Mercurial > dropbear

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

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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 Initialize a CCM state
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15 @param ccm The CCM state to initialize
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16 @param cipher The index of the cipher to use
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17 @param key The secret key
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18 @param keylen The length of the secret key
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19 @param ptlen The length of the plain/cipher text that will be processed
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20 @param taglen The max length of the MAC tag
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21 @param aadlen The length of the AAD
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22
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23 @return CRYPT_OK on success
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24 */
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25 int ccm_init(ccm_state *ccm, int cipher,
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26 const unsigned char *key, int keylen, int ptlen, int taglen, int aadlen)
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27 {
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28 int err;
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29
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30 LTC_ARGCHK(ccm != NULL);
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31 LTC_ARGCHK(key != NULL);
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32 LTC_ARGCHK(taglen != 0);
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33
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34 XMEMSET(ccm, 0, sizeof(ccm_state));
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35
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36 /* check cipher input */
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37 if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
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38 return err;
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39 }
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40 if (cipher_descriptor[cipher].block_length != 16) {
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41 return CRYPT_INVALID_CIPHER;
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42 }
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43
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44 /* make sure the taglen is even and <= 16 */
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45 ccm->taglen = taglen;
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46 ccm->taglen &= ~1;
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47 if (ccm->taglen > 16) {
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48 ccm->taglen = 16;
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49 }
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50
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51 /* can't use < 4 */
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52 if (ccm->taglen < 4) {
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53 return CRYPT_INVALID_ARG;
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54 }
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55
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56 /* schedule key */
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57 if ((err = cipher_descriptor[cipher].setup(key, keylen, 0, &ccm->K)) != CRYPT_OK) {
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58 return err;
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59 }
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60 ccm->cipher = cipher;
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61
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62 /* let's get the L value */
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63 ccm->ptlen = ptlen;
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64 ccm->L = 0;
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65 while (ptlen) {
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66 ++ccm->L;
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67 ptlen >>= 8;
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68 }
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69 if (ccm->L <= 1) {
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70 ccm->L = 2;
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71 }
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72
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73 ccm->aadlen = aadlen;
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74 return CRYPT_OK;
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75 }
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76
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77 #endif
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78
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79 /* ref: $Format:%D$ */
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80 /* git commit: $Format:%H$ */
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81 /* commit time: $Format:%ai$ */