近些年来，随着手机技术迭代更新越来越快，用户更换手机的周期也在缩短，在这样的背景下，开发者不得不面临以下问题：

同一开发者旗下常常有多个安卓应用和多形态应用（快应用和Web应用），用户更换一个新的设备（手机或平板）后，在新设备上登录各应用时每次都需要重复输入帐号和密码，导致用户在登录阶段流失率增加，同时开发者还需要承担额外的短信成本（如用户使用短信登录）。

华为HMS Core[钥匙环服务](https://developer.huawei.com/consumer/cn/doc/development/Security-Guides/introduction-0000001133141068?ha_source=hms1)（Keyring）提供凭据管理接口（Credentials Management API），为Android手机、平板提供用户登录凭据存储和跨应用、跨应用形态、跨设备共享的能力。

钥匙环服务提供了[Android API](https://developer.huawei.com/consumer/cn/doc/development/Security-References/overview-0000001133344960?ha_source=hms1)、[Web API](https://developer.huawei.com/consumer/cn/doc/development/Security-References/javascript-overview-0000001214568685?ha_source=hms1)和[快应用API](https://developer.huawei.com/consumer/cn/doc/development/quickApp-Guides/quickapp-access-keyring-kit-0000001161177180?ha_source=hms1)，应用程序通过调用这些API来使用钥匙环服务。无论调用哪种形式的接口，所有的用户凭据最终都会存储在HMS Core的钥匙环服务中，以便实现统一的凭据管理能力和共享能力。

### 一、功能特点

钥匙环服务提供登录凭据本地储存和跨形态、跨应用共享能力。钥匙环服务将用户登录凭据加密储存在本地设备，被保存的凭据通过钥匙环服务共享至同一开发者旗下的其他快应用、Web应用和安卓应用；实现跨形态、跨应用无缝登录体验。

钥匙环服务使用端到端加密同步技术实现登录凭据跨设备同步能力。用户在新老设备上打开“凭据多设备同步”功能，就可以在新设备上免密登录同一开发者旗下的各形态应用，实现跨设备无缝登录体验。

例如，同一开发者将旗下的两个安卓应用和两个快应用接入钥匙环服务后，用户只需要在手机A和手机B上打开“凭据多设备同步”功能，手机A上登录一个应用后，用手机B登录时无需再输入帐号和密码，实现跨设备、跨应用、跨形态的无缝登录体验。
 
 ![](https://oscimg.oschina.net/oscnet/up-210aadfe089c41bf1ec277623ebc1e97f45.png)
 
### 二、接入优势

**打造无缝登录体验**

通过钥匙环服务接口获取本地存储的用户凭据，实现便捷登录。

**保障数据安全可靠**

用户登录凭据在设备内加密存储，在设备间通过端到端加密技术同步，云端无法解密。

**降低登录流失率**

简化用户登录时操作流程，降低流失率

**降低运营成本**

减少使用短信登录，降低运营成本

### 三、开发步骤

**开发准备**

详细准备步骤可参考[华为开发者联盟官网](https://developer.huawei.com/consumer/cn/doc/development/Security-Guides/config-agc-0000001181242769?ha_source=hms1)。

#### 集成Keyring客户端

**用户登录场景**

1、使用一个Activity实例初始化[CredentialClient](https://developer.huawei.com/consumer/cn/doc/development/Security-References/credentialclient-0000001133185186?ha_source=hms1)，可以写在Activity的onCreate方法中。

```
CredentialClient credentialClient = CredentialManager.getCredentialClient(this);
```

2、查询是否存在可用的凭据。
```
List<AppIdentity> trustedAppList = new ArrayList<>();
trustedAppList.add(new AndroidAppIdentity("yourAppName", "yourAppPackageName", "yourAppCodeSigningCertHash"));
trustedAppList.add(new WebAppIdentity("youWebSiteName", "www.yourdomain.com"));
trustedAppList.add(new WebAppIdentity("youWebSiteName", "login.yourdomain.com"));
SharedCredentialFilter sharedCredentialFilter = SharedCredentialFilter.acceptTrustedApps(trustedAppList);
credentialClient.findCredential(sharedCredentialFilter, new CredentialCallback<List<Credential>>() {
    @Override
    public void onSuccess(List<Credential> credentials) {
        if (credentials.isEmpty()) {
            Toast.makeText(MainActivity.this, R.string.no_available_credential, Toast.LENGTH_SHORT).show();
        } else {
            for (Credential credential : credentials) {
            }
        }
    }
    @Override
    public void onFailure(long errorCode, CharSequence description) {
        Toast.makeText(MainActivity.this, R.string.query_credential_failed, Toast.LENGTH_SHORT).show();
    }
});
```

