Mercurial > dropbear
view libtomcrypt/src/encauth/eax/eax_init.c @ 297:79bf1023cf11 agent-client
propagate from branch 'au.asn.ucc.matt.dropbear' (head 0501e6f661b5415eb76f3b312d183c3adfbfb712)
to branch 'au.asn.ucc.matt.dropbear.cli-agent' (head 01038174ec27245b51bd43a66c01ad930880f67b)
author | Matt Johnston <matt@ucc.asn.au> |
---|---|
date | Tue, 21 Mar 2006 16:20:59 +0000 |
parents | 1b9e69c058d2 |
children | 0cbe8f6dbf9e |
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis * * LibTomCrypt is a library that provides various cryptographic * algorithms in a highly modular and flexible manner. * * The library is free for all purposes without any express * guarantee it works. * * Tom St Denis, [email protected], http://libtomcrypt.org */ /** @file eax_init.c EAX implementation, initialized EAX state, by Tom St Denis */ #include "tomcrypt.h" #ifdef EAX_MODE /** Initialized an EAX state @param eax [out] The EAX state to initialize @param cipher The index of the desired cipher @param key The secret key @param keylen The length of the secret key (octets) @param nonce The use-once nonce for the session @param noncelen The length of the nonce (octets) @param header The header for the EAX state @param headerlen The header length (octets) @return CRYPT_OK if successful */ int eax_init(eax_state *eax, int cipher, const unsigned char *key, unsigned long keylen, const unsigned char *nonce, unsigned long noncelen, const unsigned char *header, unsigned long headerlen) { unsigned char *buf; int err, blklen; omac_state *omac; unsigned long len; LTC_ARGCHK(eax != NULL); LTC_ARGCHK(key != NULL); LTC_ARGCHK(nonce != NULL); if (headerlen > 0) { LTC_ARGCHK(header != NULL); } if ((err = cipher_is_valid(cipher)) != CRYPT_OK) { return err; } blklen = cipher_descriptor[cipher].block_length; /* allocate ram */ buf = XMALLOC(MAXBLOCKSIZE); omac = XMALLOC(sizeof(*omac)); if (buf == NULL || omac == NULL) { if (buf != NULL) { XFREE(buf); } if (omac != NULL) { XFREE(omac); } return CRYPT_MEM; } /* N = OMAC_0K(nonce) */ zeromem(buf, MAXBLOCKSIZE); if ((err = omac_init(omac, cipher, key, keylen)) != CRYPT_OK) { goto LBL_ERR; } /* omac the [0]_n */ if ((err = omac_process(omac, buf, blklen)) != CRYPT_OK) { goto LBL_ERR; } /* omac the nonce */ if ((err = omac_process(omac, nonce, noncelen)) != CRYPT_OK) { goto LBL_ERR; } /* store result */ len = sizeof(eax->N); if ((err = omac_done(omac, eax->N, &len)) != CRYPT_OK) { goto LBL_ERR; } /* H = OMAC_1K(header) */ zeromem(buf, MAXBLOCKSIZE); buf[blklen - 1] = 1; if ((err = omac_init(&eax->headeromac, cipher, key, keylen)) != CRYPT_OK) { goto LBL_ERR; } /* omac the [1]_n */ if ((err = omac_process(&eax->headeromac, buf, blklen)) != CRYPT_OK) { goto LBL_ERR; } /* omac the header */ if (headerlen != 0) { if ((err = omac_process(&eax->headeromac, header, headerlen)) != CRYPT_OK) { goto LBL_ERR; } } /* note we don't finish the headeromac, this allows us to add more header later */ /* setup the CTR mode */ if ((err = ctr_start(cipher, eax->N, key, keylen, 0, CTR_COUNTER_BIG_ENDIAN, &eax->ctr)) != CRYPT_OK) { goto LBL_ERR; } /* setup the OMAC for the ciphertext */ if ((err = omac_init(&eax->ctomac, cipher, key, keylen)) != CRYPT_OK) { goto LBL_ERR; } /* omac [2]_n */ zeromem(buf, MAXBLOCKSIZE); buf[blklen-1] = 2; if ((err = omac_process(&eax->ctomac, buf, blklen)) != CRYPT_OK) { goto LBL_ERR; } err = CRYPT_OK; LBL_ERR: #ifdef LTC_CLEAN_STACK zeromem(buf, MAXBLOCKSIZE); zeromem(omac, sizeof(*omac)); #endif XFREE(omac); XFREE(buf); return err; } #endif /* $Source: /cvs/libtom/libtomcrypt/src/encauth/eax/eax_init.c,v $ */ /* $Revision: 1.4 $ */ /* $Date: 2005/05/05 14:35:58 $ */