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, version 3 of the License.
8 // This program is distributed in the hope that it will be useful,
9 // but WITHOUT ANY WARRANTY; without even the implied warranty of
10 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 // GNU General Public License for more details.
13 // You should have received a copy of the GNU General Public License
14 // along with this program. If not, see <http://www.gnu.org/licenses/>.
16 // GOST R 34.13-2015 padding methods.
19 func PadSize(dataSize, blockSize int) int {
20 if dataSize < blockSize {
21 return blockSize - dataSize
23 if dataSize%blockSize == 0 {
26 return blockSize - dataSize%blockSize
29 func Pad1(data []byte, blockSize int) []byte {
30 padSize := PadSize(len(data), blockSize)
34 return append(data, make([]byte, padSize)...)
37 func Pad2(data []byte, blockSize int) []byte {
38 pad := make([]byte, 1+PadSize(len(data)+1, blockSize))
40 return append(data, pad...)
43 func Pad3(data []byte, blockSize int) []byte {
44 if PadSize(len(data), blockSize) == 0 {
47 return Pad2(data, blockSize)