i need to decrypt some cypherd text (aes 128 ctr) programming in C using openssl, since libraries version i'm using don't support EVP for aes ctr i'm tring to use AES_ctr128_encrypt(), but i get segmentation fault, here's the code i'm using:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <openssl/aes.h>
int chartoint(char car)开发者_运维知识库;
char * extochar(char * in, int inLen);
struct ctr_state {
unsigned char ivec[16];
unsigned int num;
unsigned char ecount[16];
};
void init_ctr(struct ctr_state *state, const unsigned char iv[16]){
state->num = 0;
memset(state->ecount, 0, 16);
memcpy(state->ivec, iv, 16);
}
void main(){
unsigned char * cypher = extochar("874d6191b620e3261bef6864990db6ce",32);
unsigned char * key = extochar("2b7e151628aed2a6abf7158809cf4f3c",32);
unsigned char * iv = extochar("f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff",32);
unsigned char out[256]; //more than needed
AES_KEY aes_key;
int msg_len = 16;
struct ctr_state status;
if (!AES_set_encrypt_key(key, 16, &aes_key)){
printf("key error");
exit(-1);
}
init_ctr(&status, iv);
AES_ctr128_encrypt(cypher, out, msg_len, &aes_key, status.ivec, status.ecount, &status.num);
//expected plaintext: "6bc1bee22e409f96e93d7e117393172a"
}
segmentation fault is on istruction AES_ctr128_encrypt(), the last one, while i'm expecting "6bc1bee22e409f96e93d7e117393172a" as plaintext (using printf("%02x", var[i]) to printf it)
Your AES key is 256 bits long. You tell AES_set_encrypt_key that it's 16 bits. And then you pass the key to AES_ctr 128 _encrypt. Your code would work a lot better if all three of those numbers were the same.
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