Botan 2.19.2
Crypto and TLS for C&
totp.cpp
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1/*
2* TOTP
3* (C) 2017 Jack Lloyd
4*
5* Botan is released under the Simplified BSD License (see license.txt)
6*/
7
8#include <botan/otp.h>
9#include <botan/calendar.h>
10
11namespace Botan {
12
13TOTP::TOTP(const uint8_t key[], size_t key_len,
14 const std::string& hash_algo,
15 size_t digits, size_t time_step)
16 : m_hotp(key, key_len, hash_algo, digits)
17 , m_time_step(time_step)
18 , m_unix_epoch(calendar_point(1970, 1, 1, 0, 0, 0).to_std_timepoint())
19 {
20 /*
21 * Technically any time step except 0 is valid, but 30 is typical
22 * and over 5 minutes seems unlikely.
23 */
24 BOTAN_ARG_CHECK(m_time_step > 0 && m_time_step < 300, "Invalid TOTP time step");
25 }
26
27uint32_t TOTP::generate_totp(std::chrono::system_clock::time_point current_time)
28 {
29 const uint64_t unix_time =
30 std::chrono::duration_cast<std::chrono::seconds>(current_time - m_unix_epoch).count();
31 return this->generate_totp(unix_time);
32 }
33
34uint32_t TOTP::generate_totp(uint64_t unix_time)
35 {
36 return m_hotp.generate_hotp(unix_time / m_time_step);
37 }
38
39bool TOTP::verify_totp(uint32_t otp, std::chrono::system_clock::time_point current_time,
40 size_t clock_drift_accepted)
41 {
42 const uint64_t unix_time =
43 std::chrono::duration_cast<std::chrono::seconds>(current_time - m_unix_epoch).count();
44 return verify_totp(otp, unix_time, clock_drift_accepted);
45 }
46
47bool TOTP::verify_totp(uint32_t otp, uint64_t unix_time,
48 size_t clock_drift_accepted)
49 {
50 uint64_t t = unix_time / m_time_step;
51
52 for(size_t i = 0; i <= clock_drift_accepted; ++i)
53 {
54 if(m_hotp.generate_hotp(t-i) == otp)
55 {
56 return true;
57 }
58 }
59
60 return false;
61 }
62
63}
#define BOTAN_ARG_CHECK(expr, msg)
Definition: assert.h:37
uint32_t generate_hotp(uint64_t counter)
Definition: hotp.cpp:42
uint32_t generate_totp(std::chrono::system_clock::time_point time_point)
Definition: totp.cpp:27
TOTP(const SymmetricKey &key, const std::string &hash_algo="SHA-1", size_t digits=6, size_t time_step=30)
Definition: otp.h:74
bool verify_totp(uint32_t otp, std::chrono::system_clock::time_point time, size_t clock_drift_accepted=0)
Definition: totp.cpp:39
Definition: alg_id.cpp:13
AlgorithmIdentifier hash_algo
Definition: x509_obj.cpp:22