[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-28 UTC."],[[["\u003cp\u003eThe latest version available is 2.37.0-rc, with a history of versions back to 2.11.0 accessible via their respective links.\u003c/p\u003e\n"],["\u003cp\u003eThe default authentication mechanism, known as Application Default Credentials, can be overridden using \u003ccode\u003egoogle::cloud::UnifiedCredentialsOption\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eAn example demonstrates loading a service account key file to override the default authentication and set credentials in \u003ccode\u003egoogle::cloud::Options\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eService account keys are used in the example, and it is recommended to consult the best practices guide for managing these keys.\u003c/p\u003e\n"],["\u003cp\u003eFor more information on the factory functions to create \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects, refer to the Authentication Components documentation.\u003c/p\u003e\n"]]],[],null,["Version latestkeyboard_arrow_down\n\n- [2.42.0-rc (latest)](/cpp/docs/reference/storage/latest/storage-auth-example)\n- [2.41.0](/cpp/docs/reference/storage/2.41.0/storage-auth-example)\n- [2.40.0](/cpp/docs/reference/storage/2.40.0/storage-auth-example)\n- [2.39.0](/cpp/docs/reference/storage/2.39.0/storage-auth-example)\n- [2.38.0](/cpp/docs/reference/storage/2.38.0/storage-auth-example)\n- [2.37.0](/cpp/docs/reference/storage/2.37.0/storage-auth-example)\n- [2.36.0](/cpp/docs/reference/storage/2.36.0/storage-auth-example)\n- [2.35.0](/cpp/docs/reference/storage/2.35.0/storage-auth-example)\n- [2.34.0](/cpp/docs/reference/storage/2.34.0/storage-auth-example)\n- [2.33.0](/cpp/docs/reference/storage/2.33.0/storage-auth-example)\n- [2.32.0](/cpp/docs/reference/storage/2.32.0/storage-auth-example)\n- [2.31.0](/cpp/docs/reference/storage/2.31.0/storage-auth-example)\n- [2.30.0](/cpp/docs/reference/storage/2.30.0/storage-auth-example)\n- [2.29.0](/cpp/docs/reference/storage/2.29.0/storage-auth-example)\n- [2.28.0](/cpp/docs/reference/storage/2.28.0/storage-auth-example)\n- [2.27.0](/cpp/docs/reference/storage/2.27.0/storage-auth-example)\n- [2.26.0](/cpp/docs/reference/storage/2.26.0/storage-auth-example)\n- [2.25.1](/cpp/docs/reference/storage/2.25.1/storage-auth-example)\n- [2.24.0](/cpp/docs/reference/storage/2.24.0/storage-auth-example)\n- [2.23.0](/cpp/docs/reference/storage/2.23.0/storage-auth-example)\n- [2.22.1](/cpp/docs/reference/storage/2.22.1/storage-auth-example)\n- [2.21.0](/cpp/docs/reference/storage/2.21.0/storage-auth-example)\n- [2.20.0](/cpp/docs/reference/storage/2.20.0/storage-auth-example)\n- [2.19.0](/cpp/docs/reference/storage/2.19.0/storage-auth-example)\n- [2.18.0](/cpp/docs/reference/storage/2.18.0/storage-auth-example)\n- [2.17.0](/cpp/docs/reference/storage/2.17.0/storage-auth-example)\n- [2.16.0](/cpp/docs/reference/storage/2.16.0/storage-auth-example)\n- [2.15.1](/cpp/docs/reference/storage/2.15.1/storage-auth-example)\n- [2.14.0](/cpp/docs/reference/storage/2.14.0/storage-auth-example)\n- [2.13.0](/cpp/docs/reference/storage/2.13.0/storage-auth-example)\n- [2.12.0](/cpp/docs/reference/storage/2.12.0/storage-auth-example)\n- [2.11.0](/cpp/docs/reference/storage/2.11.0/storage-auth-example) \n\nOverride the authentication configuration\n=========================================\n\nSome applications cannot use the default authentication mechanism (known as [Application Default Credentials](https://cloud.google.com/docs/authentication#adc)). You can override this default using [`google::cloud::UnifiedCredentialsOption`](https://cloud.google.com/cpp/docs/reference/common/latest/structgoogle_1_1cloud_1_1UnifiedCredentialsOption.html). The following example shows how to explicitly load a service account key file. \n\n namespace gcs = ::google::cloud::storage;\n [](std::string const& filename, std::string const& bucket_name,\n std::string const& object_name) {\n auto is = std::ifstream(filename);\n is.exceptions(std::ios::badbit);\n auto json_string =\n std::string(std::istreambuf_iterator\u003cchar\u003e(is.rdbuf()), {});\n auto credentials =\n google::cloud::MakeServiceAccountCredentials(json_string);\n auto client = gcs::Client(\n google::cloud::Options{}.set\u003cgoogle::cloud::UnifiedCredentialsOption\u003e(\n credentials));\n PerformSomeOperations(client, bucket_name, object_name);\n }\n\nKeep in mind that we chose this as an example because it is relatively easy to understand. Consult the [Best practices for managing service account keys](https://cloud.google.com/iam/docs/best-practices-for-managing-service-account-keys) guide for more details.\n\n###### See Also\n\n[Authentication Components](https://cloud.google.com/cpp/docs/reference/common/latest/group__guac.html) - for more information on the factory functions to create [`google::cloud::Credentials`](https://cloud.google.com/cpp/docs/reference/common/latest/classgoogle_1_1cloud_1_1Credentials.html) objects."]]