One-time pad
You are encouraged to solve this task according to the task description, using any language you may know.
Implement a One-time pad, for encrypting and decrypting messages.
To keep it simple, we will be using letters only.
- Sub-Tasks
- Generate the data for a One-time pad (user needs to specify a filename and length)
- The important part is to get "true random" numbers, e.g. from /dev/random
- encryption / decryption ( basically the same operation, much like Rot-13 )
- For this step, much of Vigenère cipher could be reused,
with the key to be read from the file containing the One-time pad.
- optional: management of One-time pads: list, mark as used, delete, etc.
- Somehow, the users needs to keep track which pad to use for which partner.
To support the management of pad-files:
- Such files have a file-extension ".1tp"
- Lines starting with "#" may contain arbitary meta-data (i.e. comments)
- Lines starting with "-" count as "used"
- Whitespace within the otp-data is ignored
For example, here is the data from Wikipedia:
# Example data - Wikipedia - 2014-11-13 -ZDXWWW EJKAWO FECIFE WSNZIP PXPKIY URMZHI JZTLBC YLGDYJ -HTSVTV RRYYEG EXNCGA GGQVRF FHZCIB EWLGGR BZXQDQ DGGIAK YHJYEQ TDLCQT HZBSIZ IRZDYS RBYJFZ AIRCWI UCVXTW YKPQMK CKHVEX VXYVCS WOGAAZ OUVVON GCNEVR LMBLYB SBDCDC PCGVJX QXAUIP PXZQIJ JIUWYH COVWMJ UZOJHL DWHPER UBSRUJ HGAAPR CRWVHI FRNTQW AJVWRT ACAKRD OZKIIB VIQGBK IJCWHF GTTSSE EXFIPJ KICASQ IOUQTP ZSGXGH YTYCTI BAZSTN JKMFXI RERYWE
- See also
- one time pad encryption in Python
- snapfractalpop - One-Time-Pad Command-Line-Utility (C).
- Crypt-OTP-2.00 on CPAN (Perl)
Go
<lang go>package main
import (
"bufio" "crypto/rand" "fmt" "io/ioutil" "log" "math/big" "os" "strconv" "strings" "unicode"
)
const (
charsPerLine = 48 chunkSize = 6 cols = 8 demo = true // would normally be set to false
)
type fileType int
const (
otp fileType = iota enc dec
)
var scnr = bufio.NewScanner(os.Stdin)
func check(err error) {
if err != nil {
log.Fatal(err)
}
}
func toAlpha(s string) string {
var filtered []rune
for _, r := range s {
if unicode.IsUpper(r) {
filtered = append(filtered, r)
}
}
return string(filtered)
}
func isOtpRelated(s string) bool {
return strings.HasSuffix(s, ".1tp") || strings.HasSuffix(s, "1tp_cpy") ||
strings.HasSuffix(s, ".1tp_enc") || strings.HasSuffix(s, "1tp_dec")
}
func makePad(nLines int) string {
nChars := nLines * charsPerLine
bytes := make([]byte, nChars)
/* generate random upper case letters */
max := big.NewInt(26)
for i := 0; i < nChars; i++ {
n, err := rand.Int(rand.Reader, max)
check(err)
bytes[i] = byte(65 + n.Uint64())
}
return inChunks(string(bytes), nLines, otp)
}
func vigenere(text, key string, encrypt bool) string {
bytes := make([]byte, len(text))
var ci byte
for i, c := range text {
if encrypt {
ci = (byte(c) + key[i] - 130) % 26
} else {
ci = (byte(c) + 26 - key[i]) % 26
}
bytes[i] = ci + 65
}
temp := len(bytes) % charsPerLine
if temp > 0 { // pad with random characters so each line is a full one
max := big.NewInt(26)
for i := temp; i < charsPerLine; i++ {
n, err := rand.Int(rand.Reader, max)
check(err)
bytes = append(bytes, byte(65+n.Uint64()))
}
}
ft := enc
if !encrypt {
ft = dec
}
return inChunks(string(bytes), len(bytes)/charsPerLine, ft)
}
func inChunks(s string, nLines int, ft fileType) string {
nChunks := len(s) / chunkSize
remainder := len(s) % chunkSize
chunks := make([]string, nChunks)
for i := 0; i < nChunks; i++ {
chunks[i] = s[i*chunkSize : (i+1)*chunkSize]
}
if remainder > 0 {
chunks = append(chunks, s[nChunks*chunkSize:])
}
var sb strings.Builder
for i := 0; i < nLines; i++ {
j := i * cols
sb.WriteString(" " + strings.Join(chunks[j:j+cols], " ") + "\n")
}
ss := " file\n" + sb.String()
switch ft {
case otp:
return "# OTP" + ss
case enc:
return "# Encrypted" + ss
default: // case dec:
