#import <CommonCrypto/CommonCryptor.h>
#import <CommonCrypto/CommonDigest.h>
#import <CommonCrypto/CommonKeyDerivation.h>

#import "PBKDF2.h"

@implementation PBKDF2

+ (NSString *) toHex:(NSData *)nsdata {
    NSString * hexStr = [NSString stringWithFormat:@"%@", nsdata];
    for(NSString * toRemove in [NSArray arrayWithObjects:@"<", @">", @" ", nil])
        hexStr = [hexStr stringByReplacingOccurrencesOfString:toRemove withString:@""];
    return hexStr;
}

+ (NSString *) derivationKey:(NSString *)password salt: (NSString *)salt iterations: (nonnull int *)iterations {
    // Data of String to generate Hash key(hexa decimal string).
    NSData *passwordData = [password dataUsingEncoding:NSUTF8StringEncoding];
    NSData *saltData = [salt dataUsingEncoding:NSUTF8StringEncoding];

    // Hash key (hexa decimal) string data length.
    NSMutableData *hashKeyData = [NSMutableData dataWithLength:CC_SHA512_DIGEST_LENGTH];

    // Key Derivation using PBKDF2 algorithm.
    int status = CCKeyDerivationPBKDF(
                    kCCPBKDF2,
                    passwordData.bytes,
                    passwordData.length,
                    saltData.bytes,
                    saltData.length,
                    kCCPRFHmacAlgSHA512,
                    iterations,
                    hashKeyData.mutableBytes,
                    hashKeyData.length);

    if (status == kCCParamError) {
        NSLog(@"Key derivation error");
        return @"";
    }

    return [self toHex:hashKeyData];
}

@end