Reset inputIsEmpty in engineInit

+ Test cases are added to ensure that inputIsEmpty is reset.

src/com/amazon/corretto/crypto/provider/AesCbcSpi.java

@@ -250,6 +250,7 @@ protected void engineInit(
     this.iv = iv;
     this.key = keyBytes;
     this.unprocessedInput = 0;
+    this.inputIsEmpty = true;
     initLastBlock();
   }
 
@@ -377,7 +378,9 @@ private int update(
       final byte[] outputArray,
       final int outputOffset) {
 
-    inputIsEmpty = inputIsEmpty && (inputLen == 0);
+    if (inputLen > 0) {
+      inputIsEmpty = false;
+    }
 
     // Unlike, doFinal (which needs to decide if a context should be released or not), update always
     // has to save the context.
@@ -549,7 +552,9 @@ private int doFinal(
       final byte[] outputArray,
       final int outputOffset) {
 
-    inputIsEmpty = inputIsEmpty && (inputLen == 0);
+    if (inputLen > 0) {
+      inputIsEmpty = false;
+    }
 
     if (inputIsEmpty && (opMode == DEC_MODE) && (!noPadding())) {
       // AWS-LC's behavior in treating empty input when decrypting with padding differs from SunJCE.

tst/com/amazon/corretto/crypto/provider/test/AesCbcIso10126Test.java

@@ -105,6 +105,39 @@ public void emptyCipherTextWithPaddingEnabledShouldProduceEmptyPlaintext() throw
     assertEquals(16, sun.doFinal().length);
   }
 
+  @Test
+  public void ensureInputEmptyIsResetAfterAnOperation() throws Exception {
+    final SecretKeySpec key = genAesKey(10, 128);
+    final IvParameterSpec iv = genIv(10, 16);
+    final Cipher accp = accpCipher();
+
+    accp.init(Cipher.ENCRYPT_MODE, key, iv);
+
+    // First we encrypt with a non-empty input.
+    assertEquals(16, accp.doFinal(genData(10, 10)).length);
+    // Now we decrypt with the same cipher object and empty input:
+    accp.init(Cipher.DECRYPT_MODE, key, iv);
+    assertEquals(0, accp.doFinal().length);
+  }
+
+  @Test
+  public void ensureInputEmptyIsResetAfterAnOperationWithBadPaddingToo() throws Exception {
+    final SecretKeySpec key = genAesKey(10, 128);
+    final IvParameterSpec iv = genIv(10, 16);
+    final Cipher accp = accpCipher();
+
+    accp.init(Cipher.DECRYPT_MODE, key, iv);
+    accp.update(new byte[8]);
+    // inputIsEmpty is false. We pass bad cipher text to cause bad padding.
+    assertThrows(BadPaddingException.class, () -> accp.doFinal(new byte[8]));
+    // The cipher must need re-initialization.
+    assertThrows(IllegalStateException.class, () -> accp.doFinal());
+    // After initialization, inputIsEmpty should be rest to true and produce zero output when
+    // decrypting empty input.
+    accp.init(Cipher.DECRYPT_MODE, key, iv);
+    assertEquals(0, accp.doFinal().length);
+  }
+
   @ParameterizedTest
   @MethodSource("arrayTestParams")
   public void testArrayOneShot(final long seed, final int keySize) throws Exception {

tst/com/amazon/corretto/crypto/provider/test/AesCbcTest.java

@@ -132,6 +132,39 @@ public void emptyCipherTextWithPaddingEnabledShouldProduceEmptyPlaintext() throw
     assertArrayEquals(sun.doFinal(), accpCipherText);
   }
 
+  @Test
+  public void ensureInputEmptyIsResetAfterAnOperation() throws Exception {
+    final SecretKeySpec key = genAesKey(10, 128);
+    final IvParameterSpec iv = genIv(10, 16);
+    final Cipher accp = accpAesCbcCipher(true);
+
+    accp.init(Cipher.ENCRYPT_MODE, key, iv);
+
+    // First we encrypt with a non-empty input.
+    assertEquals(16, accp.doFinal(genData(10, 10)).length);
+    // Now we decrypt with the same cipher object and empty input:
+    accp.init(Cipher.DECRYPT_MODE, key, iv);
+    assertEquals(0, accp.doFinal().length);
+  }
+
+  @Test
+  public void ensureInputEmptyIsResetAfterAnOperationWithBadPaddingToo() throws Exception {
+    final SecretKeySpec key = genAesKey(10, 128);
+    final IvParameterSpec iv = genIv(10, 16);
+    final Cipher accp = accpAesCbcCipher(true);
+
+    accp.init(Cipher.DECRYPT_MODE, key, iv);
+    accp.update(new byte[8]);
+    // inputIsEmpty is false. We pass bad cipher text to cause bad padding.
+    assertThrows(BadPaddingException.class, () -> accp.doFinal(new byte[8]));
+    // The cipher must need re-initialization.
+    assertThrows(IllegalStateException.class, () -> accp.doFinal());
+    // After initialization, inputIsEmpty should be rest to true and produce zero output when
+    // decrypting empty input.
+    accp.init(Cipher.DECRYPT_MODE, key, iv);
+    assertEquals(0, accp.doFinal().length);
+  }
+
   @Test
   public void testPkcs7Name() throws Exception {
     // SunJCE does not recognize AES/CBC/PKCS7Padding, but BouncyCastle does: