实现openssl evp加密

我目前正在对暴力进行一些测试，在C中使用EVP强制一些简单的文本 .

提供了明文，密文，密钥大小，加密方法和方法 . 我们只需要尝试不同的密钥，这是一个已知的字典单词 .

THE MAIN ISSUE IS IF I TRY TO CALL THE EVP METHOD DIRECTLY FROM MAIN LIKE THIS:

int main(int argc, char const *argv[]) {
    evp((unsigned char *)"This is a top secret.");
    return 0;
}

它找不到密钥（无法生成相同的密码）

但是 clock(); 的召唤叫：

int main(int argc, char const *argv[])
{
    clock_t begin = clock();
    evp((unsigned char *)"This is a top secret.");
    return 0;
}

它工作正常！为什么会这样？我究竟做错了什么？有人能解释一下问题是什么吗？

使用aes-128-cbc加密明文的加密，而iv是16字节NULL，密钥是长度小于16的单个字典字，当长度小于16时将以空格提供 .

以下代码用于执行整个过程：

void evp(unsigned char * plaintext) {
    FILE *fp = fopen("words.txt", "r");
    const char cipher[]  ="8d20e5056a8d24d0462ce74e4904c1b513e10d1df4a2ef2ad4540fae1ca0aaf9";
    unsigned char iv[16];
    unsigned char ciphertext[256];

    /**Init OpenSSL**/
    ERR_load_crypto_strings();
    OPENSSL_config(NULL);
    OpenSSL_add_all_algorithms();

    unsigned char word[17];
    while(read_word(fp, word)==0) {
        if(strlen((char *)word) < 16) {
            add_space(word, sizeof(word));
            encrypt(plaintext, strlen((char *)plaintext), word, iv, ciphertext);

            if(strcmp((char *)ciphertext, cipher) == 0 ) {
                printf("The key is : %s\n", word);
                fclose(fp);
                exit(0);
            };
        }
    }

    fclose(fp);
}

add_space 方法只是用空格提供密钥：

int add_space(unsigned char *str, size_t len) {

    int eol_pos = strlen((char *)str);
    int empty_space = len - eol_pos - 1 ;

    //set space and eol
    memset(str+eol_pos, ' ', empty_space);
    memset(str+len, '\0', 0);

    return 0;
}

read_word 方法从字典中读取单个单词：

int read_word(FILE *file, unsigned char * word) {
    //Using fscanf
    unsigned char word_buf[255];

    if(fscanf(file, "%s", word_buf) != EOF) {
        if( strlen( (char *)word_buf ) < 15 ) {
            strcpy((char *)word,(char *) word_buf);
        }
        return 0;
    } 
    return 1;
}

而 encrypt 方法是加密明文的主要过程：

void encrypt(unsigned char *plaintext, int plain_len ,unsigned char *key, unsigned char * iv, unsigned char * ciphertext) {
    EVP_CIPHER_CTX *ctx;
    int out_len;
    int ciphertext_len;
    char *buff;

    if(! (ctx = EVP_CIPHER_CTX_new()) ) {
        handleErrors();
    }

    if( EVP_EncryptInit_ex(ctx, EVP_aes_128_cbc(), NULL, key, iv) != 1 )
        handleErrors();

    if( EVP_EncryptUpdate(ctx, ciphertext, &out_len, plaintext, plain_len ) != 1 ) {
        handleErrors();
    }
    ciphertext_len = out_len;

    if( EVP_EncryptFinal_ex(ctx, ciphertext+out_len, &out_len) != 1 ) {
        handleErrors();
    }
    ciphertext_len += out_len;

    EVP_CIPHER_CTX_cleanup(ctx);

    buff = malloc(ciphertext_len*2+1);
    memset(buff, 0, ciphertext_len*2+1);

    for (int i = 0; i < ciphertext_len; ++i)
    {
        char tmp[3];
        sprintf(tmp, "%02x", ciphertext[i]);
        strcat(buff, tmp);
    }

    strcpy((char *)ciphertext, buff);
    free(buff);
}