forked from awgh/bencrypt
-
Notifications
You must be signed in to change notification settings - Fork 0
/
utils.go
225 lines (209 loc) · 5.4 KB
/
utils.go
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
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
package bc
import (
"bytes"
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"crypto/sha256"
"errors"
"fmt"
"io"
"io/ioutil"
"os"
"golang.org/x/crypto/hkdf"
"github.com/rainycape/vfs"
)
// GenerateRandomBytes : Generates as many random bytes as you ask for, returns them as []byte
func GenerateRandomBytes(count int) ([]byte, error) {
b := make([]byte, count)
if _, err := io.ReadFull(rand.Reader, b); err != nil {
return nil, err
}
return b, nil
}
// Pkcs7Pad : Appends padding, PKCS-7 style
func Pkcs7Pad(data []byte, blocklen int) ([]byte, error) {
if blocklen <= 0 {
return nil, fmt.Errorf("invalid blocklen %d", blocklen)
}
padlen := 1
for ((len(data) + padlen) % blocklen) != 0 {
padlen = padlen + 1
}
pad := bytes.Repeat([]byte{byte(padlen)}, padlen)
return append(data, pad...), nil
}
// Pkcs7Unpad : Returns slice of the original data without padding.
func Pkcs7Unpad(data []byte, blocklen int) ([]byte, error) {
if blocklen <= 0 {
return nil, fmt.Errorf("invalid blocklen %d", blocklen)
}
if len(data)%blocklen != 0 || len(data) == 0 {
return nil, fmt.Errorf("invalid data len %d", len(data))
}
padlen := int(data[len(data)-1])
if padlen > blocklen || padlen == 0 {
return nil, fmt.Errorf("invalid padding")
}
// check padding
pad := data[len(data)-padlen:]
for i := 0; i < padlen; i++ {
if pad[i] != byte(padlen) {
return nil, fmt.Errorf("invalid padding")
}
}
return data[:len(data)-padlen], nil
}
// Kdf : Key derivation function
func Kdf(key []byte, label, salt []byte) ([]byte, error) {
hkdf := hkdf.New(sha256.New, key[:], salt[:], label)
derivedKey := make([]byte, 32)
if n, err := io.ReadFull(hkdf, derivedKey); err != nil || n != len(derivedKey) {
return nil, errors.New("Failure in Key Derivation")
}
return derivedKey, nil
}
// AesEncrypt : Encrypt some bytes with a given key using AES-CBC-aes.BlockSize
func AesEncrypt(clear, aesKey []byte) ([]byte, error) {
clear, _ = Pkcs7Pad(clear, aes.BlockSize)
block, err := aes.NewCipher(aesKey)
if err != nil {
return nil, err
}
ciphertext := make([]byte, aes.BlockSize+len(clear))
iv := ciphertext[:aes.BlockSize]
if _, err := io.ReadFull(rand.Reader, iv); err != nil {
return nil, err
}
cbc := cipher.NewCBCEncrypter(block, iv)
cbc.CryptBlocks(ciphertext[aes.BlockSize:], []byte(clear))
return ciphertext, nil
}
// AesDecrypt : Decrypt some bytes with a given key using AES-CBC-aes.BlockSize
func AesDecrypt(ciphertext, aesKey []byte) ([]byte, error) {
block, err := aes.NewCipher(aesKey)
if err != nil {
return nil, err
}
if len(ciphertext) < aes.BlockSize {
return nil, errors.New("ciphertext too short")
}
iv := ciphertext[:aes.BlockSize]
text := ciphertext[aes.BlockSize:]
cbc := cipher.NewCBCDecrypter(block, iv)
clear := make([]byte, len(text))
cbc.CryptBlocks(clear, text)
clear, _ = Pkcs7Unpad(clear, aes.BlockSize)
return clear, nil
}
// OpenAndDecrypt returns an in-memory VFS initialized with the contents
// of the given filename, which will be decrypted with the given AES key,
//
// and which must have one of the following fileTypes:
//
// - .zip
// - .tar
// - .tar.gz
// - .tar.bz2
func OpenAndDecrypt(filename string, fileType string, aesKey []byte) (vfs.VFS, error) {
f, err := os.Open(filename)
if err != nil {
return nil, err
}
defer f.Close()
b, err := ioutil.ReadAll(f)
if err != nil {
return nil, err
}
clear, err := AesDecrypt(b, aesKey)
if err != nil {
return nil, err
}
bb := bytes.NewBuffer(clear)
switch fileType {
case ".zip":
return vfs.Zip(bb, int64(bb.Len()))
case ".tar":
return vfs.Tar(bb)
case ".tar.gz":
return vfs.TarGzip(bb)
case ".tar.bz2":
return vfs.TarBzip2(bb)
}
return nil, fmt.Errorf("can't open a VFS from a %s file", fileType)
}
// SaveAndEncrypt converts the given VFS to the given archive type,
// and then encrypts the archive with the given AES key.
// Supported fileTypes:
//
// - .zip
// - .tar
// - .tar.gz
// TODO: NOT SUPPORTED - .tar.bz2
func SaveAndEncrypt(fs vfs.VFS, outfile string, fileType string, aesKey []byte) error {
bb := bytes.NewBuffer(nil)
switch fileType {
case ".zip":
if err := vfs.WriteZip(bb, fs); err != nil {
return err
}
case ".tar":
if err := vfs.WriteTar(bb, fs); err != nil {
return err
}
case ".tar.gz":
if err := vfs.WriteTarGzip(bb, fs); err != nil {
return err
}
default:
return fmt.Errorf("can't write a VFS to a %s file", fileType)
}
cipher, err := AesEncrypt(bb.Bytes(), aesKey)
if err != nil {
return err
}
if err := ioutil.WriteFile(outfile, cipher, 0600); err != nil {
return err
}
return nil
}
// EncryptFile will encrypt clearfile with aesKey and save it to outfile
func EncryptFile(clearfile string, outfile string, aesKey []byte) error {
f, err := os.Open(clearfile)
if err != nil {
return err
}
defer f.Close()
clear, err := ioutil.ReadAll(f)
if err != nil {
return err
}
cipher, err := AesEncrypt(clear, aesKey)
if err != nil {
return err
}
if err := ioutil.WriteFile(outfile, cipher, 0600); err != nil {
return err
}
return nil
}
// DecryptFile will decrypt file with aesKey
func DecryptFile(file string, outfile string, aesKey []byte) error {
f, err := os.Open(file)
if err != nil {
return err
}
defer f.Close()
encrypt, err := ioutil.ReadAll(f)
if err != nil {
return err
}
cipher, err := AesDecrypt(encrypt, aesKey)
if err != nil {
return err
}
if err := ioutil.WriteFile(outfile, cipher, 0600); err != nil {
return err
}
return nil
}