From cf2bdbc65ee3bd3dcbf683e09d3a236d51310762 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Niels=20M=C3=B6ller?= <nisse@lysator.liu.se> Date: Fri, 14 Oct 2005 23:54:33 +0200 Subject: [PATCH] * x86/aes-decrypt-internal.asm: New file. Rev: src/nettle/x86/aes-decrypt-internal.asm:1.1 --- x86/aes-decrypt-internal.asm | 164 +++++++++++++++++++++++++++++++++++ 1 file changed, 164 insertions(+) create mode 100644 x86/aes-decrypt-internal.asm diff --git a/x86/aes-decrypt-internal.asm b/x86/aes-decrypt-internal.asm new file mode 100644 index 00000000..aa6e3930 --- /dev/null +++ b/x86/aes-decrypt-internal.asm @@ -0,0 +1,164 @@ +C -*- mode: asm; asm-comment-char: ?C; -*- +C nettle, low-level cryptographics library +C +C Copyright (C) 2001, 2002, 2005 Rafael R. Sevilla, Niels Möller +C +C The nettle library is free software; you can redistribute it and/or modify +C it under the terms of the GNU Lesser General Public License as published by +C the Free Software Foundation; either version 2.1 of the License, or (at your +C option) any later version. +C +C The nettle library is distributed in the hope that it will be useful, but +C WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY +C or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public +C License for more details. +C +C You should have received a copy of the GNU Lesser General Public License +C along with the nettle library; see the file COPYING.LIB. If not, write to +C the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, +C MA 02111-1307, USA. + +C Register usage: + +C AES state +define(<SA>,<%eax>) +define(<SB>,<%ebx>) +define(<SC>,<%ecx>) +define(<SD>,<%edx>) + +C Primary use of these registers. They're also used temporarily for other things. +define(<T>,<%ebp>) +define(<TMP>,<%edi>) +define(<KEY>,<%esi>) + +define(<FRAME_CTX>, <28(%esp)>) +define(<FRAME_TABLE>, <32(%esp)>) +define(<FRAME_LENGTH>, <36(%esp)>) +define(<FRAME_DST>, <40(%esp)>) +define(<FRAME_SRC>, <44(%esp)>) + +define(<FRAME_KEY>, <4(%esp)>) +define(<FRAME_COUNT>, <(%esp)>) + +C The aes state is kept in %eax, %ebx, %ecx and %edx +C +C %esi is used as temporary, to point to the input, and to the +C subkeys, etc. +C +C %ebp is used as the round counter, and as a temporary in the final round. +C +C %edi is a temporary, often used as an accumulator. + + .file "aes-decrypt-internal.asm" + + C _aes_decrypt(struct aes_context *ctx, + C const struct aes_table *T, + C unsigned length, uint8_t *dst, + C uint8_t *src) + .text + .align 16 +PROLOGUE(_nettle_aes_decrypt) + C save all registers that need to be saved + pushl %ebx C 20(%esp) + pushl %ebp C 16(%esp) + pushl %esi C 12(%esp) + pushl %edi C 8(%esp) + + subl $8, %esp C loop counter and save area for the key pointer + + movl FRAME_LENGTH, %ebp + testl %ebp,%ebp + jz .Lend + +.Lblock_loop: + movl FRAME_CTX,KEY C address of context struct ctx + C get number of rounds to do from ctx struct + + movl FRAME_SRC,TMP C address of plaintext + AES_LOAD(SA, SB, SC, SD, TMP, KEY) + addl $16, FRAME_SRC C Increment src pointer + movl FRAME_TABLE, T + + C get number of rounds to do from ctx struct + movl AES_NROUNDS (KEY),TMP + subl $1,TMP + + C Loop counter on stack + movl TMP, FRAME_COUNT + + addl $16,KEY C point to next key + movl KEY,FRAME_KEY + .align 16 +.Lround_loop: + AES_ROUND(T, SA,SD,SC,SB, TMP, KEY) + pushl TMP + + AES_ROUND(T, SB,SA,SD,SC, TMP, KEY) + pushl TMP + + AES_ROUND(T, SC,SB,SA,SD, TMP, KEY) + pushl TMP + + AES_ROUND(T, SD,SC,SB,SA, TMP, KEY) + + movl TMP,SD + popl SC + popl SB + popl SA + + movl FRAME_KEY, KEY + + xorl (KEY),SA C add current session key to plaintext + xorl 4(KEY),SB + xorl 8(KEY),SC + xorl 12(KEY),SD + addl $16,FRAME_KEY C point to next key + decl FRAME_COUNT + jnz .Lround_loop + + C last round + + AES_FINAL_ROUND(SA,SD,SC,SB, TMP, KEY) + pushl TMP + + AES_FINAL_ROUND(SB,SA,SD,SC, TMP, KEY) + pushl TMP + + AES_FINAL_ROUND(SC,SB,SA,SD, TMP, KEY) + pushl TMP + + AES_FINAL_ROUND(SD,SC,SB,SA, TMP, KEY) + + movl TMP,SD + popl SC + popl SB + popl SA + + C Inverse S-box substitution + mov $4,TMP +.Lsubst: + AES_SUBST_BYTE(T, KEY) + + decl TMP + jnz .Lsubst + + C Add last subkey, and store decrypted data + movl FRAME_DST,TMP + movl FRAME_KEY, KEY + AES_STORE(SA,SB,SC,SD, KEY, TMP) + + addl $16, FRAME_DST C Increment destination pointer + subl $16, FRAME_LENGTH C Length + + C NOTE: Will loop forever if input data is not an + C integer number of blocks. + jnz .Lblock_loop + +.Lend: + addl $8, %esp + popl %edi + popl %esi + popl %ebp + popl %ebx + ret +EPILOGUE(_nettle_aes_decrypt) -- GitLab