VBA CBC 256 和 Java 充气城堡加密

Question

我正在尝试从 Rijndael VBA 代码解密加密的字符串。 Java8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

行给我一个错误“解密中的最后一个块不完整”

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

这是VBA密码加密：

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

我正在尝试对VBA发送的数据进行加密，解密后使用。帮助我更正 Java 代码以匹配 VBA 代码

Answer 1

问题是 B64Encode() 和 encrypt() 中字节数组的长度指定不正确 UBound() (see Fix 1, Fix 2 in the code). UBound() returns the largest index, so the length is UBound() + 1. Alternatively LenB() 可以使用。

以下VBA代码加密明文：

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

可以使用以下 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，代码使用块大小为 256 字节的 Rijndael，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（Rijndael 不是）。

VBA CBC 256 和 Java 充气城堡加密

VBA CBC 256 and Java Bouncy castle encryption

vba

bouncycastle

rijndael

java-8