1414
1515using json = nlohmann::json;
1616
17+ static size_t ProofBufferMinSize ()
18+ {
19+ return 726 ;
20+ }
1721
18- int
19- groth16_prover ( const void *zkey_buffer, unsigned long zkey_size,
20- const void *wtns_buffer, unsigned long wtns_size,
21- char *proof_buffer, unsigned long proof_size,
22- char *public_buffer, unsigned long public_size,
23- char *error_msg, unsigned long error_msg_maxsize )
22+ static size_t PublicBufferMinSize ( size_t count)
23+ {
24+ return count * 81 + 3 ;
25+ }
26+
27+ static void VerifyPrimes (mpz_srcptr zkey_prime, mpz_srcptr wtns_prime )
2428{
2529 mpz_t altBbn128r;
2630
2731 mpz_init (altBbn128r);
2832 mpz_set_str (altBbn128r, " 21888242871839275222246405745257275088548364400416034343698204186575808495617" 10 );
2933
34+ if (mpz_cmp (zkey_prime, altBbn128r) != 0 ) {
35+ throw std::invalid_argument ( " zkey curve not supported"
36+ }
37+
38+ if (mpz_cmp (wtns_prime, altBbn128r) != 0 ) {
39+ throw std::invalid_argument ( " different wtns curve"
40+ }
41+
42+ mpz_clear (altBbn128r);
43+ }
44+
45+ std::string BuildPublicString (AltBn128::FrElement *wtnsData, size_t nPublic)
46+ {
47+ json jsonPublic;
48+ AltBn128::FrElement aux;
49+ for (u_int32_t i=1 ; i<= nPublic; i++) {
50+ AltBn128::Fr.toMontgomery (aux, wtnsData[i]);
51+ jsonPublic.push_back (AltBn128::Fr.toString (aux));
52+ }
53+
54+ return jsonPublic.dump ();
55+ }
56+
57+ int
58+ groth16_prover (const void *zkey_buffer, unsigned long zkey_size,
59+ const void *wtns_buffer, unsigned long wtns_size,
60+ char *proof_buffer, unsigned long *proof_size,
61+ char *public_buffer, unsigned long *public_size,
62+ char *error_msg, unsigned long error_msg_maxsize)
63+ {
3064 try {
3165 BinFileUtils::BinFile zkey (zkey_buffer, zkey_size, " zkey" 1 );
32-
3366 auto zkeyHeader = ZKeyUtils::loadHeader (&zkey);
3467
35- std::string proofStr;
36- if (mpz_cmp (zkeyHeader->rPrime , altBbn128r) != 0 ) {
37- throw std::invalid_argument ( " zkey curve not supported"
38- }
39-
4068 BinFileUtils::BinFile wtns (wtns_buffer, wtns_size, " wtns" 2 );
4169 auto wtnsHeader = WtnsUtils::loadHeader (&wtns);
4270
43- if (mpz_cmp (wtnsHeader->prime , altBbn128r) != 0 ) {
44- throw std::invalid_argument ( " different wtns curve"
71+ size_t proofMinSize = ProofBufferMinSize ();
72+ size_t publicMinSize = PublicBufferMinSize (zkeyHeader->nPublic );
73+
74+ if (*proof_size < proofMinSize || *public_size < publicMinSize) {
75+
76+ *proof_size = proofMinSize;
77+ *public_size = publicMinSize;
78+
79+ return PPROVER_ERROR_SHORT_BUFFER;
4580 }
4681
82+ VerifyPrimes (zkeyHeader->rPrime , wtnsHeader->prime );
83+
4784 auto prover = Groth16::makeProver<AltBn128::Engine>(
4885 zkeyHeader->nVars ,
4986 zkeyHeader->nPublic ,
@@ -65,30 +102,43 @@ groth16_prover(const void *zkey_buffer, unsigned long zkey_size,
65102 auto proof = prover->prove (wtnsData);
66103
67104 std::string stringProof = proof->toJson ().dump ();
105+ std::string stringPublic = BuildPublicString (wtnsData, zkeyHeader->nPublic );
68106
69- std::strncpy (proof_buffer, stringProof.data (), proof_size);
107+ size_t stringProofSize = stringProof.length ();
108+ size_t stringPublicSize = stringPublic.length ();
70109
71- json jsonPublic;
72- AltBn128::FrElement aux;
73- for (u_int32_t i=1 ; i<=zkeyHeader->nPublic ; i++) {
74- AltBn128::Fr.toMontgomery (aux, wtnsData[i]);
75- jsonPublic.push_back (AltBn128::Fr.toString (aux));
76- }
110+ if (*proof_size < stringProofSize || *public_size < stringPublicSize) {
77111
78- std::string stringPublic = jsonPublic.dump ();
112+ *proof_size = stringProofSize;
113+ *public_size = stringPublicSize;
79114
80- std::strncpy (public_buffer, stringPublic.data (), public_size);
115+ return PPROVER_ERROR_SHORT_BUFFER;
116+ }
117+
118+ std::strncpy (proof_buffer, stringProof.data (), *proof_size);
119+ std::strncpy (public_buffer, stringPublic.data (), *public_size);
81120
82121 } catch (std::exception & e) {
83- mpz_clear (altBbn128r);
84122
85123 if (error_msg) {
86124 strncpy (error_msg, e.what (), error_msg_maxsize);
87125 }
88126 return PPROVER_ERROR;
89- }
90127
91- mpz_clear (altBbn128r);
128+ } catch (std::exception *e) {
129+
130+ if (error_msg) {
131+ strncpy (error_msg, e->what (), error_msg_maxsize);
132+ }
133+ delete e;
134+ return PPROVER_ERROR;
135+
136+ } catch (...) {
137+ if (error_msg) {
138+ strncpy (error_msg, " unknown error"
139+ }
140+ return PPROVER_ERROR;
141+ }
92142
93143 return PRPOVER_OK;
94144}
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