Mercurial > dropbear
view libtomcrypt/src/modes/lrw/lrw_start.c @ 1508:47f36d8565cf
more linting (#55)
* dropbear_exit: remove priority parameter
confusion with dropbear_log()
* const parameter
author | François Perrad <francois.perrad@gadz.org> |
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date | Sat, 17 Feb 2018 04:27:37 +0100 |
parents | 6dba84798cd5 |
children |
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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. */ #include "tomcrypt.h" /** @file lrw_start.c LRW_MODE implementation, start mode, Tom St Denis */ #ifdef LTC_LRW_MODE /** Initialize the LRW context @param cipher The cipher desired, must be a 128-bit block cipher @param IV The index value, must be 128-bits @param key The cipher key @param keylen The length of the cipher key in octets @param tweak The tweak value (second key), must be 128-bits @param num_rounds The number of rounds for the cipher (0 == default) @param lrw [out] The LRW state @return CRYPT_OK on success. */ int lrw_start( int cipher, const unsigned char *IV, const unsigned char *key, int keylen, const unsigned char *tweak, int num_rounds, symmetric_LRW *lrw) { int err; #ifdef LTC_LRW_TABLES unsigned char B[16]; int x, y, z, t; #endif LTC_ARGCHK(IV != NULL); LTC_ARGCHK(key != NULL); LTC_ARGCHK(tweak != NULL); LTC_ARGCHK(lrw != NULL); #ifdef LTC_FAST if (16 % sizeof(LTC_FAST_TYPE)) { return CRYPT_INVALID_ARG; } #endif /* is cipher valid? */ if ((err = cipher_is_valid(cipher)) != CRYPT_OK) { return err; } if (cipher_descriptor[cipher].block_length != 16) { return CRYPT_INVALID_CIPHER; } /* schedule key */ if ((err = cipher_descriptor[cipher].setup(key, keylen, num_rounds, &lrw->key)) != CRYPT_OK) { return err; } lrw->cipher = cipher; /* copy the IV and tweak */ XMEMCPY(lrw->tweak, tweak, 16); #ifdef LTC_LRW_TABLES /* setup tables */ /* generate the first table as it has no shifting (from which we make the other tables) */ zeromem(B, 16); for (y = 0; y < 256; y++) { B[0] = y; gcm_gf_mult(tweak, B, &lrw->PC[0][y][0]); } /* now generate the rest of the tables based the previous table */ for (x = 1; x < 16; x++) { for (y = 0; y < 256; y++) { /* now shift it right by 8 bits */ t = lrw->PC[x-1][y][15]; for (z = 15; z > 0; z--) { lrw->PC[x][y][z] = lrw->PC[x-1][y][z-1]; } lrw->PC[x][y][0] = gcm_shift_table[t<<1]; lrw->PC[x][y][1] ^= gcm_shift_table[(t<<1)+1]; } } #endif /* generate first pad */ return lrw_setiv(IV, 16, lrw); } #endif /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */