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
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
|
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Digests;
using Org.BouncyCastle.Security;
namespace Org.BouncyCastle.Pqc.Crypto.Sike
{
internal sealed class SikeEngine
{
//private readonly SecureRandom random;
protected internal Internal param;
protected internal Isogeny isogeny;
protected internal Fpx fpx;
private Sidh sidh;
private SidhCompressed sidhCompressed;
private bool isCompressed;
public uint GetDefaultSessionKeySize()
{
return param.MSG_BYTES * 8;
}
public int GetCipherTextSize()
{
return param.CRYPTO_CIPHERTEXTBYTES;
}
public uint GetPrivateKeySize()
{
return param.CRYPTO_SECRETKEYBYTES;
}
public uint GetPublicKeySize()
{
return param.CRYPTO_PUBLICKEYBYTES;
}
public SikeEngine(int ver, bool isCompressed, SecureRandom random)
{
//this.random = random;
this.isCompressed = isCompressed;
//todo switch for different parameters
switch(ver)
{
case 434:
param = new P434(isCompressed);
break;
case 503:
param = new P503(isCompressed);
break;
case 610:
param = new P610(isCompressed);
break;
case 751:
param = new P751(isCompressed);
break;
default:
break;
}
fpx = new Fpx(this);
isogeny = new Isogeny(this);
if(isCompressed)
{
sidhCompressed = new SidhCompressed(this);
}
sidh = new Sidh(this);
}
// SIKE's key generation
// Outputs: secret key sk (CRYPTO_SECRETKEYBYTES = MSG_BYTES + SECRETKEY_B_BYTES + CRYPTO_PUBLICKEYBYTES bytes)
// public key pk (CRYPTO_PUBLICKEYBYTES bytes)
public int crypto_kem_keypair(byte[] pk, byte[] sk, SecureRandom random)
{
random.NextBytes(sk, 0, (int)param.MSG_BYTES);
if (isCompressed)
{
// Generation of Alice's secret key
// Outputs random value in [0, 2^eA - 1]
random.NextBytes(sk, (int)param.MSG_BYTES, (int)param.SECRETKEY_A_BYTES);
sk[param.MSG_BYTES] &= 0xFE; // Make private scalar even
sk[param.MSG_BYTES + param.SECRETKEY_A_BYTES - 1] &= (byte)param.MASK_ALICE; // Masking last
sidhCompressed.EphemeralKeyGeneration_A_extended(sk, pk);
// Append public key pk to secret key sk
System.Array.Copy(pk, 0, sk, param.MSG_BYTES + param.SECRETKEY_A_BYTES, param.CRYPTO_PUBLICKEYBYTES);
}
else
{
// Generation of Bob's secret key
// Outputs random value in [0, 2^Floor(Log(2, oB)) - 1]
// todo/org: SIDH.random_mod_order_B(sk, random);
random.NextBytes(sk, (int)param.MSG_BYTES, (int)param.SECRETKEY_B_BYTES);
sk[param.MSG_BYTES + param.SECRETKEY_B_BYTES - 1] &= (byte)param.MASK_BOB;
sidh.EphemeralKeyGeneration_B(sk, pk);
// Append public key pk to secret key sk
System.Array.Copy(pk, 0, sk, param.MSG_BYTES + param.SECRETKEY_B_BYTES, param.CRYPTO_PUBLICKEYBYTES);
}
return 0;
}
// SIKE's encapsulation
// Input: public key pk (CRYPTO_PUBLICKEYBYTES bytes)
// Outputs: shared secret ss (CRYPTO_BYTES bytes)
// ciphertext message ct (CRYPTO_CIPHERTEXTBYTES = CRYPTO_PUBLICKEYBYTES + MSG_BYTES bytes)
public int crypto_kem_enc(byte[] ct, byte[] ss, byte[] pk, SecureRandom random)
{
if(isCompressed)
{
byte[] ephemeralsk = new byte[param.SECRETKEY_B_BYTES];
byte[] jinvariant = new byte[param.FP2_ENCODED_BYTES];
byte[] h = new byte[param.MSG_BYTES];
byte[] temp = new byte[param.CRYPTO_CIPHERTEXTBYTES + param.MSG_BYTES];
// Generate ephemeralsk <- G(m||pk) mod oB
random.NextBytes(temp, 0, (int)param.MSG_BYTES);
