使用 openssl 库手动查找加密密钥

Question

我有一个可能的密码列表，其中一个用于加密“这是最高机密”。小于16字节的字需要用#号补齐。但不知何故我无法生成正确的密文。这里是这个问题的已知信息：十六进制格式的密文： 764aa26b55a4da654df6b19e4bce00f4ed05e09346fb0e762583cb7da2ac93a2 十六进制格式的 IV： aabbccddeeff00998877665544332211 我知道密码是“Syracuse########”，我在 linux 上尝试了 openssl 命令来解密它。我的代码获取这个单词列表，然后创建 matchingresult.txt，其中包含可能的密码的所有密文。不知道哪里弄错了none这些密文是真的Used wordlist

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <openssl/evp.h>

void pad(char *s, int length);
int print_result(unsigned char *buf, char *s, int len, FILE *outFile, char *match);
int strcicmp(char const *a, char const *b);

int main(){
    unsigned char match[] = "MATCH";
    unsigned char noMATCH[] = "NO MATCH";
    int i;
    char words[16],t; // each word in dictionary
    FILE *key, *outFile;
    unsigned char outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
    unsigned char iv[] = {0xaa,0xbb, 0xcc, 0xdd,0xee, 0xff, 0x00, 0x99,0x88,0x77,0x66,0x55,0x44,0x33,0x22,0x11};// given in the description of task 5
    int outlen, tmplen;
    int num;

    EVP_CIPHER_CTX ctx;
    EVP_CIPHER_CTX_init(&ctx);
    char inText[] = "This is a top secret.";  //given in the decription of task 5
    char cipherTextGiven[] = "764aa26b55a4da654df6b19e4bce00f4ed05e09346fb0e762583cb7da2ac93a2";  //given in the description of task 5
    key = fopen("words.txt", "r");  //provided file by SEED Labs
    if(remove("matchingResult.txt") == -1){  // the file contains result of each key
        perror("Error deleting file");
    }
    outFile = fopen("matchingResult.txt","a+");
    if(key<0 || outFile < 0){
        perror("Cannot open file");
        exit(1);
    }
    char pbuffer[1024];
    while ( fgets(words,16,key)) // get each word from dictionary that suppose to be a key to encrypt
    {
        i=strlen(words);
        words[i-1]='[=10=]'; // in the text editor it automatically adds null or end of file so we need to remove that
        i=strlen(words);
        if (i < 16){ // 16 because we use AES-128
            // since the word has less than 16 characters (i.e. 128 bits), pound signs (#: hexadecimal value is 0x23)
            // are appended to the end of the word to form a key of 128 bits
            pad(words, (16));
        }
        EVP_EncryptInit_ex(&ctx, EVP_aes_128_cbc(), NULL, words, iv);
        if(!EVP_EncryptUpdate(&ctx, outbuf, &outlen, inText, strlen(inText))){
            EVP_CIPHER_CTX_cleanup(&ctx);
            return 0;
        }
        if(!EVP_EncryptFinal_ex(&ctx, outbuf + outlen, &tmplen)){
            EVP_CIPHER_CTX_cleanup(&ctx);
            return 0;
        }
        outlen += tmplen;

        int i;
        char* buf_str = (char*) malloc (2*outlen + 1);
        char* buf_ptr = buf_str;
        for (i = 0; i<outlen;i++){
            buf_ptr += sprintf(buf_ptr, "%02X" , outbuf[i]);
        }
        *(buf_ptr + 1) = '[=10=]';
        if (strcicmp(cipherTextGiven, buf_str) == 0)
        print_result(outbuf, words, outlen, outFile, match);
        else
        print_result(outbuf, words, outlen, outFile, noMATCH);
    }
    fclose(key);
    fclose(outFile);
    return 1;
}

// print result to output file matchresult.txt
int print_result(unsigned char *buf, char *s, int len, FILE *outFile, char *match){
    int i,n,j,k;
    char x='\n';
    char space = ' ';
    for ( j=0; j<strlen(s); j++){
        fprintf(outFile,"%c",s[j]);
    }
    fprintf(outFile,"%c",space);
    for ( i = 0 ; i<len; i++){
        fprintf(outFile,"%02x", buf[i]);
    }
    fprintf(outFile, "%c", space);
    for (k=0; k< strlen(match); k++){
        fprintf(outFile,"%c", match[k]);
    }
    fprintf(outFile,"%c",x);
    return(0);
}

// add padding to the key
void pad(char *s, int length){
    int l;
    l= strlen(s); // its length
    while(l<length){
        s[l] = '#'; // insert a pound sign
        l++;
    }
    s[l] = '[=10=]'; // strings need to be terminated in a null
}

// compare case insensitive
int strcicmp(char const *a, char const *b){
    for(;;a++,b++){
        int d = tolower(*a) - tolower(*b);
        if (d != 0 || !*a)
        return d;
    }
}

Answer 1

问题是由这部分代码引起的： s[l] = '\0';

使用 openssl 库手动查找加密密钥

Finding the encryption key manually using openssl library

c

openssl

aes

cbc-mode