#include <des.h>
#include <stdlib.h>
#include <strings.h>

#include "algs.h"
#include "alg-util.h"

typedef struct tdes_state TDES_STATE;

struct tdes_state {
  unsigned char key[24];
  unsigned char iv[8];
  int direction;
  } ;

static void *enc_3des_cbc_init_enc(const void *key, const void *iv)
{
 TDES_STATE *s;

 s = malloc(sizeof(TDES_STATE));
 if (s == 0) return(0);
 bcopy(key,&s->key[0],24);
 bcopy(iv,&s->iv[0],8);
 s->direction = ENCRYPT;
 return(s);
}

static void *enc_3des_cbc_init_dec(const void *key, const void *iv)
{
 TDES_STATE *s;

 s = malloc(sizeof(TDES_STATE));
 if (s == 0) return(0);
 bcopy(key,&s->key[0],24);
 bcopy(iv,&s->iv[0],8);
 s->direction = DECRYPT;
 return(s);
}

static void enc_3des_cbc_process(void *state, const void *in, void *out, int datalen)
{
 TDES_STATE *s;
 const unsigned char *ip;
 unsigned char *op;

 s = state;
 ip = in;
 op = out;
 if (datalen & 7) abort();
 switch (s->direction)
  { case ENCRYPT:
	{ unsigned char xorbuf[8];
	  bcopy(&s->iv[0],&xorbuf[0],8);
	  while (datalen > 0)
	   { xor_block(&xorbuf[0],ip,&xorbuf[0],8);
	     des3(&xorbuf[0],&xorbuf[0],&s->key[0],ENCRYPT);
	     bcopy(&xorbuf[0],op,8);
	     ip += 8;
	     op += 8;
	     datalen -= 8;
	   }
	  bcopy(&xorbuf[0],&s->iv[0],8);
	}
       break;
    case DECRYPT:
	{ unsigned char iv1[8] __attribute__((__aligned__));
	  unsigned char iv2[8] __attribute__((__aligned__));
	  bcopy(&s->iv[0],&iv1[0],8);
	  while (datalen > 0)
	   { bcopy(ip,&iv2[0],8);
	     des3(op,ip,&s->key[0],DECRYPT);
	     xor_block(&iv1[0],op,op,8);
	     bcopy(&iv2[0],&iv1[0],8);
	     ip += 8;
	     op += 8;
	     datalen -= 8;
	   }
	  bcopy(&iv1[0],&s->iv[0],8);
	}
       break;
    default:
       abort();
       break;
  }
}

static void enc_3des_cbc_done(void *state)
{
 free(state);
}

ENCALG encalg_3des_cbc
 = { "3des-cbc", 8, 8, 24,
     &enc_3des_cbc_init_enc, &enc_3des_cbc_init_dec,
     &enc_3des_cbc_process,
     &enc_3des_cbc_done };