System.Array.Copy(pk, 0, temp, param.MSG_BYTES, param.CRYPTO_PUBLICKEYBYTES);
IXof digest = new ShakeDigest(256);
digest.BlockUpdate(temp, 0, (int) (param.CRYPTO_PUBLICKEYBYTES + param.MSG_BYTES));
digest.OutputFinal(ephemeralsk, 0, (int) param.SECRETKEY_B_BYTES);
sidhCompressed.FormatPrivKey_B(ephemeralsk);
// System.out.println("ephemeralsk: " + Hex.toHexstring(ephemeralsk));
// Encrypt
sidhCompressed.EphemeralKeyGeneration_B_extended(ephemeralsk, ct, 1);
// System.out.println("ct: " + Hex.toHexstring(ct));
// System.out.println("pk: " + Hex.toHexstring(pk));
sidhCompressed.EphemeralSecretAgreement_B(ephemeralsk, pk, jinvariant);
// System.out.println("jinv: " + Hex.toHexstring(jinvariant));
digest.BlockUpdate(jinvariant, 0, (int) param.FP2_ENCODED_BYTES);
digest.OutputFinal(h, 0, (int) param.MSG_BYTES);
// System.out.println("h: " + Hex.toHexstring(h));
// System.out.println("temp: " + Hex.toHexstring(temp));
for (int i = 0; i < param.MSG_BYTES; i++)
{
ct[i + param.PARTIALLY_COMPRESSED_CHUNK_CT] = (byte) (temp[i] ^ h[i]);
}
// Generate shared secret ss <- H(m||ct)
System.Array.Copy(ct, 0, temp, param.MSG_BYTES, param.CRYPTO_CIPHERTEXTBYTES);
digest.BlockUpdate(temp, 0, (int) (param.CRYPTO_CIPHERTEXTBYTES + param.MSG_BYTES));
digest.OutputFinal(ss, 0, (int) param.CRYPTO_BYTES);
return 0;
}
else
{
byte[] ephemeralsk = new byte[param.SECRETKEY_A_BYTES];
byte[] jinvariant = new byte[param.FP2_ENCODED_BYTES];
byte[] h = new byte[param.MSG_BYTES];
byte[] temp = new byte[param.CRYPTO_CIPHERTEXTBYTES + param.MSG_BYTES];
// Generate ephemeralsk <- G(m||pk) mod oA
random.NextBytes(temp, 0, (int)param.MSG_BYTES);
System.Array.Copy(pk, 0, temp, param.MSG_BYTES, param.CRYPTO_PUBLICKEYBYTES);
IXof digest = new ShakeDigest(256);
digest.BlockUpdate(temp, 0, (int) (param.CRYPTO_PUBLICKEYBYTES + param.MSG_BYTES));
digest.OutputFinal(ephemeralsk, 0, (int) param.SECRETKEY_A_BYTES);
ephemeralsk[param.SECRETKEY_A_BYTES - 1] &= (byte) param.MASK_ALICE;
// Encrypt
sidh.EphemeralKeyGeneration_A(ephemeralsk, ct);
sidh.EphemeralSecretAgreement_A(ephemeralsk, pk, jinvariant);
digest.BlockUpdate(jinvariant, 0, (int) param.FP2_ENCODED_BYTES);
digest.OutputFinal(h, 0, (int) param.MSG_BYTES);
for (int i = 0; i < param.MSG_BYTES; i++)
{
ct[i + param.CRYPTO_PUBLICKEYBYTES] = (byte) (temp[i] ^ h[i]);
}
// Generate shared secret ss <- H(m||ct)
System.Array.Copy(ct, 0, temp, param.MSG_BYTES, param.CRYPTO_CIPHERTEXTBYTES);
digest.BlockUpdate(temp, 0, (int) (param.CRYPTO_CIPHERTEXTBYTES + param.MSG_BYTES));
digest.OutputFinal(ss, 0, (int) param.CRYPTO_BYTES);
return 0;
}
}
// SIKE's decapsulation
// Input: secret key sk (CRYPTO_SECRETKEYBYTES = MSG_BYTES + SECRETKEY_B_BYTES + CRYPTO_PUBLICKEYBYTES bytes)
// ciphertext message ct (CRYPTO_CIPHERTEXTBYTES = CRYPTO_PUBLICKEYBYTES + MSG_BYTES bytes)
// Outputs: shared secret ss (CRYPTO_BYTES bytes)
public int crypto_kem_dec(byte[] ss, byte[] ct, byte[] sk)
{
if (isCompressed)
{
byte[] ephemeralsk_ = new byte[param.SECRETKEY_B_BYTES];
byte[] jinvariant_ = new byte[param.FP2_ENCODED_BYTES + 2*param.FP2_ENCODED_BYTES + param.SECRETKEY_A_BYTES],
h_ = new byte[param.MSG_BYTES];
byte[] temp = new byte[param.CRYPTO_CIPHERTEXTBYTES + param.MSG_BYTES];
byte[] tphiBKA_t = jinvariant_;//jinvariant_[param.FP2_ENCODED_BYTES];
