Mercurial > dropbear
view libtomcrypt/src/encauth/ccm/ccm_memory.c @ 1215:d058e15ea213
A few minor style fixes
author | Matt Johnston <matt@ucc.asn.au> |
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date | Tue, 15 Dec 2015 22:09:55 +0800 |
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 */ #include "tomcrypt.h" /** @file ccm_memory.c CCM support, process a block of memory, Tom St Denis */ #ifdef CCM_MODE /** CCM encrypt/decrypt and produce an authentication tag @param cipher The index of the cipher desired @param key The secret key to use @param keylen The length of the secret key (octets) @param uskey A previously scheduled key [optional can be NULL] @param nonce The session nonce [use once] @param noncelen The length of the nonce @param header The header for the session @param headerlen The length of the header (octets) @param pt [out] The plaintext @param ptlen The length of the plaintext (octets) @param ct [out] The ciphertext @param tag [out] The destination tag @param taglen [in/out] The max size and resulting size of the authentication tag @param direction Encrypt or Decrypt direction (0 or 1) @return CRYPT_OK if successful */ int ccm_memory(int cipher, const unsigned char *key, unsigned long keylen, symmetric_key *uskey, const unsigned char *nonce, unsigned long noncelen, const unsigned char *header, unsigned long headerlen, unsigned char *pt, unsigned long ptlen, unsigned char *ct, unsigned char *tag, unsigned long *taglen, int direction) { unsigned char PAD[16], ctr[16], CTRPAD[16], b; symmetric_key *skey; int err; unsigned long len, L, x, y, z, CTRlen; if (uskey == NULL) { LTC_ARGCHK(key != NULL); } LTC_ARGCHK(nonce != NULL); if (headerlen > 0) { LTC_ARGCHK(header != NULL); } LTC_ARGCHK(pt != NULL); LTC_ARGCHK(ct != NULL); LTC_ARGCHK(tag != NULL); LTC_ARGCHK(taglen != NULL); #ifdef LTC_FAST if (16 % sizeof(LTC_FAST_TYPE)) { return CRYPT_INVALID_ARG; } #endif /* check cipher input */ if ((err = cipher_is_valid(cipher)) != CRYPT_OK) { return err; } if (cipher_descriptor[cipher].block_length != 16) { return CRYPT_INVALID_CIPHER; } /* make sure the taglen is even and <= 16 */ *taglen &= ~1; if (*taglen > 16) { *taglen = 16; } /* can't use < 4 */ if (*taglen < 4) { return CRYPT_INVALID_ARG; } /* is there an accelerator? */ if (cipher_descriptor[cipher].accel_ccm_memory != NULL) { return cipher_descriptor[cipher].accel_ccm_memory( key, keylen, uskey, nonce, noncelen, header, headerlen, pt, ptlen, ct, tag, taglen, direction); } /* let's get the L value */ len = ptlen; L = 0; while (len) { ++L; len >>= 8; } if (L <= 1) { L = 2; } /* increase L to match the nonce len */ noncelen = (noncelen > 13) ? 13 : noncelen; if ((15 - noncelen) > L) { L = 15 - noncelen; } /* decrease noncelen to match L */ if ((noncelen + L) > 15) { noncelen = 15 - L; } /* allocate mem for the symmetric key */ if (uskey == NULL) { skey = XMALLOC(sizeof(*skey)); if (skey == NULL) { return CRYPT_MEM; } /* initialize the cipher */ if ((err = cipher_descriptor[cipher].setup(key, keylen, 0, skey)) != CRYPT_OK) { XFREE(skey); return err; } } else { skey = uskey; } /* form B_0 == flags | Nonce N | l(m) */ x = 0; PAD[x++] = (unsigned char)(((headerlen > 0) ? (1<<6) : 0) | (((*taglen - 2)>>1)<<3) | (L-1)); /* nonce */ for (y = 0; y < (16 - (L + 1)); y++) { PAD[x++] = nonce[y]; } /* store len */ len = ptlen; /* shift len so the upper bytes of len are the contents of the length */ for (y = L; y < 4; y++) { len <<= 8; } /* store l(m) (only store 32-bits) */ for (y = 0; L > 4 && (L-y)>4; y++) { PAD[x++] = 0; } for (; y < L; y++) { PAD[x++] = (unsigned char)((len >> 24) & 255); len <<= 8; } /* encrypt PAD */ if ((err = cipher_descriptor[cipher].ecb_encrypt(PAD, PAD, skey)) != CRYPT_OK) { goto error; } /* handle header */ if (headerlen > 0) { x = 0; /* store length */ if (headerlen < ((1UL<<16) - (1UL<<8))) { PAD[x++] ^= (headerlen>>8) & 255; PAD[x++] ^= headerlen & 255; } else { PAD[x++] ^= 0xFF; PAD[x++] ^= 0xFE; PAD[x++] ^= (headerlen>>24) & 255; PAD[x++] ^= (headerlen>>16) & 255; PAD[x++] ^= (headerlen>>8) & 255; PAD[x++] ^= headerlen & 255; } /* now add the data */ for (y = 0; y < headerlen; y++) { if (x == 16) { /* full block so let's encrypt it */ if ((err = cipher_descriptor[cipher].ecb_encrypt(PAD, PAD, skey)) != CRYPT_OK) { goto error; } x = 0; } PAD[x++] ^= header[y]; } /* remainder? */ if (x != 0) { if ((err = cipher_descriptor[cipher].ecb_encrypt(PAD, PAD, skey)) != CRYPT_OK) { goto error; } } } /* setup the ctr counter */ x = 0; /* flags */ ctr[x++] = (unsigned char)L-1; /* nonce */ for (y = 0; y < (16 - (L+1)); ++y) { ctr[x++] = nonce[y]; } /* offset */ while (x < 16) { ctr[x++] = 0; } x = 0; CTRlen = 16; /* now handle the PT */ if (ptlen > 0) { y = 0; #ifdef LTC_FAST if (ptlen & ~15) { if (direction == CCM_ENCRYPT) { for (; y < (ptlen & ~15); y += 16) { /* increment the ctr? */ for (z = 15; z > 15-L; z--) { ctr[z] = (ctr[z] + 1) & 255; if (ctr[z]) break; } if ((err = cipher_descriptor[cipher].ecb_encrypt(ctr, CTRPAD, skey)) != CRYPT_OK) { goto error; } /* xor the PT against the pad first */ for (z = 0; z < 16; z += sizeof(LTC_FAST_TYPE)) { *((LTC_FAST_TYPE*)(&PAD[z])) ^= *((LTC_FAST_TYPE*)(&pt[y+z])); *((LTC_FAST_TYPE*)(&ct[y+z])) = *((LTC_FAST_TYPE*)(&pt[y+z])) ^ *((LTC_FAST_TYPE*)(&CTRPAD[z])); } if ((err = cipher_descriptor[cipher].ecb_encrypt(PAD, PAD, skey)) != CRYPT_OK) { goto error; } } } else { for (; y < (ptlen & ~15); y += 16) { /* increment the ctr? */ for (z = 15; z > 15-L; z--) { ctr[z] = (ctr[z] + 1) & 255; if (ctr[z]) break; } if ((err = cipher_descriptor[cipher].ecb_encrypt(ctr, CTRPAD, skey)) != CRYPT_OK) { goto error; } /* xor the PT against the pad last */ for (z = 0; z < 16; z += sizeof(LTC_FAST_TYPE)) { *((LTC_FAST_TYPE*)(&pt[y+z])) = *((LTC_FAST_TYPE*)(&ct[y+z])) ^ *((LTC_FAST_TYPE*)(&CTRPAD[z])); *((LTC_FAST_TYPE*)(&PAD[z])) ^= *((LTC_FAST_TYPE*)(&pt[y+z])); } if ((err = cipher_descriptor[cipher].ecb_encrypt(PAD, PAD, skey)) != CRYPT_OK) { goto error; } } } } #endif for (; y < ptlen; y++) { /* increment the ctr? */ if (CTRlen == 16) { for (z = 15; z > 15-L; z--) { ctr[z] = (ctr[z] + 1) & 255; if (ctr[z]) break; } if ((err = cipher_descriptor[cipher].ecb_encrypt(ctr, CTRPAD, skey)) != CRYPT_OK) { goto error; } CTRlen = 0; } /* if we encrypt we add the bytes to the MAC first */ if (direction == CCM_ENCRYPT) { b = pt[y]; ct[y] = b ^ CTRPAD[CTRlen++]; } else { b = ct[y] ^ CTRPAD[CTRlen++]; pt[y] = b; } if (x == 16) { if ((err = cipher_descriptor[cipher].ecb_encrypt(PAD, PAD, skey)) != CRYPT_OK) { goto error; } x = 0; } PAD[x++] ^= b; } if (x != 0) { if ((err = cipher_descriptor[cipher].ecb_encrypt(PAD, PAD, skey)) != CRYPT_OK) { goto error; } } } /* setup CTR for the TAG (zero the count) */ for (y = 15; y > 15 - L; y--) { ctr[y] = 0x00; } if ((err = cipher_descriptor[cipher].ecb_encrypt(ctr, CTRPAD, skey)) != CRYPT_OK) { goto error; } if (skey != uskey) { cipher_descriptor[cipher].done(skey); } /* store the TAG */ for (x = 0; x < 16 && x < *taglen; x++) { tag[x] = PAD[x] ^ CTRPAD[x]; } *taglen = x; #ifdef LTC_CLEAN_STACK zeromem(skey, sizeof(*skey)); zeromem(PAD, sizeof(PAD)); zeromem(CTRPAD, sizeof(CTRPAD)); #endif error: if (skey != uskey) { XFREE(skey); } return err; } #endif /* $Source: /cvs/libtom/libtomcrypt/src/encauth/ccm/ccm_memory.c,v $ */ /* $Revision: 1.18 $ */ /* $Date: 2006/12/04 21:34:03 $ */