1 /*############################################################################
2 # Copyright 2017 Intel Corporation
3 #
4 # Licensed under the Apache License, Version 2.0 (the "License");
5 # you may not use this file except in compliance with the License.
6 # You may obtain a copy of the License at
7 #
8 # http://www.apache.org/licenses/LICENSE-2.0
9 #
10 # Unless required by applicable law or agreed to in writing, software
11 # distributed under the License is distributed on an "AS IS" BASIS,
12 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 # See the License for the specific language governing permissions and
14 # limitations under the License.
15 ############################################################################*/
16 /// Tiny member CreateJoinRequest implementation.
17 /*! \file */
18
19 #define EXPORT_EPID_APIS
20 #include <epid/member/api.h>
21
22 #include "epid/common/types.h"
23 #include "epid/member/tiny/math/efq.h"
24 #include "epid/member/tiny/math/fp.h"
25 #include "epid/member/tiny/math/hashwrap.h"
26 #include "epid/member/tiny/math/mathtypes.h"
27 #include "epid/member/tiny/math/serialize.h"
28 #include "epid/member/tiny/src/context.h"
29 #include "epid/member/tiny/src/native_types.h"
30 #include "epid/member/tiny/src/serialize.h"
31 #include "epid/member/tiny/src/validate.h"
32 #include "epid/member/tiny/stdlib/tiny_stdlib.h"
33
34 static const FpElemStr epid20_p_str = {
35 {{0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFC, 0xF0, 0xCD, 0x46, 0xE5, 0xF2,
36 0x5E, 0xEE, 0x71, 0xA4, 0x9E, 0x0C, 0xDC, 0x65, 0xFB, 0x12, 0x99,
37 0x92, 0x1A, 0xF6, 0x2D, 0x53, 0x6C, 0xD1, 0x0B, 0x50, 0x0D}}};
38
39 static const G2ElemStr epid20_g2_str = {
40 {{{{0xE2, 0x01, 0x71, 0xC5, 0x4A, 0xA3, 0xDA, 0x05, 0x21, 0x67, 0x04,
41 0x13, 0x74, 0x3C, 0xCF, 0x22, 0xD2, 0x5D, 0x52, 0x68, 0x3D, 0x32,
42 0x47, 0x0E, 0xF6, 0x02, 0x13, 0x43, 0xBF, 0x28, 0x23, 0x94}}},
43 {{{0x59, 0x2D, 0x1E, 0xF6, 0x53, 0xA8, 0x5A, 0x80, 0x46, 0xCC, 0xDC,
44 0x25, 0x4F, 0xBB, 0x56, 0x56, 0x43, 0x43, 0x3B, 0xF6, 0x28, 0x96,
45 0x53, 0xE2, 0x7D, 0xF7, 0xB2, 0x12, 0xBA, 0xA1, 0x89, 0xBE}}}},
46 {{{{0xAE, 0x60, 0xA4, 0xE7, 0x51, 0xFF, 0xD3, 0x50, 0xC6, 0x21, 0xE7,
47 0x03, 0x31, 0x28, 0x26, 0xBD, 0x55, 0xE8, 0xB5, 0x9A, 0x4D, 0x91,
48 0x68, 0x38, 0x41, 0x4D, 0xB8, 0x22, 0xDD, 0x23, 0x35, 0xAE}}},
49 {{{0x1A, 0xB4, 0x42, 0xF9, 0x89, 0xAF, 0xE5, 0xAD, 0xF8, 0x02, 0x74,
50 0xF8, 0x76, 0x45, 0xE2, 0x53, 0x2C, 0xDC, 0x61, 0x81, 0x90, 0x93,
51 0xD6, 0x13, 0x2C, 0x90, 0xFE, 0x89, 0x51, 0xB9, 0x24, 0x21}}}}};
52
53 static const G1ElemStr epid20_g1_str = {
54 {{{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
55 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
56 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01}}},
57 {{{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
58 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
59 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02}}}};
60
EpidCreateJoinRequest(MemberCtx * ctx,GroupPubKey const * pub_key,IssuerNonce const * ni,JoinRequest * join_request)61 EpidStatus EPID_API EpidCreateJoinRequest(MemberCtx* ctx,
62 GroupPubKey const* pub_key,
63 IssuerNonce const* ni,
64 JoinRequest* join_request) {
65 EccPointFq F;
66 EccPointFq R_str;
67 FpElem r;
68 FpElem c;
69 FpElem t;
70 tiny_sha sha_state;
71 sha_digest digest;
72 G1ElemStr g1_str;
73 NativeGroupPubKey deserialized_pkey;
74
75 if (!ctx || !pub_key || !ni || !join_request) {
76 return kEpidBadArgErr;
77 }
78 if (!ctx->f_is_set) {
79 return kEpidBadArgErr;
80 }
81
82 GroupPubKeyDeserialize(&deserialized_pkey, pub_key);
83 if (!GroupPubKeyIsInRange(&deserialized_pkey)) {
84 return kEpidBadArgErr;
85 }
86 // pick number r between 1 - (p-1)
87 if (!FpRandNonzero(&r, ctx->rnd_func, ctx->rnd_param)) {
88 return kEpidMathErr;
89 }
90
91 // F = h1^f
92 EFqAffineExp(&F, &deserialized_pkey.h1, &ctx->f);
93 // R_str = h1^r
94 EFqAffineExp(&R_str, &deserialized_pkey.h1, &r);
95
96 // c = hash(p || g1 || g2 || h1 || h2 || w || F || R || NI) mod p
97 tinysha_init(ctx->hash_alg, &sha_state);
98 tinysha_update(&sha_state, (void const*)&epid20_p_str, sizeof(epid20_p_str));
99 tinysha_update(&sha_state, (void const*)&epid20_g1_str,
100 sizeof(epid20_g1_str));
101 tinysha_update(&sha_state, (void const*)&epid20_g2_str,
102 sizeof(epid20_g2_str));
103 tinysha_update(&sha_state, (void const*)&pub_key->h1, sizeof(pub_key->h1));
104 tinysha_update(&sha_state, (void const*)&pub_key->h2, sizeof(pub_key->h2));
105 tinysha_update(&sha_state, (void const*)&pub_key->w, sizeof(pub_key->w));
106 EFqSerialize(&join_request->F, &F);
107 tinysha_update(&sha_state, (void const*)&join_request->F,
108 sizeof(join_request->F));
109 EFqSerialize(&g1_str, &R_str);
110 tinysha_update(&sha_state, (void const*)&g1_str, sizeof(g1_str));
111 tinysha_update(&sha_state, (void const*)ni, sizeof(*ni));
112 tinysha_final(digest.digest, &sha_state);
113 FpFromHash(&c, digest.digest, tinysha_digest_size(&sha_state));
114 FpSerialize(&join_request->c, &c);
115
116 // computes s = (r + c * f) mod p
117 FpMul(&t, &c, &ctx->f);
118 FpAdd(&t, &t, &r);
119 FpSerialize(&join_request->s, &t);
120 return kEpidNoErr;
121 }
122