example3.c

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/* NOCW */
/*
        Please read the README file for condition of use, before
        using this software.

        Maurice Gittens  <[email protected]>   January 1997

*/

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <openssl/evp.h>

#define STDIN       0
#define STDOUT      1
#define BUFLEN      512 
#define INIT_VECTOR     "12345678"
#define ENCRYPT     1
#define DECRYPT         0
#define ALG     EVP_des_ede3_cbc()

static const char *usage = "Usage: example3 [-d] password\n";

void do_cipher(char *,int);

int main(int argc, char *argv[])
{
    if ((argc == 2))    
    {
        do_cipher(argv[1],ENCRYPT);
    }   
    else if ((argc == 3) && !strcmp(argv[1],"-d"))
    {
        do_cipher(argv[2],DECRYPT);
    }
    else
    {
        fprintf(stderr,"%s", usage);
        exit(1);
    }

    return 0;       
}

void do_cipher(char *pw, int operation)
{
    char buf[BUFLEN];
    char ebuf[BUFLEN + 8];
    unsigned int ebuflen; /* rc; */
        unsigned char iv[EVP_MAX_IV_LENGTH], key[EVP_MAX_KEY_LENGTH];
    /* unsigned int ekeylen, net_ekeylen;  */
    EVP_CIPHER_CTX ectx;
        
    memcpy(iv, INIT_VECTOR, sizeof(iv));

    EVP_BytesToKey(ALG, EVP_md5(), "salu", pw, strlen(pw), 1, key, iv);

    EVP_CIPHER_CTX_init(&ectx);
    EVP_CipherInit_ex(&ectx, ALG, NULL, key, iv, operation);

    while(1)
    {
        int readlen = read(STDIN, buf, sizeof(buf));
    
        if (readlen <= 0)
        {
            if (!readlen)
               break;
            else
            {
                perror("read");
                exit(1);
            }
        }

        EVP_CipherUpdate(&ectx, ebuf, &ebuflen, buf, readlen);

        write(STDOUT, ebuf, ebuflen);
    }

        EVP_CipherFinal_ex(&ectx, ebuf, &ebuflen); 
    EVP_CIPHER_CTX_cleanup(&ectx);

    write(STDOUT, ebuf, ebuflen); 
}