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/*
* HOTP/TOTP
* (C) 2017 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_ONE_TIME_PASSWORDS_H_
#define BOTAN_ONE_TIME_PASSWORDS_H_
#include <botan/mac.h>
#include <chrono>
namespace Botan {
/**
* HOTP one time passwords (RFC 4226)
*/
class BOTAN_PUBLIC_API(2,2) HOTP final
{
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) :
HOTP(key.begin(), key.size(), hash_algo, digits) {}
/**
* @param key the secret key shared between client and server
* @param key_len length of key param
* @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 uint8_t key[], size_t key_len,
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;
};
/**
* TOTP (time based) one time passwords (RFC 6238)
*/
class BOTAN_PUBLIC_API(2,2) TOTP final
{
public:
/**
* @param key the secret key shared between client and server
* @param hash_algo the hash algorithm to use, should be SHA-1, SHA-256 or SHA-512
* @param digits the number of digits in the OTP (must be 6, 7, or 8)
* @param time_step granularity of OTP in seconds
*/
TOTP(const SymmetricKey& key,
const std::string& hash_algo = "SHA-1",
size_t digits = 6, size_t time_step = 30) :
TOTP(key.begin(), key.size(), hash_algo, digits, time_step) {}
/**
* @param key the secret key shared between client and server
* @param key_len length of key
* @param hash_algo the hash algorithm to use, should be SHA-1, SHA-256 or SHA-512
* @param digits the number of digits in the OTP (must be 6, 7, or 8)
* @param time_step granularity of OTP in seconds
*/
TOTP(const uint8_t key[], size_t key_len,
const std::string& hash_algo = "SHA-1",
size_t digits = 6,
size_t time_step = 30);
/**
* Convert the provided time_point to a Unix timestamp and call generate_totp
*/
uint32_t generate_totp(std::chrono::system_clock::time_point time_point);
/**
* Generate the OTP corresponding the the provided "Unix timestamp" (ie
* number of seconds since midnight Jan 1, 1970)
*/
uint32_t generate_totp(uint64_t unix_time);
bool verify_totp(uint32_t otp,
std::chrono::system_clock::time_point time,
size_t clock_drift_accepted = 0);
bool verify_totp(uint32_t otp, uint64_t unix_time,
size_t clock_drift_accepted = 0);
private:
HOTP m_hotp;
size_t m_time_step;
std::chrono::system_clock::time_point m_unix_epoch;
};
}
#endif