Secure code by using NSSecureCoding instead of NSCoding

[guraghav]

Hello,

Created this issue to address the vulnerability with using NSCoding. The NSCoding does not verify the type of object upon deserialization and therefore is vulnerable to object substitution attacks.

To mitigate this vulnerability, Apple introduced the NSSecureCoding protocol along with the following secure methods of NSKeyedArchiver and NSKeyedUnarchiver, which are robust against this type of attack:

// Secure NSKeyedUnarchiver methods
- (instancetype)initForReadingFromData:(NSData *)data error:(NSError **)error;
+ (id)unarchivedObjectOfClass:(Class)cls fromData:(NSData *)data error:(NSError **)error;
+ (id)unarchivedObjectOfClasses:(NSSet<Class> *)classes fromData:(NSData *)data error:(NSError **)error;

// Secure NSKeyedArchiver methods
- (instancetype)initRequiringSecureCoding:(BOOL)requiresSecureCoding;
+ (NSData *)archivedDataWithRootObject:(id)object requiringSecureCoding:(BOOL)requiresSecureCoding error:(NSError **)error;

Apple provides more information in the WWDC20 session, 'Securing Your App'.

Various Places where NSCoding is being used: https://github.com/pinterest/PINCache/search?q=NSCoding