#include <openssl/evp.h>
#include <stdio.h>

int
main(int argc, char *argv[])
{

        EVP_CIPHER_CTX ctx;
                char key[EVP_MAX_KEY_LENGTH];
                        char iv[EVP_MAX_IV_LENGTH];
                                char *ct, *out;
                                        char final[EVP_MAX_BLOCK_LENGTH];
                                                char str[] = "123456789abcdef";
                                                        int i;
                                                        
                                                                strcpy(key,"secret");
                                                                        strcpy(iv,"foo");
                                                                                ct = malloc(EVP_MAX_BLOCK_LENGTH);
                                                                                        out = malloc(EVP_MAX_BLOCK_LENGTH);
                                                                                        
                                                                                                EVP_EncryptInit(&ctx, EVP_bf_cbc(), key, iv);
                                                                                                        EVP_EncryptUpdate(&ctx, ct, &i, str, strlen(str));
                                                                                                                printf("Ciphertext is %d bytes.\n",i);
                                                                                                                        printf("Ciphertext is >>%s<<\n",ct);
                                                                                                                        
                                                                                                                        
                                                                                                                                EVP_DecryptInit(&ctx, EVP_bf_cbc(), key, iv);
                                                                                                                                        EVP_DecryptUpdate(&ctx, out, &i, ct, i);
                                                                                                                                                printf("Decrypted: >>%s<<\n",out);
                                                                                                                                                        EVP_DecryptUpdate(&ctx, out, &i, ct, i);
                                                                                                                                                                printf("Decrypted: >>%s<<\n",out);
                                                                                                                                                                
                                                                                                                                                                        if (!EVP_DecryptFinal(&ctx, final, &i))
                                                                                                                                                                                        err(-1,"padding incorrect");
                                                                                                                                                                                        
                                                                                                                                                                                                final[i] = 0;
                                                                                                                                                                                                        printf("Decrypted: >>%s<<\n",final);
                                                                                                                                                                                                                exit(0);
                                                                                                                                                                                                                }