return "# Decrypted" + ss
}
}
func menu() int {
fmt.Println(`
1. Create one time pad file.
2. Delete one time pad file.
3. List one time pad files.
4. Encrypt plain text.
5. Decrypt cipher text.
6. Quit program. `)
choice := 0
for choice < 1 || choice > 6 {
fmt.Print("Your choice (1 to 6) : ")
scnr.Scan()
choice, _ = strconv.Atoi(scnr.Text())
check(scnr.Err())
}
return choice
}
func main() {
for {
choice := menu()
fmt.Println()
switch choice {
case 1: // Create OTP
fmt.Println("Note that encrypted lines always contain 48 characters.\n")
fmt.Print("OTP file name to create (without extension) : ")
scnr.Scan()
fileName := scnr.Text() + ".1tp"
nLines := 0
for nLines < 1 || nLines > 1000 {
fmt.Print("Number of lines in OTP (max 1000) : ")
scnr.Scan()
nLines, _ = strconv.Atoi(scnr.Text())
}
check(scnr.Err())
key := makePad(nLines)
file, err := os.Create(fileName)
check(err)
_, err = file.WriteString(key)
check(err)
file.Close()
fmt.Printf("\n'%s' has been created in the current directory.\n", fileName)
if demo {
// a copy of the OTP file would normally be on a different machine
fileName2 := fileName + "_cpy" // copy for decryption
file, err := os.Create(fileName2)
check(err)
_, err = file.WriteString(key)
check(err)
file.Close()
fmt.Printf("'%s' has been created in the current directory.\n", fileName2)
fmt.Println("\nThe contents of these files are :\n")
fmt.Println(key)
}
case 2: // Delete OTP
fmt.Println("Note that this will also delete ALL associated files.\n")
fmt.Print("OTP file name to delete (without extension) : ")
scnr.Scan()
toDelete1 := scnr.Text() + ".1tp"
check(scnr.Err())
toDelete2 := toDelete1 + "_cpy"
toDelete3 := toDelete1 + "_enc"
toDelete4 := toDelete1 + "_dec"
allToDelete := []string{toDelete1, toDelete2, toDelete3, toDelete4}
deleted := 0
fmt.Println()
for _, name := range allToDelete {
if _, err := os.Stat(name); !os.IsNotExist(err) {
err = os.Remove(name)
check(err)
deleted++
fmt.Printf("'%s' has been deleted from the current directory.\n", name)
}
}
if deleted == 0 {
fmt.Println("There are no files to delete.")
}
case 3: // List OTPs
fmt.Println("The OTP (and related) files in the current directory are:\n")
files, err := ioutil.ReadDir(".") // already sorted by file name
check(err)
for _, fi := range files {
name := fi.Name()
if !fi.IsDir() && isOtpRelated(name) {
fmt.Println(name)
}
}
case 4: // Encrypt
fmt.Print("OTP file name to use (without extension) : ")
scnr.Scan()
keyFile := scnr.Text() + ".1tp"
if _, err := os.Stat(keyFile); !os.IsNotExist(err) {
file, err := os.Open(keyFile)
check(err)
bytes, err := ioutil.ReadAll(file)
check(err)
file.Close()
lines := strings.Split(string(bytes), "\n")
le := len(lines)
first := le
for i := 0; i < le; i++ {
if strings.HasPrefix(lines[i], " ") {
first = i
break
}
}
if first == le {
fmt.Println("\nThat file has no unused lines.")
