int
pgp_cfb_create(PGP_CFB **ctx_p, int algo, const uint8 *key, int key_len,
int resync, uint8 *iv)
{
int res;
PX_Cipher *ciph;
PGP_CFB *ctx;
res = pgp_load_cipher(algo, &ciph);
if (res < 0)
return res;
res = px_cipher_init(ciph, key, key_len, NULL);
if (res < 0)
{
px_cipher_free(ciph);
return res;
}
ctx = px_alloc(sizeof(*ctx));
memset(ctx, 0, sizeof(*ctx));
ctx->ciph = ciph;
ctx->block_size = px_cipher_block_size(ciph);
ctx->resync = resync;
if (iv)
memcpy(ctx->fr, iv, ctx->block_size);
*ctx_p = ctx;
return 0;
}
static int
combo_decrypt(PX_Combo *cx, const uint8 *data, unsigned dlen,
uint8 *res, unsigned *rlen)
{
unsigned bs,
i,
pad;
unsigned pad_ok;
PX_Cipher *c = cx->cipher;
/* decide whether zero-length input is allowed */
if (dlen == 0)
{
/* with padding, empty ciphertext is not allowed */
if (cx->padding)
return PXE_DECRYPT_FAILED;
/* without padding, report empty result */
*rlen = 0;
return 0;
}
bs = px_cipher_block_size(c);
if (bs > 1 && (dlen % bs) != 0)
goto block_error;
/* decrypt */
*rlen = dlen;
px_cipher_decrypt(c, data, dlen, res);
/* unpad */
if (bs > 1 && cx->padding)
{
pad = res[*rlen - 1];
pad_ok = 0;
if (pad > 0 && pad <= bs && pad <= *rlen)
{
pad_ok = 1;
for (i = *rlen - pad; i < *rlen; i++)
if (res[i] != pad)
{
pad_ok = 0;
break;
}
}
if (pad_ok)
*rlen -= pad;
}
return 0;
block_error:
return PXE_NOTBLOCKSIZE;
}
static int
combo_init(PX_Combo *cx, const uint8 *key, unsigned klen,
const uint8 *iv, unsigned ivlen)
{
int err;
unsigned bs,
ks,
ivs;
PX_Cipher *c = cx->cipher;
uint8 *ivbuf = NULL;
uint8 *keybuf;
bs = px_cipher_block_size(c);
ks = px_cipher_key_size(c);
ivs = px_cipher_iv_size(c);
if (ivs > 0)
{
ivbuf = px_alloc(ivs);
memset(ivbuf, 0, ivs);
if (ivlen > ivs)
memcpy(ivbuf, iv, ivs);
else
memcpy(ivbuf, iv, ivlen);
}
if (klen > ks)
klen = ks;
keybuf = px_alloc(ks);
memset(keybuf, 0, ks);
memcpy(keybuf, key, klen);
err = px_cipher_init(c, keybuf, klen, ivbuf);
if (ivbuf)
px_free(ivbuf);
px_free(keybuf);
return err;
}
static int
combo_encrypt(PX_Combo *cx, const uint8 *data, unsigned dlen,
uint8 *res, unsigned *rlen)
{
int err = 0;
uint8 *bbuf;
unsigned bs,
bpos,
i,
pad;
PX_Cipher *c = cx->cipher;
bbuf = NULL;
bs = px_cipher_block_size(c);
/* encrypt */
if (bs > 1)
{
bbuf = px_alloc(bs * 4);
bpos = dlen % bs;
*rlen = dlen - bpos;
memcpy(bbuf, data + *rlen, bpos);
/* encrypt full-block data */
if (*rlen)
{
err = px_cipher_encrypt(c, data, *rlen, res);
if (err)
goto out;
}
/* bbuf has now bpos bytes of stuff */
if (cx->padding)
{
pad = bs - (bpos % bs);
for (i = 0; i < pad; i++)
bbuf[bpos++] = pad;
}
else if (bpos % bs)
{
/* ERROR? */
pad = bs - (bpos % bs);
for (i = 0; i < pad; i++)
bbuf[bpos++] = 0;
}
/* encrypt the rest - pad */
if (bpos)
{
err = px_cipher_encrypt(c, bbuf, bpos, res + *rlen);
*rlen += bpos;
}
}
else
{
/* stream cipher/mode - no pad needed */
err = px_cipher_encrypt(c, data, dlen, res);
if (err)
goto out;
*rlen = dlen;
}
out:
if (bbuf)
px_free(bbuf);
return err;
}