annotate libtomcrypt/src/encauth/ccm/ccm_done.c @ 1715:3974f087d9c0

Disallow leading lines before the ident for server (#102) Per RFC4253 4.2 clients must be able to process other lines of data before the version string, server behavior is not defined neither with MUST/SHOULD nor with MAY. If server process up to 50 lines too - it may cause too long hanging session with invalid/evil client that consume host resources and potentially may lead to DDoS on poor embedded boxes. Let's require first line from client to be version string and fail early if it's not - matches both RFC and real OpenSSH behavior.
author Vladislav Grishenko <themiron@users.noreply.github.com>
date Mon, 15 Jun 2020 18:22:18 +0500
parents 6dba84798cd5
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
1471
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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 #include "tomcrypt.h"
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10
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11 #ifdef LTC_CCM_MODE
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12
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13 /**
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14 Terminate a CCM stream
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15 @param ccm The CCM state
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16 @param tag [out] The destination for the MAC tag
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17 @param taglen [in/out] The length of the MAC tag
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18 @return CRYPT_OK on success
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19 */
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20 int ccm_done(ccm_state *ccm,
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21 unsigned char *tag, unsigned long *taglen)
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22 {
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23 unsigned long x, y;
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24 int err;
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25
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26 LTC_ARGCHK(ccm != NULL);
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27
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28 /* Check all data have been processed */
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29 if (ccm->ptlen != ccm->current_ptlen) {
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30 return CRYPT_ERROR;
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31 }
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32
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33 LTC_ARGCHK(tag != NULL);
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34 LTC_ARGCHK(taglen != NULL);
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35
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36 if (ccm->x != 0) {
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37 if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->PAD, ccm->PAD, &ccm->K)) != CRYPT_OK) {
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38 return err;
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39 }
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40 }
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41
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42 /* setup CTR for the TAG (zero the count) */
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43 for (y = 15; y > 15 - ccm->L; y--) {
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44 ccm->ctr[y] = 0x00;
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45 }
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46 if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->ctr, ccm->CTRPAD, &ccm->K)) != CRYPT_OK) {
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47 return err;
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48 }
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49
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50 cipher_descriptor[ccm->cipher].done(&ccm->K);
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51
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52 /* store the TAG */
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53 for (x = 0; x < 16 && x < *taglen; x++) {
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54 tag[x] = ccm->PAD[x] ^ ccm->CTRPAD[x];
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55 }
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56 *taglen = x;
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57
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58 return CRYPT_OK;
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59 }
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60
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61 #endif
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62
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63 /* ref: $Format:%D$ */
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64 /* git commit: $Format:%H$ */
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65 /* commit time: $Format:%ai$ */