#2474 9x faster Pack.longToBigEndian and longToLittleEndian on JDK 23+

Author: winne42

core/src/main/java/org/bouncycastle/util/Pack.java

@@ -192,8 +192,15 @@ public static byte[] longToBigEndian(long n)
 
     public static void longToBigEndian(long n, byte[] bs, int off)
     {
-        intToBigEndian((int)(n >>> 32), bs, off);
-        intToBigEndian((int)(n & 0xffffffffL), bs, off + 4);
+        // #2474: on JDK 23+, this code is ~9x faster than the previous implementation (cf. JDK-8318446)
+        bs[off] = (byte)(n >>> 56);
+        bs[++off] = (byte)(n >>> 48);
+        bs[++off] = (byte)(n >>> 40);
+        bs[++off] = (byte)(n >>> 32);
+        bs[++off] = (byte)(n >>> 24);
+        bs[++off] = (byte)(n >>> 16);
+        bs[++off] = (byte)(n >>> 8);
+        bs[++off] = (byte)(n);
     }
 
     public static byte[] longToBigEndian(long[] ns)
@@ -547,8 +554,15 @@ public static byte[] longToLittleEndian(long n)
 
     public static void longToLittleEndian(long n, byte[] bs, int off)
     {
-        intToLittleEndian((int)(n & 0xffffffffL), bs, off);
-        intToLittleEndian((int)(n >>> 32), bs, off + 4);
+        // #2474: on JDK 23+, this code is ~9x faster than the previous implementation (cf. JDK-8318446)
+        bs[off] = (byte)(n);
+        bs[++off] = (byte)(n >>> 8);
+        bs[++off] = (byte)(n >>> 16);
+        bs[++off] = (byte)(n >>> 24);
+        bs[++off] = (byte)(n >>> 32);
+        bs[++off] = (byte)(n >>> 40);
+        bs[++off] = (byte)(n >>> 48);
+        bs[++off] = (byte)(n >>> 56);
     }
 
     public static byte[] longToLittleEndian(long[] ns)

core/src/test/java/org/bouncycastle/util/utiltest/AllTests.java

@@ -22,6 +22,7 @@ public static Test suite()
         suite.addTestSuite(StringsTest.class);
         suite.addTestSuite(StreamsTest.class);
         suite.addTestSuite(AggregateRuntimeExceptionTest.class);
+        suite.addTestSuite(PackTest.class);
         return new BCTestSetup(suite);
     }
 