continue
}
lines2 := lines[first:] // get rid of comments and used lines
fmt.Println("Text to encrypt :-\n")
scnr.Scan()
text := toAlpha(strings.ToUpper(scnr.Text()))
check(scnr.Err())
tl := len(text)
nLines := tl / charsPerLine
if tl%charsPerLine > 0 {
nLines++
}
if len(lines2) >= nLines {
key := toAlpha(strings.Join(lines2[0:nLines], ""))
encrypted := vigenere(text, key, true)
encFile := keyFile + "_enc"
file2, err := os.Create(encFile)
check(err)
_, err = file2.WriteString(encrypted)
check(err)
file2.Close()
fmt.Printf("\n'%s' has been created in the current directory.\n", encFile)
for i := first; i < first+nLines; i++ {
lines[i] = "-" + lines[i][1:]
}
file3, err := os.Create(keyFile)
check(err)
_, err = file3.WriteString(strings.Join(lines, "\n"))
check(err)
file3.Close()
if demo {
fmt.Println("\nThe contents of the encrypted file are :\n")
fmt.Println(encrypted)
}
} else {
fmt.Println("Not enough lines left in that file to do encryption.")
}
} else {
fmt.Println("\nThat file does not exist.")
}
case 5: // Decrypt
fmt.Print("OTP file name to use (without extension) : ")
scnr.Scan()
keyFile := scnr.Text() + ".1tp_cpy"
check(scnr.Err())
if _, err := os.Stat(keyFile); !os.IsNotExist(err) {
file, err := os.Open(keyFile)
check(err)
bytes, err := ioutil.ReadAll(file)
check(err)
file.Close()
keyLines := strings.Split(string(bytes), "\n")
le := len(keyLines)
first := le
for i := 0; i < le; i++ {
if strings.HasPrefix(keyLines[i], " ") {
first = i
break
}
}
if first == le {
fmt.Println("\nThat file has no unused lines.")
continue
}
keyLines2 := keyLines[first:] // get rid of comments and used lines
encFile := keyFile[0:len(keyFile)-3] + "enc"
if _, err := os.Stat(encFile); !os.IsNotExist(err) {
file2, err := os.Open(encFile)
check(err)
bytes, err := ioutil.ReadAll(file2)
check(err)
file2.Close()
encLines := strings.Split(string(bytes), "\n")[1:] // exclude comment line
nLines := len(encLines)
if len(keyLines2) >= nLines {
encrypted := toAlpha(strings.Join(encLines, ""))
key := toAlpha(strings.Join(keyLines2[0:nLines], ""))
decrypted := vigenere(encrypted, key, false)
decFile := keyFile[0:len(keyFile)-3] + "dec"
file3, err := os.Create(decFile)
check(err)
_, err = file3.WriteString(decrypted)
check(err)
file3.Close()
fmt.Printf("\n'%s' has been created in the current directory.\n", decFile)
for i := first; i < first+nLines; i++ {
keyLines[i] = "-" + keyLines[i][1:]
}
file4, err := os.Create(keyFile)
check(err)
_, err = file4.WriteString(strings.Join(keyLines, "\n"))
check(err)
file4.Close()
if demo {
fmt.Println("\nThe contents of the decrypted file are :\n")
fmt.Println(decrypted)
}
}
} else {
fmt.Println("Not enough lines left in that file to do decryption.")
}
} else {
fmt.Println("\nThat file does not exist.")
}
case 6: // Quit program
return
}
}
}</lang>
- Output:
Similar (not exactly the same, of course) as the Kotlin sample session.
Java
Implementation supports multiple pads using the control name.
Implementation also includes the start and end ASCII characters. One usage shows support for uppercase only, a second usage shows allowing spaces, upper case, and lower case in the input text.
