5.

Learn Encryption Techniques with BASIC and C++
(Publisher: Wordware Publishing, Inc.)
Author(s): Gil Held
ISBN: 1556225989
Publication Date: 10/01/98

Table of Contents

Index

A

alphabet,

cipher, 230

ciphertext, 18, 25

displacement, 27

keyword-based mixed, 95

numeric-based transposition, 142

plaintext, 18, 25

reverse ciphertext, 31

alphabetic relationships, 25-27

alternative, 133

common, 134

alphabetic shift key, 30

combining with keyword-based mixed alphabet, 104

using, 33

authentication, 370-371

B

backslash character, (\), 58

BASIC subroutines, 354-355

Baudot code, 274-275

binary random number sequences, 274

C

C++ language, 19

Caesar cipher, 16, 24

challenge message, 366

checkInput function, 100

cipher alphabet, 230

cipher disk, 222

cipher system, 2-4

cipher systems,

substitution, 15-17

transposition, 15, 17-18

types of, 15-18

cipher,

Caesar, 16, 24

Playfair, 218-219

Vigenere, 223-229

ciphers, 2-4

ciphertext, 6

converting to, 39-47

ciphertext alphabet, 18, 25

cleartext, see plaintext

code positions, 307

code system, 2-4

codes, 2-4

CONVERTSTORE subroutine, 58-60, 354

createAlphabet function, 100

createCipher function, 42, 94

cryptology, 1-2

D

DCONVERTSTORE subroutine, 129-130, 354

decipher function, 94

DECIPHER subroutine, 84, 354

DECIPHER.EXE execution, 364-366

decipherment, 3, 6-8, 32-33

reducing probability of, 232-233

decipherment process, 6-8

decoding, 3

decrypt function, 335

decryptFile function, 335

decryptKeyboardText function, 335

Diffie-Hellman concept, 372-373

digital signature, 370

displacement, 26-27, 31

displacement alphabet, 27

DMSGFILE subroutine, 82-84, 128-129, 264, 354

DO UNTIL loop, 59

DPCONVERTSTORE subroutine, 264-265

DPRTOUT subroutine, 85, 354

E

electronic mail systems, 18-19

ENCIPHER subroutine, 282

ENCIPHER.EXE execution, 362-364

encipherment, 3, 5, 31-32

RSA, 386-387

encipherment process, 5-6

encoding, 3

encryptFile function, 322

encryption systems,

private key based, 10-12

public key based, 10-12

types of, 10

encryptKeyboardText function, 322

errors, limiting, 47

Euclidean algorithm, 382-384

exponentiation, 387-390

F

Fermat’s theorem, 391

formatData function, 94

FORMCIPHER subroutine, 34, 354

formCipheredMessage function, 42

FOR-NEXT statement, 35, 41

frequency analysis, 136, 217, 221

G

getFileToDecipher function, 94

getKeyword function, 100

getMessage function, 42

getShiftKey function, 42, 94

GOSUB statement, 67

greatest common divisor, 382

GROUPBY5 subroutine, 47-48, 354

modified, 63-64

I

INITIALIZE subroutine, 33, 96, 354

modified, 105, 356-358

INPUT statement, 34

INT function, 279

interval extraction, 143-144

interval function, 187

INTERVAL subroutine, 151-152, 354

K

Kerckhoffs method, 234

key, 4, 8-10

distribution, 11, 13-14

generation, 11, 13, 391

management, 12-14

key space, 8-10

keyword phrase, 96

KEYWORD subroutine, 96, 98-99, 354, 358-359

keyword-based mixed alphabet, 95

combining with alphabetic shift key, 104

constructing, 95-96

keyword-based monoalphabetic substitution,

deciphering process, 125-133

enciphering process, 106-125

weaknesses of, 135-136

L

LEN statement, 40

LTRIM$ statement, 58

M

MAGIC, 17

Manhattan Project, 143

matrix-based systems,

automating, 144-216

decipherment of, 211-216

encipherment of, 144-211

matrix-based transposition, 137-144

mnemonic key, 98

modular addition, 375-377

modular arithmetic, 375-380

finding multiplicative inverse in, 380

modular multiplication, 378-380

modular subtraction, 378

modulo arithmetic, 6-8

modulo 9 arithmetic, 376

modulo 26 arithmetic, 291

encipherment/decipherment, 291-292

monoalphabetic substitution, 23

transposition-based, 137-144

monoalphabetic unilateral substitution, 23

MSGDCIPHER subroutine, 354

MSGENCIPHER subroutine, 40-41, 354

MSGFILE subroutine, 57-58, 354

multiple-line messages, processing, 56-57

multiplicative inverses, 380

N

numeric transposition, 141-143

numeric-based transposition alphabet, 142

numericExtraction function, 187

O

Oite, 48

one-time pad, 277-278

P

PA-K2, 48

PCONVERTSTORE subroutine, 237-238

periodic polyalphabetic substitution, 230-233

PFORMCIPHER subroutine, 236-237

modified, 360

