annotate libtomcrypt/src/stream/chacha/chacha_setup.c @ 1860:5001e9c5641f

Merge netio changes
author Matt Johnston <matt@ucc.asn.au>
date Thu, 27 Jan 2022 15:09:29 +0800
parents 6dba84798cd5
children
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1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
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2 *
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3 * LibTomCrypt is a library that provides various cryptographic
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4 * algorithms in a highly modular and flexible manner.
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5 *
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6 * The library is free for all purposes without any express
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7 * guarantee it works.
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8 */
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9
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10 /* The implementation is based on:
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11 * chacha-ref.c version 20080118
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12 * Public domain from D. J. Bernstein
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13 */
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14
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15 #include "tomcrypt.h"
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16
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17 #ifdef LTC_CHACHA
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18
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19 static const char * const sigma = "expand 32-byte k";
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20 static const char * const tau = "expand 16-byte k";
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21
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22 /**
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23 Initialize an ChaCha context (only the key)
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24 @param st [out] The destination of the ChaCha state
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25 @param key The secret key
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26 @param keylen The length of the secret key (octets)
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27 @param rounds Number of rounds (e.g. 20 for ChaCha20)
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28 @return CRYPT_OK if successful
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29 */
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30 int chacha_setup(chacha_state *st, const unsigned char *key, unsigned long keylen, int rounds)
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31 {
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32 const char *constants;
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33
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34 LTC_ARGCHK(st != NULL);
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35 LTC_ARGCHK(key != NULL);
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36 LTC_ARGCHK(keylen == 32 || keylen == 16);
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37
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38 if (rounds == 0) rounds = 20;
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39
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40 LOAD32L(st->input[4], key + 0);
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41 LOAD32L(st->input[5], key + 4);
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42 LOAD32L(st->input[6], key + 8);
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43 LOAD32L(st->input[7], key + 12);
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44 if (keylen == 32) { /* 256bit */
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45 key += 16;
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46 constants = sigma;
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47 } else { /* 128bit */
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48 constants = tau;
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49 }
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50 LOAD32L(st->input[8], key + 0);
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51 LOAD32L(st->input[9], key + 4);
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52 LOAD32L(st->input[10], key + 8);
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53 LOAD32L(st->input[11], key + 12);
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54 LOAD32L(st->input[0], constants + 0);
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55 LOAD32L(st->input[1], constants + 4);
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56 LOAD32L(st->input[2], constants + 8);
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57 LOAD32L(st->input[3], constants + 12);
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58 st->rounds = rounds; /* e.g. 20 for chacha20 */
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59 st->ivlen = 0; /* will be set later by chacha_ivctr(32|64) */
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60 return CRYPT_OK;
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61 }
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62
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63 #endif
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64
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65 /* ref: $Format:%D$ */
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66 /* git commit: $Format:%H$ */
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67 /* commit time: $Format:%ai$ */