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C nettle, low-level cryptographics library
C
C Copyright (C) 2013 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., 51 Franklin Street, Fifth Floor, Boston,
C MA 02111-1301, USA.
include_src(<arm/aes.m4>)
define(<PARAM_ROUNDS>, <r0>)
define(<PARAM_KEYS>, <r1>)
define(<TABLE>, <r2>)
define(<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(<X0>, <r0>) C Overlaps PARAM_ROUNDS and PARAM_KEYS
define(<X1>, <r1>)
define(<X2>, <r12>)
define(<X3>, <r14>) C lr
define(<FRAME_ROUNDS>>, <[sp]>)
define(<FRAME_KEYS>, <[sp, #+4]>)
C 8 saved registers
define(<FRAME_DST>, <[sp, #+40]>)
define(<FRAME_SRC>, <[sp, #+44]>)
define(<SRC>, <%r12>) C Overlap registers used in inner loop.
define(<DST>, <COUNT>)
C AES_DECRYPT_ROUND(x0,x1,x2,x3,w0,w1,w2,w3,key)
define(<AES_DECRYPT_ROUND>, <
uxtb T0, $1
ldr $5, [TABLE, T0, lsl #2]
uxtb T0, $2
ldr $6, [TABLE, T0, lsl #2]
uxtb T0, $3
ldr $7, [TABLE, T0, lsl #2]
uxtb T0, $4
ldr $8, [TABLE, T0, lsl #2]
uxtb T0, $4, ror #8
add TABLE, TABLE, #1024
ldr T0, [TABLE, T0, lsl #2]
eor $5, $5, T0
uxtb T0, $1, ror #8
ldr T0, [TABLE, T0, lsl #2]
eor $6, $6, T0
uxtb T0, $2, ror #8
ldr T0, [TABLE, T0, lsl #2]
eor $7, $7, T0
uxtb T0, $3, ror #8
ldr T0, [TABLE, T0, lsl #2]
eor $8, $8, T0
uxtb T0, $3, ror #16
add TABLE, TABLE, #1024
ldr T0, [TABLE, T0, lsl #2]
eor $5, $5, T0
uxtb T0, $4, ror #16
ldr T0, [TABLE, T0, lsl #2]
eor $6, $6, T0
uxtb T0, $1, ror #16
ldr T0, [TABLE, T0, lsl #2]
eor $7, $7, T0
uxtb T0, $2, ror #16
ldr T0, [TABLE, T0, lsl #2]
eor $8, $8, T0
uxtb T0, $2, ror #24
add TABLE, TABLE, #1024
ldr T0, [TABLE, T0, lsl #2]
eor $5, $5, T0
uxtb T0, $3, ror #24
ldr T0, [TABLE, T0, lsl #2]
eor $6, $6, T0
uxtb T0, $4, ror #24
ldr T0, [TABLE, T0, lsl #2]
eor $7, $7, T0
uxtb T0, $1, ror #24
ldr T0, [TABLE, T0, lsl #2]
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 LENGTH, #0
beq .Lend
ldr SRC, [sp, #+4]
push {r0,r1, r4,r5,r6,r7,r8,r10,r11,lr}
ALIGN(16)
.Lblock_loop:
ldm sp, {COUNT, KEY}
add TABLE, TABLE, #AES_TABLE0
AES_LOAD(SRC,KEY,W0)
AES_LOAD(SRC,KEY,W1)
AES_LOAD(SRC,KEY,W2)
AES_LOAD(SRC,KEY,W3)
str SRC, FRAME_SRC
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
sub TABLE, TABLE, #AES_TABLE0
C Final round
ldr DST, FRAME_DST
AES_FINAL_ROUND_V6(X0, X3, X2, X1, KEY, W0)
AES_FINAL_ROUND_V6(X1, X0, X3, X2, KEY, W1)
AES_FINAL_ROUND_V6(X2, X1, X0, X3, KEY, W2)
AES_FINAL_ROUND_V6(X3, X2, X1, X0, KEY, W3)
ldr SRC, FRAME_SRC
AES_STORE(DST,W0)
AES_STORE(DST,W1)
AES_STORE(DST,W2)
AES_STORE(DST,W3)
str DST, FRAME_DST
subs LENGTH, LENGTH, #16
bhi .Lblock_loop
add sp, sp, #8 C Drop saved r0, r1
pop {r4,r5,r6,r7,r8,r10,r11,pc}
.Lend:
bx lr
EPILOGUE(_nettle_aes_decrypt)
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