1 /* 2 * Copyright 2019 Google LLC. 3 * Licensed under the Apache License, Version 2.0 (the "License"); 4 * you may not use this file except in compliance with the License. 5 * You may obtain a copy of the License at 6 * 7 * https://www.apache.org/licenses/LICENSE-2.0 8 * 9 * Unless required by applicable law or agreed to in writing, software 10 * distributed under the License is distributed on an "AS IS" BASIS, 11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 * See the License for the specific language governing permissions and 13 * limitations under the License. 14 */ 15 16 #ifndef PRIVATE_JOIN_AND_COMPUTE_EC_POINT_UTIL_H_ 17 #define PRIVATE_JOIN_AND_COMPUTE_EC_POINT_UTIL_H_ 18 19 #include <memory> 20 #include <string> 21 22 #include "absl/strings/string_view.h" 23 #include "private_join_and_compute/crypto/big_num.h" 24 #include "private_join_and_compute/crypto/context.h" 25 #include "private_join_and_compute/crypto/ec_commutative_cipher.h" 26 #include "private_join_and_compute/crypto/ec_group.h" 27 #include "private_join_and_compute/crypto/ec_point.h" 28 #include "private_join_and_compute/util/status.inc" 29 30 namespace private_join_and_compute { 31 32 // ECPointUtil class to allow generating random EC points, hashing to the 33 // elliptic curve, and checking if strings encode curve points. 34 35 class ECPointUtil { 36 public: 37 // ECPointUtil is neither copyable nor assignable. 38 ECPointUtil(const ECPointUtil&) = delete; 39 ECPointUtil& operator=(const ECPointUtil&) = delete; 40 41 // Creates an ECPointUtil object. 42 // Returns INVALID_ARGUMENT status instead if the curve_id is not valid 43 // or INTERNAL status when crypto operations are not successful. 44 static StatusOr<std::unique_ptr<ECPointUtil>> Create(int curve_id); 45 46 // Returns a random EC point on the curve 47 StatusOr<std::string> GetRandomCurvePoint(); 48 49 // Hashes the given string to the curve. 50 // 51 // Suggested default hash_type is ECCommutativeCipher::HashType::Sha256. 52 StatusOr<std::string> HashToCurve(absl::string_view input, 53 ECCommutativeCipher::HashType hash_type); 54 55 // Checks if a string represents a curve point. 56 // May give a false negative if an internal error occurs. 57 bool IsCurvePoint(absl::string_view input); 58 59 private: 60 ECPointUtil(std::unique_ptr<Context> context, ECGroup group); 61 62 // Context used for storing temporary values to be reused across openssl 63 // function calls for better performance. 64 std::unique_ptr<Context> context_; 65 66 // The EC Group representing the curve definition. 67 ECGroup group_; 68 }; 69 70 } // namespace private_join_and_compute 71 72 #endif // PRIVATE_JOIN_AND_COMPUTE_EC_POINT_UTIL_H_ 73