Can I access the keychain on the iPhone?

Question

This question discusses encrypting data on the iPhone using the crypt() function. As an alternative, is there a keychain on the iPhone and if so, what code would I use to access it in order to store login details and then retrieve them for us in an application?

Answer 1

With the latest version 1.2 of the GenericKeychain sample Apple provides a keychain wrapper that also runs on the iPhone Simulator. Check out at this article for details: http://dev-metal.blogspot.com/2010/08/howto-use-keychain-in-iphone-sdk-to.html

Answer 2

Also remember that when generating an AppID, if you want more than one application to access the same Keychain information, you have to generate a wild card AppID (#####.com.prefix.*)...

Answer 3

I really like Buzz Anderson's Keychain abstraction layer and I eagerly await Jens Alfke's MYCrypto to reach a usable state. The latter does a competent job of allowing use on Mac OS X and the iPhone using the same code, though its features only mimic a small subset of the Keychain's.

Answer 4

There is a keychain you can use - for code, the best bet is to check out the GenericKeychain sample application from Apple:

GenericKeychain sample

Answer 5

Here is what i use to store Key/Value pairs in the keychain. Make sure to add Security.framework to your project

#import <Security/Security.h>

// -------------------------------------------------------------------------
-(NSString *)getSecureValueForKey:(NSString *)key {
    /*

     Return a value from the keychain

     */

    // Retrieve a value from the keychain
    NSDictionary *result;
    NSArray *keys = [[[NSArray alloc] initWithObjects: (NSString *) kSecClass, kSecAttrAccount, kSecReturnAttributes, nil] autorelease];
    NSArray *objects = [[[NSArray alloc] initWithObjects: (NSString *) kSecClassGenericPassword, key, kCFBooleanTrue, nil] autorelease];
    NSDictionary *query = [[NSDictionary alloc] initWithObjects: objects forKeys: keys];

    // Check if the value was found
    OSStatus status = SecItemCopyMatching((CFDictionaryRef) query, (CFTypeRef *) &result);
    [query release];
    if (status != noErr) {
        // Value not found
        return nil;
    } else {
        // Value was found so return it
        NSString *value = (NSString *) [result objectForKey: (NSString *) kSecAttrGeneric];
        return value;
    }
}




// -------------------------------------------------------------------------
-(bool)storeSecureValue:(NSString *)value forKey:(NSString *)key {
    /*

     Store a value in the keychain

     */

    // Get the existing value for the key
    NSString *existingValue = [self getSecureValueForKey:key];

    // Check if a value already exists for this key
    OSStatus status;
    if (existingValue) {
        // Value already exists, so update it
        NSArray *keys = [[[NSArray alloc] initWithObjects: (NSString *) kSecClass, kSecAttrAccount, nil] autorelease];
        NSArray *objects = [[[NSArray alloc] initWithObjects: (NSString *) kSecClassGenericPassword, key, nil] autorelease];
        NSDictionary *query = [[[NSDictionary alloc] initWithObjects: objects forKeys: keys] autorelease];
        status = SecItemUpdate((CFDictionaryRef) query, (CFDictionaryRef) [NSDictionary dictionaryWithObject:value forKey: (NSString *) kSecAttrGeneric]);
    } else {
        // Value does not exist, so add it
        NSArray *keys = [[[NSArray alloc] initWithObjects: (NSString *) kSecClass, kSecAttrAccount, kSecAttrGeneric, nil] autorelease];
        NSArray *objects = [[[NSArray alloc] initWithObjects: (NSString *) kSecClassGenericPassword, key, value, nil] autorelease];
        NSDictionary *query = [[[NSDictionary alloc] initWithObjects: objects forKeys: keys] autorelease];
        status = SecItemAdd((CFDictionaryRef) query, NULL);
    }

    // Check if the value was stored
    if (status != noErr) {
        // Value was not stored
        return false;
    } else {
        // Value was stored
        return true;
    }
}

It is worth noting that these key/values will not get deleted if the user deletes your app. If a user deletes your app, then reinstalls it, the key/values will still be accessible.

Answer 6

One other thing to note: the keychain APIs don't work in the simulator when using older versions (2.x, 3.x) of the iPhone SDK. This could save you a lot of frustration when testing!