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annotate libtomcrypt/src/stream/chacha/chacha_crypt.c @ 1696:d18fa38c1fd4

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initialise variable to stop warning
author Matt Johnston <matt@ucc.asn.au>
date Thu, 28 May 2020 22:02:03 +0800
parents 6dba84798cd5
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
1471
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
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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 #define QUARTERROUND(a,b,c,d) \
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20 x[a] += x[b]; x[d] = ROL(x[d] ^ x[a], 16); \
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21 x[c] += x[d]; x[b] = ROL(x[b] ^ x[c], 12); \
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22 x[a] += x[b]; x[d] = ROL(x[d] ^ x[a], 8); \
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23 x[c] += x[d]; x[b] = ROL(x[b] ^ x[c], 7);
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24
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25 static void _chacha_block(unsigned char *output, const ulong32 *input, int rounds)
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26 {
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27 ulong32 x[16];
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28 int i;
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29 XMEMCPY(x, input, sizeof(x));
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30 for (i = rounds; i > 0; i -= 2) {
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31 QUARTERROUND(0, 4, 8,12)
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32 QUARTERROUND(1, 5, 9,13)
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33 QUARTERROUND(2, 6,10,14)
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34 QUARTERROUND(3, 7,11,15)
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35 QUARTERROUND(0, 5,10,15)
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36 QUARTERROUND(1, 6,11,12)
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37 QUARTERROUND(2, 7, 8,13)
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38 QUARTERROUND(3, 4, 9,14)
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39 }
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40 for (i = 0; i < 16; ++i) {
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41 x[i] += input[i];
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42 STORE32L(x[i], output + 4 * i);
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43 }
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44 }
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45
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46 /**
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47 Encrypt (or decrypt) bytes of ciphertext (or plaintext) with ChaCha
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48 @param st The ChaCha state
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49 @param in The plaintext (or ciphertext)
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50 @param inlen The length of the input (octets)
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51 @param out [out] The ciphertext (or plaintext), length inlen
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52 @return CRYPT_OK if successful
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53 */
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54 int chacha_crypt(chacha_state *st, const unsigned char *in, unsigned long inlen, unsigned char *out)
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55 {
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56 unsigned char buf[64];
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57 unsigned long i, j;
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58
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59 if (inlen == 0) return CRYPT_OK; /* nothing to do */
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60
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61 LTC_ARGCHK(st != NULL);
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62 LTC_ARGCHK(in != NULL);
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63 LTC_ARGCHK(out != NULL);
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64 LTC_ARGCHK(st->ivlen != 0);
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65
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66 if (st->ksleft > 0) {
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67 j = MIN(st->ksleft, inlen);
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68 for (i = 0; i < j; ++i, st->ksleft--) out[i] = in[i] ^ st->kstream[64 - st->ksleft];
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69 inlen -= j;
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70 if (inlen == 0) return CRYPT_OK;
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71 out += j;
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72 in += j;
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73 }
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74 for (;;) {
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75 _chacha_block(buf, st->input, st->rounds);
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76 if (st->ivlen == 8) {
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77 /* IV-64bit, increment 64bit counter */
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78 if (0 == ++st->input[12] && 0 == ++st->input[13]) return CRYPT_OVERFLOW;
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79 }
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80 else {
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81 /* IV-96bit, increment 32bit counter */
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82 if (0 == ++st->input[12]) return CRYPT_OVERFLOW;
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83 }
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84 if (inlen <= 64) {
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85 for (i = 0; i < inlen; ++i) out[i] = in[i] ^ buf[i];
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86 st->ksleft = 64 - inlen;
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87 for (i = inlen; i < 64; ++i) st->kstream[i] = buf[i];
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88 return CRYPT_OK;
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89 }
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90 for (i = 0; i < 64; ++i) out[i] = in[i] ^ buf[i];
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91 inlen -= 64;
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92 out += 64;
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93 in += 64;
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94 }
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95 }
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96
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97 #endif
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98
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99 /* ref: $Format:%D$ */
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100 /* git commit: $Format:%H$ */
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101 /* commit time: $Format:%ai$ */