core/src/test/java/org/bouncycastle/util/utiltest/PackTest.java

@@ -0,0 +1,175 @@
+package org.bouncycastle.util.utiltest;
+
+import java.util.Random;
+
+import org.bouncycastle.util.Arrays;
+import org.bouncycastle.util.Pack;
+
+import junit.framework.TestCase;
+
+public class PackTest
+    extends TestCase
+{
+    private static final byte FILL = (byte)0xA5;
+
+    private static final long[] EXTREMES = { 0L, -1L, Long.MIN_VALUE, Long.MAX_VALUE, 0x8080808080808080L,
+        0x0102030405060708L };
+
+    /*
+     * Enough calls for C2 to compile the methods under test, so that the merged stores it generates for them are
+     * checked as well as the interpreter.
+     */
+    private static final int ITERATIONS = 200000;
+
+    public void testLongToBigEndian()
+    {
+        Random random = new Random(1);
+        byte[] bs = new byte[24];
+        for (int i = 0; i < ITERATIONS; ++i)
+        {
+            long n = nextValue(random, i);
+            int off = i % 9;
+
+            Arrays.fill(bs, FILL);
+            Pack.longToBigEndian(n, bs, off);
+            checkBytes(n, true, bs, off);
+            if (Pack.bigEndianToLong(bs, off) != n)
+            {
+                fail("round trip of " + Long.toHexString(n));
+            }
+        }
+
+        assertTrue(Arrays.areEqual(new byte[]{ 1, 2, 3, 4, 5, 6, 7, 8 }, Pack.longToBigEndian(0x0102030405060708L)));
+    }
+
+    public void testLongToLittleEndian()
+    {
+        Random random = new Random(2);
+        byte[] bs = new byte[24];
+        for (int i = 0; i < ITERATIONS; ++i)
+        {
+            long n = nextValue(random, i);
+            int off = i % 9;
+
+            Arrays.fill(bs, FILL);
+            Pack.longToLittleEndian(n, bs, off);
+            checkBytes(n, false, bs, off);
+            if (Pack.littleEndianToLong(bs, off) != n)
+            {
+                fail("round trip of " + Long.toHexString(n));
+            }
+        }
+
+        assertTrue(Arrays.areEqual(new byte[]{ 8, 7, 6, 5, 4, 3, 2, 1 }, Pack.longToLittleEndian(0x0102030405060708L)));
+    }
+
+    public void testLongArrays()
+    {
+        Random random = new Random(3);
+        for (int i = 0; i < 2000; ++i)
+        {
+            long[] ns = new long[1 + random.nextInt(25)];
+            for (int j = 0; j < ns.length; ++j)
+            {
+                ns[j] = nextValue(random, i + j);
+            }
+            int nsOff = random.nextInt(ns.length);
+            int nsLen = random.nextInt(ns.length - nsOff + 1);
+            int bsOff = random.nextInt(9);
+            int bsLen = bsOff + 8 * nsLen + random.nextInt(9);
+
+            byte[] be = new byte[bsLen];
+            Arrays.fill(be, FILL);
+            Pack.longToBigEndian(ns, nsOff, nsLen, be, bsOff);
+            byte[] le = new byte[bsLen];
+            Arrays.fill(le, FILL);
+            Pack.longToLittleEndian(ns, nsOff, nsLen, le, bsOff);
+            for (int j = 0; j < nsLen; ++j)
+            {
+                assertEquals(ns[nsOff + j], Pack.bigEndianToLong(be, bsOff + 8 * j));
+                assertEquals(ns[nsOff + j], Pack.littleEndianToLong(le, bsOff + 8 * j));
+            }
+            checkUntouched(be, 0, bsOff);
+            checkUntouched(be, bsOff + 8 * nsLen, bsLen);
+            checkUntouched(le, 0, bsOff);
+            checkUntouched(le, bsOff + 8 * nsLen, bsLen);
+
+            long[] part = Arrays.copyOfRange(ns, nsOff, nsOff + nsLen);
+            assertTrue(Arrays.areEqual(Arrays.copyOfRange(be, bsOff, bsOff + 8 * nsLen), Pack.longToBigEndian(part)));
+            assertTrue(Arrays.areEqual(Arrays.copyOfRange(le, bsOff, bsOff + 8 * nsLen), Pack.longToLittleEndian(part)));
+        }
+    }
+
+    public void testOutOfBounds()
+    {
+        for (int len = 0; len < 8; ++len)
+        {
+            try
+            {
+                Pack.longToBigEndian(-1L, new byte[len], 0);
+                fail("no exception for " + len + " bytes");
+            }
+            catch (ArrayIndexOutOfBoundsException e)
+            {
+                // expected
+            }
+            try
+            {
+                Pack.longToLittleEndian(-1L, new byte[len], 0);
+                fail("no exception for " + len + " bytes");
+            }
+            catch (ArrayIndexOutOfBoundsException e)
+            {
+                // expected
+            }
+        }
+    }
+
+    /**
+     * Check the 8 bytes at off against the definition of the encoding, one byte at a time, and that the bytes around
+     * them are untouched.
+     */
+    private static void checkBytes(long n, boolean bigEndian, byte[] bs, int off)
+    {
+        for (int i = 0; i < 8; ++i)
+        {
+            int shift = bigEndian ? 56 - 8 * i : 8 * i;
+            if (bs[off + i] != (byte)(n >>> shift))
+            {
+                fail("byte " + i + " of " + Long.toHexString(n) + (bigEndian ? " big" : " little") + " endian");
+            }
+        }
+        checkUntouched(bs, 0, off);
+        checkUntouched(bs, off + 8, bs.length);
+    }
+
+    private static void checkUntouched(byte[] bs, int from, int to)
+    {
+        for (int i = from; i < to; ++i)
+        {
+            if (bs[i] != FILL)
+            {
+                fail("byte " + i + " overwritten");
+            }
+        }
+    }
+
+    /**
+     * Random values, values with a single byte set or clear at each position in turn, and extremes.
+     */
+    private static long nextValue(Random random, int i)
+    {
+        long oneByte = (long)(1 + random.nextInt(255)) << (8 * ((i >> 2) & 7));
+        switch (i & 3)
+        {
+        case 0:
+            return random.nextLong();
+        case 1:
+            return oneByte;
+        case 2:
+            return ~oneByte;
+        default:
+            return EXTREMES[(i >> 2) % EXTREMES.length];
+        }
+    }
+}

