FRAOathMechanism.m revision 415243fbc81341293a852ff6aa14e9608d08685c
/*
* The contents of this file are subject to the terms of the Common Development and
* Distribution License (the License). You may not use this file except in compliance with the
* License.
*
* You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
* specific language governing permission and limitations under the License.
*
* When distributing Covered Software, include this CDDL Header Notice in each file and include
* the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
* Header, with the fields enclosed by brackets [] replaced by your own identifying
* information: "Portions copyright [year] [name of copyright owner]".
*
* Copyright 2016 ForgeRock AS.
*
* Portions Copyright 2014 Nathaniel McCallum, Red Hat
*/
#import "FRAIdentityDatabase.h"
#import "FRAOathMechanism.h"
#import "FRAOathCode.h"
#import "FRAModelObjectProtected.h"
#include <CommonCrypto/CommonHMAC.h>
#include <sys/time.h>
#include "base32.h"
@implementation FRAOathMechanism {
CCHmacAlgorithm algo;
NSData* key;
uint64_t counter;
uint32_t period;
}
#pragma mark -
#pragma mark Lifecyle
- (instancetype)initWithDatabase:(FRAIdentityDatabase *)database type:(NSString *)type usingSecretKey:(NSData *)secretKey andHMACAlgorithm:(CCHmacAlgorithm)algorithm withKeyLength:(NSUInteger)digits andEitherPeriod:(NSUInteger)timePeriod orCounter:(NSUInteger)hmacCounter {
self = [super initWithDatabase:database];
if (self) {
_type = type;
key = secretKey;
algo = algorithm;
_digits = digits;
period = timePeriod;
counter = hmacCounter;
_version = 1;
}
return self;
}
+ (instancetype)oathMechanismWithDatabase:(FRAIdentityDatabase *)database type:(NSString *)type usingSecretKey:(NSData *)secretKey andHMACAlgorithm:(CCHmacAlgorithm)algorithm withKeyLength:(NSUInteger)digits andEitherPeriod:(NSUInteger)period orCounter:(NSUInteger)counter {
return [[FRAOathMechanism alloc] initWithDatabase:database type:type usingSecretKey:secretKey andHMACAlgorithm:algorithm withKeyLength:digits andEitherPeriod:period orCounter:counter];
}
- (void)generateNextCode {
time_t now = time(NULL);
if (now == (time_t) -1) {
now = 0;
}
if ([_type isEqualToString:@"hotp"]) {
NSString* code = getHOTP(algo, _digits, key, counter++);
uint64_t startTime = now;
uint64_t endTime = startTime + period;
_code = [[FRAOathCode alloc] initWithValue:code startTime:startTime endTime:endTime];
[self.database updateMechanism:self];
} if ([_type isEqualToString:@"totp"]) {
NSString* code = getHOTP(algo, _digits, key, now / period);
uint64_t startTime = now / period * period;
uint64_t endTime = startTime + period;
_code = [[FRAOathCode alloc] initWithValue:code startTime:startTime endTime:endTime];
}
}
#pragma mark --
#pragma mark FRAOathMechanism (static private)
static inline size_t getDigestLength(CCHmacAlgorithm algo) {
switch (algo) {
case kCCHmacAlgMD5:
return CC_MD5_DIGEST_LENGTH;
case kCCHmacAlgSHA256:
return CC_SHA256_DIGEST_LENGTH;
case kCCHmacAlgSHA512:
return CC_SHA512_DIGEST_LENGTH;
case kCCHmacAlgSHA1:
default:
return CC_SHA1_DIGEST_LENGTH;
}
}
static NSString* getHOTP(CCHmacAlgorithm algo, uint8_t digits, NSData* key, uint64_t counter) {
#ifdef __LITTLE_ENDIAN__
// Network byte order
counter = (((uint64_t) htonl(counter)) << 32) + htonl(counter >> 32);
#endif
// Create digits divisor
uint32_t div = 1;
for (int i = digits; i > 0; i--) {
div *= 10;
}
// Create the HMAC
uint8_t digest[getDigestLength(algo)];
CCHmac(algo, [key bytes], [key length], &counter, sizeof(counter), digest);
// Truncate
uint32_t binary;
uint32_t off = digest[sizeof(digest) - 1] & 0xf;
binary = (digest[off + 0] & 0x7f) << 0x18;
binary |= (digest[off + 1] & 0xff) << 0x10;
binary |= (digest[off + 2] & 0xff) << 0x08;
binary |= (digest[off + 3] & 0xff) << 0x00;
binary = binary % div;
return [NSString stringWithFormat:[NSString stringWithFormat:@"%%0%hhulu", digits], binary];
}
@end