IOS 8 关于 Touch ID

一、什么是Touch ID?

Touch ID是在iPhone 5s后的设备上出现的指纹识别。Apple在IOS 8中开放给第三方APP使用。 可以使用 Touch ID 来验证用户的身份，用户经验证后才能访问你 app 中的部分或全部内容。指纹数据将受到保护，不会被 iOS 或其他 app 存取。另外即将推出的Apple pay也是与Touch ID紧密相关的。

二、比较适合哪些应用场景？

涉及到个⼈私密性信息较强的应⽤（银⾏账号密码等）

优点：相对于以往的密码验证更安全，方便；

缺点：当前每台设备最多设置5个Touch ID，重启手机需要重新输入密码。

三、如何使用？

1.验证Touch ID是否可用，即当前设备是否支持Touch ID,且用户是否在设置中设置了一个Touch ID

- (void)canEvaluatePolicy
{
    LAContext *context = [[LAContext alloc] init];
    __block  NSString *msg;
    NSError *error;
    BOOL success;

    // test if we can evaluate the policy, this test will tell us if Touch ID is available and enrolled
    success = [context canEvaluatePolicy: LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&error];
    if (success) {
        msg =[NSString stringWithFormat:NSLocalizedString(@"TOUCH_ID_IS_AVAILABLE", nil)];
    } else {
        msg =[NSString stringWithFormat:NSLocalizedString(@"TOUCH_ID_IS_NOT_AVAILABLE", nil)];
    }
    [super printResult:self.textView message:msg];

}

　　

2.验证

- (void)evaluatePolicy
{
    LAContext *context = [[LAContext alloc] init];
    __block  NSString *msg;

    // show the authentication UI with our reason string
    [context evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics localizedReason:NSLocalizedString(@"UNLOCK_ACCESS_TO_LOCKED_FATURE", nil) reply:
     ^(BOOL success, NSError *authenticationError) {
         if (success) {
             msg =[NSString stringWithFormat:NSLocalizedString(@"EVALUATE_POLICY_SUCCESS", nil)];
         } else {
             msg = [NSString stringWithFormat:NSLocalizedString(@"EVALUATE_POLICY_WITH_ERROR", nil), authenticationError.localizedDescription];
         }
         [self printResult:self.textView message:msg];
     }];

}

　　支持自定义密码验证：

- (void)evaluatePolicy2
{
    LAContext *context = [[LAContext alloc] init];
    __block  NSString *msg;

    // set text for the localized fallback button
    context.localizedFallbackTitle = NSLocalizedString(@"TOUCH_ID_FALLBACK",nil);

    // show the authentication UI with our reason string
    [context evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics localizedReason:NSLocalizedString(@"UNLOCK_ACCESS_TO_LOCKED_FATURE", nil) reply:
     ^(BOOL success, NSError *authenticationError) {
         if (success) {
             msg =[NSString stringWithFormat:NSLocalizedString(@"EVALUATE_POLICY_SUCCESS", nil)];
         } else {
             msg = [NSString stringWithFormat:NSLocalizedString(@"EVALUATE_POLICY_WITH_ERROR", nil), authenticationError.localizedDescription];
         }
         [self printResult:self.textView message:msg];
     }];

}

　

四、KeyChain 验证

说到Touch ID就必须提Keychain，系统提供给APP存放密码的”数据库“。一般我们将密码存在APP 的独立存储中，当用户删除APP后其密码也就一并删除了，用Keychain可以将用户的密码长久保存。以前获取keychain中的密码需要输入设备的密码，有了Touch ID后就可以更安全快捷的获取密码。另外，⾃⼰的程序只能访问⾃⼰的keychain,相同bundle的程序通过设置group可以互相共享同组的keychain，从⽽实现程序间可以共同访问⼀些数

据。

旧的未使用Touch ID的方式添加密码到Keychain：

    NSDictionary *attributes = @{
        (__bridge id)kSecClass: (__bridge id)kSecClassGenericPassword,
        (__bridge id)kSecAttrService: @"SampleService",
        (__bridge id)kSecValueData: [@"SECRET_PASSWORD_TEXT" dataUsingEncoding:NSUTF8StringEncoding],
        (__bridge id)kSecUseNoAuthenticationUI: @YES,
//        (__bridge id)kSecAttrAccessControl: (__bridge_transfer id)sacObject
        };

    dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        OSStatus status =  SecItemAdd((__bridge CFDictionaryRef)attributes, nil);

