openjdk
diff --git a/‎src/java.base/share/classes/com/sun/crypto/provider/ML_KEM.java‎
Lines changed: 20 additions & 2 deletions b/‎src/java.base/share/classes/com/sun/crypto/provider/ML_KEM.java‎
Lines changed: 20 additions & 2 deletions
@@ -703,7 +703,7 @@ private K_PKE_KeyPair generateK_PkeKeyPair(byte[] seed) {
 
     private K_PKE_CipherText kPkeEncrypt(
             K_PKE_EncryptionKey publicKey, byte[] message, byte[] sigma) {
-        short[][] zeroes = new short[mlKem_k][ML_KEM_N];
+        short[][] zeroes = shortMatrixAlloc(mlKem_k, ML_KEM_N);
         byte[] pkBytes = publicKey.keyBytes;
         byte[] rho = Arrays.copyOfRange(pkBytes,
                 pkBytes.length - 32, pkBytes.length);
@@ -792,7 +792,7 @@ private short[][][] generateA(byte[] rho, Boolean transposed) {
         System.arraycopy(rho, 0, seedBuf, 0, rho.length);
         seedBuf[rhoLen + 2] = 0x1F;
         seedBuf[XOF_BLOCK_LEN - 1] = (byte)0x80;
-        byte[][] xofBufArr = new byte[nrPar][XOF_BLOCK_LEN + XOF_PAD];
+        byte[][] xofBufArr = byteMatrixAlloc(nrPar, XOF_BLOCK_LEN + XOF_PAD);
         int[] iIndex = new int[nrPar];
         int[] jIndex = new int[nrPar];
 
@@ -1550,4 +1550,22 @@ private static int montMul(int b, int c) {
 
         return (aHigh - ((m * MONT_Q) >> MONT_R_BITS)); // subtract signed high product
     }
+
+    // For multidimensional array initialization, manually allocating each entry is
+    // faster than doing the entire initialization in one go
+    static short[][] shortMatrixAlloc(int first, int second) {
+        short[][] res = new short[first][];
+        for (int i = 0; i < first; i++) {
+            res[i] = new short[second];
+        }
+        return res;
+    }
+
+    static byte[][] byteMatrixAlloc(int first, int second) {
+        byte[][] res = new byte[first][];
+        for (int i = 0; i < first; i++) {
+            res[i] = new byte[second];
+        }
+        return res;
+    }
 }