| /* |
| * Copyright (C) 2020 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 <android-base/logging.h> |
| #include <android-base/result.h> |
| |
| #include <openssl/bn.h> |
| #include <openssl/crypto.h> |
| #include <openssl/pkcs7.h> |
| #include <openssl/rsa.h> |
| #include <openssl/x509v3.h> |
| |
| #include <fcntl.h> |
| #include <vector> |
| |
| #include "KeyConstants.h" |
| |
| const char kBasicConstraints[] = "CA:TRUE"; |
| const char kKeyUsage[] = "critical,keyCertSign,cRLSign,digitalSignature"; |
| const char kSubjectKeyIdentifier[] = "hash"; |
| constexpr int kCertLifetimeSeconds = 10 * 365 * 24 * 60 * 60; |
| |
| using android::base::Result; |
| // using android::base::ErrnoError; |
| using android::base::Error; |
| |
| static bool add_ext(X509* cert, int nid, const char* value) { |
| size_t len = strlen(value) + 1; |
| std::vector<char> mutableValue(value, value + len); |
| X509V3_CTX context; |
| |
| X509V3_set_ctx_nodb(&context); |
| |
| X509V3_set_ctx(&context, cert, cert, nullptr, nullptr, 0); |
| X509_EXTENSION* ex = X509V3_EXT_nconf_nid(nullptr, &context, nid, mutableValue.data()); |
| if (!ex) { |
| return false; |
| } |
| |
| X509_add_ext(cert, ex, -1); |
| X509_EXTENSION_free(ex); |
| return true; |
| } |
| |
| Result<bssl::UniquePtr<RSA>> getRsa(const std::vector<uint8_t>& publicKey) { |
| bssl::UniquePtr<RSA> rsaPubkey(RSA_new()); |
| rsaPubkey->n = BN_new(); |
| rsaPubkey->e = BN_new(); |
| |
| BN_bin2bn(publicKey.data(), publicKey.size(), rsaPubkey->n); |
| BN_set_word(rsaPubkey->e, kRsaKeyExponent); |
| |
| return rsaPubkey; |
| } |
| |
| Result<void> verifySignature(const std::string& message, const std::string& signature, |
| const std::vector<uint8_t>& publicKey) { |
| auto rsaKey = getRsa(publicKey); |
| uint8_t hashBuf[SHA256_DIGEST_LENGTH]; |
| SHA256(const_cast<uint8_t*>(reinterpret_cast<const uint8_t*>(message.c_str())), |
| message.length(), hashBuf); |
| |
| bool success = RSA_verify(NID_sha256, hashBuf, sizeof(hashBuf), |
| (const uint8_t*)signature.c_str(), signature.length(), rsaKey->get()); |
| |
| if (!success) { |
| return Error() << "Failed to verify signature."; |
| } |
| return {}; |
| } |
| |
| Result<void> createSelfSignedCertificate( |
| const std::vector<uint8_t>& publicKey, |
| const std::function<Result<std::string>(const std::string&)>& signFunction, |
| const std::string& path) { |
| bssl::UniquePtr<X509> x509(X509_new()); |
| if (!x509) { |
| return Error() << "Unable to allocate x509 container"; |
| } |
| X509_set_version(x509.get(), 2); |
| |
| ASN1_INTEGER_set(X509_get_serialNumber(x509.get()), 1); |
| X509_gmtime_adj(X509_get_notBefore(x509.get()), 0); |
| X509_gmtime_adj(X509_get_notAfter(x509.get()), kCertLifetimeSeconds); |
| |
| // "publicKey" corresponds to the raw public key bytes - need to create |
| // a new RSA key with the correct exponent. |
| auto rsaPubkey = getRsa(publicKey); |
| |
| EVP_PKEY* public_key = EVP_PKEY_new(); |
| EVP_PKEY_assign_RSA(public_key, rsaPubkey->release()); |
| |
| if (!X509_set_pubkey(x509.get(), public_key)) { |
| return Error() << "Unable to set x509 public key"; |
| } |
| |
| X509_NAME* name = X509_get_subject_name(x509.get()); |
| if (!name) { |
| return Error() << "Unable to get x509 subject name"; |
| } |
