Mercurial > dropbear
view libtomcrypt/src/encauth/gcm/gcm_done.c @ 1294:56aba7dedbea
options for disabling "normal" DH
author | Matt Johnston <matt@ucc.asn.au> |
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date | Mon, 02 May 2016 23:48:16 +0200 |
parents | 0cbe8f6dbf9e |
children | f849a5ca2efc |
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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.com */ /** @file gcm_done.c GCM implementation, Terminate the stream, by Tom St Denis */ #include "tomcrypt.h" #ifdef GCM_MODE /** Terminate a GCM stream @param gcm The GCM state @param tag [out] The destination for the MAC tag @param taglen [in/out] The length of the MAC tag @return CRYPT_OK on success */ int gcm_done(gcm_state *gcm, unsigned char *tag, unsigned long *taglen) { unsigned long x; int err; LTC_ARGCHK(gcm != NULL); LTC_ARGCHK(tag != NULL); LTC_ARGCHK(taglen != NULL); if (gcm->buflen > 16 || gcm->buflen < 0) { return CRYPT_INVALID_ARG; } if ((err = cipher_is_valid(gcm->cipher)) != CRYPT_OK) { return err; } if (gcm->mode != GCM_MODE_TEXT) { return CRYPT_INVALID_ARG; } /* handle remaining ciphertext */ if (gcm->buflen) { gcm->pttotlen += gcm->buflen * CONST64(8); gcm_mult_h(gcm, gcm->X); } /* length */ STORE64H(gcm->totlen, gcm->buf); STORE64H(gcm->pttotlen, gcm->buf+8); for (x = 0; x < 16; x++) { gcm->X[x] ^= gcm->buf[x]; } gcm_mult_h(gcm, gcm->X); /* encrypt original counter */ if ((err = cipher_descriptor[gcm->cipher].ecb_encrypt(gcm->Y_0, gcm->buf, &gcm->K)) != CRYPT_OK) { return err; } for (x = 0; x < 16 && x < *taglen; x++) { tag[x] = gcm->buf[x] ^ gcm->X[x]; } *taglen = x; cipher_descriptor[gcm->cipher].done(&gcm->K); return CRYPT_OK; } #endif /* $Source: /cvs/libtom/libtomcrypt/src/encauth/gcm/gcm_done.c,v $ */ /* $Revision: 1.9 $ */ /* $Date: 2006/03/31 14:15:35 $ */