plaintext, 3, 5

plaintext alphabet, 18, 25

Playfair cipher, 218-219

pocket cipher, 229

polyalphabetic substitution systems, 221-234

periodic, 230-233

simple, 223-229

weaknesses of, 234

prime numbers, 381

large, 391-392

locating, 391-392

Mersenne primes, 381

Sophie Germain primes, 381

twin primes, 381

PRINTIT subroutine, 224

printResults function, 42

private key based encryption, 10-12

private key encryption, 371

private key generation, RSA, 386

probability of decipherment, reducing, 232-233

probable word attack, 229

program listings

ASCII.CPP, 309-310

CIPHER1.BAS, 33-34

CIPHER1.CPP, 35-39

CIPHER2.BAS, 39-40

CIPHER2.CPP, 42-47

CIPHER3.BAS, 49-50

CIPHER3.CPP, 51-56

CIPHER4.BAS, 64-67

CIPHER4.CPP, 70-81

CIPHER5.BAS (main portion), 105

CIPHER5.CPP, 109-125

CIPHER6.BAS, 184-185

CIPHER6.CPP, 187-211

CIPHERTR.BAS (main portion), 148-149

CIPHERTR.CPP, 161-183

combining random number sequence and three-numeric key, 304

COUNT.CPP, 240-245

DCIPHER4.BAS (main portion), 86

DCIPHER4.CPP, 88-94

DCIPHER5.BAS (main portion), 127-128

DCIPHER5.CPP, 132-133

DCIPHER6.BAS (main portion), 212

DCIPHER6.CPP (decipher function),215-216

DPOLY2.BAS (main portion), 263

DPOLY2.CPP, 267-269

DPOLY2.CPP (decipher and getFileToDecipher functions), 269-271

DRANDOM2.BAS, 292-293

DRANDOM2.CPP, 295-299

DRANDOM3.BAS (main portion), 332

DRANDOM3.CPP, 336-345

ENCIPHER.BAS (main portion), 356

POLY1.BAS, 224-225

POLY1.CPP, 226-228

POLY2.BAS (main portion), 235-236

POLY2.CPP, 246-262

POSITION.BAS, 313

POSITION.CPP, 314-317

random number generator, 301-302

RANDOM1.BAS, 280

RANDOM1.CPP, 283-285

RANDOM2.BAS, 281

RANDOM2.CPP, 286-291

RANDOM3.BAS (statements in main portion), 319

RANDOM3.CPP, 322-331

ROTOR.BAS, 347-348

RTEST.BAS, 318

SHIFT.BAS, 28

SHIFT.CPP, 29-30

TRANSPORT.CPP, 153-161

using ASCII character values, 308

WORD.BAS, 96-97

WORD.CPP, 100-103

PRTOUT subroutine, 35, 60-63, 354

pseudo-random number generator, creating, 305-306

pseudo-random number sequences, 273, 276

generating, 276-279

pseudo-random sequence, 16

public key based encryption, 10-12

public key encryption, 369-370

advantages, 373

disadvantages, 373-374

general operation of, 369-370

public key generation, RSA, 386

PURPLE, 17

Q

QuickBASIC language, 19

R

random number generation, 277-279

alternative process for, 345-351

random number generator, creating, 305

random number sequences, 273

generating, 275

random numbers, 273

extending security of, 301, 303

RANDOMIZE SEED1 statement, 349

RANDOMIZE SEED2 statement, 349

RANDOMIZE statement, 278-279

RCONVERTSTORE subroutine, 319-321, 354

modified, 360-361

RDCONVERTSTORE subroutine, 332-333, 355

REM statement, 98

repetition period, 231

RESTORE statement, 106

reverse ciphertext alphabet, 31

RND function, 276-277

ROTOR subroutine, 350

RSA, 385-387

S

SETUP subroutine, 354, 361-362

simple transposition, 140-141

six-position code, 310-312

slash character (/), 58

subroutines,

CONVERTSTORE, 58-60, 354

DCONVERTSTORE, 129-130, 354

DECIPHER, 84, 354

DMSGFILE, 82-84, 128-129, 264, 354

DPRTOUT, 85, 354

ENCIPHER, 282

FORMCIPHER, 34-35, 354

GROUPBY5, 47-48, 354

GROUPBY5, modified, 63-64

INITIALIZE, 33, 96, 354

INITIALIZE, modified, 105, 356-358

INTERVAL, 151-152, 354

KEYWORD, 96, 98-99, 354, 358-359

MSGDCIPHER, 354

MSGENCIPHER, 40-41, 354

MSGFILE, 57-58, 354

PCONVERTSTORE, 237-238

PFORMCIPHER, 236-237

PFORMCIPHER, modified, 360

PRINTIT, 224

PRTOUT, 35, 60-63, 354

RCONVERTSTORE, 319-321, 354

RCONVERTSTORE, modified, 360-361

RDCONVERTSTORE, 332-333, 355

ROTOR, 350

SETUP, 354, 361-362

SPCONVERTSTORE, 264-265

TABLE, 224

TRANSPORT, 145-148, 354

substitution cipher systems, 15-17

symmetric key system, see private key based encryption

T

TABLE subroutine, 224

totient function, 384-385

TRANSPORT subroutine, 145-148, 354

transposition,

matrix-based, 137-144

simple, 140-141

transposition cipher systems, 15, 17-18

transposition-based monoalphabetic substitution, 137-144

U

unilateral substitution, 23-24

UUDECODE, 18

UUENCODE, 18

V

Vigenére cipher system, 223-229

basic tableau, 223-224

encipherment, 228-229

W

WHILE-WEND loop, 62

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