| X509_NAME_add_entry_by_txt(name, "C", MBSTRING_ASC, |
| reinterpret_cast<const unsigned char*>("US"), -1, -1, 0); |
| X509_NAME_add_entry_by_txt(name, "O", MBSTRING_ASC, |
| reinterpret_cast<const unsigned char*>("Android"), -1, -1, 0); |
| X509_NAME_add_entry_by_txt(name, "CN", MBSTRING_ASC, |
| reinterpret_cast<const unsigned char*>("ODS"), -1, -1, 0); |
| if (!X509_set_issuer_name(x509.get(), name)) { |
| return Error() << "Unable to set x509 issuer name"; |
| } |
| |
| add_ext(x509.get(), NID_basic_constraints, kBasicConstraints); |
| add_ext(x509.get(), NID_key_usage, kKeyUsage); |
| add_ext(x509.get(), NID_subject_key_identifier, kSubjectKeyIdentifier); |
| add_ext(x509.get(), NID_authority_key_identifier, "keyid:always"); |
| |
| X509_ALGOR_set0(x509->cert_info->signature, OBJ_nid2obj(NID_sha256WithRSAEncryption), |
| V_ASN1_NULL, NULL); |
| X509_ALGOR_set0(x509->sig_alg, OBJ_nid2obj(NID_sha256WithRSAEncryption), V_ASN1_NULL, NULL); |
| |
| // Get the data to be signed |
| char* to_be_signed_buf(nullptr); |
| size_t to_be_signed_length = i2d_re_X509_tbs(x509.get(), (unsigned char**)&to_be_signed_buf); |
| |
| auto signed_data = signFunction(std::string(to_be_signed_buf, to_be_signed_length)); |
| if (!signed_data.ok()) { |
| return signed_data.error(); |
| } |
| |
| // This is the only part that doesn't use boringssl default functions - we manually copy in the |
| // signature that was provided to us. |
| x509->signature->data = (unsigned char*)OPENSSL_malloc(signed_data->size()); |
| memcpy(x509->signature->data, signed_data->c_str(), signed_data->size()); |
| x509->signature->length = signed_data->size(); |
| |
| x509->signature->flags &= ~(ASN1_STRING_FLAG_BITS_LEFT | 0x07); |
| x509->signature->flags |= ASN1_STRING_FLAG_BITS_LEFT; |
| auto f = fopen(path.c_str(), "wbe"); |
| if (f == nullptr) { |
| return Error() << "Failed to open " << path; |
| } |
| i2d_X509_fp(f, x509.get()); |
| fclose(f); |
| |
| EVP_PKEY_free(public_key); |
| return {}; |
| } |
| |
| Result<std::vector<uint8_t>> extractPublicKey(EVP_PKEY* pkey) { |
| if (pkey == nullptr) { |
| return Error() << "Failed to extract public key from x509 cert"; |
| } |
| |
| if (EVP_PKEY_type(pkey->type) != EVP_PKEY_RSA) { |
| return Error() << "The public key is not an RSA key"; |
| } |
| |
| RSA* rsa = EVP_PKEY_get1_RSA(pkey); |
| auto num_bytes = BN_num_bytes(rsa->n); |
| std::vector<uint8_t> pubKey(num_bytes); |
| int res = BN_bn2bin(rsa->n, pubKey.data()); |
| RSA_free(rsa); |
| |
| if (!res) { |
| return Error() << "Failed to convert public key to bytes"; |
| } |
| |
| return pubKey; |
| } |
| |
| Result<std::vector<uint8_t>> |
| extractPublicKeyFromSubjectPublicKeyInfo(const std::vector<uint8_t>& keyData) { |
| auto keyDataBytes = keyData.data(); |
| EVP_PKEY* public_key = d2i_PUBKEY(nullptr, &keyDataBytes, keyData.size()); |
| |
| return extractPublicKey(public_key); |
| } |
| |
| Result<std::vector<uint8_t>> extractPublicKeyFromX509(const std::vector<uint8_t>& keyData) { |
| auto keyDataBytes = keyData.data(); |
| bssl::UniquePtr<X509> decoded_cert(d2i_X509(nullptr, &keyDataBytes, keyData.size())); |
| if (decoded_cert.get() == nullptr) { |
| return Error() << "Failed to decode X509 certificate."; |
| } |
| bssl::UniquePtr<EVP_PKEY> decoded_pkey(X509_get_pubkey(decoded_cert.get())); |
