📄 des.a51
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$IF __PHILIPS != 2
$IF __PHILIPS != 0
$include(regmf2.inc)
$ENDIF
NAME DES ; Name of the module
?PR?DES?DES SEGMENT CODE ; Segment for prg code in 'des'
PUBLIC _DES_CORE ; Public symbols for 'C' function call
RSEG ?PR?DES?DES ; Program segment
; Table data for DES
BITS EQU 020H ; The start of the bit-addressing block
BITS_0 EQU 020H ; The first bit-addressing block (8 bytes)
BITS_1 EQU 028H ; The second bit-addressing block (8 bytes)
BUF EQU BITS_0 ; The input block of the SP-box and the output buffer
; youyang 20030625
$IF __EMOSYN != 3
BLOCK EQU 03DH
$ELSE
BLOCK EQU 03CH
$ENDIF
;BLOCK EQU 045H
B_DES EQU 02FH.0
; S-Boxes
S1BOX:
DB 0EFH, 003H, 041H, 0FDH, 0D8H, 074H, 01EH, 047H
DB 026H, 0EFH, 0FBH, 022H, 0B3H, 0D8H, 084H, 01EH
DB 039H, 0ACH, 0A7H, 060H, 062H, 0C1H, 0CDH, 0BAH
DB 05CH, 096H, 090H, 059H, 005H, 03BH, 07AH, 085H
DB 040H, 0FDH, 01EH, 0C8H, 0E7H, 08AH, 08BH, 021H
DB 0DAH, 043H, 064H, 09FH, 02DH, 014H, 0B1H, 072H
DB 0F5H, 05BH, 0C8H, 0B6H, 09CH, 037H, 076H, 0ECH
DB 039H, 0A0H, 0A3H, 005H, 052H, 06EH, 00FH, 0D9H
S3BOX:
DB 0A7H, 0DDH, 00DH, 078H, 09EH, 00BH, 0E3H, 095H
DB 060H, 036H, 036H, 04FH, 0F9H, 060H, 05AH, 0A3H
DB 011H, 024H, 0D2H, 087H, 0C8H, 052H, 075H, 0ECH
DB 0BBH, 0C1H, 04CH, 0BAH, 024H, 0FEH, 08FH, 019H
DB 0DAH, 013H, 066H, 0AFH, 049H, 0D0H, 090H, 006H
DB 08CH, 06AH, 0FBH, 091H, 037H, 08DH, 00DH, 078H
DB 0BFH, 049H, 011H, 0F4H, 023H, 0E5H, 0CEH, 03BH
DB 055H, 0BCH, 0A2H, 057H, 0E8H, 022H, 074H, 0CEH
S5BOX:
DB 02CH, 0EAH, 0C1H, 0BFH, 04AH, 024H, 01FH, 0C2H
DB 079H, 047H, 0A2H, 07CH, 0B6H, 0D9H, 068H, 015H
DB 080H, 056H, 05DH, 001H, 033H, 0FDH, 0F4H, 0AEH
DB 0DEH, 030H, 007H, 09BH, 0E5H, 083H, 09BH, 068H
DB 049H, 0B4H, 02EH, 083H, 01FH, 0C2H, 0B5H, 07CH
DB 0A2H, 019H, 0D8H, 0E5H, 07CH, 02FH, 083H, 0DAH
DB 0F7H, 06BH, 090H, 0FEH, 0C4H, 001H, 05AH, 097H
DB 061H, 0A6H, 03DH, 040H, 00BH, 058H, 0E6H, 03DH
S7BOX:
DB 04DH, 0D1H, 0B2H, 00FH, 028H, 0BDH, 0E4H, 078H
DB 0F6H, 04AH, 00FH, 093H, 08BH, 017H, 0D1H, 0A4H
DB 03AH, 0ECH, 0C9H, 035H, 093H, 056H, 07EH, 0CBH
DB 055H, 020H, 0A0H, 0FEH, 06CH, 089H, 017H, 062H
DB 017H, 062H, 04BH, 0B1H, 0B4H, 0DEH, 0D1H, 087H
DB 0C9H, 014H, 03CH, 04AH, 07EH, 0A8H, 0E2H, 07DH
DB 0A0H, 09FH, 0F6H, 05CH, 06AH, 009H, 08DH, 0F0H
DB 00FH, 0E3H, 053H, 025H, 095H, 036H, 028H, 0CBH
SBOX EQU S1BOX
; Rotation count in key-generation
; Pls note here the count series is the reversal of the conventional ones
; Since when processing loop, it is relatively easier to count DOWN than
; count UP, thus we reverse the direction of the table
LROT: DB 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1, 1
RROT: DB 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1, 0
; End of DES_DATA segment
;The DES encryption/decryption subroutine segment
; This module do NOT save ANY registers' value, and it do NOT use any stacks.
; It is up to the caller to care about stacks and registers.
