Question

我正在尝试从Rijndael VBA代码解密加密的字符串。 Java 8代码

public static void Decrypt() throws Exception{
        String mydata = "3m/WeZ1cAUEqexeH64gPehkMdQSRvx7K9TKhtpUfEg==";

        byte[] encryptedBytes = Base64.getDecoder().decode(mydata);
        byte[] key = Base64.getDecoder().decode("VGhpcnR5VHdvQnl0ZXMzJFRoaXJ0eVR3b0J5dGVzMyQ=");          
        byte[] iv = Base64.getDecoder().decode("MyRUaHJlZVR3b0J5dGVzMzMkVGhyZWVUd29CeXRlczM=");
        
        PaddedBufferedBlockCipher bufferedBlock = new PaddedBufferedBlockCipher(new CBCBlockCipher(new RijndaelEngine(256)), new PKCS7Padding());
        CipherParameters keyAndIV = new ParametersWithIV(new KeyParameter(key), iv);
        bufferedBlock.init(false, keyAndIV);        
        
        byte[] decryptedBytes = new byte[bufferedBlock.getOutputSize(encryptedBytes.length)];
        int processed = bufferedBlock.processBytes(encryptedBytes, 0, encryptedBytes.length, decryptedBytes, 0);
        processed += bufferedBlock.doFinal(decryptedBytes, processed);
                
        System.out.println(new String(decryptedBytes, 0, processed, StandardCharsets.UTF_8));       
    }

上面的代码在行中给我一个错误“解密中的最后一块未完成”

processed += bufferedBlock.doFinal(decryptedBytes, processed);

这是VBA代码加密：

Function Encrypt(plaintext, aesKey)
    Dim cipherBytes, aesKeyBytes, ivKeyBytes, plainBytes() As Byte
    
    Dim utf8, AES, aesEnc, cipherMode As Object
    Dim aesIV() As Byte
        
    Set AES = CreateObject("System.Security.Cryptography.RijndaelManaged")
    Set utf8 = CreateObject("System.Text.UTF8Encoding")
   
    AES.KeySize = 256
    AES.BlockSize = 256
    'CipherMode.CBC
    AES.Mode = 1
    'PaddingMode.PKCS7
    AES.Padding = 2
    AES.Key = utf8.GetBytes_4("ThirtyTwoBytes3$ThirtyTwoBytes3$")
    AES.IV = utf8.GetBytes_4("3$ThreeTwoBytes33$ThreeTwoBytes3")
    plainBytes = utf8.GetBytes_4(plaintext)
    'plainBytes = B64Decode(plaintext)
    'Set aesEnc = AES.CreateEncryptor_2((aesKeyBytes), (ivKeyBytes))
    cipherBytes = AES.CreateEncryptor().TransformFinalBlock((plainBytes), 0, UBound(plainBytes))
    Encrypt = B64Encode(cipherBytes)
End Function

我正在尝试加密VBA发送的数据，然后解密并使用它。帮助我更正Java代码以使其与VBA代码VBA AES CBC encryption

相匹配

Answer 1

问题是在B64Encode()和encrypt()中，字节数组的长度用UBound()指定的错误（请参见修复1 ，在代码中修复2 ）。 UBound()返回最大索引，因此长度为UBound() + 1。另外，也可以使用LenB()。

以下VBA代码对纯文本进行加密：

Function Min(a, b)
    Min = a
    If b < a Then Min = b
End Function

Function B64Encode(bytes)
    Set b64Enc = CreateObject("System.Security.Cryptography.ToBase64Transform")
    Set utf8 = CreateObject("System.Text.UTF8Encoding")
    BlockSize = b64Enc.InputBlockSize
    For Offset = 0 To LenB(bytes) - 1 Step BlockSize                        ' LenB(bytes) - 1 --> UBound(bytes)
        Length = Min(BlockSize, LenB(bytes) - Offset)                       ' LenB(bytes)     --> UBound(bytes) + 1                             Fix 1
        b64Block = b64Enc.TransformFinalBlock((bytes), Offset, Length)
        result = result & utf8.GetString((b64Block))
    Next
    B64Encode = result
End Function

Function encrypt(plaintext)
    Set AES = CreateObject("System.Security.Cryptography.RijndaelManaged")
    Set utf8 = CreateObject("System.Text.UTF8Encoding")
    AES.KeySize = 256
    AES.BlockSize = 256
    AES.Mode = 1 'CipherMode.CBC
    AES.Padding = 2 'PaddingMode.PKCS7
    AES.Key = utf8.GetBytes_4("ThirtyTwoBytes3$ThirtyTwoBytes3$")
    AES.IV = utf8.GetBytes_4("3$ThreeTwoBytes33$ThreeTwoBytes3")
    plainBytes = utf8.GetBytes_4(plaintext)
    cipherBytes = AES.CreateEncryptor().TransformFinalBlock((plainBytes), 0, LenB(plainBytes)) ' LenB(plainBytes) --> UBound(plainBytes) + 1    Fix 2
    encrypt = B64Encode(cipherBytes)
End Function

Sub encryptData()
Debug.Print encrypt("The quick brown fox jumps over the lazy dog") ' 2WVYo0DvgbKXBUn+/eI/yTvUJs0zYxEN9lU5ytxhJRWPDnRn5y4HuwPjaMSg47gTG4dc2ABL5EyIvDg1N91T5A==
End Sub

可以用以下Java代码（使用BouncyCastle）解密：

public static void Decrypt() throws Exception{
    String mydata = "2WVYo0DvgbKXBUn+/eI/yTvUJs0zYxEN9lU5ytxhJRWPDnRn5y4HuwPjaMSg47gTG4dc2ABL5EyIvDg1N91T5A==";

    byte[] encryptedBytes = Base64.getDecoder().decode(mydata);
    byte[] key = "ThirtyTwoBytes3$ThirtyTwoBytes3$".getBytes(StandardCharsets.UTF_8);          
    byte[] iv = "3$ThreeTwoBytes33$ThreeTwoBytes3".getBytes(StandardCharsets.UTF_8);       
    //byte[] key = Base64.getDecoder().decode("VGhpcnR5VHdvQnl0ZXMzJFRoaXJ0eVR3b0J5dGVzMyQ=");  // works also with Base64 encoded key and IV        
    //byte[] iv = Base64.getDecoder().decode("MyRUaHJlZVR3b0J5dGVzMzMkVGhyZWVUd29CeXRlczM=");
    
    PaddedBufferedBlockCipher bufferedBlock = new PaddedBufferedBlockCipher(new CBCBlockCipher(new RijndaelEngine(256)), new PKCS7Padding());
    CipherParameters keyAndIV = new ParametersWithIV(new KeyParameter(key), iv);
    bufferedBlock.init(false, keyAndIV);        
    
    byte[] decryptedBytes = new byte[bufferedBlock.getOutputSize(encryptedBytes.length)];
    int processed = bufferedBlock.processBytes(encryptedBytes, 0, encryptedBytes.length, decryptedBytes, 0);
    processed += bufferedBlock.doFinal(decryptedBytes, processed);
            
    System.out.println(new String(decryptedBytes, 0, processed, StandardCharsets.UTF_8));       
}

请注意，代码使用的Rijndael块大小为256字节，因此没有AES。 AES是Rijndael的子集，块大小为128字节。应用AES更有意义，因为这是标准（不是Rijndael）。

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