LCOV - code coverage report
Current view: top level - lib - chacha.c (source / functions) Hit Total Coverage
Test: gcov_data_raspi2_real_modules_combined.info Lines: 43 49 87.8 %
Date: 2020-09-30 20:25:40 Functions: 2 3 66.7 %
Branches: 5 8 62.5 %

           Branch data     Line data    Source code
       1                 :            : // SPDX-License-Identifier: GPL-2.0-or-later
       2                 :            : /*
       3                 :            :  * The "hash function" used as the core of the ChaCha stream cipher (RFC7539)
       4                 :            :  *
       5                 :            :  * Copyright (C) 2015 Martin Willi
       6                 :            :  */
       7                 :            : 
       8                 :            : #include <linux/kernel.h>
       9                 :            : #include <linux/export.h>
      10                 :            : #include <linux/bitops.h>
      11                 :            : #include <linux/cryptohash.h>
      12                 :            : #include <asm/unaligned.h>
      13                 :            : #include <crypto/chacha.h>
      14                 :            : 
      15                 :    1480362 : static void chacha_permute(u32 *x, int nrounds)
      16                 :            : {
      17                 :            :         int i;
      18                 :            : 
      19                 :            :         /* whitelist the allowed round counts */
      20   [ -  +  #  # ]:    1480362 :         WARN_ON_ONCE(nrounds != 20 && nrounds != 12);
      21                 :            : 
      22         [ +  + ]:   14803620 :         for (i = 0; i < nrounds; i += 2) {
      23                 :   29607240 :                 x[0]  += x[4];    x[12] = rol32(x[12] ^ x[0],  16);
      24                 :   29607240 :                 x[1]  += x[5];    x[13] = rol32(x[13] ^ x[1],  16);
      25                 :   29607240 :                 x[2]  += x[6];    x[14] = rol32(x[14] ^ x[2],  16);
      26                 :   29607240 :                 x[3]  += x[7];    x[15] = rol32(x[15] ^ x[3],  16);
      27                 :            : 
      28                 :   29607240 :                 x[8]  += x[12];   x[4]  = rol32(x[4]  ^ x[8],  12);
      29                 :   29607240 :                 x[9]  += x[13];   x[5]  = rol32(x[5]  ^ x[9],  12);
      30                 :   29607240 :                 x[10] += x[14];   x[6]  = rol32(x[6]  ^ x[10], 12);
      31                 :   29607240 :                 x[11] += x[15];   x[7]  = rol32(x[7]  ^ x[11], 12);
      32                 :            : 
      33                 :   29607240 :                 x[0]  += x[4];    x[12] = rol32(x[12] ^ x[0],   8);
      34                 :   29607240 :                 x[1]  += x[5];    x[13] = rol32(x[13] ^ x[1],   8);
      35                 :   29607240 :                 x[2]  += x[6];    x[14] = rol32(x[14] ^ x[2],   8);
      36                 :   29607240 :                 x[3]  += x[7];    x[15] = rol32(x[15] ^ x[3],   8);
      37                 :            : 
      38                 :   29607240 :                 x[8]  += x[12];   x[4]  = rol32(x[4]  ^ x[8],   7);
      39                 :   29607240 :                 x[9]  += x[13];   x[5]  = rol32(x[5]  ^ x[9],   7);
      40                 :   29607240 :                 x[10] += x[14];   x[6]  = rol32(x[6]  ^ x[10],  7);
      41                 :   29607240 :                 x[11] += x[15];   x[7]  = rol32(x[7]  ^ x[11],  7);
      42                 :            : 
      43                 :   29607240 :                 x[0]  += x[5];    x[15] = rol32(x[15] ^ x[0],  16);
      44                 :   29607240 :                 x[1]  += x[6];    x[12] = rol32(x[12] ^ x[1],  16);
      45                 :   29607240 :                 x[2]  += x[7];    x[13] = rol32(x[13] ^ x[2],  16);
      46                 :   29607240 :                 x[3]  += x[4];    x[14] = rol32(x[14] ^ x[3],  16);
      47                 :            : 
      48                 :   29607240 :                 x[10] += x[15];   x[5]  = rol32(x[5]  ^ x[10], 12);
      49                 :   29607240 :                 x[11] += x[12];   x[6]  = rol32(x[6]  ^ x[11], 12);
      50                 :   29607240 :                 x[8]  += x[13];   x[7]  = rol32(x[7]  ^ x[8],  12);
      51                 :   29607240 :                 x[9]  += x[14];   x[4]  = rol32(x[4]  ^ x[9],  12);
      52                 :            : 
