annotate libtomcrypt/src/encauth/chachapoly/chacha20poly1305_setiv.c @ 1471:6dba84798cd5

Update to libtomcrypt 1.18.1, merged with Dropbear changes
author Matt Johnston <matt@ucc.asn.au>
date Fri, 09 Feb 2018 21:44:05 +0800
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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 #include "tomcrypt.h"
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11
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12 #ifdef LTC_CHACHA20POLY1305_MODE
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13
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14 /**
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15 Set IV + counter data to the ChaCha20Poly1305 state and reset the context
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16 @param st The ChaCha20Poly1305 state
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17 @param iv The IV data to add
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18 @param ivlen The length of the IV (must be 12 or 8)
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19 @return CRYPT_OK on success
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20 */
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21 int chacha20poly1305_setiv(chacha20poly1305_state *st, const unsigned char *iv, unsigned long ivlen)
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22 {
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23 chacha_state tmp_st;
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24 int i, err;
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25 unsigned char polykey[32];
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26
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27 LTC_ARGCHK(st != NULL);
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28 LTC_ARGCHK(iv != NULL);
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29 LTC_ARGCHK(ivlen == 12 || ivlen == 8);
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30
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31 /* set IV for chacha20 */
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32 if (ivlen == 12) {
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33 /* IV 96bit */
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34 if ((err = chacha_ivctr32(&st->chacha, iv, ivlen, 1)) != CRYPT_OK) return err;
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35 }
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36 else {
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37 /* IV 64bit */
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38 if ((err = chacha_ivctr64(&st->chacha, iv, ivlen, 1)) != CRYPT_OK) return err;
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39 }
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40
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41 /* copy chacha20 key to temporary state */
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42 for(i = 0; i < 12; i++) tmp_st.input[i] = st->chacha.input[i];
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43 tmp_st.rounds = 20;
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44 /* set IV */
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45 if (ivlen == 12) {
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46 /* IV 32bit */
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47 if ((err = chacha_ivctr32(&tmp_st, iv, ivlen, 0)) != CRYPT_OK) return err;
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48 }
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49 else {
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50 /* IV 64bit */
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51 if ((err = chacha_ivctr64(&tmp_st, iv, ivlen, 0)) != CRYPT_OK) return err;
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52 }
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53 /* (re)generate new poly1305 key */
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54 if ((err = chacha_keystream(&tmp_st, polykey, 32)) != CRYPT_OK) return err;
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55 /* (re)initialise poly1305 */
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56 if ((err = poly1305_init(&st->poly, polykey, 32)) != CRYPT_OK) return err;
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57 st->ctlen = 0;
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58 st->aadlen = 0;
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59 st->aadflg = 1;
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60
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61 return CRYPT_OK;
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62 }
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63
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64 #endif
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65
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66 /* ref: $Format:%D$ */
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67 /* git commit: $Format:%H$ */
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68 /* commit time: $Format:%ai$ */