Getting different encryption strings between openssl CLI and C codeHello - c

Question

I've been playing with openssl and am trying to write a simple program in C for encrypting a string. I'm trying to replicate the following command to encrypt the string "test" and then see the encrypted version using a given key and IV and AES-CBC-128:
echo test | openssl enc -e -aes-128-cbc -nosalt -K 5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a -iv 00000000000000000000000000000000 | xxd
and this returns the encrypted string in hex of
a63b e13d 47a5 b94c c1cb 466e 28af 19d8
I'm trying to replicate this in C with the following:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/aes.h>
int main() {
AES_KEY aes;
unsigned char* input_string = "test";
unsigned char* encrypt_string;
unsigned int len;
unsigned char key[] = {0x5A, 0x5A, 0x5A, 0x5A, 0x5A, 0x5A, 0x5A, 0x5A,
0x5A, 0x5A, 0x5A, 0x5A, 0x5A, 0x5A, 0x5A, 0x5A};
unsigned char iv[] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
uint32_t result;
result = AES_set_encrypt_key(key, 128, &aes);
if (result < 0) {
fprintf(stderr, "Unable to set encryption key in AES\n");
printf("%i", result);
exit(-1);
}
// set the encryption length
len = 0;
if ((strlen("test") + 1) % AES_BLOCK_SIZE == 0) {
len = strlen("test") + 1;
} else {
len = ((strlen("test") + 1) / AES_BLOCK_SIZE + 1) * AES_BLOCK_SIZE;
}
encrypt_string = (unsigned char*)calloc(len, sizeof(unsigned char));
AES_cbc_encrypt(input_string, encrypt_string, 128, &aes, iv , AES_ENCRYPT);
printf("encrypted string = ");
for (int i=0; i<len; ++i) {
printf("%02X ", encrypt_string[i]);
}
printf("\n");
return 0;
}
and this returns the encrypted string as
encrypted string = C2 5D 07 2D D5 EC DB 94 3B FE 31 9F 51 DE EE 93
which doesn't match what I get from the CLI. What am I missing here that causing these not to match?