1 // GoGOST -- Pure Go GOST cryptographic functions library
2 // Copyright (C) 2015-2019 Sergey Matveev <stargrave@stargrave.org>
4 // This program is free software: you can redistribute it and/or modify
5 // it under the terms of the GNU General Public License as published by
6 // the Free Software Foundation, either version 3 of the License, or
7 // (at your option) any later version.
9 // This program is distributed in the hope that it will be useful,
10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 // GNU General Public License for more details.
14 // You should have received a copy of the GNU General Public License
15 // along with this program. If not, see <http://www.gnu.org/licenses/>.
19 type CFBEncrypter struct {
24 func (c *Cipher) NewCFBEncrypter(iv [BlockSize]byte) *CFBEncrypter {
25 return &CFBEncrypter{c, iv[:]}
28 func (c *CFBEncrypter) XORKeyStream(dst, src []byte) {
33 c.c.Encrypt(c.iv, c.iv)
34 for n = 0; n < BlockSize; n++ {
35 if i*BlockSize+n == len(src) {
38 c.iv[n] ^= src[i*BlockSize+n]
39 dst[i*BlockSize+n] = c.iv[n]
46 type CFBDecrypter struct {
51 func (c *Cipher) NewCFBDecrypter(iv [BlockSize]byte) *CFBDecrypter {
52 return &CFBDecrypter{c, iv[:]}
55 func (c *CFBDecrypter) XORKeyStream(dst, src []byte) {
60 c.c.Encrypt(c.iv, c.iv)
61 for n = 0; n < BlockSize; n++ {
62 if i*BlockSize+n == len(src) {
65 dst[i*BlockSize+n] = c.iv[n] ^ src[i*BlockSize+n]
66 c.iv[n] = src[i*BlockSize+n]