在.NET中使用零填充进行AES加密并使用Node.js解密

Question

I'm trying to decrypt some data with a NodeJS.

This data was created with C# and the AES-CBC-256 algorithm. The keySize and blockSize are 256 and the Padding is ZeroPadding .

I cant' decrypt it with Node.js, the error is:

Error: error:0606506D:digital envelope routines:EVP_DecryptFinal_ex:wrong final block length

Here is my javascript code:

decipher = crypto.createDecipheriv('aes-256-cbc', key, iv.slice(0, 16));
decrypted = decipher.update(encryptedPayloadBuffer, 'base64', 'ascii');
decrypted += decipher.final('ascii');
decipher = null;

return decrypted;

I use the library "crypto". I read somewhere that node.js decryption works only with PKSC7 padding. Is it true ? I can't change anything in the C# project, I must find a solution on the node side.

Can you help me please ?

Edit: I tried to disable autoPadding with this:

decipher.setAutoPadding(false);
//next line of code:
//decrypted = decipher.update(encryptedPayloadBuffer, 'base64', 'ascii');

But I received this error:

Error: error:0606508A:digital envelope routines:EVP_DecryptFinal_ex:data not multiple of block length

Answer 1

A look at the Crypto Node.js doc finds this:

decipher.setAutoPadding(auto_padding=true)

You can disable auto padding if the data has been encrypted without standard block padding to prevent decipher.final from checking and removing it. Can only work if the input data's length is a multiple of the ciphers block size. You must call this before streaming data to decipher.update.

Try decipher.setAutoPadding(false) before decipher.update.

Answer 2

There is a difference between AES and Rijndael. Both specify key sizes of 128, 192 and 256 bits, but only Rijndael provides all three block sizes: 128, 192 and 256 bits. AES is actually Rijndael with a fixed block size of 128 bit.

Node.js uses OpenSSL to provide all the available ciphers ( crypto.getCiphers() ). If there is no rijndael implementation available for your version, then you can't use node.js' Crypto module. You'll either need to find a node module that implements Rijndael or simply set the block size to 128 bit in your C# code.