box-auth0-swift-skeleton-app-sample/Carthage/Checkouts/Auth0.swift/Auth0/A0ChallengeGenerator.m
// A0ChallengeGenerator.m
//
// Copyright (c) 2016 Auth0 (http://auth0.com)
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

#import "A0ChallengeGenerator.h"
#import <CommonCrypto/CommonCrypto.h>

const NSUInteger kVerifierSize = 32;

@implementation A0SHA256ChallengeGenerator

- (instancetype)init {
    NSMutableData *data = [NSMutableData dataWithLength:kVerifierSize];
    int result __attribute__((unused)) = SecRandomCopyBytes(kSecRandomDefault, kVerifierSize, data.mutableBytes);
    return [self initWithVerifier:data];
}

- (instancetype)initWithVerifier:(NSData *)verifier {
    self = [super init];
    if (self) {
        _verifier = [[[[verifier base64EncodedStringWithOptions:0]
                       stringByReplacingOccurrencesOfString:@"+" withString:@"-"]
                      stringByReplacingOccurrencesOfString:@"/" withString:@"_"]
                     stringByTrimmingCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:@"="]];
        _method = @"S256";
    }
    return self;
}

- (NSString *)challenge {
    CC_SHA256_CTX ctx;

    uint8_t * hashBytes = malloc(CC_SHA256_DIGEST_LENGTH * sizeof(uint8_t));
    memset(hashBytes, 0x0, CC_SHA256_DIGEST_LENGTH);

    NSData *valueData = [self.verifier dataUsingEncoding:NSUTF8StringEncoding];

    CC_SHA256_Init(&ctx);
    CC_SHA256_Update(&ctx, [valueData bytes], (CC_LONG)[valueData length]);
    CC_SHA256_Final(hashBytes, &ctx);

    NSData *hash = [NSData dataWithBytes:hashBytes length:CC_SHA256_DIGEST_LENGTH];

    if (hashBytes) {
        free(hashBytes);
    }

    return [[[[hash base64EncodedStringWithOptions:0]
              stringByReplacingOccurrencesOfString:@"+" withString:@"-"]
             stringByReplacingOccurrencesOfString:@"/" withString:@"_"]
            stringByTrimmingCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:@"="]];
}
@end
