KeychainItemWrapper.h文件
********************************
#import "KeychainItemWrapper.h"
#import <Security/Security.h>
/*
These are the default constants and their respective types,
available for the kSecClassGenericPassword Keychain Item class:
kSecAttrAccessGroup - CFStringRef
kSecAttrCreationDate - CFDateRef
kSecAttrModificationDate - CFDateRef
kSecAttrDescription - CFStringRef
kSecAttrComment - CFStringRef
kSecAttrCreator - CFNumberRef
kSecAttrType - CFNumberRef
kSecAttrLabel - CFStringRef
kSecAttrIsInvisible - CFBooleanRef
kSecAttrIsNegative - CFBooleanRef
kSecAttrAccount - CFStringRef
kSecAttrService - CFStringRef
kSecAttrGeneric - CFDataRef
See the header file Security/SecItem.h for more details.
*/
@interface KeychainItemWrapper (PrivateMethods)
/*
The decision behind the following two methods (secItemFormatToDictionary and dictionaryToSecItemFormat) was
to encapsulate the transition between what the detail view controller was expecting (NSString *) and what the
Keychain API expects as a validly constructed container class.
*/
- (NSMutableDictionary *)secItemFormatToDictionary:(NSDictionary *)dictionaryToConvert;
- (NSMutableDictionary *)dictionaryToSecItemFormat:(NSDictionary *)dictionaryToConvert;
// Updates the item in the keychain, or adds it if it doesn't exist.
- (void)writeToKeychain;
@end
@implementation KeychainItemWrapper
@synthesize keychainItemData, genericPasswordQuery;
- (id)initWithAccount:(NSString *)account service:(NSString *)service accessGroup:(NSString *) accessGroup;
{
if (self = [super init])
{
NSAssert(account != nil || service != nil, @"Both account and service are nil. Must specifiy at least one.");
// Begin Keychain search setup. The genericPasswordQuery the attributes kSecAttrAccount and
// kSecAttrService are used as unique identifiers differentiating keychain items from one another
genericPasswordQuery = [[NSMutableDictionary alloc] init];
[genericPasswordQuery setObject:(id)kSecClassGenericPassword forKey:(id)kSecClass];
[genericPasswordQuery setObject:account forKey:(id)kSecAttrAccount];
[genericPasswordQuery setObject:service forKey:(id)kSecAttrService];
// The keychain access group attribute determines if this item can be shared
// amongst multiple apps whose code signing entitlements contain the same keychain access group.
if (accessGroup != nil)
{
#if TARGET_IPHONE_SIMULATOR
// Ignore the access group if running on the iPhone simulator.
//
// Apps that are built for the simulator aren't signed, so there's no keychain access group
// for the simulator to check. This means that all apps can see all keychain items when run
// on the simulator.
//
// If a SecItem contains an access group attribute, SecItemAdd and SecItemUpdate on the
// simulator will return -25243 (errSecNoAccessForItem).
#else
[genericPasswordQuery setObject:accessGroup forKey:(id)kSecAttrAccessGroup];
#endif
}
// Use the proper search constants, return only the attributes of the first match.
[genericPasswordQuery setObject:(id)kSecMatchLimitOne forKey:(id)kSecMatchLimit];
[genericPasswordQuery setObject:(id)kCFBooleanTrue forKey:(id)kSecReturnAttributes];
NSDictionary *tempQuery = [NSDictionary dictionaryWithDictionary:genericPasswordQuery];
NSMutableDictionary *outDictionary = nil;
if (! SecItemCopyMatching((CFDictionaryRef)tempQuery, (CFTypeRef *)&outDictionary) == noErr)
{
// Stick these default values into keychain item if nothing found.
[self resetKeychainItem];
//Adding the account and service identifiers to the keychain
[keychainItemData setObject:account forKey:(id)kSecAttrAccount];
[keychainItemData setObject:service forKey:(id)kSecAttrService];
if (accessGroup != nil)
{
#if TARGET_IPHONE_SIMULATOR
// Ignore the access group if running on the iPhone simulator.
//
// Apps that are built for the simulator aren't signed, so there's no keychain access group
// for the simulator to check. This means that all apps can see all keychain items when run
// on the simulator.
//
// If a SecItem contains an access group attribute, SecItemAdd and SecItemUpdate on the
// simulator will return -25243 (errSecNoAccessForItem).
