1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
|
// {{{ Copyright (c) Paul R. Tagliamonte <paultag@gmail.com>, 2017
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE. }}}
package pkcs1v15
import (
"fmt"
)
// PKCS#1 1.5 defines a method to pad data passed into a signing operation
// which is (basically) to set some bits at the lower indexes, then a bunch of
// 0xFF, finally, a 0x00, then the data until the end of the block.
// Pad a message to padLen bytes according to PKCS#1 v1.5 rules
func Pad(message []byte, padLen int) []byte {
padding := make([]byte, (padLen - 3 - len(message)))
for i := 0; i < len(padding); i++ {
padding[i] = 0xFF
}
return expandBytes([]byte{0x00, 0x01}, padding, []byte{0x00}, message)
}
// Unpad a message according to PKCS#1 v1.5 rules
func Unpad(message []byte) ([]byte, error) {
for i := 2; i < len(message); i++ {
if message[i] == 0x00 {
return message[i+1:], nil
}
// if message[i] != 0xFF {
// return nil, fmt.Errorf("ykpiv: pkcs1v15: Invalid padding byte: %x", message[i])
// }
}
return nil, fmt.Errorf("ykpiv: pkcs1v15: Input does not appear to be in PKCS#1 v 1.5 padded format")
}
// Take some byte arrays, and return the concatenation of all of those byte
// arrays. It's basically like append, but for byte arrays, not bytes.
func expandBytes(els ...[]byte) []byte {
out := []byte{}
for _, el := range els {
out = append(out, el...)
}
return out
}
// vim: foldmethod=marker
|