      53                 :   29607240 :                 x[0]  += x[5];    x[15] = rol32(x[15] ^ x[0],   8);
      54                 :   29607240 :                 x[1]  += x[6];    x[12] = rol32(x[12] ^ x[1],   8);
      55                 :   29607240 :                 x[2]  += x[7];    x[13] = rol32(x[13] ^ x[2],   8);
      56                 :   29607240 :                 x[3]  += x[4];    x[14] = rol32(x[14] ^ x[3],   8);
      57                 :            : 
      58                 :   29607240 :                 x[10] += x[15];   x[5]  = rol32(x[5]  ^ x[10],  7);
      59                 :   29607240 :                 x[11] += x[12];   x[6]  = rol32(x[6]  ^ x[11],  7);
      60                 :   29607240 :                 x[8]  += x[13];   x[7]  = rol32(x[7]  ^ x[8],   7);
      61                 :   29607240 :                 x[9]  += x[14];   x[4]  = rol32(x[4]  ^ x[9],   7);
      62                 :            :         }
      63                 :    1480362 : }
      64                 :            : 
      65                 :            : /**
      66                 :            :  * chacha_block - generate one keystream block and increment block counter
      67                 :            :  * @state: input state matrix (16 32-bit words)
      68                 :            :  * @stream: output keystream block (64 bytes)
      69                 :            :  * @nrounds: number of rounds (20 or 12; 20 is recommended)
      70                 :            :  *
      71                 :            :  * This is the ChaCha core, a function from 64-byte strings to 64-byte strings.
      72                 :            :  * The caller has already converted the endianness of the input.  This function
      73                 :            :  * also handles incrementing the block counter in the input matrix.
      74                 :            :  */
      75                 :    1480362 : void chacha_block(u32 *state, u8 *stream, int nrounds)
      76                 :            : {
      77                 :            :         u32 x[16];
      78                 :            :         int i;
      79                 :            : 
      80                 :    1480362 :         memcpy(x, state, 64);
      81                 :            : 
      82                 :    1480362 :         chacha_permute(x, nrounds);
      83                 :            : 
      84         [ +  + ]:   25166154 :         for (i = 0; i < ARRAY_SIZE(x); i++)
      85                 :   23685792 :                 put_unaligned_le32(x[i] + state[i], &stream[i * sizeof(u32)]);
      86                 :            : 
      87                 :    1480362 :         state[12]++;
      88                 :    1480362 : }
      89                 :            : EXPORT_SYMBOL(chacha_block);
      90                 :            : 
      91                 :            : /**
      92                 :            :  * hchacha_block - abbreviated ChaCha core, for XChaCha
      93                 :            :  * @in: input state matrix (16 32-bit words)
      94                 :            :  * @out: output (8 32-bit words)
      95                 :            :  * @nrounds: number of rounds (20 or 12; 20 is recommended)
      96                 :            :  *
      97                 :            :  * HChaCha is the ChaCha equivalent of HSalsa and is an intermediate step
      98                 :            :  * towards XChaCha (see https://cr.yp.to/snuffle/xsalsa-20081128.pdf).  HChaCha
      99                 :            :  * skips the final addition of the initial state, and outputs only certain words
     100                 :            :  * of the state.  It should not be used for streaming directly.
     101                 :            :  */
     102                 :          0 : void hchacha_block(const u32 *in, u32 *out, int nrounds)
     103                 :            : {
     104                 :            :         u32 x[16];
     105                 :            : 
     106                 :          0 :         memcpy(x, in, 64);
     107                 :            : 
     108                 :          0 :         chacha_permute(x, nrounds);
     109                 :            : 
     110                 :          0 :         memcpy(&out[0], &x[0], 16);
     111                 :          0 :         memcpy(&out[4], &x[12], 16);
     112                 :          0 : }
     113                 :            : EXPORT_SYMBOL(hchacha_block);

Generated by: LCOV version 1.14