/usr/share/gocode/src/github.com/jacobsa/crypto/siv/s2v.go is in golang-github-jacobsa-crypto-dev 0.0~git20161111.0.293ce0c-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 | // Copyright 2012 Aaron Jacobs. All Rights Reserved.
// Author: aaronjjacobs@gmail.com (Aaron Jacobs)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package siv
import (
"bytes"
"crypto/aes"
"fmt"
"github.com/jacobsa/crypto/cmac"
"github.com/jacobsa/crypto/common"
)
var s2vZero []byte
func init() {
s2vZero = bytes.Repeat([]byte{0x00}, aes.BlockSize)
}
// The output size of the s2v function.
const s2vSize = cmac.Size
// Run the S2V "string to vector" function of RFC 5297 using the input key and
// string vector, which must be non-empty. (RFC 5297 defines S2V to handle the
// empty vector case, but it is never used that way by higher-level functions.)
//
// If provided, the supplied scatch space will be used to avoid an allocation.
// It should be (but is not required to be) as large as the last element of
// strings.
//
// The result is guaranteed to be of length s2vSize.
func s2v(key []byte, strings [][]byte, scratch []byte) []byte {
numStrings := len(strings)
if numStrings == 0 {
panic("strings vector must be non-empty.")
}
// Create a CMAC hash.
h, err := cmac.New(key)
if err != nil {
panic(fmt.Sprintf("cmac.New: %v", err))
}
// Initialize.
if _, err := h.Write(s2vZero); err != nil {
panic(fmt.Sprintf("h.Write: %v", err))
}
d := h.Sum([]byte{})
h.Reset()
// Handle all strings but the last.
for i := 0; i < numStrings-1; i++ {
if _, err := h.Write(strings[i]); err != nil {
panic(fmt.Sprintf("h.Write: %v", err))
}
common.Xor(d, dbl(d), h.Sum([]byte{}))
h.Reset()
}
// Handle the last string.
lastString := strings[numStrings-1]
var t []byte
if len(lastString) >= aes.BlockSize {
// Make an output buffer the length of lastString.
if cap(scratch) >= len(lastString) {
t = scratch[:len(lastString)]
} else {
t = make([]byte, len(lastString))
}
// XOR d on the end of lastString.
xorend(t, lastString, d)
} else {
t = make([]byte, aes.BlockSize)
common.Xor(t, dbl(d), common.PadBlock(lastString))
}
if _, err := h.Write(t); err != nil {
panic(fmt.Sprintf("h.Write: %v", err))
}
return h.Sum([]byte{})
}
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