#else
[keychainItemData setObject:accessGroup forKey:(id)kSecAttrAccessGroup];
#endif
}
}
else
{
// load the saved data from Keychain.
self.keychainItemData = [self secItemFormatToDictionary:outDictionary];
}
[outDictionary release];
}
return self;
}
- (id)initWithIdentifier: (NSString *)identifier accessGroup:(NSString *) accessGroup;
{
if (self = [super init])
{
// Begin Keychain search setup. The genericPasswordQuery leverages the special user
// defined attribute kSecAttrGeneric to distinguish itself between other generic Keychain
// items which may be included by the same application.
genericPasswordQuery = [[NSMutableDictionary alloc] init];
[genericPasswordQuery setObject:(id)kSecClassGenericPassword forKey:(id)kSecClass];
[genericPasswordQuery setObject:identifier forKey:(id)kSecAttrGeneric];
// The keychain access group attribute determines if this item can be shared
// amongst multiple apps whose code signing entitlements contain the same keychain access group.
if (accessGroup != nil)
{
#if TARGET_IPHONE_SIMULATOR
// Ignore the access group if running on the iPhone simulator.
//
// Apps that are built for the simulator aren't signed, so there's no keychain access group
// for the simulator to check. This means that all apps can see all keychain items when run
// on the simulator.
//
// If a SecItem contains an access group attribute, SecItemAdd and SecItemUpdate on the
// simulator will return -25243 (errSecNoAccessForItem).
#else
[genericPasswordQuery setObject:accessGroup forKey:(id)kSecAttrAccessGroup];
#endif
}
// Use the proper search constants, return only the attributes of the first match.
[genericPasswordQuery setObject:(id)kSecMatchLimitOne forKey:(id)kSecMatchLimit];
[genericPasswordQuery setObject:(id)kCFBooleanTrue forKey:(id)kSecReturnAttributes];
NSDictionary *tempQuery = [NSDictionary dictionaryWithDictionary:genericPasswordQuery];
NSMutableDictionary *outDictionary = nil;
if (! SecItemCopyMatching((CFDictionaryRef)tempQuery, (CFTypeRef *)&outDictionary) == noErr)
{
// Stick these default values into keychain item if nothing found.
[self resetKeychainItem];
// Add the generic attribute and the keychain access group.
[keychainItemData setObject:identifier forKey:(id)kSecAttrGeneric];
if (accessGroup != nil)
{
#if TARGET_IPHONE_SIMULATOR
// Ignore the access group if running on the iPhone simulator.
//
// Apps that are built for the simulator aren't signed, so there's no keychain access group
// for the simulator to check. This means that all apps can see all keychain items when run
// on the simulator.
//
// If a SecItem contains an access group attribute, SecItemAdd and SecItemUpdate on the
// simulator will return -25243 (errSecNoAccessForItem).
#else
[keychainItemData setObject:accessGroup forKey:(id)kSecAttrAccessGroup];
#endif
}
}
else
{
// load the saved data from Keychain.
self.keychainItemData = [self secItemFormatToDictionary:outDictionary];
}
[outDictionary release];
}
return self;
}
- (void)dealloc
{
[keychainItemData release];
[genericPasswordQuery release];
[super dealloc];
}
- (void)setObject:(id)inObject forKey:(id)key
{
if (inObject == nil) return;
id currentObject = [keychainItemData objectForKey:key];
if (![currentObject isEqual:inObject])
{
[keychainItemData setObject:inObject forKey:key];
[self writeToKeychain];
}
}
- (id)objectForKey:(id)key
{
return [keychainItemData objectForKey:key];
}
- (void)resetKeychainItem
{
OSStatus junk = noErr;
if (!keychainItemData)
{
self.keychainItemData = [[NSMutableDictionary alloc] init];
}
else if (keychainItemData)
{
NSMutableDictionary *tempDictionary = [self dictionaryToSecItemFormat:keychainItemData];
junk = SecItemDelete((CFDictionaryRef)tempDictionary);
NSAssert( junk == noErr || junk == errSecItemNotFound, @"Problem deleting current dictionary." );
}
// Default attributes for keychain item.
[keychainItemData setObject:@"" forKey:(id)kSecAttrAccount];
[keychainItemData setObject:@"" forKey:(id)kSecAttrLabel];
[keychainItemData setObject:@"" forKey:(id)kSecAttrDescription];
// Default data for keychain item.
