将3个单独的字节数组合成一个字节数组

Question

我想将3字节数组合成一个字节数组.我尝试了以下代码,我不确定为什么不将所有数组都复制到一个字节数组中.

似乎正在发生的是,正在复制所有hmacDigest数组和密码数组,但随后又会再次复制密码数组的一部分.我想要完成的是组合密码数组,iv数组和hmacDigest数组,并将组合数组存储到组合字节数组中.另外,我想按顺序组合这些数组:cipher,iv,hmacdigest

#include "mbed.h"

#include "cyassl/ctaocrypt/hmac.h"
#include "cyassl/ctaocrypt/aes.h"

#include "MbedJSONValue.h"
#include "LinearTempSensor.h"

#include <string>

using namespace std;

Serial pc(USBTX, USBRX);

LinearTempSensor sensor(p20, 300, LinearTempSensor::MCP9701);
MbedJSONValue sensorResults;

Aes enc;
Aes dec;

Hmac hmac;

float Vout, Tav, To, TempValue;

std::string s;

int main() {

    pc.baud(115200);

    const byte key[16] = { 0x6d, 0x6e, 0x62, 0x76, 0x63, 0x78, 0x7a, 0x6c, 0x6b, 0x6a, 0x68, 0x67, 0x66, 0x64, 0x73, 0x61 };
    const byte iv[16]  = { 0x61, 0x73, 0x64, 0x66, 0x67, 0x68, 0x6a, 0x6b, 0x6c, 0x70, 0x6f, 0x69, 0x75, 0x79, 0x74, 0x72 };

    byte plain[128] = { 'a', 'b', 'c', 'd', 'e', 'f' };   // an increment of 16, fill with data
    byte cipher[128];
    byte deciphered[128];

    byte hkey[24] = { 0x8b, 0x21, 0x31, 0x21, 0xb7, 0xbe, 0x33, 0x1a, 0xcf, 0x1f, 0x71, 0x70, 0x45, 0xaf, 0x5c, 0x02, 0xa7, 0xa1, 0x4c, 0x34, 0xd4, 0xbc, 0x4b, 0x4a };    // fill key with keying material
    byte buffer[2048];   // fill buffer with data to digest
    byte hmacDigest[SHA256_DIGEST_SIZE];

    Vout = sensor.Sense();          // Sample data (read sensor)
    Tav  = sensor.GetAverageTemp(); // Calculate average temperature from N samples
    To   = sensor.GetLatestTemp();  // Calculate temperature from the latest sample

    TempValue = sensor.GetAverageTemp();

    //Create JSON
    sensorResults["DATA1"][0] = "Result";
    sensorResults["DATA1"][1] = 5.5;
    sensorResults["DATA2"][0] = "Result";
    sensorResults["DATA2"][1] = 700;
    sensorResults["DATA3"][0] = "Result";
    sensorResults["DATA3"][1] = TempValue;

    //Serialize JSON
    s = sensorResults.serialize();
    //sl = s.size();

    //Print JSON string
    pc.printf("json: %s\r\n", s.c_str());

    //Convert JSON string to a char array to encrypt
    //char *a=new char[s.size()+1];
    plain[s.size()]=0;
    memcpy(plain,s.c_str(),s.size());//<-- Fills plain array with the JSON values

    // encrypt
    AesSetKey(&enc, key, sizeof(key), iv, AES_ENCRYPTION);
    AesCbcEncrypt(&enc, cipher, plain, sizeof(plain));

    HmacSetKey(&hmac, SHA256, hkey, sizeof(key));
    HmacUpdate(&hmac, buffer, sizeof(buffer));
    HmacFinal(&hmac, hmacDigest);

    //cipher now contains the cipher text from the plain text.

    pc.printf("\r\nAES Key: ");
    for(int i=0; i<sizeof(key); i++) 
    {
        //if(i%16==0) pc.printf("\r\n");
        pc.printf("%.2X",key[i]);
    }

    pc.printf("\r\nAES IV: ");
    for(int i=0; i<sizeof(iv); i++) 
    {
        //if(i%16==0) pc.printf("\r\n");
        pc.printf("%.2X",iv[i]);
    }

    pc.printf("\r\nPlain HEX: ");
    for(int i=0; i<sizeof(plain); i++) 
    {
        //if(i%16==0) pc.printf("\r\n");
        pc.printf("%.2X",plain[i]);
    }

    pc.printf("\r\nEncrypted: ");
    for(int i=0; i<sizeof(cipher); i++) 
    {
        //if(i%16==0) pc.printf("\r\n");
        pc.printf("%.2X",cipher[i]);
    }

    pc.printf("\r\nhmacDigest: ");
    for(int i=0; i<sizeof(hmacDigest); i++) 
    {
        //if(i%16==0) pc.printf("\r\n");
        pc.printf("%.2X",hmacDigest[i]);
    }

    // decrypt
    AesSetKey(&dec, key, sizeof(key), iv, AES_DECRYPTION);
    AesCbcDecrypt(&dec, deciphered, cipher, sizeof(cipher));

    pc.printf("\r\nDecrypted: ");
    for(int  i=0; i<sizeof(deciphered); i++) 
    {
        //if(i%16==0) pc.printf("\r\n");
        //pc.printf("%.2X",deciphered[i]);
        pc.printf("%c",deciphered[i]);
    }

    //Combine the EncryptedData + IV + HMAC
    const int S_CIPHER = sizeof(cipher);
    const int S_IV = sizeof(iv);
    const int S_HMACDIGEST = sizeof(hmacDigest);

    const int S_TOTAL = S_CIPHER + S_IV + S_HMACDIGEST;

    byte combined[S_TOTAL];
    //Copy arrays in individually.
    memcpy(combined, cipher, S_CIPHER);
    memcpy(combined, iv, S_IV);
    memcpy(combined, hmacDigest, S_HMACDIGEST);

    pc.printf("\r\nOutput: ");
    for(int i=0; i<sizeof(combined); i++) 
    {
        //if(i%16==0) pc.printf("\r\n");
        //pc.printf("%.2X",deciphered[i]);
        pc.printf("%.2X",combined[i]);
    }   
}

Answer 1

memcpy数组总是在组合数组的同一点

将其更改为:

memcpy(combined, cipher, S_CIPHER);
memcpy(combined+S_CIPHER, iv, S_IV);
memcpy(combined+S_CIPHER+S_IV, hmacDigest, S_HMACDIGEST);

memcpy 原型是

空虚 *memcpy(void *dest, const void *src, size_t n);

dest每次复制单个数组时,都必须将指针移动到正确的位置.