlv.TLVList;
 
-import java.util.Arrays;
-import java.util.List;
-import java.util.Optional;
+import java.util.*;
 
 
 /**
@@ -34,6 +33,22 @@
  */
 public interface CryptogramDataBuilder {
 
+    final PaddingMethod ZERO_PADDING = data -> data;
+
+    /**
+     * ISO/IEC 9797-1 padding method 1
+     * for Block size 8,  n = 64
+     */
+    final PaddingMethod ISO9797Method1 = data -> data.isEmpty() ?
+            "0000000000000000" :
+            ISOUtil.zeropadRight(data, data.length() % 16 == 0 ? data.length() : data.length() + 16 - data.length() % 16);
+
+    /**
+     * ISO/IEC 9797-1 padding method 2
+     *  for Block size 8,  n = 64
+     */
+    final PaddingMethod ISO9797Method2 = data -> ISO9797Method1.apply(data + "80");
+
     /**
      * Method that selects the  minimum set of data elements recommended for
      * the generation of application cryptograms described in EMV Book 2 sec 8.1.1
@@ -67,7 +82,7 @@ static List<String> minimumSetOfDataElement(TLVList data) {
     String getDefaultARPCRequest(boolean approved);
 
     /**
-     * Select necessary data elements and create the string used to generate the ARQC
+     * Select necessary data elements and create the string used to generate the ARQC with no padding
      * <p>
      *
      * @param data ICC data received
@@ -76,4 +91,22 @@ static List<String> minimumSetOfDataElement(TLVList data) {
      */
     String buildARQCRequest(TLVList data, IssuerApplicationData iad);
 
+
+    /**
+     * Select necessary data elements and create the string used to generate the ARQC with padding
+     * <p>
+     *
+     * @param data          ICC data received
+     * @param iad           Issuer application Data
+     * @param paddingMethod Padding method to use
+     * @return String used to generate the ARQC
+     */
+    String buildARQCRequest_padded(TLVList data, IssuerApplicationData iad, PaddingMethod paddingMethod);
+
+    /**
+     * Padding Method Interface
+     */
+    interface PaddingMethod {
+        String apply(String data);
+    }
 }
diff --git a/jpos/src/test/java/org/jpos/emv/cryptogram/CVN10DataBuilderTest.java b/jpos/src/test/java/org/jpos/emv/cryptogram/CVN10DataBuilderTest.java
@@ -56,6 +56,11 @@ void testBuildARQCRequest() {
                 builder.buildARQCRequest(data, iad)
         );
 
+        assertEquals(
+                "00000000010000000000000008400000000000084018123101ABCDEF101800000203000000000000",
+                builder.buildARQCRequest_padded(data, iad, builder.ISO9797Method1)
+        );
+
 
     }
 }
diff --git a/jpos/src/test/java/org/jpos/emv/cryptogram/CVN18DataBuilderTest.java b/jpos/src/test/java/org/jpos/emv/cryptogram/CVN18DataBuilderTest.java
@@ -56,6 +56,11 @@ void testBuildARQCRequest() {
                 builder.buildARQCRequest(data, iad)
         );
 
+        assertEquals(
+                "00000000010000000000000008400000000000084018123101ABCDEF101800000106011203000000",
+                builder.buildARQCRequest_padded(data, iad, builder.ISO9797Method1)
+        );
+
 
     }
 }
diff --git a/jpos/src/test/java/org/jpos/emv/cryptogram/CryptogramDataBuilderTest.java b/jpos/src/test/java/org/jpos/emv/cryptogram/CryptogramDataBuilderTest.java
@@ -0,0 +1,94 @@
+package org.jpos.emv.cryptogram;
+
+import org.jpos.iso.ISOUtil;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.Random;
+
+import static org.jpos.emv.cryptogram.CryptogramDataBuilder.ISO9797Method2;
+import static org.jpos.emv.cryptogram.CryptogramDataBuilder.ISO9797Method1;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+/**
+ * @author Elias Terranti
+ */
+public class CryptogramDataBuilderTest {
+
+    Random r;
+    byte[] r0;
+    byte[] r1;
+    byte[] r2;
+
+    @BeforeEach
+    public void setUp() {
+        Random r = new Random();
+
+        r0 = new byte[0];
+        r1 = new byte[8];
+        r2 = new byte[r.nextInt(256)];
+
+        r.nextBytes(r0);
+        r.nextBytes(r1);
+        r.nextBytes(r2);
+    }
+
+    @Test
+    void testPaddingMethod2() {
+        int n = 8; // block size
+        Arrays.asList(r0, r1, r2).forEach(b -> {
+
+            byte[] b_padded = ISOUtil.hex2byte(ISO9797Method2.apply(ISOUtil.hexString(b)));
+
+            assertEquals(0, b_padded.length % n);
+
+            // if data is empty, padded data should be a block of 1 bit followed by 0s
+            if (b.length == 0) {
+                assertArrayEquals(ISOUtil.hex2byte("8000000000000000"), b_padded);
+            }
+            // if data length is multiple of n, data is padded with a new block of 1 bit followed by 0s
+            if (b.length % n == 0 && b.length > 0) {
+                assertArrayEquals(ISOUtil.concat(b, ISOUtil.hex2byte("8000000000000000")), b_padded);
+            }
+
+            // if data length is not multiple of n, data is padded  with 1 bit followed by 0s
+            if (b.length % n > 0) {
+                byte[] padding = Arrays.copyOfRange(b_padded,  b.length, b_padded.length);
+                assertEquals(((byte) 0x80), padding[0]);
+                if (padding.length > 1) {
+                    assertArrayEquals(ISOUtil.concat(new byte[]{(byte) 0x80}, new byte[n - b.length % n - 1]), padding);
+                }
+            }
+        });
+    }
+
+    @Test
+    void testPaddingMethod1() {
+        int n = 8; // block size
+
+        Arrays.asList(r0, r1, r2).forEach(b -> {
+            byte[] b_padded = ISOUtil.hex2byte(ISO9797Method1.apply(ISOUtil.hexString(b)));
+
+            assertEquals(0, b_padded.length % n);
+
+            // if data is empty, padded data should be a block of 0s
+            if (b.length == 0) {
+                assertArrayEquals(new byte[n], b_padded);
+            }
+
+            // if data length  is multiple of n,  no padding is added
+            if (b.length % n == 0 && b.length > 0) {
+                assertArrayEquals(b, b_padded);
+            }
+
+            // if data length is not multiple of n, data is padded  with 0s
+            if (b.length % n > 0) {
+                assertArrayEquals(ISOUtil.concat(b, new byte[n - b.length % n]), b_padded);
+            }
+        });
+    }
+
+}