这是我用来解密C中的AES的程序的一部分。程序应该从外部文件中获取IV，读取然后设置为IV。不幸的是，IV被声明为代码中的char数组（我无法更改）所以我尝试做的是将外部文件读取为byte []，然后将其转换为char []。
我目前面临的一个问题是关于AES_IV变量，如下所示：
#define AES_BLOCK_SIZE 0x10
char AES_IV[AES_BLOCK_SIZE] = {0x00,0x11,0x22,0x33,0x44,0x55,0x66,0x77,0x88,0x99,0xAA,0xBB,0xCC,0xDD,0xEE,0xFF};
当我尝试使用代码
打印出AES_IV时printf("\nAES_IV: ");
for (i3 = 0; i3 < AES_BLOCK_SIZE; i3++) {
printf("%02x", AES_IV[i3]);
}
printf("\n");
输出结果为：
AES_IV: 0c0a513398f1eda13ed2fc7213b50b10
这与我声明的AES_IV不同。
我将for循环更改为
for (i3 = 0; i3 < 50; i3++) {
并且结果输出更长
AES_IV: 0c0a513398f1eda13ed2fc7213b50b105369a...(100 chars in total)
我检查了AES_IV的长度，它仍然是16，但为什么我的for循环返回如此长的结果？另外为什么AES_IV的值会发生变化？我已经检查过，在此部分之前的任何地方都没有引用AES_IV。
非常感谢您的帮助。
参考源代码：
#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>
#include <dlfcn.h>
#include "SmartSDLib.h"
#define SDCARD_PATH "/boot"
#define P1_INDEX 2
#define P2_INDEX 3
#define P3_INDEX 4
#define AES_BLOCK_SIZE 0x10
#define APDU_HEADER_SIZE 5
#define FILELEN 32 // For reading IV from file
void To_Hex(char s8Data[],char hexBuffer[], int offset, int nlen)
{
int j;
int nSize = (nlen - offset);
char finalhash[8192];
char hexval [] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
for(j=0 ; j < nSize; j++)
{
finalhash[j*2] = hexval[(s8Data[j] >> 4) & 0xF];
finalhash[(j*2) + 1] = hexval[s8Data[j] & 0x0F];
}
memset(hexBuffer,0x00,8192);
memcpy(hexBuffer, finalhash, nSize*2);
}
char * AccessAPDU(char command[], int size)
{
unsigned char u8Ret;
int s32Len[1];
char s8Buffer[512], hexBuffer[8192];
To_Hex(command, hexBuffer, 0, size);
//printf ("%s\n%s%s\n", "AccessAPDUCommand:","CMD:" , hexBuffer);
u8Ret = OT_SmartSDCard_AccessAPDUCommand(size, command, s32Len, s8Buffer, 0);
if(u8Ret == 0x00)
{
printResult(s32Len, s8Buffer);
}
else
{
printf ("%s%x\n\n", "Error 0x", u8Ret);
}
return s8Buffer;
}
void printResult (int s32Len[], char s8Buffer[])
{
char hexBuffer[8192];
if(s32Len[0] >= 2)
{
To_Hex(s8Buffer, hexBuffer, 0, s32Len[0]);
// printf ("%s%s\n", "Ret:", hexBuffer);
// printf ("%s%d\n\n", "Len: ", s32Len[0]);
}
else
{
printf ("%s%d\n", "Len: ", s32Len[0]);
}
}
void CopyBuffer(char Dest[], char Source[], unsigned int length){
while(length){
Dest[length - 1] = Source[length - 1];
length--;
}
}
int ascii_to_hex(char c) // For reading IV from file
{
int num = (int) c;
if(num < 58 && num > 47) // Handle numbers (0-9)
{
return num - 48;
}
if(num < 103 && num > 96) // Handle lowercase alphabets (a-f)
{
return num - 87;
}
if(num < 71 && num > 64) // Handle uppercase alphabets (A-F)
{
return num - 55;
}
return num;
}
int main()
{
unsigned char u8Ret;
char SDCard_Path[64];
char line[64];
int s32Len[1];
char s8Buffer[512], hexBuffer[8192];
int exit = 1;
int iChoice;
char * response;
int test;
char testchar[32];
bool flag = true;
char fileName[100];
char encrypted[100];
char decrypted[100];
int i;
int j;
int blockCounter = 0;
int commandCounter = 0;
char imageBuffer[1];
/* APDU commands */
char AES_encrypt_cmd[APDU_HEADER_SIZE + AES_BLOCK_SIZE] = {0x80, 0x2A, 0x01,0x00, AES_BLOCK_SIZE}; //encryption APDU
char AES_decrypt_cmd[APDU_HEADER_SIZE + AES_BLOCK_SIZE] = {0x80, 0x2A, 0x02,0x00, AES_BLOCK_SIZE}; //decryption APDU
char GetResponse_cmd[] = {0x00, 0xC0, 0x00,0x00, 0x00}; //Le to be changed before use
char SelectAESapplet_cmd[] = {0x00, 0xA4, 0x04,0x00, 0x10, 0xA0, 0x00, 0x00, 0x00, 0x77, 0x01, 0x03, 0x03, 0x00, 0x00, 0x00, 0xF1, 0x00, 0x00, 0x00, 0x04};
//char PutKeyAES_cmd[] = {0x80, 0xD8, 0x00,0xF8, 0x20, 0x00,0x11,0x22,0x33,0x44,0x55,0x66,0x77,0x88,0x99,0xAA,0xBB,0xCC,0xDD,0xEE,0xFF,0xFF,0xEE,0xDD,0xCC,0xBB,0xAA,0x99,0x88,0x77,0x66,0x55,0x44,0x33,0x22,0x11,0x00};
char PutKeyAES_cmd[] = {0x80, 0xD8, 0x00,0xF8, 0x20, 0xCF,0x10,0xF9,0xBD,0xF6,0xAA,0x15,0xC5,0x0E,0xCD,0x79,0xE6,0x28,0x3D,0xA8,0x0A,0x79,0x7A,0x2D,0x27,0x03,0xAE,0x07,0xD5,0x2F,0x5D,0x8F,0x60,0x1F,0x1E,0xF2,0x6F};
/* AES variables */
int AES_keyIndex = 0;
char AES_IV[AES_BLOCK_SIZE] = {0x00,0x11,0x22,0x33,0x44,0x55,0x66,0x77,0x88,0x99,0xAA,0xBB,0xCC,0xDD,0xEE,0xFF};
//char AES_IV[AES_BLOCK_SIZE] = {0x12,0xFB,0x87,0x11,0x62,0x7E,0xBB,0x55,0x71,0x7B,0x2F,0x70,0xA4,0x97,0x55,0x7B};
//char AES_IV[AES_BLOCK_SIZE];
char AES_CBC_vector[AES_BLOCK_SIZE];
char AES_cmdBuffer[APDU_HEADER_SIZE + AES_BLOCK_SIZE];
FILE * rFile;
FILE * wFile;
FILE *fileptr;char *buffer;long filelen;int i2,i3,i4;char IV_temp[AES_BLOCK_SIZE]; // This line for the file --> byte --> Hex
printf ("%s\n", "This program will run 1, 2 followed by 6");
// case 1 :
printf ("%s\n", "Initializing: ");
u8Ret = OT_SmartSDCard_Initialization(SDCARD_PATH);
if(u8Ret == 0x00)
printf ("%s\n\n", "Initialization OK");
else
printf ("%s%x\n\n", "Initialization: Error 0x",u8Ret);
// printf ("%s\n\n", "-------------------------------------");
/* ATR */
u8Ret = OT_SmartSDCard_Reset(s32Len, s8Buffer);
if(u8Ret == 0x00)
{
To_Hex(s8Buffer,hexBuffer, 0, s32Len[0]);
// printf ("%s%s\n", "ATR : ", hexBuffer);
// printf ("%s%d\n\n", "Len : ", s32Len[0]);
}
else
printf ("%s%x\n\n", "Reset: Error 0x",u8Ret);
// printf ("%s\n\n", "-------------------------------------");
/* Select AES applet */
printf("%s\n", "Selecting AES applet...");
response = AccessAPDU(SelectAESapplet_cmd, sizeof(SelectAESapplet_cmd));
if(response[0] == 0x61){
GetResponse_cmd[P3_INDEX] = response[1];
AccessAPDU(GetResponse_cmd, sizeof(GetResponse_cmd));
}
// printf ("%s\n\n", "-------------------------------------");
// case 2 :
printf("Putting key...");
AES_keyIndex = 0;
memset(line, 0x00, sizeof(line));
PutKeyAES_cmd[2] = AES_keyIndex;
printf("putting key on index %d\n", AES_keyIndex);
response = AccessAPDU(PutKeyAES_cmd, sizeof(PutKeyAES_cmd));
AES_encrypt_cmd[P2_INDEX] = AES_keyIndex;
AES_decrypt_cmd[P2_INDEX] = AES_keyIndex;
// printf ("%s\n\n", "-------------------------------------");
// case 6 :
printf ("Decrypting in CBC...");
// printf ("File Name: /home/pi/test_encrypted\n");
// printf ("Encrypted File Name: /home/pi/test_decrypted\n");
rFile = fopen("/home/pi/test_encrypted","rb");
wFile = fopen("/home/pi/test_decrypted","wb");
////////////////////////////////////////////////////////////////
// This part to read rFile and store as a byte [WORKING!]
