totp algorithm
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priscilla
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468006c60b
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@ -591,7 +591,17 @@ enum TALER_MerchantConfirmationAlgorithm
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/**
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* No purchase confirmation.
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*/
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TALER_MCA_NONE = 0
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TALER_MCA_NONE = 0,
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/**
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* Purchase confirmation without payment
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*/
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TALER_MCA_WITHOUT_PRICE = 1,
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/**
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* Purchase confirmation with payment
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*/
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TALER_MCA_WITH_PRICE = 2
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};
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@ -939,7 +949,13 @@ GNUNET_NETWORK_STRUCT_END
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/**
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* FIXME.
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* It is build pos confirmation to verify paiement.
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*
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* @param pos_key encoded key for verification payment
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* @param pos_alg algorithm to compute the payment verification
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* @param total of the order paid
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* @parmam ts is the time given
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*
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*/
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char *
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TALER_build_pos_confirmation (const char *pos_key,
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@ -17,23 +17,283 @@
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* @file util/crypto_confirmation.c
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* @brief confirmation computation
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* @author Christian Grothoff
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* @author Priscilla Huang
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*/
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#include "platform.h"
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#include "taler_util.h"
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#include <taler/taler_mhd_lib.h>
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#include <gnunet/gnunet_db_lib.h>
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#include <gcrypt.h>
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/**
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* How long is a TOTP code valid?
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*/
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#define TOTP_VALIDITY_PERIOD GNUNET_TIME_relative_multiply ( \
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GNUNET_TIME_UNIT_SECONDS, 30)
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/**
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* Range of time we allow (plus-minus).
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*/
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#define TIME_INTERVAL_RANGE 2
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/**
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* Compute TOTP code at current time with offset
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* @a time_off for the @a key.
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*
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* @param ts current time
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* @param time_off offset to apply when computing the code
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* @param key pos_key in binary
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* @param key_size number of bytes in @a key
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*/
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static uint64_t
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compute_totp (struct GNUNET_TIME_Timestamp ts,
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int time_off,
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const void *key,
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size_t key_size)
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{
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struct GNUNET_TIME_Absolute now;
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time_t t;
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uint64_t ctr;
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uint8_t hmac[20]; /* SHA1: 20 bytes */
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now = ts.abs_time;
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while (time_off < 0)
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{
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now = GNUNET_TIME_absolute_subtract (now,
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TOTP_VALIDITY_PERIOD);
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time_off++;
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}
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while (time_off > 0)
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{
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now = GNUNET_TIME_absolute_add (now,
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TOTP_VALIDITY_PERIOD);
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time_off--;
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}
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t = now.abs_value_us / GNUNET_TIME_UNIT_SECONDS.rel_value_us;
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ctr = GNUNET_htonll (t / 30LLU);
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{
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gcry_md_hd_t md;
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const unsigned char *mc;
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GNUNET_assert (GPG_ERR_NO_ERROR ==
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gcry_md_open (&md,
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GCRY_MD_SHA1,
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GCRY_MD_FLAG_HMAC));
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gcry_md_setkey (md,
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key,
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key_size);
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gcry_md_write (md,
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&ctr,
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sizeof (ctr));
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mc = gcry_md_read (md,
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GCRY_MD_SHA1);
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GNUNET_assert (NULL != mc);
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memcpy (hmac,
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mc,
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sizeof (hmac));
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gcry_md_close (md);
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}
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{
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uint32_t code = 0;
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int offset;
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offset = hmac[sizeof (hmac) - 1] & 0x0f;
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for (int count = 0; count < 4; count++)
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code |= hmac[offset + 3 - count] << (8 * count);
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code &= 0x7fffffff;
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/* always use 8 digits (maximum) */
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code = code % 100000000;
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return code;
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}
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}
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/**
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* Compute RFC 3548 base32 decoding of @a val and write
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* result to @a udata.
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*
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* @param val value to decode
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* @param val_size number of bytes in @a val
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* @param key is the val in bits
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* @param key_len is the size of @a key
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*/
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static int
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base32decode (const char *val,
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size_t val_size,
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void *key,
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size_t key_len)
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{
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/**
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* 32 characters for decoding, using RFC 3548.
