2012-10-01 11:02:15 -07:00
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; This Source Code Form is subject to the terms of the Mozilla Public
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; License, v. 2.0. If a copy of the MPL was not distributed with this
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; file, You can obtain one at http://mozilla.org/MPL/2.0/.
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2009-04-06 18:36:45 -07:00
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; ** ARCFOUR implementation optimized for AMD64.
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; **
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; ** The throughput achieved by this code is about 320 MBytes/sec, on
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; ** a 1.8 GHz AMD Opteron (rev C0) processor.
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.CODE
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; extern void ARCFOUR(RC4Context *cx, unsigned long long inputLen,
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; const unsigned char *input, unsigned char *output);
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ARCFOUR PROC
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push rbp
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push rbx
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push rsi
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push rdi
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mov rbp, rcx ; key = ARG(key)
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mov rbx, rdx ; rbx = ARG(len)
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mov rsi, r8 ; in = ARG(in)
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mov rdi, r9 ; out = ARG(out)
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mov rcx, [rbp] ; x = key->x
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mov rdx, [rbp+8] ; y = key->y
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add rbp, 16 ; d = key->data
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inc rcx ; x++
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and rcx, 0ffh ; x &= 0xff
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lea rbx, [rbx+rsi-8] ; rbx = in+len-8
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mov r9, rbx ; tmp = in+len-8
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mov rax, [rbp+rcx*8] ; tx = d[x]
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cmp rbx, rsi ; cmp in with in+len-8
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jl Lend ; jump if (in+len-8 < in)
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Lstart:
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add rsi, 8 ; increment in
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add rdi, 8 ; increment out
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;
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; generate the next 8 bytes of the rc4 stream into r8
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;
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mov r11, 8 ; byte counter
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@@:
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add dl, al ; y += tx
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mov ebx, [rbp+rdx*8] ; ty = d[y]
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mov [rbp+rcx*8], ebx ; d[x] = ty
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add bl, al ; val = ty + tx
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mov [rbp+rdx*8], eax ; d[y] = tx
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inc cl ; x++ (NEXT ROUND)
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mov eax, [rbp+rcx*8] ; tx = d[x] (NEXT ROUND)
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mov r8b, [rbp+rbx*8] ; val = d[val]
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dec r11b
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ror r8, 8 ; (ror does not change ZF)
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jnz @b
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;
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; xor 8 bytes
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;
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xor r8, [rsi-8]
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cmp rsi, r9 ; cmp in+len-8 with in
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mov [rdi-8], r8
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jle Lstart
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Lend:
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add r9, 8 ; tmp = in+len
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;
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; handle the last bytes, one by one
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;
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@@:
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cmp r9, rsi ; cmp in with in+len
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jle Lfinished ; jump if (in+len <= in)
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add dl, al ; y += tx
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mov ebx, [rbp+rdx*8] ; ty = d[y]
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mov [rbp+rcx*8], ebx ; d[x] = ty
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add bl, al ; val = ty + tx
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mov [rbp+rdx*8], eax ; d[y] = tx
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inc cl ; x++ (NEXT ROUND)
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mov eax, [rbp+rcx*8] ; tx = d[x] (NEXT ROUND)
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mov r8b, [rbp+rbx*8] ; val = d[val]
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xor r8b, [rsi] ; xor 1 byte
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mov [rdi], r8b
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inc rsi ; in++
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inc rdi
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jmp @b
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Lfinished:
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dec rcx ; x--
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mov [rbp-8], dl ; key->y = y
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mov [rbp-16], cl ; key->x = x
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pop rdi
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pop rsi
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pop rbx
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pop rbp
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ret
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ARCFOUR ENDP
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END
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