example3.c   [plain text]

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

        Maurice Gittens  <mgittens@gits.nl>   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); 
}