+
−/* LibTomCrypt, modular cryptographic library -- Tom St Denis
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− *
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− * LibTomCrypt is a library that provides various cryptographic
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− * algorithms in a highly modular and flexible manner.
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− *
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− * The library is free for all purposes without any express
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− * guarantee it works.
+
− */
+
−#include "tomcrypt.h"
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−
+
−#ifdef LTC_CCM_MODE
+
−
+
−/**
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−  Initialize a CCM state
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−  @param ccm     The CCM state to initialize
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−  @param cipher  The index of the cipher to use
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−  @param key     The secret key
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−  @param keylen  The length of the secret key
+
−  @param ptlen   The length of the plain/cipher text that will be processed
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−  @param taglen  The max length of the MAC tag
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−  @param aadlen  The length of the AAD
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−
+
−  @return CRYPT_OK on success
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− */
+
−int ccm_init(ccm_state *ccm, int cipher,
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−             const unsigned char *key, int keylen, int ptlen, int taglen, int aadlen)
+
−{
+
−   int            err;
+
−
+
−   LTC_ARGCHK(ccm    != NULL);
+
−   LTC_ARGCHK(key    != NULL);
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−   LTC_ARGCHK(taglen != 0);
+
−
+
−   XMEMSET(ccm, 0, sizeof(ccm_state));
+
−
+
−   /* check cipher input */
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−   if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
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−      return err;
+
−   }
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−   if (cipher_descriptor[cipher].block_length != 16) {
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−      return CRYPT_INVALID_CIPHER;
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−   }
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−
+
−   /* make sure the taglen is even and <= 16 */
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−   ccm->taglen = taglen;
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−   ccm->taglen &= ~1;
+
−   if (ccm->taglen > 16) {
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−      ccm->taglen = 16;
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−   }
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−
+
−   /* can't use < 4 */
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−   if (ccm->taglen < 4) {
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−      return CRYPT_INVALID_ARG;
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−   }
+
−
+
−   /* schedule key */
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−   if ((err = cipher_descriptor[cipher].setup(key, keylen, 0, &ccm->K)) != CRYPT_OK) {
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−      return err;
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−   }
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−   ccm->cipher = cipher;
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−
+
−   /* let's get the L value */
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−   ccm->ptlen = ptlen;
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−   ccm->L   = 0;
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−   while (ptlen) {
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−      ++ccm->L;
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−      ptlen >>= 8;
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−   }
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−   if (ccm->L <= 1) {
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−      ccm->L = 2;
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−   }
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−
+
−   ccm->aadlen = aadlen;
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−   return CRYPT_OK;
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−}
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−
+
−#endif
+
−
+
−/* ref:         $Format:%D$ */
+
−/* git commit:  $Format:%H$ */
+
−/* commit time: $Format:%ai$ */