taler-xotp_fw

xOTP generator firmware
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talerAmount.h (4723B)

      1 /**
      2  * @file talerAmount.h
      3  * @author Adrian STEINER (steia19@bfh.ch)
      4  * @author Sree Harsha Totakura <sreeharsha@totakura.in>
      5  * @brief Amount representation and utility function to handle the data.
      6  * This file consists of parts of the file taler_amount_lib.h
      7  * from the git repository https://git.gnunet.org/exchange.git.
      8  * This is used to generate the same hash.
      9  * The library cannot be used directly due to memory optimizations and MCU
     10  * runtime capability.
     11  * @version 0.1
     12  * @date 19-02-2025
     13  *
     14  * @copyright (C) 2025 Adrian STEINER
     15  * This program is free software: you can redistribute it and/or modify
     16  * it under the terms of the GNU General Public License as published by
     17  * the Free Software Foundation, either version 3 of the License, or
     18  * (at your option) any later version.
     19  *pbm_renderImage
     20  * This program is distributed in the hope that it will be useful,
     21  * but WITHOUT ANY WARRANTY; without even the implied warranty of
     22  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     23  * GNU General Public License for more details.
     24  *
     25  * You should have received a copy of the GNU General Public License
     26  * along with this program.  If not, see <https: //www.gnu.org/licenses/>.
     27  *
     28  */
     29 #ifndef TALER_AMOUNT_H
     30 #define TALER_AMOUNT_H
     31 
     32 #ifdef __cplusplus
     33 extern "C" {
     34 #endif
     35 
     36 #include "xtotpConfig.h"
     37 
     38 #include <stdbool.h>
     39 #include <stdint.h>
     40 /**
     41  * @brief Number of bytes to store a secret.
     42  *
     43  */
     44 #define TALER_SECRET_LEN (20)
     45 
     46 /**
     47  * @brief Max length of an base8 input of a secret
     48  *
     49  */
     50 #define TALER_SECRET_BASE8_LENGTH (((TALER_SECRET_LEN * 8) + 2) / 3)
     51 
     52 /**
     53  * @brief Number of characters (plus 1 for 0-termination) we use to
     54  * represent currency names (i.e. EUR, USD, etc.).  We use 8+4 for
     55  * alignment in the `struct TALER_Amount`.  The amount is typically an
     56  * ISO 4217 currency code when an alphanumeric 3-digit code is used.
     57  * For regional currencies, the first character should be a "*" followed
     58  * by a region-specific name (i.e. "*BRETAGNEFR").
     59  */
     60 #define TALER_CURRENCY_LEN (12)
     61 
     62 /**
     63  * @brief The "fraction" value in a `struct TALER_Amount` represents which
     64  * fraction of the "main" value.
     65  *
     66  * @note that we need sub-cent precision here as transaction fees might
     67  * be that low, and as we want to support microdonations.
     68  *
     69  * An actual `struct Amount a` thus represents
     70  * "a.value + (a.fraction / #TALER_AMOUNT_FRAC_BASE)" units of "a.currency".
     71  */
     72 #define TALER_AMOUNT_FRAC_BASE (100000000)
     73 
     74 /**
     75  * @brief How many digits behind the comma are required to represent the
     76  * fractional value in human readable decimal format?  Must match
     77  * lg(#TALER_AMOUNT_FRAC_BASE).
     78  */
     79 #define TALER_AMOUNT_FRAC_LEN (8)
     80 
     81 /**
     82  * @brief Defines the maximum of digits to be calculated.
     83  *
     84  */
     85 #define TALER_MAX_PASSCODE_LENGTH (8)
     86 
     87 /**
     88  * @brief Defines a packed attribute in a structure.
     89  * Packed avoids padding bytes.
     90  *
     91  */
     92 #define PACKED __attribute__((packed))
     93 
     94 /**
     95  * @brief Amount, encoded for network transmission.
     96  */
     97 typedef struct {
     98   uint64_t value PACKED;    ///< Value in the main currency, in NBO. */
     99   uint32_t fraction PACKED; ///< Fraction (integer multiples of
    100                             ///< #TALER_AMOUNT_FRAC_BASE), in NBO.
    101   uint8_t
    102       currency[TALER_CURRENCY_LEN]; ///< Type of the currency being represented.
    103 } TALER_AmountNBO;
    104 
    105 /**
    106  * @brief Taler extended data for xTOTP and autopay
    107  *
    108  */
    109 typedef struct {
    110   uint8_t currency[TALER_CURRENCY_LEN]; ///< Currency
    111   uint32_t fraction;                    ///< Fraction of currency
    112   uint8_t merchantTemplateName[XTOTP_MERCHANT_TEMPLATE_SIZE]; ///< Merchant
    113                                                               ///< template name
    114 } TALER_xData;
    115 
    116 /**
    117  * @brief Convert the amount to the needed @ref TALER_AmountNBO to calculate the
    118  * xTOTP passcode.
    119  *
    120  * @param target The target @ref TALER_AmountNBO structure
    121  * @param amountInfo xData reference to get the currency and the fraction of it
    122  * @param enteredAmount The entered amount to convert
    123  */
    124 void TALER_amount2AmountNBO(TALER_AmountNBO *target,
    125                             const TALER_xData *amountInfo,
    126                             const uint64_t enteredAmount);
    127 
    128 /**
    129  * @brief Initialise a @ref TALER_xDATA structure
    130  *
    131  * @param dataHandler The data structure to initlialise
    132  * @param currency The currency to add
    133  * @param fraction The fraction of the currency (e.g. 100 for Euro/CHF/Dollar)
    134  * @param templateName Linked template for auto paying, can be set or not(use
    135  * NULL or empty string)
    136  */
    137 void TALER_xDataInit(TALER_xData *dataHandler,
    138                      const uint8_t *currency,
    139                      uint32_t fraction,
    140                      const uint8_t *templateName);
    141 #ifdef __cplusplus
    142 }
    143 #endif
    144 
    145 #endif /* TALER_AMOUNT_H*/