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   1 // Bit-sliced Crypto-1 implementation
   2 // The cipher states are stored with the least significant bit first, hence all bit indexes are reversed here
   3 /*
   4 Copyright (c) 2015-2016 Aram Verstegen
   5
   6 Permission is hereby granted, free of charge, to any person obtaining a copy
   7 of this software and associated documentation files (the "Software"), to deal
   8 in the Software without restriction, including without limitation the rights
   9 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10 copies of the Software, and to permit persons to whom the Software is
  11 furnished to do so, subject to the following conditions:
  12
  13 The above copyright notice and this permission notice shall be included in
  14 all copies or substantial portions of the Software.
  15
  16 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  19 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22 THE SOFTWARE.
  23 */
  24
  25 #include "crypto1_bs.h"
  26 #include <inttypes.h>
  27 #define __STDC_FORMAT_MACROS
  28 #define llx PRIx64
  29 #define lli PRIi64
  30 #define lu PRIu32
  31
  32 // The following functions use this global or thread-local state
  33 // It is sized to fit exactly KEYSTREAM_SIZE more states next to the initial state
  34 __thread bitslice_t states[KEYSTREAM_SIZE+STATE_SIZE];
  35 __thread bitslice_t * restrict state_p;
  36
  37 void crypto1_bs_init(){
  38     // initialize constant one and zero bit vectors
  39     memset(bs_ones.bytes, 0xff, VECTOR_SIZE);
  40     memset(bs_zeroes.bytes, 0x00, VECTOR_SIZE);
  41 }
  42
  43 // The following functions have side effects on 48 bitslices at the state_p pointer
  44 // use the crypto1_bs_rewind_* macros to (re-)initialize them as needed
  45
  46 inline const bitslice_value_t crypto1_bs_bit(const bitslice_value_t input, const bool is_encrypted){
  47     bitslice_value_t feedback = (state_p[47- 0].value ^ state_p[47- 5].value ^ state_p[47- 9].value ^
  48                                  state_p[47-10].value ^ state_p[47-12].value ^ state_p[47-14].value ^
  49                                  state_p[47-15].value ^ state_p[47-17].value ^ state_p[47-19].value ^
  50                                  state_p[47-24].value ^ state_p[47-25].value ^ state_p[47-27].value ^
  51                                  state_p[47-29].value ^ state_p[47-35].value ^ state_p[47-39].value ^
  52                                  state_p[47-41].value ^ state_p[47-42].value ^ state_p[47-43].value);
  53     const bitslice_value_t ks_bits = crypto1_bs_f20(state_p);
  54     if(is_encrypted){
  55         feedback ^= ks_bits;
  56     }
  57     state_p--;
  58     state_p[0].value = feedback ^ input;
  59     return ks_bits;
  60 }
  61
  62 inline const bitslice_value_t crypto1_bs_lfsr_rollback(const bitslice_value_t input, const bool is_encrypted){
  63     bitslice_value_t feedout = state_p[0].value;
  64     state_p++;
  65     const bitslice_value_t ks_bits = crypto1_bs_f20(state_p);
  66     if(is_encrypted){
  67         feedout ^= ks_bits;
  68     }
  69     const bitslice_value_t feedback = (feedout              ^ state_p[47- 5].value ^ state_p[47- 9].value ^
  70                                        state_p[47-10].value ^ state_p[47-12].value ^ state_p[47-14].value ^
  71                                        state_p[47-15].value ^ state_p[47-17].value ^ state_p[47-19].value ^
  72                                        state_p[47-24].value ^ state_p[47-25].value ^ state_p[47-27].value ^
  73                                        state_p[47-29].value ^ state_p[47-35].value ^ state_p[47-39].value ^
  74                                        state_p[47-41].value ^ state_p[47-42].value ^ state_p[47-43].value);
  75     state_p[47].value = feedback ^ input;
  76     return ks_bits;
  77 }
  78
  79 // side-effect free from here on
  80 // note that bytes are sliced and unsliced with reversed endianness
  81 inline void crypto1_bs_convert_states(bitslice_t bitsliced_states[], state_t regular_states[]){
  82     size_t bit_idx = 0, slice_idx = 0;
  83         state_t values[MAX_BITSLICES];
  84         memset(values, 0x0, sizeof(values));
  85
  86     for(slice_idx = 0; slice_idx < MAX_BITSLICES; slice_idx++){
  87         for(bit_idx = 0; bit_idx < STATE_SIZE; bit_idx++){
  88             bool bit = get_vector_bit(slice_idx, bitsliced_states[bit_idx]);
  89             values[slice_idx].value <<= 1;
  90             values[slice_idx].value |= bit;
  91         }
  92         // swap endianness
  93         values[slice_idx].value = rev_state_t(values[slice_idx].value);
  94         // roll off unused bits
  95         //values[slice_idx].value >>= ((sizeof(state_t)*8)-STATE_SIZE); // - 48
  96                 values[slice_idx].value >>= 16;
  97     }
  98     memcpy(regular_states, values, sizeof(values));
  99 }
 100
 101 // bitslice a value
 102 void crypto1_bs_bitslice_value32(uint32_t value, bitslice_t bitsliced_value[], size_t bit_len){
 103     // load nonce bytes with unswapped endianness
 104     size_t bit_idx;
 105     for(bit_idx = 0; bit_idx < bit_len; bit_idx++){
 106         bool bit = get_bit(bit_len-1-bit_idx, rev32(value));
 107         if(bit){
 108             bitsliced_value[bit_idx].value = bs_ones.value;
 109         } else {
 110             bitsliced_value[bit_idx].value = bs_zeroes.value;
 111         }
 112     }
 113 }
 114
 115 void crypto1_bs_print_states(bitslice_t bitsliced_states[]){
 116     size_t slice_idx = 0;
 117     state_t values[MAX_BITSLICES]  = {{0x00}};
 118     crypto1_bs_convert_states(bitsliced_states, values);
 119     for(slice_idx = 0; slice_idx < MAX_BITSLICES; slice_idx++){
 120         printf("State %03zu: %012"llx"\n", slice_idx, values[slice_idx].value);
 121     }
 122 }
 123