// Decrypt
sidhCompressed.EphemeralSecretAgreement_A_extended(sk, param.MSG_BYTES, ct, jinvariant_, 1);
IXof digest = new ShakeDigest(256);
digest.BlockUpdate(jinvariant_, 0, (int) param.FP2_ENCODED_BYTES);
digest.OutputFinal(h_, 0, (int) param.MSG_BYTES);
// System.out.println("h_: " + Hex.toHexstring(h_));
for (int i = 0; i < param.MSG_BYTES; i++)
{
temp[i] = (byte) (ct[i + param.PARTIALLY_COMPRESSED_CHUNK_CT] ^ h_[i]);
}
// Generate ephemeralsk_ <- G(m||pk) mod oB
System.Array.Copy(sk, param.MSG_BYTES + param.SECRETKEY_A_BYTES, temp, param.MSG_BYTES, param.CRYPTO_PUBLICKEYBYTES);
digest.BlockUpdate(temp, 0, (int) (param.CRYPTO_PUBLICKEYBYTES + param.MSG_BYTES));
digest.OutputFinal(ephemeralsk_, 0, (int) param.SECRETKEY_B_BYTES);
sidhCompressed.FormatPrivKey_B(ephemeralsk_);
// Generate shared secret ss <- H(m||ct), or output ss <- H(s||ct) in case of ct verification failure
// No need to recompress, just check if x(phi(P) + t*phi(Q)) == x((a0 + t*a1)*R1 + (b0 + t*b1)*R2)
byte selector = sidhCompressed.validate_ciphertext(ephemeralsk_, ct, sk, param.MSG_BYTES + param.SECRETKEY_A_BYTES + param.CRYPTO_PUBLICKEYBYTES, tphiBKA_t, param.FP2_ENCODED_BYTES);
// If ct validation passes (selector = 0) then do ss = H(m||ct), otherwise (selector = -1) load s to do ss = H(s||ct)
fpx.ct_cmov(temp, sk, param.MSG_BYTES, selector);
System.Array.Copy(ct, 0, temp, param.MSG_BYTES, param.CRYPTO_CIPHERTEXTBYTES);
digest.BlockUpdate(temp, 0, (int) (param.CRYPTO_CIPHERTEXTBYTES + param.MSG_BYTES));
digest.OutputFinal(ss, 0, (int) param.CRYPTO_BYTES);
return 0;
}
else
{
byte[] ephemeralsk_ = new byte[param.SECRETKEY_A_BYTES];
byte[] jinvariant_ = new byte[param.FP2_ENCODED_BYTES];
byte[] h_ = new byte[param.MSG_BYTES];
byte[] c0_ = new byte[param.CRYPTO_PUBLICKEYBYTES];
byte[] temp = new byte[param.CRYPTO_CIPHERTEXTBYTES + param.MSG_BYTES];
// Decrypt
// int EphemeralSecretAgreement_B(PrivateKeyB, PublicKeyA, SharedSecretB)
sidh.EphemeralSecretAgreement_B(sk, ct, jinvariant_);
IXof digest = new ShakeDigest(256);
digest.BlockUpdate(jinvariant_, 0, (int) param.FP2_ENCODED_BYTES);
digest.OutputFinal(h_, 0, (int) param.MSG_BYTES);
for (int i = 0; i < param.MSG_BYTES; i++)
{
temp[i] = (byte) (ct[i + param.CRYPTO_PUBLICKEYBYTES] ^ h_[i]);
}
// Generate ephemeralsk_ <- G(m||pk) mod oA
System.Array.Copy(sk, param.MSG_BYTES + param.SECRETKEY_B_BYTES, temp, param.MSG_BYTES, param.CRYPTO_PUBLICKEYBYTES);
digest.BlockUpdate(temp, 0, (int) (param.CRYPTO_PUBLICKEYBYTES + param.MSG_BYTES));
digest.OutputFinal(ephemeralsk_, 0, (int) param.SECRETKEY_A_BYTES);
ephemeralsk_[param.SECRETKEY_A_BYTES - 1] &= (byte) param.MASK_ALICE;
// Generate shared secret ss <- H(m||ct), or output ss <- H(s||ct) in case of ct verification failure
sidh.EphemeralKeyGeneration_A(ephemeralsk_, c0_);
// If selector = 0 then do ss = H(m||ct), else if selector = -1 load s to do ss = H(s||ct)
byte selector = fpx.ct_compare(c0_, ct, param.CRYPTO_PUBLICKEYBYTES);
fpx.ct_cmov(temp, sk, param.MSG_BYTES, selector);
System.Array.Copy(ct, 0, temp, param.MSG_BYTES, param.CRYPTO_CIPHERTEXTBYTES);
digest.BlockUpdate(temp, 0, (int) (param.CRYPTO_CIPHERTEXTBYTES + param.MSG_BYTES));
digest.OutputFinal(ss, 0, (int) param.CRYPTO_BYTES);
return 0;
}
}
}
}
|