fseek(rFile, 0, SEEK_END); // Jump to the end of the file
filelen = ftell(rFile); // Get the current byte offset in the file
rewind(rFile); // Jump back to the beginning of the file
buffer = (char *)malloc((filelen+1)*sizeof(char)); // Enough memory for file + \0
fread(buffer, filelen, 1, rFile); // Read in the entire file
// This part to convert buffer to hex value [WORKING!]
for (i2 = 0; i2 < 100; i2++)
{
if (i2 > 0) printf(" ");
printf("%02X", buffer[i2]);
IV_temp[i2] = buffer[i2];
}
// This part to print stuff [AES_IV not printing out correctly]
printf("\nAES_IV: ");
//fwrite(AES_IV, 1, sizeof(AES_IV), stdout);
for (i3 = 0; i3 < 50; i3++) {
printf("%02x", AES_IV[i3]);
}
printf("\n");
/*
printf("IV_temp: ");
for (i4 = 0; i4 < AES_BLOCK_SIZE; i4++) {
printf("%02x", IV_temp[i4]);
}
printf("\n");
*/
for (i3 = 0; i3 < AES_BLOCK_SIZE; i3++) {
AES_IV[i3] = IV_temp[i3];
}
printf("\nLength of AES_IV = %d\n", sizeof(AES_IV));
printf("\nAES_IV: ");
for (i3 = 0; i3 < 50; i3++) {
printf("%02x", AES_IV[i3]);
}
printf("\n");
// Return the file pointer to start of file
rewind(rFile);
////////////////////////////////////////////////////////////////
if (rFile == NULL || wFile == NULL)
perror("Error opening File");
else{
int IsEOF = false;
// Initialize the CBC block with IV
CopyBuffer(AES_CBC_vector, AES_IV, AES_BLOCK_SIZE);
while (IsEOF == false) {
i = 0;
while(i < AES_BLOCK_SIZE){ // i run from 0 to (AES_BLOCK_SIZE - 1)
AES_cmdBuffer[APDU_HEADER_SIZE + i] = fgetc(rFile);
if(feof(rFile)) {
IsEOF = true;
if(i == 0) { // break out of while loop if a new block is not yet in progress
break;
} else { // continue to finish the block and pad with zeros
AES_cmdBuffer[APDU_HEADER_SIZE + i] = 0x00; //padding
}
}
i++;
}
if(i == 0) break; //break out of while loop, nothing to send to card
// Fill in the APDU header
CopyBuffer(AES_cmdBuffer, AES_decrypt_cmd, APDU_HEADER_SIZE);
response = AccessAPDU(AES_cmdBuffer, sizeof(AES_cmdBuffer));
if(response[0] == 0x61){
if(response[1] != AES_BLOCK_SIZE) {
perror("Card returning wrong block size");
}
GetResponse_cmd[P3_INDEX] = AES_BLOCK_SIZE;
response = AccessAPDU(GetResponse_cmd, sizeof(GetResponse_cmd));
/* CBC mode */
for(i = 0; i < AES_BLOCK_SIZE; i++){
response[i] ^= AES_CBC_vector[i];
}
fwrite(response, sizeof(char), AES_BLOCK_SIZE, wFile);
// Take the ciphertext to perform XOR next time
CopyBuffer(AES_CBC_vector, &AES_cmdBuffer[APDU_HEADER_SIZE], AES_BLOCK_SIZE);
} else {
perror("Error decrypting file using the smart card");
}
}
}
fclose (rFile);
fclose (wFile);
// printf ("%s\n\n", "-------------------------------------");
return 0;
}
答案 0 :(得分：1)
正如一条评论已经说过，您应该使用unsigned char，否则默认情况下每个元素都会被视为signed char。更好的是，您可能希望使用来自uint8_t的固定宽度#include <stdint.h>。
这是一个按预期工作的最小示例：
#include <stdint.h>
#include <stdio.h>
#define AES_BLOCK_SIZE 0x10
uint8_t AES_IV[AES_BLOCK_SIZE] = {0x00,0x11,0x22,0x33,0x44,0x55,0x66,0x77,0x88,0x99,0xAA,0xBB,0xCC,0xDD,0xEE,0xFF};
int
main( void )
{
int i;
for ( i = 0; i < sizeof(AES_IV); i++ ) {
printf( "%02x", AES_IV[i] );
}
return 0;
}