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C arm/aes-decrypt-internal.asm
ifelse(`
Copyright (C) 2013 Niels Möller
This file is part of GNU Nettle.
GNU Nettle is free software: you can redistribute it and/or
modify it under the terms of either:
* the GNU Lesser General Public License as published by the Free
Software Foundation; either version 3 of the License, or (at your
option) any later version.
or
* 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.
or both in parallel, as here.
GNU Nettle 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 copies of the GNU General Public License and
the GNU Lesser General Public License along with this program. If
not, see http://www.gnu.org/licenses/.
')
include_src(`arm/aes.m4')
define(`PARAM_ROUNDS', `r0')
define(`PARAM_KEYS', `r1')
define(`TABLE', `r2')
define(`PARAM_LENGTH', `r3')
C On stack: DST, SRC
define(`W0', `r4')
define(`W1', `r5')
define(`W2', `r6')
define(`W3', `r7')
define(`T0', `r8')
define(`COUNT', `r10')
define(`KEY', `r11')
define(`MASK', `r0') C Overlaps inputs, except TABLE
define(`X0', `r1')
define(`X1', `r3')
define(`X2', `r12')
define(`X3', `r14') C lr
define(`FRAME_ROUNDS', `[sp]')
define(`FRAME_KEYS', `[sp, #+4]')
define(`FRAME_LENGTH', `[sp, #+8]')
C 8 saved registers
define(`FRAME_DST', `[sp, #+44]')
define(`FRAME_SRC', `[sp, #+48]')
define(`AES_DECRYPT_ROUND', `
and T0, MASK, $1, lsl #2
ldr $5, [TABLE, T0]
and T0, MASK, $2, lsl #2
ldr $6, [TABLE, T0]
and T0, MASK, $3, lsl #2
ldr $7, [TABLE, T0]
and T0, MASK, $4, lsl #2
ldr $8, [TABLE, T0]
and T0, MASK, $4, ror #6
add TABLE, TABLE, #1024
ldr T0, [TABLE, T0]
eor $5, $5, T0
and T0, MASK, $1, ror #6
ldr T0, [TABLE, T0]
eor $6, $6, T0
and T0, MASK, $2, ror #6
ldr T0, [TABLE, T0]
eor $7, $7, T0
and T0, MASK, $3, ror #6
ldr T0, [TABLE, T0]
eor $8, $8, T0
and T0, MASK, $3, ror #14
add TABLE, TABLE, #1024
ldr T0, [TABLE, T0]
eor $5, $5, T0
and T0, MASK, $4, ror #14
ldr T0, [TABLE, T0]
eor $6, $6, T0
and T0, MASK, $1, ror #14
ldr T0, [TABLE, T0]
eor $7, $7, T0
and T0, MASK, $2, ror #14
ldr T0, [TABLE, T0]
eor $8, $8, T0
and T0, MASK, $2, ror #22
add TABLE, TABLE, #1024
ldr T0, [TABLE, T0]
eor $5, $5, T0
and T0, MASK, $3, ror #22
ldr T0, [TABLE, T0]
eor $6, $6, T0
and T0, MASK, $4, ror #22
ldr T0, [TABLE, T0]
eor $7, $7, T0
and T0, MASK, $1, ror #22
ldr T0, [TABLE, T0]
ldm $9!, {$1,$2,$3,$4}
eor $8, $8, T0
sub TABLE, TABLE, #3072
eor $5, $5, $1
eor $6, $6, $2
eor $7, $7, $3
eor $8, $8, $4
')
.file "aes-decrypt-internal.asm"
C _aes_decrypt(unsigned rounds, const uint32_t *keys,
C const struct aes_table *T,
C size_t length, uint8_t *dst,
C uint8_t *src)
.text
ALIGN(4)
PROLOGUE(_nettle_aes_decrypt)
teq PARAM_LENGTH, #0
beq .Lend
push {r0,r1,r3, r4,r5,r6,r7,r8,r10,r11,lr}
mov MASK, #0x3fc
ALIGN(16)
.Lblock_loop:
ldr X0, FRAME_SRC C Use X0 as SRC pointer
ldm sp, {COUNT, KEY}
AES_LOAD(X0,KEY,W0)
AES_LOAD(X0,KEY,W1)
AES_LOAD(X0,KEY,W2)
AES_LOAD(X0,KEY,W3)
str X0, FRAME_SRC
add TABLE, TABLE, #AES_TABLE0
b .Lentry
ALIGN(16)
.Lround_loop:
C Transform X -> W
AES_DECRYPT_ROUND(X0, X1, X2, X3, W0, W1, W2, W3, KEY)
.Lentry:
subs COUNT, COUNT,#2
C Transform W -> X
AES_DECRYPT_ROUND(W0, W1, W2, W3, X0, X1, X2, X3, KEY)
bne .Lround_loop
lsr COUNT, MASK, #2 C Put the needed mask in the unused COUNT register
sub TABLE, TABLE, #AES_TABLE0
C Final round
AES_FINAL_ROUND_V5(X0, X3, X2, X1, KEY, W0, COUNT)
AES_FINAL_ROUND_V5(X1, X0, X3, X2, KEY, W1, COUNT)
AES_FINAL_ROUND_V5(X2, X1, X0, X3, KEY, W2, COUNT)
AES_FINAL_ROUND_V5(X3, X2, X1, X0, KEY, W3, COUNT)
ldr X0, FRAME_DST
ldr X1, FRAME_LENGTH
AES_STORE(X0,W0)
AES_STORE(X0,W1)
AES_STORE(X0,W2)
AES_STORE(X0,W3)
subs X1, X1, #16
str X0, FRAME_DST
str X1, FRAME_LENGTH
bhi .Lblock_loop
add sp, sp, #12 C Drop saved r0, r1, r3
pop {r4,r5,r6,r7,r8,r10,r11,pc}
.Lend:
bx lr
EPILOGUE(_nettle_aes_decrypt)
|
