1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
|
/*
* HOTP
* (C) 2017 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_HOTP_H__
#define BOTAN_HOTP_H__
#include <botan/mac.h>
namespace Botan {
/**
* HOTP one time passwords (RFC 4226)
*/
class BOTAN_PUBLIC_API(2,2) HOTP
{
public:
/**
* @param key the secret key shared between client and server
* @param hash_algo the hash algorithm to use, should be SHA-1 or SHA-256
* @param digits the number of digits in the OTP (must be 6, 7, or 8)
*/
HOTP(const SymmetricKey& key, const std::string& hash_algo = "SHA-1", size_t digits = 6);
/**
* Generate the HOTP for a particular counter value
* @warning if the counter value is repeated the OTP ceases to be one-time
*/
uint32_t generate_hotp(uint64_t counter);
/**
* Check an OTP value using a starting counter and a resync range
* @param otp the client provided OTP
* @param starting_counter the server's guess as to the current counter state
* @param resync_range if 0 then only HOTP(starting_counter) is accepted
* If larger than 0, up to resync_range values after HOTP are also checked.
* @return (valid,next_counter). If the OTP does not validate, always
* returns (false,starting_counter). Otherwise returns (true,next_counter)
* where next_counter is at most starting_counter + resync_range + 1
*/
std::pair<bool,uint64_t> verify_hotp(uint32_t otp, uint64_t starting_counter, size_t resync_range = 0);
private:
std::unique_ptr<MessageAuthenticationCode> m_mac;
uint32_t m_digit_mod;
};
}
#endif
|