docs/releasenotes.md

@@ -81,6 +81,8 @@ Date: 2026, TBD
 
 - The BCJSSE provider adds an org.bouncycastle.jsse.BCSSLContext interface exposing extended functionality of its SSLContext, obtained with org.bouncycastle.jsse.util.ContextUtil.getBCSSLContext() by way of the new BCSSLSessionContext interface the context's session contexts implement. Its getDefaultParameters(boolean) and getSupportedParameters(boolean) return the context's default and supported parameters as a BCSSLParameters for either client or server mode, including the BC-specific properties, where SSLContext.getDefaultSSLParameters() and getSupportedSSLParameters() report client mode only and cannot carry those properties. A BCSSLContext describes the initialization of the SSLContext it was obtained from, and is not updated if the SSLContext is re-initialized.
 
+- org.bouncycastle.util.Pack.longToBigEndian() and longToLittleEndian() rewritten so it can be optimized by JDK 23+'s JIT. JDK 25 measurements show packing longs into bytes is ~9x as fast, which makes squeezing SHAKE output about 8% faster per block, a 64-byte SHA-512 or BLAKE2b digest 6-7% faster and ML-DSA key generation and verification 3-5% faster; JDK 17 and 21 performance decreases slighty, within 3%.
+
 ### 2.1.4 Additional Notes
 
 - The sources and javadoc jars of the Ant-built distributions (jdk14, jdk15to18 and jdk13) no longer carry test material. Each module's javadoc target copies the package documentation it needs - org/bouncycastle/<area>/**/*.html - back into the module source directory that has already been compiled from, and zip-src zips that directory afterwards, so every test package's package.html arrived in the sources jar by that route; javadoc-util additionally copied org/bouncycastle/asn1/isismtt/**/*.java, which put test classes into the bcutil javadoc as generated pages, and javadoc-pg deliberately copied the gpg and bcpg test sources in order to document them. Separately the source copies excluded test material only one directory deep and only for *.java, because Ant reads ** as an any-depth wildcard just where it is a whole path segment, so anything nested further or with another extension - the PEM certificate fixtures under org/bouncycastle/est/test/san corrected in 1.86, and an ICAO master list under org/bouncycastle/asn1/icao/test - went through. The source and javadoc copies of every module now exclude test directories at any depth, and javadoc-pg no longer documents the test packages. org.bouncycastle.util.test is unaffected and still ships in the bcprov binary, sources and javadoc jars, as it does from the Gradle build: it is the SimpleTest framework the light-weight API's own test classes are written against, not test material of the distribution. No binary changes - the classes and resources of every Ant-built jar are identical to those of the 1.86 release - and the Gradle-built jdk18on artifacts never carried any of this.