Mercurial > dropbear

annotate libtomcrypt/src/modes/cfb/cfb_decrypt.c @ 1830:c32976db772f

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Merge
author Matt Johnston <matt@ucc.asn.au>
date Mon, 11 Oct 2021 15:46:49 +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 #include "tomcrypt.h"
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10
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11 /**
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12 @file cfb_decrypt.c
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13 CFB implementation, decrypt data, Tom St Denis
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14 */
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15
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16 #ifdef LTC_CFB_MODE
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18 /**
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19 CFB decrypt
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20 @param ct Ciphertext
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21 @param pt [out] Plaintext
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22 @param len Length of ciphertext (octets)
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23 @param cfb CFB state
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24 @return CRYPT_OK if successful
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25 */
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26 int cfb_decrypt(const unsigned char *ct, unsigned char *pt, unsigned long len, symmetric_CFB *cfb)
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27 {
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28 int err;
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30 LTC_ARGCHK(pt != NULL);
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31 LTC_ARGCHK(ct != NULL);
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32 LTC_ARGCHK(cfb != NULL);
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34 if ((err = cipher_is_valid(cfb->cipher)) != CRYPT_OK) {
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35 return err;
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36 }
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38 /* is blocklen/padlen valid? */
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39 if (cfb->blocklen < 0 || cfb->blocklen > (int)sizeof(cfb->IV) ||
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40 cfb->padlen < 0 || cfb->padlen > (int)sizeof(cfb->pad)) {
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41 return CRYPT_INVALID_ARG;
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42 }
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44 while (len-- > 0) {
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45 if (cfb->padlen == cfb->blocklen) {
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46 if ((err = cipher_descriptor[cfb->cipher].ecb_encrypt(cfb->pad, cfb->IV, &cfb->key)) != CRYPT_OK) {
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47 return err;
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48 }
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49 cfb->padlen = 0;
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50 }
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51 cfb->pad[cfb->padlen] = *ct;
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52 *pt = *ct ^ cfb->IV[cfb->padlen];
1471
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
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53 ++pt;
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54 ++ct;
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55 ++(cfb->padlen);
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56 }
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57 return CRYPT_OK;
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58 }
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60 #endif
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62
1471
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
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63 /* ref: $Format:%D$ */
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
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64 /* git commit: $Format:%H$ */
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
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65 /* commit time: $Format:%ai$ */