3、调用[Credential.getContent](https://developer.huawei.com/consumer/cn/doc/development/Security-References/credential-0000001133185188#section5681103510191?ha_source=hms1)获取凭据内容，在[CredentialCallback<T>](https://developer.huawei.com/consumer/cn/doc/development/Security-References/credentialcallback-0000001179304555?ha_source=hms1)获取结果。

```
private Credential mCredential; 
//获取的凭据
mCredential.getContent(new CredentialCallback<byte[]>() {
    @Override
    public void onSuccess(byte[] bytes) {
        String hint = String.format(getResources().getString(R.string.get_password_ok),
                new String(bytes));
        Toast.makeText(MainActivity.this, hint, Toast.LENGTH_SHORT).show();
        mResult.setText(new String(bytes));
    }
 
    @Override
    public void onFailure(long l, CharSequence charSequence) {
        Toast.makeText(MainActivity.this, R.string.get_password_failed,
                Toast.LENGTH_SHORT).show();
        mResult.setText(R.string.get_password_failed);
    }
});
```

4、用户输入了新凭据，调用凭据存储接口。

```
AndroidAppIdentity app2 = new AndroidAppIdentity(sharedToAppName,
                sharedToAppPackage, sharedToAppCertHash);
List<AppIdentity> sharedAppList = new ArrayList<>();
sharedAppList.add(app2);

Credential credential = new Credential(username, CredentialType.PASSWORD, userAuth,
                password.getBytes());
credential.setDisplayName("user_niceday");
credential.setSharedWith(sharedAppList);
credential.setSyncable(true);

credentialClient.saveCredential(credential, new CredentialCallback<Void>() {
    @Override
    public void onSuccess(Void unused) {
        Toast.makeText(MainActivity.this,
                R.string.save_credential_ok,
                Toast.LENGTH_SHORT).show();
    }
 
    @Override
    public void onFailure(long errorCode, CharSequence description) {
        Toast.makeText(MainActivity.this,
                R.string.save_credential_failed + " " + errorCode + ":" + description,
                Toast.LENGTH_SHORT).show();
    }
});
```

#### 用户登出场景

1、使用一个Activity实例初始化[CredentialClient](https://developer.huawei.com/consumer/cn/doc/development/Security-References/credentialclient-0000001133185186?ha_source=hms1)，可以写在Activity的onCreate方法中。

```
CredentialClient credentialClient = CredentialManager.getCredentialClient(this);
```

2、查询是否存在可用的凭据。

```
List<AppIdentity> trustedAppList = new ArrayList<>();
trustedAppList.add(new AndroidAppIdentity("yourAppName", "yourAppPackageName", "yourAppCodeSigningCertHash"));
trustedAppList.add(new WebAppIdentity("youWebSiteName", "www.yourdomain.com"));
trustedAppList.add(new WebAppIdentity("youWebSiteName", "login.yourdomain.com"));
SharedCredentialFilter sharedCredentialFilter = SharedCredentialFilter.acceptTrustedApps(trustedAppList);
credentialClient.findCredential(sharedCredentialFilter, new CredentialCallback<List<Credential>>() {
    @Override
    public void onSuccess(List<Credential> credentials) {
        if (credentials.isEmpty()) {
            Toast.makeText(MainActivity.this, R.string.no_available_credential, Toast.LENGTH_SHORT).show();
        } else {
            for (Credential credential : credentials) {
                //可以对可用凭据进行进一步处理，包括：获取凭据相关信息、获取凭据内容、删除
            }
        }
    }
 
    @Override
    public void onFailure(long errorCode, CharSequence description) {
        Toast.makeText(MainActivity.this, R.string.query_credential_failed, Toast.LENGTH_SHORT).show();
    }
});
```