<lang java> import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; import java.util.Random; import java.util.regex.Matcher; import java.util.regex.Pattern;
public class OneTimePad {
public static void main(String[] args) {
String controlName = "AtomicBlonde";
generatePad(controlName, 5, 60, 65, 90);
String text = "IT WAS THE BEST OF TIMES IT WAS THE WORST OF TIMES";
String encrypted = parse(true, controlName, text.replaceAll(" ", ""));
String decrypted = parse(false, controlName, encrypted);
System.out.println("Input text = " + text);
System.out.println("Encrypted text = " + encrypted);
System.out.println("Decrypted text = " + decrypted);
controlName = "AtomicBlondeCaseSensitive";
generatePad(controlName, 5, 60, 32, 126);
text = "It was the best of times, it was the worst of times.";
encrypted = parse(true, controlName, text);
decrypted = parse(false, controlName, encrypted);
System.out.println();
System.out.println("Input text = " + text);
System.out.println("Encrypted text = " + encrypted);
System.out.println("Decrypted text = " + decrypted);
}
private static String parse(boolean encryptText, String controlName, String text) {
StringBuilder sb = new StringBuilder();
int minCh = 0;
int maxCh = 0;
Pattern minChPattern = Pattern.compile("^# MIN_CH = ([\\d]+)$");
Pattern maxChPattern = Pattern.compile("^# MAX_CH = ([\\d]+)$");
boolean validated = false;
try (BufferedReader in = new BufferedReader(new FileReader(getFileName(controlName))); ) {
String inLine = null;
while ( (inLine = in.readLine()) != null ) {
Matcher minMatcher = minChPattern.matcher(inLine);
if ( minMatcher.matches() ) {
minCh = Integer.parseInt(minMatcher.group(1));
continue;
}
Matcher maxMatcher = maxChPattern.matcher(inLine);
if ( maxMatcher.matches() ) {
maxCh = Integer.parseInt(maxMatcher.group(1));
continue;
}
if ( ! validated && minCh > 0 && maxCh > 0 ) {
validateText(text, minCh, maxCh);
validated = true;
}
// # is comment. - is used key.
if ( inLine.startsWith("#") || inLine.startsWith("-") ) {
continue;
}
// Have encryption key.
String key = inLine;
if ( encryptText ) {
for ( int i = 0 ; i < text.length(); i++) {
sb.append((char) (((text.charAt(i) - minCh + key.charAt(i) - minCh) % (maxCh - minCh + 1)) + minCh));
}
}
else {
for ( int i = 0 ; i < text.length(); i++) {
int decrypt = text.charAt(i) - key.charAt(i);
if ( decrypt < 0 ) {
decrypt += maxCh - minCh + 1;
}
decrypt += minCh;
sb.append((char) decrypt);
}
}
break;
}
} catch (IOException e) {
throw new RuntimeException(e);
}
return sb.toString();
}
private static void validateText(String text, int minCh, int maxCh) {
// Validate text is in range
for ( char ch : text.toCharArray() ) {
if ( ch != ' ' && (ch < minCh || ch > maxCh) ) {
throw new IllegalArgumentException("ERROR 103: Invalid text.");
}
}
}
private static String getFileName(String controlName) {
return controlName + ".1tp";
}
private static void generatePad(String controlName, int keys, int keyLength, int minCh, int maxCh) {
Random random = new Random();
try ( BufferedWriter writer = new BufferedWriter(new FileWriter(getFileName(controlName), false)); ) {
writer.write("# Lines starting with '#' are ignored.");
writer.newLine();
writer.write("# Lines starting with '-' are previously used.");
writer.newLine();
writer.write("# MIN_CH = " + minCh);
writer.newLine();
writer.write("# MAX_CH = " + maxCh);
writer.newLine();
for ( int line = 0 ; line < keys ; line++ ) {
StringBuilder sb = new StringBuilder();
for ( int ch = 0 ; ch < keyLength ; ch++ ) {
sb.append((char) (random.nextInt(maxCh - minCh + 1) + minCh));
}
writer.write(sb.toString());
writer.newLine();
}
writer.write("# EOF");
writer.newLine();
} catch (Exception e) {
throw new RuntimeException(e);
}
}
} </lang>
- Output:
Demonstration of job:
Input text = IT WAS THE BEST OF TIMES IT WAS THE WORST OF TIMES Encrypted text = ANFNPULTOZRSUNBACQXBMUVIGNWSRJFFNCBVCNF Decrypted text = ITWASTHEBESTOFTIMESITWASTHEWORSTOFTIMES Input text = It was the best of times, it was the worst of times. Encrypted text = jF,2abB`:3f9}@85"Y.k[JyWRNO\(q~0Z-5_P:E_H3Q0U(2>'eWy Decrypted text = It was the best of times, it was the worst of times.
Generated one time pad supporting uppercase only.
