iOS開發——密碼儲存之keychain的使用

標籤：

iOS的keychain服務提供了一種安全的儲存私密資訊（密碼，序號，認證等）的方式。每個ios程式都有一個獨立的keychain儲存。從ios 3.0開始，跨程式分享keychain變得可行。

下面就使用keychain來實現存取使用者名稱和密碼。

蘋果已經有現成的類封裝好了keychain,KeychainItemWrapper.h和KeychainItemWrapper.m檔案,可以在GenericKeychain執行個體裡找到。

但是這裡我只需要存取使用者名稱和密碼，就不用蘋果提供的類了，自己寫個簡單的類來實現就好。

代碼如下：

CHKeychain.h

#import #import @interface CHKeychain : NSObject+ (void)save:(NSString *)service data:(id)data;+ (id)load:(NSString *)service;+ (void)delete:(NSString *)service;@end

CHKeychain.m

#import "CHKeychain.h"@implementation CHKeychain+ (NSMutableDictionary *)getKeychainQuery:(NSString *)service {    return [NSMutableDictionary dictionaryWithObjectsAndKeys:            (id)kSecClassGenericPassword,(id)kSecClass,            service, (id)kSecAttrService,            service, (id)kSecAttrAccount,            (id)kSecAttrAccessibleAfterFirstUnlock,(id)kSecAttrAccessible,            nil];}+ (void)save:(NSString *)service data:(id)data {    //Get search dictionary    NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];    //Delete old item before add new item    SecItemDelete((CFDictionaryRef)keychainQuery);    //Add new object to search dictionary(Attention:the data format)    [keychainQuery setObject:[NSKeyedArchiver archivedDataWithRootObject:data] forKey:(id)kSecValueData];    //Add item to keychain with the search dictionary    SecItemAdd((CFDictionaryRef)keychainQuery, NULL);}+ (id)load:(NSString *)service {    id ret = nil;    NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];    //Configure the search setting    //Since in our simple case we are expecting only a single attribute to be returned (the password) we can set the attribute kSecReturnData to kCFBooleanTrue    [keychainQuery setObject:(id)kCFBooleanTrue forKey:(id)kSecReturnData];    [keychainQuery setObject:(id)kSecMatchLimitOne forKey:(id)kSecMatchLimit];    CFDataRef keyData = NULL;    if (SecItemCopyMatching((CFDictionaryRef)keychainQuery, (CFTypeRef *)&keyData) == noErr) {        @try {            ret = [NSKeyedUnarchiver unarchiveObjectWithData:(NSData *)keyData];        } @catch (NSException *e) {            NSLog(@"Unarchive of %@ failed: %@", service, e);        } @finally {}    }    if (keyData)    CFRelease(keyData);    return ret;}+ (void)delete:(NSString *)service {    NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];    SecItemDelete((CFDictionaryRef)keychainQuery);}@end

首先需要定義幾個字串用來做key：

NSString * const KEY_USERNAME_PASSWORD = @"com.company.app.usernamepassword";NSString * const KEY_USERNAME = @"com.company.app.username";NSString * const KEY_PASSWORD = @"com.company.app.password";

把使用者名稱和密碼存入keychain：

NSMutableDictionary *usernamepasswordKVPairs = [NSMutableDictionary dictionary];[usernamepasswordKVPairs setObject:txtfldUsername.text forKey:KEY_USERNAME];[usernamepasswordKVPairs setObject:txtfldPassword.text forKey:KEY_PASSWORD];[CHKeychain save:KEY_USERNAME_PASSWORD data:usernamepasswordKVPairs];

從keychain中取出使用者名稱和密碼：

NSMutableDictionary *usernamepasswordKVPairs = (NSMutableDictionary *)[CHKeychain load:KEY_USERNAME_PASSWORD];txtfldUsername.text = [usernamepasswordKVPairs objectForKey:KEY_USERNAME];txtfldPassword.text = [usernamepasswordKVPairs objectForKey:KEY_PASSWORD];

刪除一個keychain item:

[CHKeychain delete:KEY_USERNAME_PASSWORD];

這樣一個簡單的使用keychain存取使用者名稱密碼的功能就做好了。

另外附上一篇寫得更詳細的e文：http://useyourloaf.com/blog/2010/3/29/simple-iphone-keychain-access.html

iOS開發——密碼儲存之keychain的使用