3、调用[deleteCredential](https://developer.huawei.com/consumer/cn/doc/development/Security-References/credentialclient-0000001133185186#section1766202311152?ha_source=hms1)删除凭据，在[CredentialCallback](https://developer.huawei.com/consumer/cn/doc/development/Security-References/credentialcallback-0000001179304555?ha_source=hms1)获取结果。

```
credentialClient.deleteCredential(credential, new CredentialCallback<Void>() {
    @Override
    public void onSuccess(Void unused) {
        String hint = String.format(getResources().getString(R.string.delete_ok),
                credential.getUsername());
        Toast.makeText(MainActivity.this, hint, Toast.LENGTH_SHORT).show();
    }
 
    @Override
    public void onFailure(long errorCode, CharSequence description) {
        String hint = String.format(getResources().getString(R.string.delete_failed),
                description);
        Toast.makeText(MainActivity.this, hint, Toast.LENGTH_SHORT).show();
    }
});
```

#### 凭据共享机制

**通过API参数实现凭据共享**

在调用[saveCredential](https://developer.huawei.com/consumer/cn/doc/development/Security-References/credentialclient-0000001133185186#section109797369169?ha_source=hms1)保存凭据时，您可以通过[setSharedWith](https://developer.huawei.com/consumer/cn/doc/development/Security-References/credential-0000001133185188#section1699664511331?ha_source=hms1)设置[Credential](https://developer.huawei.com/consumer/cn/doc/development/Security-References/credential-0000001133185188?ha_source=hms1)对象的属性实现凭据共享，最多支持共享给128个应用。

示例如下：

```
AndroidAppIdentity app1 = new AndroidAppIdentity("your android app name",
                "your android app package name", "3C:99:C3:....");
QuickAppIdentity app2 = new QuickAppIdentity("your quick app name",
                "your quick app package name", "DC:99:C4:....");
List<AppIdentity> sharedAppList = new ArrayList<>(); // 共享关系列表
sharedAppList.add(app1);
sharedAppList.add(app2);
Credential credential = new Credential("username", CredentialType.PASSWORD, true,
                "password".getBytes());
credential.setSharedWith(sharedAppList); // 设置共享关系
credentialClient.saveCredential(credential, new CredentialCallback<Void>() {
    @Override
    public void onSuccess(Void unused) {
        Toast.makeText(MainActivity.this,
                R.string.save_credential_ok,
                Toast.LENGTH_SHORT).show();
    }
    @Override
    public void onFailure(long errorCode, CharSequence description) {
        Toast.makeText(MainActivity.this,
                R.string.save_credential_failed + " " + errorCode + ":" + description,
                Toast.LENGTH_SHORT).show();
    }
});
```

**通过Digital Asset Links资源实现凭据共享**

您可以在Android应用的AndroidManifest.xml中添加凭据共享关系，方法如下：

1、在AndroidManifest.xml的<application>节点中添加以下内容：

```
<application>
           <meta-data
            android:name="asset_statements"
            android:value="@string/asset_statements" />
</application>
```

2. 在res\values\strings.xml中添加以下内容：

```
<string name="asset_statements">your digital asset links statements</string>
```

Digital asset links statements是一个遵循Digital Asset links规范的JSON字符串，示例如下：

```
[{
                   "relation": ["delegate_permission/common.get_login_creds"],
                   "target": {
                            "namespace": "web",
                            "site": "https://developer.huawei.com" // 您的网站域名
                   }
         },
         {
                   "relation": ["delegate_permission/common.get_login_creds"],
                   "target": {
                            "namespace": "android_app",
                            "package_name": "your android app package name",
                            "sha256_cert_fingerprints": [
                                     "F2:52:4D:..."
                            ]
                   }
         },
         {
                   "relation": ["delegate_permission/common.get_login_creds"],
                   "target": {
                            "namespace": "quick_app",
                            "package_name": "your quick app package name",
                            "sha256_cert_fingerprints": [
                                     "C3:68:9F:..."
                            ]
                   }
         }
]
```

relation属性的值固定为["delegate_permission/common.get_login_creds"]，表示把凭据共享给target属性所描述的应用。

### 案例分享

[航班管家和高铁管家集成华为钥匙环服务，为两亿用户打造无缝登录体验。](https://developer.huawei.com/consumer/cn/doc/development/Security-Guides/example1-0000001227569382?ha_source=hms1)

**了解更多详情>>**

访问[华为开发者联盟官网](http://developer.huawei.com/consumer/cn/hms?ha_source=hms1)  
获取[开发指导文档](http://developer.huawei.com/consumer/cn/doc/development?ha_source=hms1)  
华为移动服务开源仓库地址：[GitHub](http://github.com/HMS-Core)、[Gitee](http://gitee.com/hms-core)

**关注我们，第一时间了解 HMS Core 最 新 技术资讯~**

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