C/C ++中用于AES加密的PKCS#5填充 [英] PKCS#5 padding for AES encryption in C/C++

问题描述

我在JAVA中进行了AES/ECB/PKCS5Padding加密.现在，我正在寻找C/C++中的等效方法.我确实使用以下代码在C中进行了加密:

I did AES/ECB/PKCS5Padding encryption in JAVA. Now I am looking for equivalent method in C/C++. I did manage to encrypt in C using the following code :

const unsigned char *key = (unsigned char *)"A2XTXFEQFOPZFAKXFOPZFAK5";
unsigned char input[] = {"Hello World"};
int iLen = strlen((char*)input);
int len = 0;
if(iLen % 16 == 0){
   len = iLen;
}
else{
   len = (iLen/16)*16 + 16;
}
unsigned char output[len]; //next 16bit

AES_KEY enc_key;
AES_set_encrypt_key(key, strlen((char*)key)*8, &enc_key);
int position = 0;
while(position < iLen){
    AES_ecb_encrypt(input+position,output+position,&enc_key,AES_ENCRYPT);    
    position += 16;
}

推荐答案

使用填充时，即使输入是块大小的倍数，也必须始终添加 .

When using padding it must always be added, even if the input is a multiple of the block size.

不正确，这是一个常见错误:

Incorrect, this is a common mistake:

if(iLen % 16 == 0){
    len = iLen;
}

正确:

int blockSize = 16;
int len = iLen + blockSize - (iLen % blockSize);

请参见 PKCS#7填充.

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