我的应用程序如何在Android 4.0中分配更多堆内存？(How can my app allocate more heap memory in Android 4.0? (Not enough memory for my app) [closed])

 AES可能比它的价值更麻烦。 就像我尊重Jeff LaMarche一样，这种实现并不好。 这对于这个目的来说已经足够了，但除非你理解它的正确性和错误，否则不能在我看来复制它。 我通过使用CommonCrypto的AES正确加密，详细讨论了这个问题，并包括如何正确地进行AES; 但是你可能不想在这里正确地做正确的AES麻烦，如果你做的话它也不会给你带来太大帮助。 
 
 我的建议是一个简单的校验和哈希： 
 
- (NSUInteger)checksumForScore:(NSUInteger)score player:(GKPlayer *)player {
  NSString *string = [NSString stringWithFormat:@"%d%@%@", score, [player playerID], kLongRandomPassword];
  return [string hash];
}
 
 然后，您将校验和与分数一起存储。 你验证它像： 
 
- (BOOL)isValidChecksum:(NSUInteger)checksum forScore:(NSUInteger)score player:(GKPlayer *)player {
  return (checksum == [checksumForScore:score player:player]);
}
 
 我在这里使用了GKPlayer playerID来挑选一些易于使用的东西，但对于设备所有者在玩游戏时更改并非易事。 这样做会使重播攻击变得困难。 我不能把我朋友的plist条目与我的plist的超高分复制。 当用户更换设备或恢复此设备时，它也非常持久。 如果你没有使用GameKit，首先，你应该：D和第二，你必须弄清楚你是否还想要使用其他键。 如果您让用户在某个时刻输入，那么“用户句柄”也可以。 任何对用户来说都是独一无二的东西，他不会只是复制他的朋友。 
 
 Keychain作为一种混淆技术很有意思。 甚至合法地阅读也是一种皇家的痛苦，因此官方SDK提供了自己的混淆：DI怀疑它值得麻烦，但它是一个“隐藏”少量数据的好地方。 
 
 NSCoding甚至都不是混淆。 任何打算打开plist的人都可以在不到一分钟的时间内读写NSCoding 。 将此转换为NSData 。 将其存储在SQLite或Core Data中也是如此。 
 
 @CocoaFu对NSDataWritingFileProtectionComplete的建议很聪明，但我怀疑它会对越狱设备产生任何实际影响。 一旦设备解锁，操作系统将为您解密任何文件，因此对于知道设备PIN的人来说，这根本不是障碍。 

AES is probably more trouble than it's worth here. Much as I respect Jeff LaMarche, this implementation is not good. It's adequate for this purpose, but it's not something to copy around in my opinion unless you understand what's right and what's wrong with it. I talk about this at length in Properly encrypting with AES with CommonCrypto and include how to do AES correctly; but you probably don't want the hassle of doing AES correctly here, and it wouldn't buy you much if you did.
 
My recommendation is a simple checksum hash:
 
- (NSUInteger)checksumForScore:(NSUInteger)score player:(GKPlayer *)player {
  NSString *string = [NSString stringWithFormat:@"%d%@%@", score, [player playerID], kLongRandomPassword];
  return [string hash];
}
 
You then store the checksum along with the score. You validate it like:
 
- (BOOL)isValidChecksum:(NSUInteger)checksum forScore:(NSUInteger)score player:(GKPlayer *)player {
  return (checksum == [checksumForScore:score player:player]);
}
 
I've used GKPlayer playerID here to pick something that's easy for you to use, but not trivial for the device owner to change while playing. Doing it this way makes replay attack hard. I can't just copy my friend's plist entry with it's super-highscore to my plist. It's also nicely persistent when the user changes devices or restores this device. If you're not using GameKit, first, you probably should :D and second, you'll have to figure out if there's some other key you want to use. A "user handle" would be fine too if you have the user enter that at some point. Anything that's unique-enough to the user that he wouldn't just copy his friend's.
 
Keychain is interesting as an obfuscation technique. It's a royal pain to read even legitimately, so the official SDK provides its own obfuscation :D I doubt it's worth the trouble, but it is a decent place to "hide" small amounts of data.
 
NSCoding isn't even obfuscation. Anyone who's going to bother to open up the plist can read and write NSCoding in less than a minute. Same for turning this into an NSData. Same for storing it in SQLite or Core Data.
 
@CocoaFu's suggestion of NSDataWritingFileProtectionComplete is clever, but I doubt it will have any real impact on a jailbroken device. Once the device is unlocked, the OS will will decrypt any file for you, so it's no barrier at all to someone who knows the device's PIN.