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
|
// Copyright (c) 2013 Kyle Isom <kyle@tyrfingr.is>
// Copyright (c) 2012 The Go Authors. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
package ecies
// This file contains parameters for ECIES encryption, specifying the
// symmetric encryption and HMAC parameters.
import (
"crypto"
"crypto/aes"
"crypto/cipher"
"crypto/elliptic"
"crypto/sha256"
"crypto/sha512"
"fmt"
"hash"
)
// The default curve for this package is the NIST P256 curve, which
// provides security equivalent to AES-128.
var DefaultCurve = elliptic.P256()
var (
ErrUnsupportedECDHAlgorithm = fmt.Errorf("ecies: unsupported ECDH algorithm")
ErrUnsupportedECIESParameters = fmt.Errorf("ecies: unsupported ECIES parameters")
)
type ECIESParams struct {
Hash func() hash.Hash // hash function
hashAlgo crypto.Hash
Cipher func([]byte) (cipher.Block, error) // symmetric cipher
BlockSize int // block size of symmetric cipher
KeyLen int // length of symmetric key
}
// Standard ECIES parameters:
// * ECIES using AES128 and HMAC-SHA-256-16
// * ECIES using AES256 and HMAC-SHA-256-32
// * ECIES using AES256 and HMAC-SHA-384-48
// * ECIES using AES256 and HMAC-SHA-512-64
var (
ECIES_AES128_SHA256 = &ECIESParams{
Hash: sha256.New,
hashAlgo: crypto.SHA256,
Cipher: aes.NewCipher,
BlockSize: aes.BlockSize,
KeyLen: 16,
}
ECIES_AES256_SHA256 = &ECIESParams{
Hash: sha256.New,
hashAlgo: crypto.SHA256,
Cipher: aes.NewCipher,
BlockSize: aes.BlockSize,
KeyLen: 32,
}
ECIES_AES256_SHA384 = &ECIESParams{
Hash: sha512.New384,
hashAlgo: crypto.SHA384,
Cipher: aes.NewCipher,
BlockSize: aes.BlockSize,
KeyLen: 32,
}
ECIES_AES256_SHA512 = &ECIESParams{
Hash: sha512.New,
hashAlgo: crypto.SHA512,
Cipher: aes.NewCipher,
BlockSize: aes.BlockSize,
KeyLen: 32,
}
)
var paramsFromCurve = map[elliptic.Curve]*ECIESParams{
elliptic.P256(): ECIES_AES128_SHA256,
elliptic.P384(): ECIES_AES256_SHA384,
elliptic.P521(): ECIES_AES256_SHA512,
}
func AddParamsForCurve(curve elliptic.Curve, params *ECIESParams) {
paramsFromCurve[curve] = params
}
// ParamsFromCurve selects parameters optimal for the selected elliptic curve.
// Only the curves P256, P384, and P512 are supported.
func ParamsFromCurve(curve elliptic.Curve) (params *ECIESParams) {
return paramsFromCurve[curve]
/*
switch curve {
case elliptic.P256():
return ECIES_AES128_SHA256
case elliptic.P384():
return ECIES_AES256_SHA384
case elliptic.P521():
return ECIES_AES256_SHA512
default:
return nil
}
*/
}
// ASN.1 encode the ECIES parameters relevant to the encryption operations.
func paramsToASNECIES(params *ECIESParams) (asnParams asnECIESParameters) {
if nil == params {
return
}
asnParams.KDF = asnNISTConcatenationKDF
asnParams.MAC = hmacFull
switch params.KeyLen {
case 16:
asnParams.Sym = aes128CTRinECIES
case 24:
asnParams.Sym = aes192CTRinECIES
case 32:
asnParams.Sym = aes256CTRinECIES
}
return
}
// ASN.1 encode the ECIES parameters relevant to ECDH.
func paramsToASNECDH(params *ECIESParams) (algo asnECDHAlgorithm) {
switch params.hashAlgo {
case crypto.SHA224:
algo = dhSinglePass_stdDH_sha224kdf
case crypto.SHA256:
algo = dhSinglePass_stdDH_sha256kdf
case crypto.SHA384:
algo = dhSinglePass_stdDH_sha384kdf
case crypto.SHA512:
algo = dhSinglePass_stdDH_sha512kdf
}
return
}
// ASN.1 decode the ECIES parameters relevant to the encryption stage.
func asnECIEStoParams(asnParams asnECIESParameters, params *ECIESParams) {
if !asnParams.KDF.Cmp(asnNISTConcatenationKDF) {
params = nil
return
} else if !asnParams.MAC.Cmp(hmacFull) {
params = nil
return
}
switch {
case asnParams.Sym.Cmp(aes128CTRinECIES):
params.KeyLen = 16
params.BlockSize = 16
params.Cipher = aes.NewCipher
case asnParams.Sym.Cmp(aes192CTRinECIES):
params.KeyLen = 24
params.BlockSize = 16
params.Cipher = aes.NewCipher
case asnParams.Sym.Cmp(aes256CTRinECIES):
params.KeyLen = 32
params.BlockSize = 16
params.Cipher = aes.NewCipher
default:
params = nil
}
}
// ASN.1 decode the ECIES parameters relevant to ECDH.
func asnECDHtoParams(asnParams asnECDHAlgorithm, params *ECIESParams) {
if asnParams.Cmp(dhSinglePass_stdDH_sha224kdf) {
params.hashAlgo = crypto.SHA224
params.Hash = sha256.New224
} else if asnParams.Cmp(dhSinglePass_stdDH_sha256kdf) {
params.hashAlgo = crypto.SHA256
params.Hash = sha256.New
} else if asnParams.Cmp(dhSinglePass_stdDH_sha384kdf) {
params.hashAlgo = crypto.SHA384
params.Hash = sha512.New384
} else if asnParams.Cmp(dhSinglePass_stdDH_sha512kdf) {
params.hashAlgo = crypto.SHA512
params.Hash = sha512.New
} else {
params = nil
}
}
|
