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/* |
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iv_gen.C -- efficiently generate IV values using AES |
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Copyright (C) 2013 Marc Lehmann <gvpe@schmorp.de> |
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This file is part of GVPE. |
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GVPE is free software; you can redistribute it and/or modify it |
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under the terms of the GNU General Public License as published by the |
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Free Software Foundation; either version 3 of the License, or (at your |
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option) any later version. |
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This program is distributed in the hope that it will be useful, but |
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WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General |
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Public License for more details. |
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You should have received a copy of the GNU General Public License along |
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with this program; if not, see <http://www.gnu.org/licenses/>. |
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Additional permission under GNU GPL version 3 section 7 |
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If you modify this Program, or any covered work, by linking or |
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combining it with the OpenSSL project's OpenSSL library (or a modified |
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version of that library), containing parts covered by the terms of the |
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OpenSSL or SSLeay licenses, the licensors of this Program grant you |
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additional permission to convey the resulting work. Corresponding |
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Source for a non-source form of such a combination shall include the |
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source code for the parts of OpenSSL used as well as that of the |
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covered work. |
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*/ |
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#include "config.h" |
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#include <cstring> |
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#include "util.h" |
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#include "iv_gen.h" |
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void |
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iv_gen::reset () |
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{ |
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u8 key[128/8]; |
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rand_fill (key); |
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require (AES_set_encrypt_key (key, 128, &ctx) >= 0); |
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rand_fill (count); |
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} |
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void |
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iv_gen::get (void *buf, int len) |
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{ |
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u8 *ptr = (u8 *)buf; |
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// we currently do not reuse partial blocks |
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for (;;) |
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{ |
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u32 block[4] = { 0x5c5c5c5c, 0x36363636, 0x88442211, ++count }; |
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AES_encrypt ((u8 *)block, (u8 *)block, &ctx); |
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if (len <= AES_BLOCK_SIZE) |
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{ |
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memcpy (ptr, block, len); |
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return; |
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} |
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memcpy (ptr, block, AES_BLOCK_SIZE); |
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ptr += AES_BLOCK_SIZE; |
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len -= AES_BLOCK_SIZE; |
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} |
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} |
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