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Greetings!
I've some working code that I'm hoping to streamline. I'm open to varying interpretations of better algorithms that accomplish the same task. Here is the code that encrypts/decrypts:
...I've attached the source, a sample text and compiled version with PB/CC 4 if you'd like to download that instead. Much thanks.
I've some working code that I'm hoping to streamline. I'm open to varying interpretations of better algorithms that accomplish the same task. Here is the code that encrypts/decrypts:
Code:
#COMPILE EXE
#DIM ALL
DEFDWD A - Z
DECLARE SUB Encrypt (BYVAL TxtFileName AS STRING)
FUNCTION PBMAIN()
Encrypt "aeotp10.txt"
END FUNCTION
'For encryption/decryption you basically just need to XOR the bytes with the correct key.
'1. Copy first 12 bytes.
'2. XOR next 12 bytes with this key:
' BYTE hkey[12] = {0xA7, 0x8F, 0x56, 0xFD, 0x3E, 0x1D, 0x7C, 0xBD, 0xDC, 0xE6, 0xBE, 0x6D };
'3. XOR the bytes to the end of the data file with this key:
' BYTE key[35] = { 0x80, 0xDD, 0x13, 0x7F, 0x8C, 0xDA, 0x80, 0xC2, 0xA7, 0x51, 0xEA, 0x21,
' 0x86, 0xA1, 0xAE, 0xF0, 0x1D, 0xB1, 0xFC, 0x1D, 0xA1, 0x55, 0xDC, 0x9C, 0x47, 0x49, 0x80,
' 0x8B, 0xBF, 0x60, 0x65, 0xFD, 0xDA, 0xFD, 0x47 };
SUB Encrypt (BYVAL TxtFileName AS STRING)
DIM sFile AS STRING ' For storing File Name to be encrypted/Decrypted
DIM lFnum1 AS LONG ' For Source File
DIM lFnum2 AS LONG ' For Temprory Destination File
DIM lPos AS LONG ' For Iterating through each byte in Source File
DIM bData AS BYTE ' For Reading Data from Source File
DIM bDataC AS BYTE ' For storing Complemented (or encrypted) bData in Destination File
DIM sKey1(12) AS INTEGER ' 0xA7, 0x8F, 0x56, 0xFD, 0x3E, 0x1D, 0x7C, 0xBD, 0xDC, 0xE6, 0xBE, 0x6D
DIM sKey2(35) AS INTEGER
sKey1(0) = &HA7
sKey1(1) = &H8F
sKey1(2) = &H56
sKey1(3) = &HFD
sKey1(4) = &H3E
sKey1(5) = &H1D
sKey1(6) = &H7C
sKey1(7) = &HBD
sKey1(8) = &HDC
sKey1(9) = &HE6
sKey1(10) = &HBE
sKey1(11) = &H6D
sKey2(0) = &H80
sKey2(1) = &HDD
sKey2(2) = &H13
sKey2(3) = &H7F
sKey2(4) = &H8C
sKey2(5) = &HDA
sKey2(6) = &H80
sKey2(7) = &HC2
sKey2(8) = &HA7
sKey2(9) = &H51
sKey2(10) = &HEA
sKey2(11) = &H21
sKey2(12) = &H86
sKey2(13) = &HA1
sKey2(14) = &HAE
sKey2(15) = &HF0
sKey2(16) = &H1D
sKey2(17) = &HB1
sKey2(18) = &HFC
sKey2(19) = &H1D
sKey2(20) = &HA1
sKey2(21) = &H55
sKey2(22) = &HDC
sKey2(23) = &H9C
sKey2(24) = &H47
sKey2(25) = &H49
sKey2(26) = &H80
sKey2(27) = &H8B
sKey2(28) = &HBF
sKey2(29) = &H60
sKey2(30) = &H65
sKey2(31) = &HFD
sKey2(32) = &HDA
sKey2(33) = &HFD
sKey2(34) = &H47
lPos = 1
sFile = TxtFileName
lFnum2 = FREEFILE
OPEN "tmp" FOR BINARY ACCESS WRITE AS #lFnum2
lFnum1 = FREEFILE
OPEN sFile FOR BINARY ACCESS READ AS #lFnum1
DO WHILE NOT EOF(lFnum1)
GET #lFnum1, lPos, bData 'Reading Data Byte by Byte from Source File
IF NOT EOF(lFnum1) THEN
IF lPos <= 12 THEN ' just copy the data
bDataC = bData
ELSE
IF lPos <= 24 THEN 'Encrypt/Decrypt with first key
bDataC = bData XOR sKey1(lPos - 12 - 1)
ELSE 'Encrypt/Decrypt with second key
bDataC = bData XOR sKey2((lPos - 24 - 1) MOD 35)
END IF
END IF
PUT #lFnum2, lPos, bDataC 'Writing Encrypted Data To Temporary Destination File
lPos = lPos + 1
END IF
LOOP
CLOSE #lFnum1
CLOSE #lFnum2
KILL sFile ' Deleting Source File
NAME "tmp" AS sFile 'Renaming Temporary Destination File to Real File Name
END SUB
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