我应该使用哪个密钥将密码存储在 iOS 钥匙串中？

Question

Apple GenericKeychain 示例中的 KeychainItemWrapper 类使用 kSecValueData 键来存储密码。

但是参考http://developer.apple.com/library/ios/#documentation/Security/Reference/keychainservices/Reference/reference.html#//apple_ref/doc/uid/TP30000898

说 kSecValueData 是 用于 SecItemCopyMatching 或 SecItemAdd 的结果字典中，表示返回值的类型。

当我调用 SecItemAdd 来创建钥匙串项时，我应该使用哪个键？

Answer 1

您应该使用 kSecValue 数据作为存储密码的密钥（以 NSData 或 CFDataRef 格式）。

这个主题的参考有点不清楚，kSecValueData 键作为输出键和输入键。也就是说，您在查询钥匙串项 (SecItemCopyMatching) 并指定 kSecReturnAttributes 键时使用它，因此结果作为字典返回，密码将存储在该字典的 kSecValueData 键下。当您将项目添加到钥匙串（SecItemAdd）时，您也可以使用它，在调用方法之前将密码的 NSData 或 CFDataRef 值存储在 kSecValueData 键中。

以下是两种情况的示例：

找回密码：

NSMutableDictionary *queryDictionary = [[NSMutableDictionary alloc] init];
[queryDictionary setObject: (__bridge id)kSecClassGenericPassword forKey: (__bridge id<NSCopying>)kSecClass];
[queryDictionary setObject:service forKey:kSecAttrService];
[queryDictionary setObject:account forKey:kSecAttrAccount];
// The result will be a dictionary containing the password attributes...
[queryDictionary setObject:YES forKey:(__bridge id<NSCopying>)(kSecReturnAttributes)];
// ...one of those attributes will be a kSecValueData with the password
[queryDictionary setObject:YES forKey:(__bridge id<NSCopying>)(kSecReturnData)];
OSStatus sanityCheck = SecItemCopyMatching((__bridge CFDictionaryRef)(queryDictionary), (CFTypeRef *)&result);
if (sanityCheck != noErr)
{
    NSDictionary * resultDict = (__bridge NSDictionary *)result;
    // here's the queried password value
    NSData *passwordValue = [resultDict objectForKey:(__bridge id)(kSecValueData)];
}

添加密码：

NSString *passwordString = @"my password value";
NSData *passwordData = [passwordString dataUsingEncoding:NSUTF8StringEncoding];
CFDictionaryRef result = nil;
NSMutableDictionary *addDictionary = [[NSMutableDictionary alloc] init];
[addDictionary setObject: (__bridge id)kSecClassGenericPassword forKey: (__bridge id<NSCopying>)kSecClass];
[addDictionary setObject:service forKey:kSecAttrService];
[addDictionary setObject:account forKey:kSecAttrAccount];

// here goes the password value
[addDictionary setObject:passwordData forKey:(__bridge id<NSCopying>)(kSecValueData)];

OSStatus sanityCheck = SecItemAdd((__bridge CFDictionaryRef)(queryDictionary), NULL)
if (sanityCheck != noErr)
{
   // if no error the password got successfully stored in the keychain
}