        NSString *msg = [NSString stringWithFormat:NSLocalizedString(@"SEC_ITEM_ADD_STATUS", nil), [self keychainErrorToString:status]];
        [self printResult:self.textView message:msg];
    });

　　使用Touch ID的 方式：

    NSDictionary *attributes = @{
        (__bridge id)kSecClass: (__bridge id)kSecClassGenericPassword,
        (__bridge id)kSecAttrService: @"SampleService",
        (__bridge id)kSecValueData: [@"SECRET_PASSWORD_TEXT" dataUsingEncoding:NSUTF8StringEncoding],
        (__bridge id)kSecUseNoAuthenticationUI: @YES,
        (__bridge id)kSecAttrAccessControl: (__bridge_transfer id)sacObject
        };

    dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        OSStatus status =  SecItemAdd((__bridge CFDictionaryRef)attributes, nil);

        NSString *msg = [NSString stringWithFormat:NSLocalizedString(@"SEC_ITEM_ADD_STATUS", nil), [self keychainErrorToString:status]];
        [self printResult:self.textView message:msg];
    });

　　

删除keychain中的密码：

- (void)deleteItemAsync
{
    NSDictionary *query = @{
        (__bridge id)kSecClass: (__bridge id)kSecClassGenericPassword,
        (__bridge id)kSecAttrService: @"SampleService"
        };

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        OSStatus status = SecItemDelete((__bridge CFDictionaryRef)(query));

        NSString *msg = [NSString stringWithFormat:NSLocalizedString(@"SEC_ITEM_DELETE_STATUS", nil), [self keychainErrorToString:status]];
        [super printResult:self.textView message:msg];
    });
}

　　

更新KeyChain中的密码：

- (void)updateItemAsync
{
    NSDictionary *query = @{
        (__bridge id)kSecClass: (__bridge id)kSecClassGenericPassword,
        (__bridge id)kSecAttrService: @"SampleService",
        (__bridge id)kSecUseOperationPrompt: @"Authenticate to update your password"
        };

    NSDictionary *changes = @{
        (__bridge id)kSecValueData: [@"UPDATED_SECRET_PASSWORD_TEXT" dataUsingEncoding:NSUTF8StringEncoding]
        };

    dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        OSStatus status = SecItemUpdate((__bridge CFDictionaryRef)query, (__bridge CFDictionaryRef)changes);
        NSString *msg = [NSString stringWithFormat:NSLocalizedString(@"SEC_ITEM_UPDATE_STATUS", nil), [self keychainErrorToString:status]];
        [super printResult:self.textView message:msg];
    });
}

　　

获取Keychain中的密码：

- (void)copyMatchingAsync
{
    NSDictionary *query = @{
        (__bridge id)kSecClass: (__bridge id)kSecClassGenericPassword,
        (__bridge id)kSecAttrService: @"SampleService",
        (__bridge id)kSecReturnData: @YES,
        (__bridge id)kSecUseOperationPrompt: NSLocalizedString(@"AUTHENTICATE_TO_ACCESS_SERVICE_PASSWORD", nil)
        };

    dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        CFTypeRef dataTypeRef = NULL;
        NSString *msg;

        OSStatus status = SecItemCopyMatching((__bridge CFDictionaryRef)(query), &dataTypeRef);
        if (status == errSecSuccess)
        {
            NSData *resultData = ( __bridge_transfer NSData *)dataTypeRef;
            NSString * result = [[NSString alloc] initWithData:resultData encoding:NSUTF8StringEncoding];

            msg = [NSString stringWithFormat:NSLocalizedString(@"RESULT", nil), result];
        } else {
            msg = [NSString stringWithFormat:NSLocalizedString(@"SEC_ITEM_COPY_MATCHING_STATUS", nil), [self keychainErrorToString:status]];
        }
        [self printResult:self.textView message:msg];
    });
}

　　

Demo地址：https://developer.apple.com/library/ios/samplecode/KeychainTouchID/Introduction/Intro.html#//apple_ref/doc/uid/TP40014530-Intro-DontLinkElementID_2