| /* |
| * Copyright 2015 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "nist_curve_key_exchange.h" |
| |
| #include <gtest/gtest.h> |
| #include <openssl/evp.h> |
| |
| #include <hardware/keymaster_defs.h> |
| #include <keymaster/android_keymaster_utils.h> |
| |
| #include "android_keymaster_test_utils.h" |
| |
| using std::string; |
| |
| namespace keymaster { |
| namespace test { |
| |
| StdoutLogger logger; |
| |
| static const keymaster_ec_curve_t kEcCurves[] = {KM_EC_CURVE_P_224, KM_EC_CURVE_P_256, |
| KM_EC_CURVE_P_384, KM_EC_CURVE_P_521}; |
| |
| /** |
| * SharedKey just tests that the basic key exchange identity holds: that both |
| * parties end up with the same key. |
| */ |
| TEST(NistCurveKeyExchange, SharedKey) { |
| for (auto& curve : kEcCurves) { |
| AuthorizationSet kex_description( |
| AuthorizationSetBuilder().Authorization(TAG_EC_CURVE, curve)); |
| for (size_t j = 0; j < 5; j++) { |
| NistCurveKeyExchange* alice_keyex = NistCurveKeyExchange::GenerateKeyExchange(curve); |
| NistCurveKeyExchange* bob_keyex = NistCurveKeyExchange::GenerateKeyExchange(curve); |
| |
| ASSERT_TRUE(alice_keyex != nullptr); |
| ASSERT_TRUE(bob_keyex != nullptr); |
| |
| Buffer alice_public_value; |
| ASSERT_TRUE(alice_keyex->public_value(&alice_public_value)); |
| Buffer bob_public_value; |
| ASSERT_TRUE(bob_keyex->public_value(&bob_public_value)); |
| |
| Buffer alice_shared, bob_shared; |
| ASSERT_TRUE(alice_keyex->CalculateSharedKey(bob_public_value, &alice_shared)); |
| ASSERT_TRUE(bob_keyex->CalculateSharedKey(alice_public_value, &bob_shared)); |
| EXPECT_EQ(alice_shared.available_read(), bob_shared.available_read()); |
| EXPECT_EQ(0, memcmp(alice_shared.peek_read(), bob_shared.peek_read(), |
| alice_shared.available_read())); |
| } |
| } |
| } |
| |
| /* |
| * This test tries a key agreement with a false public key (i.e. with |
| * a point not on the curve.) |
| * The expected result of such a protocol should be that the |
| * key agreement fails and returns an error. |
| */ |
| static const char* kInvalidPublicKeys[] = { |
| "04" // uncompressed public key |
| "deadbeef7f56584c5cc632ca65640db91b6bacce3a4df6b42ce7cc838833d287" |
| "db71e509e3fd9b060ddb20ba5c51dcc5948d46fbf640dfe0441782cab85fa4ac", |
| }; |
| |
| TEST(NistCurveKeyExchange, InvalidPublicKey) { |
| for (auto& curve : kEcCurves) { |
| AuthorizationSet kex_description( |
| AuthorizationSetBuilder().Authorization(TAG_EC_CURVE, curve)); |
| KeyExchange* key_exchange = NistCurveKeyExchange::GenerateKeyExchange(curve); |
| ASSERT_TRUE(key_exchange != nullptr); |
| |
| string peer_public_key = hex2str(kInvalidPublicKeys[0]); |
| Buffer computed_shared_secret; |
| ASSERT_FALSE(key_exchange->CalculateSharedKey( |
| reinterpret_cast<const uint8_t*>(peer_public_key.data()), peer_public_key.size(), |
| &computed_shared_secret)); |
| } |
| } |
| |
| /** |
| * Test that key exchange fails when peer public key is the point at infinity. |
| */ |
| TEST(NistCurveKeyExchange, TestInfinity) { |
| for (auto& curve : kEcCurves) { |
| /* Obtain the point at infinity */ |
| EC_GROUP* group = ec_get_group(curve); |
| EC_POINT* point_at_infinity = EC_POINT_new(group); |
| EC_POINT_set_to_infinity(group, point_at_infinity); |
| EXPECT_EQ(1, EC_POINT_is_on_curve(group, point_at_infinity, nullptr)); |
| size_t field_len_in_bits; |
| ec_get_group_size(group, &field_len_in_bits); |
| size_t field_len = (field_len_in_bits + 7) / 8; |
| size_t public_key_len = (field_len * 2) + 1; |
| uint8_t* public_key = new uint8_t[public_key_len]; |
| public_key_len = EC_POINT_point2oct(group, point_at_infinity, POINT_CONVERSION_UNCOMPRESSED, |
| public_key, public_key_len, nullptr /* ctx */); |
| |
| /* Perform the key exchange */ |
| AuthorizationSet kex_description( |
| AuthorizationSetBuilder().Authorization(TAG_EC_CURVE, curve)); |
| NistCurveKeyExchange* key_exchange = NistCurveKeyExchange::GenerateKeyExchange(curve); |
| ASSERT_TRUE(key_exchange != nullptr); |
| Buffer computed_shared_secret; |
| /* It should fail */ |
| ASSERT_FALSE(key_exchange->CalculateSharedKey(reinterpret_cast<const uint8_t*>(public_key), |
| public_key_len, &computed_shared_secret)); |
| |