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*/
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static const char *decTable__ = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
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unsigned int wpos;
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unsigned int rpos;
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unsigned int bits;
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unsigned int vbit;
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unsigned char *udata;
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udata = val;
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vbit = 0;
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wpos = 0;
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rpos = 0;
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bits = 0;
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while ((rpos < val_size) || (vbit >= 8))
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{
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if ((rpos < val_size) && (vbit < 8))
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{
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char c = val[rpos++];
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if (c == '=') { // padding character
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break;
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}
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const char *p = strchr(decTable__, toupper(c));
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if (! p)
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{ // invalid character
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return -1;
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}
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bits = (bits << 5) | (p - decTable__);
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vbit += 5;
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}
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if (vbit >= 8)
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{
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udata[wpos++] = (bits >> (vbit - 8)) & 0xFF;
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vbit -= 8;
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}
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}
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return wpos;
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}
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/**
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* It is build pos confirmation to verify payment.
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*
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* @param pos_key base32 (RFC 3548, not Crockford!) encoded key for verification payment
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* @param pos_alg algorithm to compute the payment verification
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* @param total of the order paid
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* @param ts is the current time given
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*/
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char *
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TALER_build_pos_confirmation (const char *pos_key,
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enum TALER_MerchantConfirmationAlgorithm pos_alg,
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const struct TALER_Amount *total,
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struct GNUNET_TIME_Timestamp ts)
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{
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size_t pos_key_length = strlen (pos_key);
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void *key; /* pos_key in binary */
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size_t key_len; /* lengh of the key */
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uint64_t code; /* totp code */
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char *ret;
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int dret;
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if (TALER_MCA_NONE == pos_alg)
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return NULL;
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key_len = pos_key_length * 5 / 8;
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key = GNUNET_malloc (key_len);
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dret = base32decode (pos_key,
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pos_key_length,
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key,
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key_len);
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if (-1 == dret)
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{
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GNUNET_free (key);
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GNUNET_break_op (0);
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return NULL;
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}
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GNUNET_assert (dret <= key_len);
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key_len = (size_t) dret;
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switch (pos_alg)
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{
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case TALER_MCA_NONE:
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return NULL;
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}
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GNUNET_break (0); // FIXME: not implemented
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GNUNET_break (0);
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GNUNET_free (key);
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return NULL;
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case TALER_MCA_WITHOUT_PRICE: /* and 30s */
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ret = NULL;
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/* Return all T-OTP codes in range separated by new lines, e.g.
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"12345678
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24522552
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25262425
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42543525
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25253552"
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*/
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for (int i = -TIME_INTERVAL_RANGE; i<= TIME_INTERVAL_RANGE; i++)
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{
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code = compute_totp (ts,
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i,
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key,
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key_len);
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if (NULL == ret)
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{
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GNUNET_asprintf (&ret,
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"%llu",
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(unsigned long long) code);
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}
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else
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{
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char *tmp;
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GNUNET_asprintf (&tmp,
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"%s\n%llu",
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ret,
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(unsigned long long) code);
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GNUNET_free (ret);
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ret = tmp;
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}
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}
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GNUNET_free (key);
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return ret;
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case TALER_MCA_WITH_PRICE:
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{
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struct GNUNET_HashCode hkey;
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struct TALER_AmountNBO ntotal;
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ret = NULL;
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TALER_amount_hton (&ntotal,
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total);
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GNUNET_assert (GNUNET_YES ==
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GNUNET_CRYPTO_kdf (&hkey,
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sizeof (hkey),
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&ntotal,
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sizeof (ntotal),
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key,
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key_len,
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NULL,
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0));
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GNUNET_free (key);
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for (int i = -TIME_INTERVAL_RANGE; i<= TIME_INTERVAL_RANGE; i++)
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{
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code = compute_totp (ts,
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i,
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&hkey,
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sizeof (hkey));
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if (NULL == ret)
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{
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GNUNET_asprintf (&ret,
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"%llu",
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(unsigned long long) code);
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}
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else
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{
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char *tmp;
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GNUNET_asprintf (&tmp,
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"%s\n%llu",
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ret,
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(unsigned long long) code);
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GNUNET_free (ret);
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ret = tmp;
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}
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}
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GNUNET_free (key);
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return ret;
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}
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}
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GNUNET_free (key);
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GNUNET_break (0);
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return NULL;
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}
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