From 8e55437993a4bd03d7163c927cf0c0e417338800 Mon Sep 17 00:00:00 2001
From: John Jiang <johnsjiang@tencent.com>
Date: Thu, 14 Nov 2024 11:11:47 +0800
Subject: [PATCH] TKSS-917: SM2 cipher would not encrypt empty message

---
 .../tencent/kona/crypto/provider/SM2Engine.java    |  2 +-
 .../kona/crypto/provider/SM2CipherTest.java        | 14 ++++++--------
 2 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/kona-crypto/src/main/java/com/tencent/kona/crypto/provider/SM2Engine.java b/kona-crypto/src/main/java/com/tencent/kona/crypto/provider/SM2Engine.java
index 322a6d6a..39690435 100644
--- a/kona-crypto/src/main/java/com/tencent/kona/crypto/provider/SM2Engine.java
+++ b/kona-crypto/src/main/java/com/tencent/kona/crypto/provider/SM2Engine.java
@@ -258,7 +258,7 @@ private byte[] kdf(byte[] input, int keyLen) {
     }
 
     private static boolean checkInputBound(byte[] input, int offset, int len) {
-        return input != null
+        return input != null && input.length > 0
                 && offset >= 0 && len >= 0
                 && (input.length >= (offset + len));
     }
diff --git a/kona-crypto/src/test/java/com/tencent/kona/crypto/provider/SM2CipherTest.java b/kona-crypto/src/test/java/com/tencent/kona/crypto/provider/SM2CipherTest.java
index 5587aea5..634fc176 100644
--- a/kona-crypto/src/test/java/com/tencent/kona/crypto/provider/SM2CipherTest.java
+++ b/kona-crypto/src/test/java/com/tencent/kona/crypto/provider/SM2CipherTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2022, 2023, THL A29 Limited, a Tencent company. All rights reserved.
+ * Copyright (C) 2022, 2024, THL A29 Limited, a Tencent company. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -308,13 +308,12 @@ public void testEmptyInput() throws Exception {
         Cipher cipher = Cipher.getInstance("SM2", PROVIDER);
 
         cipher.init(Cipher.ENCRYPT_MODE, pubKey);
-        byte[] ciphertext = cipher.doFinal(EMPTY);
+        Assertions.assertThrows(BadPaddingException.class,
+                () -> cipher.doFinal(EMPTY));
 
         cipher.init(Cipher.DECRYPT_MODE, priKey);
         Assertions.assertThrows(BadPaddingException.class,
                 () -> cipher.doFinal(EMPTY));
-        byte[] cleartext = cipher.doFinal(ciphertext);
-        Assertions.assertArrayEquals(EMPTY, cleartext);
     }
 
     @Test
@@ -329,16 +328,15 @@ public void testEmptyInputWithByteBuffer() throws Exception {
 
         cipher.init(Cipher.ENCRYPT_MODE, pubKey);
         ByteBuffer ciphertextBuf = ByteBuffer.allocate(150);
-        cipher.doFinal(ByteBuffer.allocate(0), ciphertextBuf);
+
+        Assertions.assertThrows(BadPaddingException.class,
+                () -> cipher.doFinal(ByteBuffer.allocate(0), ciphertextBuf));
         ciphertextBuf.flip();
 
         cipher.init(Cipher.DECRYPT_MODE, priKey);
         ByteBuffer cleartextBuf = ByteBuffer.allocate(150);
         Assertions.assertThrows(BadPaddingException.class,
                 () -> cipher.doFinal(ByteBuffer.allocate(0), cleartextBuf));
-        cipher.doFinal(ciphertextBuf, cleartextBuf);
-
-        Assertions.assertEquals(0, cleartextBuf.position());
     }
 
     @Test