example4.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 

static const char *usage = "Usage: example4 [-d]\n";

void do_encode(void);
void do_decode(void);

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

    return 0;       
}

void do_encode()
{
    char buf[BUFLEN];
    char ebuf[BUFLEN+24];
    unsigned int ebuflen;
    EVP_ENCODE_CTX ectx;
        
    EVP_EncodeInit(&ectx);

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

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

        write(STDOUT, ebuf, ebuflen);
    }

        EVP_EncodeFinal(&ectx, ebuf, &ebuflen); 

    write(STDOUT, ebuf, ebuflen);
}

void do_decode()
{
    char buf[BUFLEN];
    char ebuf[BUFLEN+24];
    unsigned int ebuflen;
    EVP_ENCODE_CTX ectx;
        
    EVP_DecodeInit(&ectx);

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

        rc = EVP_DecodeUpdate(&ectx, ebuf, &ebuflen, buf, readlen);
        if (rc <= 0)
        {
            if (!rc)
            {
                write(STDOUT, ebuf, ebuflen);
                break;
            }

            fprintf(stderr, "Error: decoding message\n");
            return;
        }

        write(STDOUT, ebuf, ebuflen);
    }

        EVP_DecodeFinal(&ectx, ebuf, &ebuflen); 

    write(STDOUT, ebuf, ebuflen); 
}