view libtommath/bn_s_mp_get_bit.c @ 1705:5b701bf529aa

Fix ChaCha20 on 32-bit platforms (#99) * Fix ChaCha20 on 32-bit platforms On 32-bit platforms with old compiler STORE64H() parameter is not auto-expanded to 64-bit value, causing wrong IV data. Spotted on BCM4706 MIPS32r2 with GCC 4.2.4: Exit before auth: Integrity error (bad packet size 2065808956) * Fix Chacha20-Poly1305 and AES-GCM debug messages Functions were renamed earlier and trace messages - not.
author Vladislav Grishenko <themiron@users.noreply.github.com>
date Fri, 29 May 2020 18:26:22 +0500
parents 1051e4eea25a
children
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#include "tommath_private.h"
#ifdef BN_S_MP_GET_BIT_C

/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */

/* Get bit at position b and return MP_YES if the bit is 1, MP_NO if it is 0 */
mp_bool s_mp_get_bit(const mp_int *a, unsigned int b)
{
   mp_digit bit;
   int limb = (int)(b / MP_DIGIT_BIT);

   if (limb >= a->used) {
      return MP_NO;
   }

   bit = (mp_digit)1 << (b % MP_DIGIT_BIT);
   return ((a->dp[limb] & bit) != 0u) ? MP_YES : MP_NO;
}

#endif