# Lines starting with '#' are ignored. # Lines starting with '-' are previously used. # MIN_CH = 65 # MAX_CH = 90 SUJNXBEPNVZZGIISQMFTTYVQNGSWDSNMZXINQJNEQHFBLCSZFCHJGKDLPQPN RQMZKUCZQZXQDTKXKSVRCFNZYTGZWCDPPMCHDHORVFWBLXJLWTJRBRGUOYWM PKEVUUBDOMBSFXVJFWGORCZPBSQOWZEOFFHZARVJWTEUQUAKGTMHFAVZSVOO DKNEKKCTQITFVSOWKMXAOQKWTUYOUXICSEWYCPGOPWFKHYZXQXOIVQUZWWZB NQUICNAJLTKDFSPXVBIVUUYUTZNNRNBQQXAGPERXZQNQLHEUXSRNIADKXZCL # EOF
Generated one time pad supporting lowercase, uppercase, symbols, and spaces.
# Lines starting with '#' are ignored.
# Lines starting with '-' are previously used.
# MIN_CH = 32
# MAX_CH = 126
AQ,: nBkQMfV8LC52r.vq\4cFNeg(y=<Z8LyPBUlT>Q@n(=T9 ckJJt6c59[
A{qjk{}x?vlu5(/I4IrkC0NJS2}?_a xF__;5V& -Nz7qh@7OD}l<u9~xGMZ
6JOW|8cZ<,O:vp*LMwU~5u@AJ5nVG7 x?_zfyY(>QMA|U37Z39B}M-lnI-GB
|Qe1*V^PHo"\M:YQo1Z$}2XUk[,L(<P+RDso>'LE.>#K)I6IvrJ&l}O<~=C^
rx0ubl%t(-tOnCQz_y5k%xlHHi$cvaRCIYD<5nUFWD5Hmd@K2.{/N^>PP.<I
# EOF
Julia
Kotlin
This uses the JDK's SecureRandom class for generating cryptographically strong random numbers. For convenience all three sub-tasks are catered for by a single, menu-based, program. <lang scala>// version 1.2.31
import java.io.File import java.security.SecureRandom
const val CHARS_PER_LINE = 48 const val CHUNK_SIZE = 6 const val COLS = 8 const val DEMO = true // would normally be set to false
enum class FileType { OTP, ENC, DEC }
fun Char.isAlpha() = this in 'A'..'Z'
fun String.toAlpha() = this.filter { it.isAlpha() }
fun String.isOtpRelated() = endsWith(".1tp") || endsWith(".1tp_cpy") ||
endsWith(".1tp_enc") || endsWith(".1tp_dec")
fun makePad(nLines: Int): String {
val nChars = nLines * CHARS_PER_LINE val sr = SecureRandom() val sb = StringBuilder(nChars) /* generate random upper case letters */ for (i in 0 until nChars) sb.append((sr.nextInt(26) + 65).toChar()) return sb.toString().inChunks(nLines, FileType.OTP)
}
fun vigenere(text: String, key: String, encrypt: Boolean = true): String {
val sb = StringBuilder(text.length)
for ((i, c) in text.withIndex()) {
val ci = if (encrypt)
(c.toInt() + key[i].toInt() - 130) % 26
else
(c.toInt() - key[i].toInt() + 26) % 26
sb.append((ci + 65).toChar())
}
val temp = sb.length % CHARS_PER_LINE
if (temp > 0) { // pad with random characters so each line is a full one
val sr = SecureRandom()
for (i in temp until CHARS_PER_LINE) sb.append((sr.nextInt(26) + 65).toChar())
}
val ft = if (encrypt) FileType.ENC else FileType.DEC
return sb.toString().inChunks(sb.length / CHARS_PER_LINE, ft)
}
fun String.inChunks(nLines: Int, ft: FileType): String {
val chunks = this.chunked(CHUNK_SIZE)
val sb = StringBuilder(this.length + nLines * (COLS + 1))
for (i in 0 until nLines) {
val j = i * COLS
sb.append(" ${chunks.subList(j, j + COLS).joinToString(" ")}\n")
}
val s = " file\n" + sb.toString()
return when (ft) {
FileType.OTP -> "# OTP" + s
FileType.ENC -> "# Encrypted" + s
FileType.DEC -> "# Decrypted" + s
}
}
fun menu(): Int {
println("""
|
|1. Create one time pad file.
|
|2. Delete one time pad file.
|
|3. List one time pad files.
