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| ; aes256-ctr.inc - AES256 Counter Mode |
| ; |
| ; Copyright (C) 2016 Ivan Baravy (dunkaist) |
| ; |
| ; This program is free software: you can redistribute it and/or modify |
| ; it under the terms of the GNU General Public License as published by |
| ; the Free Software Foundation, either version 3 of the License, or |
| ; (at your option) any later version. |
| ; |
| ; This program is distributed in the hope that it will be useful, |
| ; but WITHOUT ANY WARRANTY; without even the implied warranty of |
| ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| ; GNU General Public License for more details. |
| ; |
| ; You should have received a copy of the GNU General Public License |
| ; along with this program. If not, see <http://www.gnu.org/licenses/>. |
| |
| struct aes256_ctr_context aes256_context |
| counter rb 16 |
| output rb 16 ; counter after aes_crypt |
| ends |
| |
| |
| proc aes256_ctr_init _counter |
| push ebx esi edi |
| |
| mcall 68, 12, sizeof.aes256_ctr_context |
| ; handle errors |
| mov ecx, 16/4 |
| mov esi, [_counter] |
| lea edi, [eax + aes256_ctr_context.counter] |
| rep movsd |
| ; rep movsd is slow, but we don't care while init |
| |
| pop edi esi ebx |
| ret |
| endp |
| |
| |
| proc aes256_ctr_crypt _ctx, _in, _out |
| |
| push ebx esi edi |
| |
| DEBUGF 1,'plain : ' |
| stdcall dump_128bit_hex, [_in] |
| DEBUGF 1,'\n' |
| |
| mov esi, [_ctx] |
| lea eax, [esi + aes256_ctr_context.key] |
| lea ebx, [esi + aes256_ctr_context.counter] |
| lea ecx, [esi + aes256_ctr_context.output] |
| |
| stdcall aes256_encrypt, eax, ebx, ecx ; Key, in, out |
| |
| mov ebx, [_ctx] |
| mov esi, [_in] |
| mov edi, [_out] |
| |
| mov eax, [esi + 4*0] |
| xor eax, dword[ebx + aes256_ctr_context.output + 4*0] |
| mov [edi + 4*0], eax |
| |
| mov eax, [esi + 4*1] |
| xor eax, dword[ebx + aes256_ctr_context.output + 4*1] |
| mov [edi + 4*1], eax |
| |
| mov eax, [esi + 4*2] |
| xor eax, dword[ebx + aes256_ctr_context.output + 4*2] |
| mov [edi + 4*2], eax |
| |
| mov eax, [esi + 4*3] |
| xor eax, dword[ebx + aes256_ctr_context.output + 4*3] |
| mov [edi + 4*3], eax |
| |
| ; Increment counter |
| mov esi, [_ctx] |
| |
| mov eax, dword[esi + aes256_ctr_context.counter + 4*0] |
| mov ebx, dword[esi + aes256_ctr_context.counter + 4*1] |
| mov ecx, dword[esi + aes256_ctr_context.counter + 4*2] |
| mov edx, dword[esi + aes256_ctr_context.counter + 4*3] |
| |
| bswap eax |
| bswap ebx |
| bswap ecx |
| bswap edx |
| |
| inc edx |
| adc ecx, 0 |
| adc ebx, 0 |
| adc eax, 0 |
| |
| bswap eax |
| bswap ebx |
| bswap ecx |
| bswap edx |
| |
| mov dword[esi + aes256_ctr_context.counter + 4*0], eax |
| mov dword[esi + aes256_ctr_context.counter + 4*1], ebx |
| mov dword[esi + aes256_ctr_context.counter + 4*2], ecx |
| mov dword[esi + aes256_ctr_context.counter + 4*3], edx |
| |
| DEBUGF 1,'cipher : ' |
| stdcall dump_128bit_hex, [_out] |
| DEBUGF 1,'\n\n' |
| |
| pop edi esi ebx |
| ret |
| endp |