; Register as parameters:
; ACC is extensively used
; B is used as CARRY buffer (only B.0 is used)
; R0, R1 are used as counter and indexer
; R5.0 == 1 --> With Initial Permutation
; R5.0 == 0 --> Without Initial Permutation
; R5.1 == 1 --> With Final Permutation
; R5.1 == 0 --> Without Final Permutation
; R7 == 0 --> Encryption
; R7 == 1 --> Decryption
; Now Begins the subroutine.
;-------------------------------------------------------
_DES_CORE:
; Step 0: Initialize the key block (from 64-bit raw key to 64-bit key vector
; by PC-1 permutation (64 bits -> 56 bits)
PC_1:
;Step 0: Hard-coded bit-moving scheme, the key vector is currently
; located at (BITS+8) - (BITS+14)
MOV A,R7
JNB ACC.0,SDF
MOV A,R5
SETB ACC.7
MOV R5,A
SDF:
;*********************************************
MOV R7,#08H
MOV R0,#27H
STEP01:
MOV R1,#28H
MOV A,@R0 ;BIT7
RLC A
XCH A,@R1
RLC A
XCH A,@R1
RLC A ;BIT6
INC R1
XCH A,@R1
RLC A
XCH A,@R1
;BIT5
RLC A
INC R1
XCH A,@R1
RLC A
XCH A,@R1
DEC R0
DJNZ R7,STEP01
;*********************************************
MOV C, 27H.4
RLC A
MOV C, 26H.4
RLC A
MOV C, 25H.4
RLC A
MOV C, 24H.4
RLC A
MOV 2BH,A
MOV C, 23H.1
RLC A
MOV C, 22H.1
RLC A
MOV C, 21H.1
RLC A
MOV C, 20H.1
RLC A
MOV 2CH,A
MOV C, 23H.2
RLC A
MOV C, 22H.2
RLC A
MOV C, 21H.2
RLC A
MOV C, 20H.2
RLC A
MOV 2DH,A
;*********************************************
MOV R7,#04H
MOV R0,#27h
STEP02:
MOV R1,#2BH
MOV A,@R0 ;BIT1
RRC A
RRC A
XCH A,@R1
RLC A
XCH A,@R1
RRC A ;BIT2
INC R1
XCH A,@R1
RLC A
XCH A,@R1
;BIT3
RRC A
INC R1
XCH A,@R1
RLC A
XCH A,@R1
DEC R0
DJNZ R7,STEP02
;*********************************************
MOV C, 23H.3
RLC A
MOV C, 22H.3
RLC A
MOV C, 21H.3
RLC A
MOV C, 20H.3
RLC A
MOV C, 23H.4
RLC A
MOV C, 22H.4
RLC A
MOV C, 21H.4
RLC A
MOV C, 20H.4
RLC A
MOV 2EH,A
; Now the processed key block is in (BITS_1) - (BITS_1+6)
; Step 1: Initial permutation of the BLOCK (IP)
MOV A, R5
JB ACC.0, IPERM
JMP STEP_2
IPERM:
;****************************************
MOV R7,#04H
MOV R0,#BLOCK+4
MOV R1,#BLOCK+0
STEP34:
MOV A,@R0
SWAP A
MOV @R0,A
XRL A,@R1
ANL A,#0F0H
XCH A,@R1
XRL A,@R1
XCH A,@R1
XRL A,@R0
SWAP A
MOV @R0,A
INC R0
INC R1
DJNZ R7,STEP34
;**********************************************
MOV R7,#02H
MOV R0,#BLOCK+2
MOV R1,#BLOCK+0
LCALL STEP12
MOV R7,#02H
MOV R0,#BLOCK+6
MOV R1,#BLOCK+4
LCALL STEP12
;**********************************************
MOV R7,#04H
MOV R0,#BLOCK+1
MOV R1,#BLOCK
STEP13:
MOV A,@R0
RL A
MOV @R0,A
XRL A,@R1
ANL A,#0AAH
XCH A,@R1
XRL A,@R1
XCH A,@R1
XRL A,@R0
RR A
MOV @R0,A
INC R0
INC R0
INC R1
INC R1
DJNZ R7,STEP13
;**********************************************
;--------------------------------------------------------
; Step 1.4:
XCH A,BLOCK
XCH A,BLOCK+3
XCH A,BLOCK+6
MOV BLOCK,A
XCH A,BLOCK+7
XCH A,BLOCK+4
XCH A,BLOCK+1
MOV BLOCK+7,A
; Step 1.5: Done
;===========================================================
;1== ***********************************************************
;===========================================================
STEP_2:
; Step 2: The 16-run block processing
; To maximize the speed, we un-roll the loop
; by factor 2 (16 round -> 8 round)
MOV R1, #16 ; Initialize the count
LOOP_1:
; The first part of the un-rolled loop
; Step 2.1: Rotate the key vector
CLR B_DES
LH_DES_1:
MOV A, R5
JB ACC.7,KEY_DE ; If decryption, rotate right
MOV DPTR, #LROT-1
MOV A, R1
MOVC A, @A+DPTR
MOV R0, A ; Get the rotation counts and store
; it in R0
; Step 2.1L: Left-rotation, for the two 28-bit blocks respectively
LROT_0: CLR C
MOV A, BITS_1+6
RLC A
MOV BITS_1+6, A
MOV A, BITS_1+5
RLC A
MOV BITS_1+5, A
MOV A, BITS_1+4
RLC A
MOV BITS_1+4, A
MOV A, BITS_1+3
RLC A
MOV BITS_1+3, A
MOV B.0, C
MOV C, ACC.4
MOV (BITS_1+6).0, C
MOV C, B.0
MOV A, BITS_1+2
RLC A
MOV BITS_1+2, A
MOV A, BITS_1+1
RLC A
MOV BITS_1+1, A
MOV A, BITS_1
RLC A
MOV BITS_1, A
MOV (BITS_1+3).4, C
DJNZ R0, LROT_0
SJMP STEP2_2
KEY_DE:
MOV DPTR, #RROT-1
MOV A, R1
MOVC A, @A+DPTR
JZ STEP2_2 ; If no rotations, go directly
MOV R0, A ; Get the rotation counts and store
; it in R0
; Step 2.2R: Right-rotation, for the two 28-bit blocks respectively
RROT_0: CLR C
MOV A, BITS_1
RRC A
MOV BITS_1, A
MOV A, BITS_1+1
RRC A
MOV BITS_1+1, A
MOV A, BITS_1+2
RRC A
MOV BITS_1+2, A
MOV A, BITS_1+3
RRC A
MOV BITS_1+3, A
MOV B.0, C
MOV C, ACC.3
MOV BITS_1.7, C
MOV C, B.0
MOV A, BITS_1+4
RRC A
MOV BITS_1+4, A
MOV A, BITS_1+5
RRC A
MOV BITS_1+5, A
MOV A, BITS_1+6
RRC A
MOV BITS_1+6, A
MOV (BITS_1+3).3, C
DJNZ R0, RROT_0
STEP2_2:
; Step 2.2: Select the key using PC-2 permutation (56 bits -> 48 bits)
; (hard-coded).
; The permutated block is in (BITS_0) - (BITS_0 + 7)
; i.e., (BUF) - (BUF+7)
CLR A
MOV C, (BITS_1+1).2
RLC A
MOV C, (BITS_1+2).7
RLC A
MOV C, (BITS_1+1).5
RLC A
MOV C, (BITS_1+2).0
RLC A
MOV C, (BITS_1+0).7
RLC A
MOV C, (BITS_1+0).3
RLC A
;-------------------------------------------------------------------------------
ANL (BUF+0),#11000000B ;*********
ORL (BUF+0),A
;-------------------------------------------------------------------------------
CLR A
MOV C, (BITS_1+0).5
RLC A
MOV C, (BITS_1+3).4
RLC A
MOV C, (BITS_1+1).1
RLC A
MOV C, (BITS_1+0).2
RLC A
MOV C, (BITS_1+2).3
RLC A
MOV C, (BITS_1+1).6
RLC A
;-------------------------------------------------------------------------------
ANL (BUF+1),#11000000B ;*********
ORL (BUF+1),A
;-------------------------------------------------------------------------------
CLR A
MOV C, (BITS_1+2).1
RLC A
MOV C, (BITS_1+2).5
RLC A
MOV C, (BITS_1+1).4
RLC A
MOV C, (BITS_1+0).4
RLC A
MOV C, (BITS_1+3).6
RLC A
MOV C, (BITS_1+0).0
RLC A
;-------------------------------------------------------------------------------
ANL (BUF+2),#11000000B ;*********
ORL (BUF+2),A
;-------------------------------------------------------------------------------
CLR A
MOV C, (BITS_1+1).0
RLC A
MOV C, (BITS_1+0).1
RLC A
MOV C, (BITS_1+3).5
RLC A
MOV C, (BITS_1+2).4
RLC A
MOV C, (BITS_1+1).3
RLC A
MOV C, (BITS_1+0).6
RLC A
;-------------------------------------------------------------------------------
ANL (BUF+3),#11000000B ;*********
ORL (BUF+3),A
;-------------------------------------------------------------------------------
CLR A
MOV C, (BITS_1+5).7
RLC A
MOV C, (BITS_1+6).4
RLC A
MOV C, (BITS_1+3).1
RLC A
MOV C, (BITS_1+4).3
RLC A
MOV C, (BITS_1+5).1
RLC A
MOV C, (BITS_1+6).1
RLC A
;-------------------------------------------------------------------------------
ANL (BUF+4),#11000000B ;*********
ORL (BUF+4),A
;-------------------------------------------------------------------------------
CLR A
MOV C, (BITS_1+3).2
RLC A
MOV C, (BITS_1+4).0
RLC A
MOV C, (BITS_1+6).5
RLC A
MOV C, (BITS_1+5).3
RLC A
MOV C, (BITS_1+4).7
RLC A
MOV C, (BITS_1+5).0
RLC A
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