Fix Blake2xs ignoring offset and specified digestLength

Author: peterdettman

core/src/main/java/org/bouncycastle/crypto/digests/Blake2xsDigest.java

@@ -9,7 +9,6 @@
  */
 
 import org.bouncycastle.crypto.CryptoServicePurpose;
-import org.bouncycastle.crypto.CryptoServicesRegistrar;
 import org.bouncycastle.crypto.Xof;
 import org.bouncycastle.util.Arrays;
 
@@ -87,7 +86,7 @@ public class Blake2xsDigest
      */
     public Blake2xsDigest()
     {
-        this(Blake2xsDigest.UNKNOWN_DIGEST_LENGTH, CryptoServicePurpose.ANY); //TODO: change this?
+        this(UNKNOWN_DIGEST_LENGTH, CryptoServicePurpose.ANY); //TODO: change this?
     }
 
     /**
@@ -125,7 +124,7 @@ public Blake2xsDigest(int digestBytes, byte[] key)
      */
     public Blake2xsDigest(int digestBytes, byte[] key, byte[] salt, byte[] personalization, CryptoServicePurpose purpose)
     {
-        if (digestBytes < 1 || digestBytes > Blake2xsDigest.UNKNOWN_DIGEST_LENGTH)
+        if (digestBytes < 1 || digestBytes > UNKNOWN_DIGEST_LENGTH)
         {
             throw new IllegalArgumentException(
                 "BLAKE2xs digest length must be between 1 and 2^16-1");
@@ -134,7 +133,7 @@ public Blake2xsDigest(int digestBytes, byte[] key, byte[] salt, byte[] personali
         digestLength = digestBytes;
         nodeOffset = computeNodeOffset();
         this.purpose = purpose;
-        hash = new Blake2sDigest(Blake2xsDigest.DIGEST_LENGTH, key, salt, personalization, nodeOffset, purpose);
+        hash = new Blake2sDigest(DIGEST_LENGTH, key, salt, personalization, nodeOffset, purpose);
     }
 
     public Blake2xsDigest(Blake2xsDigest digest)
@@ -189,7 +188,7 @@ public int getByteLength()
      */
     public long getUnknownMaxLength()
     {
-        return Blake2xsDigest.MAX_NUMBER_BLOCKS * Blake2xsDigest.DIGEST_LENGTH;
+        return MAX_NUMBER_BLOCKS * DIGEST_LENGTH;
     }
 
     /**
@@ -223,7 +222,7 @@ public void reset()
         hash.reset();
 
         h0 = null;
-        bufPos = Blake2xsDigest.DIGEST_LENGTH;
+        bufPos = DIGEST_LENGTH;
         digestPos = 0;
         blockPos = 0;
         nodeOffset = computeNodeOffset();
@@ -238,7 +237,7 @@ public void reset()
      */
     public int doFinal(byte[] out, int outOffset)
     {
-        return doFinal(out, outOffset, out.length);
+        return doFinal(out, outOffset, digestLength);
     }
 
     /**
@@ -275,7 +274,7 @@ public int doOutput(byte[] out, int outOff, int outLen)
             hash.doFinal(h0, 0);
         }
 
-        if (digestLength != Blake2xsDigest.UNKNOWN_DIGEST_LENGTH)
+        if (digestLength != UNKNOWN_DIGEST_LENGTH)
         {
             if (digestPos + outLen > digestLength)
             {
@@ -291,9 +290,9 @@ else if (blockPos << 5 >= getUnknownMaxLength())
 
         for (int i = 0; i < outLen; i++)
         {
-            if (bufPos >= Blake2xsDigest.DIGEST_LENGTH)
+            if (bufPos >= DIGEST_LENGTH)
             {
-                Blake2sDigest h = new Blake2sDigest(computeStepLength(), Blake2xsDigest.DIGEST_LENGTH, nodeOffset);
+                Blake2sDigest h = new Blake2sDigest(computeStepLength(), DIGEST_LENGTH, nodeOffset);
                 h.update(h0, 0, h0.length);
 