[keychainItemData setObject:@"" forKey:(id)kSecValueData];
}
- (NSMutableDictionary *)dictionaryToSecItemFormat:(NSDictionary *)dictionaryToConvert
{
// The assumption is that this method will be called with a properly populated dictionary
// containing all the right key/value pairs for a SecItem.
// Create a dictionary to return populated with the attributes and data.
NSMutableDictionary *returnDictionary = [NSMutableDictionary dictionaryWithDictionary:dictionaryToConvert];
// Add the Generic Password keychain item class attribute.
[returnDictionary setObject:(id)kSecClassGenericPassword forKey:(id)kSecClass];
// Convert the NSString to NSData to meet the requirements for the value type kSecValueData.
// This is where to store sensitive data that should be encrypted.
NSString *passwordString = [dictionaryToConvert objectForKey:(id)kSecValueData];
[returnDictionary setObject:[passwordString dataUsingEncoding:NSUTF8StringEncoding] forKey:(id)kSecValueData];
return returnDictionary;
}
- (NSMutableDictionary *)secItemFormatToDictionary:(NSDictionary *)dictionaryToConvert
{
// The assumption is that this method will be called with a properly populated dictionary
// containing all the right key/value pairs for the UI element.
// Create a dictionary to return populated with the attributes and data.
NSMutableDictionary *returnDictionary = [NSMutableDictionary dictionaryWithDictionary:dictionaryToConvert];
// Add the proper search key and class attribute.
[returnDictionary setObject:(id)kCFBooleanTrue forKey:(id)kSecReturnData];
[returnDictionary setObject:(id)kSecClassGenericPassword forKey:(id)kSecClass];
// Acquire the password data from the attributes.
NSData *passwordData = NULL;
if (SecItemCopyMatching((CFDictionaryRef)returnDictionary, (CFTypeRef *)&passwordData) == noErr)
{
// Remove the search, class, and identifier key/value, we don't need them anymore.
[returnDictionary removeObjectForKey:(id)kSecReturnData];
// Add the password to the dictionary, converting from NSData to NSString.
NSString *password = [[[NSString alloc] initWithBytes:[passwordData bytes] length:[passwordData length]
encoding:NSUTF8StringEncoding] autorelease];
[returnDictionary setObject:password forKey:(id)kSecValueData];
}
else
{
// Don't do anything if nothing is found.
NSAssert(NO, @"Serious error, no matching item found in the keychain.\n");
}
[passwordData release];
return returnDictionary;
}
- (void)writeToKeychain
{
NSDictionary *attributes = NULL;
NSMutableDictionary *updateItem = NULL;
OSStatus result;
if (SecItemCopyMatching((CFDictionaryRef)genericPasswordQuery, (CFTypeRef *)&attributes) == noErr)
{
// First we need the attributes from the Keychain.
updateItem = [NSMutableDictionary dictionaryWithDictionary:attributes];
// Second we need to add the appropriate search key/values.
[updateItem setObject:[genericPasswordQuery objectForKey:(id)kSecClass] forKey:(id)kSecClass];
// Lastly, we need to set up the updated attribute list being careful to remove the class.
NSMutableDictionary *tempCheck = [self dictionaryToSecItemFormat:keychainItemData];
[tempCheck removeObjectForKey:(id)kSecClass];
#if TARGET_IPHONE_SIMULATOR
// Remove the access group if running on the iPhone simulator.
//
// Apps that are built for the simulator aren't signed, so there's no keychain access group
// for the simulator to check. This means that all apps can see all keychain items when run
// on the simulator.
//
// If a SecItem contains an access group attribute, SecItemAdd and SecItemUpdate on the
// simulator will return -25243 (errSecNoAccessForItem).
//
// The access group attribute will be included in items returned by SecItemCopyMatching,
// which is why we need to remove it before updating the item.
[tempCheck removeObjectForKey:(id)kSecAttrAccessGroup];
#endif
// An implicit assumption is that you can only update a single item at a time.
result = SecItemUpdate((CFDictionaryRef)updateItem, (CFDictionaryRef)tempCheck);
NSAssert( result == noErr, @"Couldn't update the Keychain Item." );
}
else
{
// No previous item found; add the new one.
result = SecItemAdd((CFDictionaryRef)[self dictionaryToSecItemFormat:keychainItemData], NULL);
NSAssert( result == noErr, @"Couldn't add the Keychain Item." );
}
}
@end
