; libcrash -- cryptographic hash (and other) functions
;
; Copyright (C) <2016> Jeffrey Amelynck
; Copyright (C) <2016,2021> Ivan Baravy
;
; SPDX-License-Identifier: GPL-2.0-or-later
;
; 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 2 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 ctx_aes_ctr
aes ctx_aes
ctr ctx_ctr
ends
assert sizeof.ctx_aes_ctr <= LIBCRASH_CTX_LEN
; _crypt: 0/1 = encrypt/decrypt
proc aes256ctr.init uses ebx, _ctx, _key, _iv, _flags
mov ebx, [_ctx]
stdcall aes256.init, ebx, [_key], LIBCRASH_CIPHER_ENCRYPT
add ebx, ctx_aes_ctr.ctr
stdcall ctr.init, [_iv]
ret
endp
proc a22es_ctr._.block_init _ctx
mov edi, [_ctx]
lea esi, [edi+ctx_aes_ctr.ctr.block_counter]
mov ecx, AES_BLOCK_SIZE/4
rep movsd
ret
endp
proc aes256ctr.update uses ebx esi edi, _ctx, _in, _len, _out
mov eax, [_len]
pushad
mov ebx, [_ctx]
mov edi, [_in]
mov edx, [ebx+ctx_aes_ctr.ctr.partial_cnt]
.next_chunk:
mov ecx, [_len]
test ecx, ecx
jz .done
test edx, edx
jnz @f
pushad
lea ecx, [ebx+ctx_aes_ctr.ctr.block_counter]
lea edx, [ebx+ctx_aes_ctr.aes.state]
stdcall aes.encrypt, ebx, ecx, edx
popad
mov edx, AES_BLOCK_SIZE
pushad
mov esi, ebx
mov eax, dword[esi+ctx_aes_ctr.ctr.block_counter+4*0]
mov ebx, dword[esi+ctx_aes_ctr.ctr.block_counter+4*1]
mov ecx, dword[esi+ctx_aes_ctr.ctr.block_counter+4*2]
mov edx, dword[esi+ctx_aes_ctr.ctr.block_counter+4*3]
bswap eax
bswap ebx
bswap ecx
bswap edx
add edx, 1
adc ecx, 0
adc ebx, 0
adc eax, 0
bswap eax
bswap ebx
bswap ecx
bswap edx
mov dword[esi+ctx_aes_ctr.ctr.block_counter+4*0], eax
mov dword[esi+ctx_aes_ctr.ctr.block_counter+4*1], ebx
mov dword[esi+ctx_aes_ctr.ctr.block_counter+4*2], ecx
mov dword[esi+ctx_aes_ctr.ctr.block_counter+4*3], edx
popad
@@:
cmp ecx, edx
jbe @f
mov ecx, edx
@@:
lea esi, [ebx+ctx_aes_ctr.aes.state]
add esi, AES_BLOCK_SIZE
sub esi, edx
sub [_len], ecx
sub edx, ecx
push ebx
mov edi, [_out]
mov ebx, [_in]
add [_in], ecx
add [_out], ecx
@@:
lodsb
xor al, [ebx]
inc ebx
stosb
loop @b
pop ebx
jmp .next_chunk
.done:
mov [ebx+ctx_aes_ctr.ctr.partial_cnt], edx
popad
ret
endp
proc aes256ctr.finish _ctx, _out
xor eax, eax
ret
endp
proc aes256ctr.oneshot _ctx, _key, _iv, _flags, _in, _len, _out
locals
.done dd ?
endl
mov [.done], 0
stdcall aes256ctr.init, [_ctx], [_key], [_iv], [_flags]
stdcall aes256ctr.update, [_ctx], [_in], [_len], [_out]
add [_out], eax
add [.done], eax
stdcall aes256ctr.finish, [_ctx], [_out]
add eax, [.done]
ret
endp