iOS-设备惟一标识符

前言

获取设备惟一标识符，开发者大脑里产生的第一方案就是获取设备MAC地址，遗憾的是苹果iOS7以后获取到的mac是固定值，所以在经过MAC地址充当惟一标识此路不通；苹果iOS6另一个新的方法（IDFA），提供了一个方法advertisingIdentifier，经过调用该方法会返回一个NSUUID实例，最后能够得到一个UUID，由系统存储着的，因为IDFA会出现取不到的状况，故毫不能够做为设备惟一标识符。还有IDFV(identifierForVendor)，应用提供商标识符，若是用户将属于此Vender的全部App卸载，则IDFV的值会被重置，即再重装此Vender的App，IDFV的值和以前不一样，所以想经过IDFV做为设备惟一标识符，须要KeyChain配合（KeyChain的优缺点）本文不阐述。

 

一、结构设计方案（KeyChain+IDFV）

（1）建立一个共用的KeyChain（钥匙串）的管理对象，负责对KeyChain中Item的增删改查以及Item是否App之间共享等等；

（2）而后根据需求二次封装，无论你要保存UUID仍是帐户密码，你须要作的就是建立特定的广利对象（好比说下文的XPQKeychainUUID用于管理UUID）封装相应的存储逻辑，最后经过XPQKeychainManager写入KeyChain。

#import <Foundation/Foundation.h>

@interface XPQKeychainManager : NSObject

- (instancetype)initSecAttrAccessGroup:(NSString *)secAttrAccessGroup;

- (id)secValueDataForService:(NSString *)aService;
- (id)secValueDataForService:(NSString *)aService account:(NSString *)account;

- (BOOL)saveKeychainData:(id)data service:(NSString *)aService;
- (BOOL)saveKeychainData:(id)data service:(NSString *)aService account:(NSString *)account;

- (BOOL)deleteKeychainDataForService:(NSString *)aService;
- (BOOL)deleteKeychainDataForService:(NSString *)aService account:(NSString *)account;

@end


#import "XPQKeychainManager.h"

@interface XPQKeychainManager ()

@property (nonatomic, copy) NSString *secAttrAccessGroup;

@end

@implementation XPQKeychainManager

- (instancetype)init
{
    return [self initSecAttrAccessGroup:nil];
}

- (instancetype)initSecAttrAccessGroup:(NSString *)secAttrAccessGroup
{
    self = [super init];
    if (self) {
        self.secAttrAccessGroup = secAttrAccessGroup;
    }
    return self;
}

- (NSMutableDictionary *)queryKeychainForService:(NSString *)aService account:(NSString *)account
{
    return [NSMutableDictionary dictionaryWithObjectsAndKeys:
            (__bridge id)kSecClassGenericPassword,(__bridge_transfer id)kSecClass,
            aService, (__bridge_transfer id)kSecAttrService,
            account, (__bridge_transfer id)kSecAttrAccount,
            (__bridge id)kSecAttrAccessibleAfterFirstUnlock,(__bridge_transfer id)kSecAttrAccessible,
            nil];
}


- (id)secValueDataForService:(NSString *)aService {
    
    return [self secValueDataForService:aService account:aService];
}

- (id)secValueDataForService:(NSString *)aService account:(NSString *)account
{
    if (!aService && !account) {
        return nil;
    }
    
    NSMutableDictionary *keychainQuery = [self queryKeychainForService:aService account:account];
    if (self.secAttrAccessGroup) {
        [keychainQuery setObject:self.secAttrAccessGroup forKey:(__bridge_transfer id)kSecAttrAccessGroup];
    }
    NSMutableDictionary *attributeQuery = [keychainQuery mutableCopy];
    [attributeQuery setObject:(id)kCFBooleanTrue forKey:(__bridge_transfer id)kSecReturnAttributes];
    
    CFTypeRef attrResult = NULL;
    OSStatus status = SecItemCopyMatching(((__bridge_retained CFDictionaryRef)attributeQuery), (CFTypeRef *)&attrResult);
    
    if (status != noErr) {
        return nil;
    }
    
    NSMutableDictionary *secValueDataQuery = [keychainQuery mutableCopy];
    [secValueDataQuery setObject:(id)kCFBooleanTrue forKey:(__bridge_transfer id)kSecReturnData];
    CFTypeRef resData = NULL;
    status = SecItemCopyMatching(((__bridge_retained CFDictionaryRef)secValueDataQuery), (CFTypeRef *)&resData);
    NSData *resultData = (__bridge_transfer NSData *)resData;
    
    if (status != noErr) {
        return nil;
    }
    
    return resultData ? [NSKeyedUnarchiver unarchiveObjectWithData:resultData] : nil;
}

