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/>.
17 // GOST R 34.13-2015 padding methods.
20 func PadSize(dataSize, blockSize int) int {
21 if dataSize < blockSize {
22 return blockSize - dataSize
24 if dataSize%blockSize == 0 {
27 return blockSize - dataSize%blockSize
30 func Pad1(data []byte, blockSize int) []byte {
31 padSize := PadSize(len(data), blockSize)
35 return append(data, make([]byte, padSize)...)
38 func Pad2(data []byte, blockSize int) []byte {
39 pad := make([]byte, 1+PadSize(len(data)+1, blockSize))
41 return append(data, pad...)
44 func Pad3(data []byte, blockSize int) []byte {
45 if PadSize(len(data), blockSize) == 0 {
48 return Pad2(data, blockSize)