sha3-shake.c

   1 /* sha3-shake.c
   2
   3    Copyright (C) 2017, 2024 Daiki Ueno
   4    Copyright (C) 2017 Red Hat, Inc.
   5    Copyright (C) 2024 Niels Möller
   6
   7    This file is part of GNU Nettle.
   8
   9    GNU Nettle is free software: you can redistribute it and/or
  10    modify it under the terms of either:
  11
  12      * the GNU Lesser General Public License as published by the Free
  13        Software Foundation; either version 3 of the License, or (at your
  14        option) any later version.
  15
  16    or
  17
  18      * the GNU General Public License as published by the Free
  19        Software Foundation; either version 2 of the License, or (at your
  20        option) any later version.
  21
  22    or both in parallel, as here.
  23
  24    GNU Nettle is distributed in the hope that it will be useful,
  25    but WITHOUT ANY WARRANTY; without even the implied warranty of
  26    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  27    General Public License for more details.
  28
  29    You should have received copies of the GNU General Public License and
  30    the GNU Lesser General Public License along with this program.  If
  31    not, see http://www.gnu.org/licenses/.
  32 */
  33
  34 #if HAVE_CONFIG_H
  35 # include "config.h"
  36 #endif
  37
  38 #include <assert.h>
  39 #include <string.h>
  40
  41 #include "sha3.h"
  42 #include "sha3-internal.h"
  43
  44 #include "nettle-write.h"
  45
  46 void
  47 _nettle_sha3_shake (struct sha3_state *state,
  48                     unsigned block_size, uint8_t *block,
  49                     unsigned index,
  50                     size_t length, uint8_t *dst)
  51 {
  52   _sha3_pad_shake (state, block_size, block, index);
  53
  54   while (length > block_size)
  55     {
  56       sha3_permute (state);
  57       _nettle_write_le64 (block_size, dst, state->a);
  58       length -= block_size;
  59       dst += block_size;
  60     }
  61
  62   sha3_permute (state);
  63   _nettle_write_le64 (length, dst, state->a);
  64 }
  65
  66 unsigned
  67 _nettle_sha3_shake_output (struct sha3_state *state,
  68                            unsigned block_size, uint8_t *block,
  69                            unsigned index,
  70                            size_t length, uint8_t *dst)
  71 {
  72   unsigned left;
  73
  74   /* We use one's complement of the index value to indicate SHAKE is
  75      initialized. */
  76   if (index < block_size)
  77     {
  78       /* This is the first call of _shake_output.  */
  79       _sha3_pad_shake (state, block_size, block, index);
  80       /* Point at the end of block to trigger fill in of the buffer.  */
  81       index = block_size;
  82     }
  83   else
  84     index = ~index;
  85
  86   assert (index <= block_size);
  87
  88   /* Write remaining data from the buffer.  */
  89   left = block_size - index;
  90   if (length <= left)
  91     {
  92       memcpy (dst, block + index, length);
  93       return ~(index + length);
  94     }
  95   else
  96     {
  97       memcpy (dst, block + index, left);
  98       length -= left;
  99       dst += left;
 100     }
 101
 102   /* Write full blocks.  */
 103   while (length > block_size)
 104     {
 105       sha3_permute (state);
 106       _nettle_write_le64 (block_size, dst, state->a);
 107       length -= block_size;
 108       dst += block_size;
 109     }
 110
 111   sha3_permute (state);
 112   /* Fill in the buffer for next call.  */
 113   _nettle_write_le64 (block_size, block, state->a);
 114   memcpy (dst, block, length);
 115   return ~length;
 116 }