                 Arrays.fill(buf, (byte)0);
@@ -302,7 +301,7 @@ else if (blockPos << 5 >= getUnknownMaxLength())
                 nodeOffset++;
                 blockPos++;
             }
-            out[i] = buf[bufPos];
+            out[outOff + i] = buf[bufPos];
             bufPos++;
             digestPos++;
         }
@@ -314,12 +313,12 @@ else if (blockPos << 5 >= getUnknownMaxLength())
     // always the maximum.
     private int computeStepLength()
     {
-        if (digestLength == Blake2xsDigest.UNKNOWN_DIGEST_LENGTH)
+        if (digestLength == UNKNOWN_DIGEST_LENGTH)
         {
-            return Blake2xsDigest.DIGEST_LENGTH;
+            return DIGEST_LENGTH;
         }
 
-        return Math.min(Blake2xsDigest.DIGEST_LENGTH, digestLength - digestPos);
+        return Math.min(DIGEST_LENGTH, digestLength - digestPos);
     }
 
     private long computeNodeOffset()

core/src/test/java/org/bouncycastle/crypto/test/Blake2xsDigestTest.java

@@ -1,5 +1,8 @@
 package org.bouncycastle.crypto.test;
 
+import java.util.Arrays;
+import java.util.Random;
+
 import org.bouncycastle.crypto.digests.Blake2xsDigest;
 import org.bouncycastle.util.encoders.Hex;
 import org.bouncycastle.util.test.SimpleTest;
@@ -2579,38 +2582,44 @@ public String getName()
 
     private void testBlake2xsTestVectors()
     {
+        Random random = new Random();
+
         for (int i = 0; i != Blake2xsDigestTest.xofTestVectors.length; i++)
         {
             String[] vector = Blake2xsDigestTest.xofTestVectors[i];
             byte[] input = Hex.decode(vector[0]);
             byte[] key = Hex.decode(vector[1]);
+            byte[] expected = Hex.decode(vector[2]);
 
-            Blake2xsDigest h = new Blake2xsDigest(vector[2].length() / 2, key);
+            int digestSize = expected.length;
+            Blake2xsDigest h = new Blake2xsDigest(digestSize, key);
             h.update(input, 0, input.length);
 
-            byte[] out = new byte[vector[2].length() / 2];
-            h.doFinal(out, 0);
-            if (!areEqual(out, Hex.decode(vector[2])))
+            byte[] out = new byte[16 + digestSize];
+            int outOff = 1 + random.nextInt(16);
+            h.doFinal(out, outOff);
+            if (!areEqual(out, outOff, outOff + digestSize, expected, 0, digestSize))
             {
-                fail("BLAKE2xs mismatch on test vector ", vector[2], Hex.toHexString(out));
+                fail("BLAKE2xs mismatch on test vector ", vector[2], Hex.toHexString(out, outOff, digestSize));
             }
 
-            out = new byte[vector[2].length() / 2];
+            Arrays.fill(out, (byte)0);
+            outOff = 1 + random.nextInt(16);
+
             h.update(input, 0, input.length);
             Blake2xsDigest clone = new Blake2xsDigest(h);
 
-            h.doOutput(out, 0, out.length);
-            if (!areEqual(out, Hex.decode(vector[2])))
+            h.doOutput(out, outOff, digestSize);
+            if (!areEqual(out, outOff, outOff + digestSize, expected, 0, digestSize))
             {
-                fail("BLAKE2xs mismatch on test vector after a reset", vector[2], Hex.toHexString(out));
+                fail("BLAKE2xs mismatch on test vector after a reset", vector[2], Hex.toHexString(out, outOff, digestSize));
             }
 
-            byte[] outClone = new byte[out.length];
+            byte[] outClone = new byte[digestSize];
             clone.doFinal(outClone, 0, outClone.length);
-            if (!areEqual(out, outClone))
+            if (!areEqual(outClone, expected))
             {
-                fail("BLAKE2xs mismatch on test vector against a clone",
-                    vector[2], Hex.toHexString(outClone));
+                fail("BLAKE2xs mismatch on test vector against a clone", vector[2], Hex.toHexString(outClone));
             }
         }
     }