| /* Explicitly test that ECDH_compute_key fails when the public key is the point at infinity |
| */ |
| UniquePtr<uint8_t[]> result(new uint8_t[field_len]); |
| EXPECT_EQ(-1 /* error */, ECDH_compute_key(result.get(), field_len, point_at_infinity, |
| key_exchange->private_key(), nullptr /* kdf */)); |
| } |
| } |
| |
| /* Test vectors for P-256, downloaded from NIST. */ |
| struct NistCurveTest { |
| const keymaster_ec_curve_t curve; |
| const char* peer_public_key; |
| const char* my_private_key; |
| const char* shared_secret; |
| }; |
| |
| static const NistCurveTest kNistCurveTests[] = { |
| { |
| KM_EC_CURVE_P_256, |
| "04" // uncompressed public key |
| "700c48f77f56584c5cc632ca65640db91b6bacce3a4df6b42ce7cc838833d287" |
| "db71e509e3fd9b060ddb20ba5c51dcc5948d46fbf640dfe0441782cab85fa4ac", |
| // https://tools.ietf.org/html/rfc5915 |
| "30770201010420" // DER-encodeded EC private key header |
| "7d7dc5f71eb29ddaf80d6214632eeae03d9058af1fb6d22ed80badb62bc1a534" // private key |
| "a00a06082a8648ce3d030107a144034200" // DER-encoded curve OID, |
| "04" |
| "ead218590119e8876b29146ff89ca61770c4edbbf97d38ce385ed281d8a6b230" |
| "28af61281fd35e2fa7002523acc85a429cb06ee6648325389f59edfce1405141", |
| "46fc62106420ff012e54a434fbdd2d25ccc5852060561e68040dd7778997bd7b", |
| }, |
| { |
| KM_EC_CURVE_P_256, "04" |
| "809f04289c64348c01515eb03d5ce7ac1a8cb9498f5caa50197e58d43a86a7ae" |
| "b29d84e811197f25eba8f5194092cb6ff440e26d4421011372461f579271cda3", |
| // https://tools.ietf.org/html/rfc5915 |
| "30770201010420" // DER-encodeded EC private key header |
| "38f65d6dce47676044d58ce5139582d568f64bb16098d179dbab07741dd5caf5" // private key |
| "a00a06082a8648ce3d030107a144034200" // DER-encoded curve OID, |
| "04" |
| "119f2f047902782ab0c9e27a54aff5eb9b964829ca99c06b02ddba95b0a3f6d0" |
| "8f52b726664cac366fc98ac7a012b2682cbd962e5acb544671d41b9445704d1d", |
| "057d636096cb80b67a8c038c890e887d1adfa4195e9b3ce241c8a778c59cda67", |
| }, |
| { |
| KM_EC_CURVE_P_256, "04" |
| "df3989b9fa55495719b3cf46dccd28b5153f7808191dd518eff0c3cff2b705ed" |
| "422294ff46003429d739a33206c8752552c8ba54a270defc06e221e0feaf6ac4", |
| // https://tools.ietf.org/html/rfc5915 |
| "30770201010420" // DER-encodeded EC private key header |
| "207c43a79bfee03db6f4b944f53d2fb76cc49ef1c9c4d34d51b6c65c4db6932d" // private key |
| "a00a06082a8648ce3d030107a144034200" // DER-encoded curve OID, |
| "04" |
| "24277c33f450462dcb3d4801d57b9ced05188f16c28eda873258048cd1607e0d" |
| "c4789753e2b1f63b32ff014ec42cd6a69fac81dfe6d0d6fd4af372ae27c46f88", |
| "96441259534b80f6aee3d287a6bb17b5094dd4277d9e294f8fe73e48bf2a0024", |
| }, |
| }; |
| |
| /** |
| * Test that key exchange works with NIST test vectors. |
| */ |
| TEST(NistCurveKeyExchange, NistTestVectors) { |
| for (auto& test : kNistCurveTests) { |
| string private_key = hex2str(test.my_private_key); |
| string shared_secret = hex2str(test.shared_secret); |
| |
| const uint8_t* private_key_data = reinterpret_cast<const uint8_t*>(private_key.data()); |
| UniquePtr<EC_KEY, EC_KEY_Delete> ec_key( |
| d2i_ECPrivateKey(nullptr, &private_key_data, private_key.size())); |
| ASSERT_TRUE(ec_key.get() && EC_KEY_check_key(ec_key.get())); |
| |
| keymaster_error_t error; |
| NistCurveKeyExchange* key_exchange = new NistCurveKeyExchange(ec_key.release(), &error); |
| EXPECT_EQ(KM_ERROR_OK, error); |
| ASSERT_TRUE(key_exchange != nullptr); |
| |
| Buffer computed_shared_secret; |
| string peer_public_key = hex2str(test.peer_public_key); |
| ASSERT_TRUE(key_exchange->CalculateSharedKey( |
| reinterpret_cast<const uint8_t*>(peer_public_key.data()), peer_public_key.size(), |
| &computed_shared_secret)); |
| EXPECT_EQ(shared_secret.size(), computed_shared_secret.available_read()); |
| EXPECT_EQ(0, memcmp(shared_secret.data(), computed_shared_secret.peek_read(), |
| shared_secret.size())); |
| |
| for (size_t i = 0; i < peer_public_key.size(); i++) { |
| // randomly flip some bits in the peer public key to make it invalid |
| peer_public_key[i] ^= 0xff; |
| ASSERT_FALSE(key_exchange->CalculateSharedKey( |
| reinterpret_cast<const uint8_t*>(peer_public_key.data()), peer_public_key.size(), |
| &computed_shared_secret)); |
| } |
| } |
| } |
| |
| } // namespace test |
| } // namespace keymaster |