| |
| return extractPublicKey(decoded_pkey.get()); |
| } |
| |
| Result<std::vector<uint8_t>> extractPublicKeyFromX509(const std::string& path) { |
| X509* cert; |
| auto f = fopen(path.c_str(), "re"); |
| if (f == nullptr) { |
| return Error() << "Failed to open " << path; |
| } |
| if (!d2i_X509_fp(f, &cert)) { |
| fclose(f); |
| return Error() << "Unable to decode x509 cert at " << path; |
| } |
| |
| fclose(f); |
| return extractPublicKey(X509_get_pubkey(cert)); |
| } |
| |
| Result<std::vector<uint8_t>> createPkcs7(const std::vector<uint8_t>& signed_digest) { |
| CBB out, outer_seq, wrapped_seq, seq, digest_algos_set, digest_algo, null; |
| CBB content_info, issuer_and_serial, signer_infos, signer_info, sign_algo, signature; |
| uint8_t *pkcs7_data, *name_der; |
| size_t pkcs7_data_len, name_der_len; |
| BIGNUM* serial = BN_new(); |
| int sig_nid = NID_rsaEncryption; |
| |
| X509_NAME* name = X509_NAME_new(); |
| if (!name) { |
| return Error() << "Unable to get x509 subject name"; |
| } |
| X509_NAME_add_entry_by_txt(name, "C", MBSTRING_ASC, |
| reinterpret_cast<const unsigned char*>("US"), -1, -1, 0); |
| X509_NAME_add_entry_by_txt(name, "O", MBSTRING_ASC, |
| reinterpret_cast<const unsigned char*>("Android"), -1, -1, 0); |
| X509_NAME_add_entry_by_txt(name, "CN", MBSTRING_ASC, |
| reinterpret_cast<const unsigned char*>("ODS"), -1, -1, 0); |
| |
| BN_set_word(serial, 1); |
| name_der_len = i2d_X509_NAME(name, &name_der); |
| CBB_init(&out, 1024); |
| |
| if (!CBB_add_asn1(&out, &outer_seq, CBS_ASN1_SEQUENCE) || |
| !OBJ_nid2cbb(&outer_seq, NID_pkcs7_signed) || |
| !CBB_add_asn1(&outer_seq, &wrapped_seq, |
| CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0) || |
| // See https://tools.ietf.org/html/rfc2315#section-9.1 |
| !CBB_add_asn1(&wrapped_seq, &seq, CBS_ASN1_SEQUENCE) || |
| !CBB_add_asn1_uint64(&seq, 1 /* version */) || |
| !CBB_add_asn1(&seq, &digest_algos_set, CBS_ASN1_SET) || |
| !CBB_add_asn1(&digest_algos_set, &digest_algo, CBS_ASN1_SEQUENCE) || |
| !OBJ_nid2cbb(&digest_algo, NID_sha256) || |
| !CBB_add_asn1(&digest_algo, &null, CBS_ASN1_NULL) || |
| !CBB_add_asn1(&seq, &content_info, CBS_ASN1_SEQUENCE) || |
| !OBJ_nid2cbb(&content_info, NID_pkcs7_data) || |
| !CBB_add_asn1(&seq, &signer_infos, CBS_ASN1_SET) || |
| !CBB_add_asn1(&signer_infos, &signer_info, CBS_ASN1_SEQUENCE) || |
| !CBB_add_asn1_uint64(&signer_info, 1 /* version */) || |
| !CBB_add_asn1(&signer_info, &issuer_and_serial, CBS_ASN1_SEQUENCE) || |
| !CBB_add_bytes(&issuer_and_serial, name_der, name_der_len) || |
| !BN_marshal_asn1(&issuer_and_serial, serial) || |
| !CBB_add_asn1(&signer_info, &digest_algo, CBS_ASN1_SEQUENCE) || |
| !OBJ_nid2cbb(&digest_algo, NID_sha256) || |
| !CBB_add_asn1(&digest_algo, &null, CBS_ASN1_NULL) || |
| !CBB_add_asn1(&signer_info, &sign_algo, CBS_ASN1_SEQUENCE) || |
| !OBJ_nid2cbb(&sign_algo, sig_nid) || !CBB_add_asn1(&sign_algo, &null, CBS_ASN1_NULL) || |
| !CBB_add_asn1(&signer_info, &signature, CBS_ASN1_OCTETSTRING) || |
| !CBB_add_bytes(&signature, signed_digest.data(), signed_digest.size()) || |
| !CBB_finish(&out, &pkcs7_data, &pkcs7_data_len)) { |
| return Error() << "Failed to create PKCS7 certificate."; |
| } |
| |
| return std::vector<uint8_t>(&pkcs7_data[0], &pkcs7_data[pkcs7_data_len]); |
| } |