- (BOOL)saveKeychainData:(id)data service:(NSString *)aService {
    
    return [self saveKeychainData:data service:aService account:aService];
}

- (BOOL)saveKeychainData:(id)data service:(NSString *)aService account:(NSString *)account
{
    if (!aService && !account) {
        return NO;
    }
    
    NSMutableDictionary *keychainQuery = [self queryKeychainForService:aService account:account];
    if (self.secAttrAccessGroup) {
        [keychainQuery setObject:self.secAttrAccessGroup forKey:(__bridge_transfer id)kSecAttrAccessGroup];
    }
    id keychainData = [self secValueDataForService:aService account:account];
    OSStatus status = noErr;
    
    if (keychainData) {
        NSMutableDictionary *updateKeychainData = [keychainQuery mutableCopy];
        if (![keychainData isEqualToString:data]) {
            NSMutableDictionary *tempCheck = [NSMutableDictionary dictionaryWithObject:[NSKeyedArchiver archivedDataWithRootObject:data] forKey:(__bridge_transfer id)kSecValueData];
            status = SecItemUpdate(((__bridge_retained  CFDictionaryRef)updateKeychainData), (__bridge_retained CFDictionaryRef)tempCheck);
        }
    }
    else {
        NSMutableDictionary *addKeychainData = [keychainQuery mutableCopy];
        [addKeychainData setObject:[NSKeyedArchiver archivedDataWithRootObject:data] forKey:(__bridge_transfer id)kSecValueData];
        status = SecItemAdd(((__bridge_retained CFDictionaryRef)addKeychainData), NULL);
    }
    
    if (status != noErr) {
        return NO;
    }
    
    return YES;
}

- (BOOL)deleteKeychainDataForService:(NSString *)aService {
    
    return [self deleteKeychainDataForService:aService account:aService];
}

- (BOOL)deleteKeychainDataForService:(NSString *)aService account:(NSString *)account
{
    if (!aService && !account) {
        return NO;
    }
    
    NSMutableDictionary *keychainQuery = [self queryKeychainForService:aService account:account];
    OSStatus status = SecItemDelete(((__bridge_retained CFDictionaryRef)keychainQuery));
    if (status != noErr) {
        return NO;
    }
    
    return YES;
}

@end

 

二、保存与获取IDFV，关键代码NSString *uuid =  
[[UIDevice currentDevice].identifierForVendor UUIDString];

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

@interface XPQKeychainUUID : NSObject

- (id)readUUID;
- (BOOL)deleteItem;

@end


#import "XPQKeychainUUID.h"
#import "XPQKeychainManager.h"

@interface XPQKeychainUUID ()

@property (nonatomic, copy) NSString *uuid;
@property (nonatomic, strong) XPQKeychainManager *keychainManager;

@end

static NSString * const KEY_IN_KEYCHAIN_UUID = @"com.xpq.keychain.uuid";

@implementation XPQKeychainUUID

- (instancetype)init
{
    self = [super init];
    if (self) {
        self.keychainManager = [[XPQKeychainManager alloc] init];
    }
    return self;
}

- (BOOL)save:(id)data service:(NSString *)service {
    
    return [self.keychainManager saveKeychainData:data service:KEY_IN_KEYCHAIN_UUID];
}

- (NSString *)getUUID {
    
    return [[UIDevice currentDevice].identifierForVendor UUIDString];
}

- (id)readUUID {
    
    if (!_uuid || _uuid.length == 0) {
        
        NSString *strUUID = [self load:KEY_IN_KEYCHAIN_UUID];
        if (!strUUID || strUUID.length == 0) {
            strUUID = [self getUUID];
            [self save:strUUID];
        }
        
        _uuid = strUUID;
    }
    
    return _uuid;
}

- (id)load:(NSString *)service {
    
    return [self.keychainManager secValueDataForService:KEY_IN_KEYCHAIN_UUID];
}

- (BOOL)save:(id)data {
    
    return [self save:data service:KEY_IN_KEYCHAIN_UUID];
}

- (BOOL)deleteItem {
    
    return [self.keychainManager deleteKeychainDataForService:KEY_IN_KEYCHAIN_UUID];
}

@end

 

总结

Keychain内部的数据会自动加密。若是设备没有越狱而且不暴力破解，keychain确实很安全。可是越狱后的设备，keychain就很危险了，所以还须要对重要信息进行加密处理再放入Keychain。