|
|4. Encrypt plain text.
|
|5. Decrypt cipher text.
|
|6. Quit program.
|
""".trimMargin())
var choice: Int?
do {
print("Your choice (1 to 6) : ")
choice = readLine()!!.toIntOrNull()
}
while (choice == null || choice !in 1..6)
return choice
}
fun main(args: Array<String>) {
mainLoop@ while (true) {
val choice = menu()
println()
when (choice) {
1 -> { // Create OTP
println("Note that encrypted lines always contain 48 characters.\n")
print("OTP file name to create (without extension) : ")
val fileName = readLine()!! + ".1tp"
var nLines: Int?
do {
print("Number of lines in OTP (max 1000) : ")
nLines = readLine()!!.toIntOrNull()
}
while (nLines == null || nLines !in 1..1000)
val key = makePad(nLines)
File(fileName).writeText(key)
println("\n'$fileName' has been created in the current directory.")
if (DEMO) {
// a copy of the OTP file would normally be on a different machine
val fileName2 = fileName + "_cpy" // copy for decryption
File(fileName2).writeText(key)
println("'$fileName2' has been created in the current directory.")
println("\nThe contents of these files are :\n")
println(key)
}
}
2 -> { // Delete OTP
println("Note that this will also delete ALL associated files.\n")
print("OTP file name to delete (without extension) : ")
val toDelete1 = readLine()!! + ".1tp"
val toDelete2 = toDelete1 + "_cpy"
val toDelete3 = toDelete1 + "_enc"
val toDelete4 = toDelete1 + "_dec"
val allToDelete = listOf(toDelete1, toDelete2, toDelete3, toDelete4)
var deleted = 0
println()
for (name in allToDelete) {
val f = File(name)
if (f.exists()) {
f.delete()
deleted++
println("'$name' has been deleted from the current directory.")
}
}
if (deleted == 0) println("There are no files to delete.")
}
3 -> { // List OTPs
println("The OTP (and related) files in the current directory are:\n")
val otpFiles = File(".").listFiles().filter {
it.isFile() && it.name.isOtpRelated()
}.map { it.name }.toMutableList()
otpFiles.sort()
println(otpFiles.joinToString("\n"))
}
4 -> { // Encrypt
print("OTP file name to use (without extension) : ")
val keyFile = readLine()!! + ".1tp"
val kf = File(keyFile)
if (kf.exists()) {
val lines = File(keyFile).readLines().toMutableList()
var first = lines.size
for (i in 0 until lines.size) {
if (lines[i].startsWith(" ")) {
first = i
break
}
}
if (first == lines.size) {
println("\nThat file has no unused lines.")
continue@mainLoop
}
val lines2 = lines.drop(first) // get rid of comments and used lines
println("Text to encrypt :-\n")
val text = readLine()!!.toUpperCase().toAlpha()
val len = text.length
var nLines = len / CHARS_PER_LINE
if (len % CHARS_PER_LINE > 0) nLines++
if (lines2.size >= nLines) {
val key = lines2.take(nLines).joinToString("").toAlpha()
val encrypted = vigenere(text, key)
val encFile = keyFile + "_enc"
File(encFile).writeText(encrypted)
println("\n'$encFile' has been created in the current directory.")
for (i in first until first + nLines) {
lines[i] = "-" + lines[i].drop(1)
}
File(keyFile).writeText(lines.joinToString("\n"))
if (DEMO) {
println("\nThe contents of the encrypted file are :\n")
println(encrypted)
}
}
else println("Not enough lines left in that file to do encryption")
}
else println("\nThat file does not exist.")
}
5 -> { // Decrypt
print("OTP file name to use (without extension) : ")
val keyFile = readLine()!! + ".1tp_cpy"
val kf = File(keyFile)
if (kf.exists()) {
val keyLines = File(keyFile).readLines().toMutableList()
var first = keyLines.size
for (i in 0 until keyLines.size) {
if (keyLines[i].startsWith(" ")) {
first = i
break
}
}
if (first == keyLines.size) {
println("\nThat file has no unused lines.")
continue@mainLoop
}
val keyLines2 = keyLines.drop(first) // get rid of comments and used lines
val encFile = keyFile.dropLast(3) + "enc"
val ef = File(encFile)
if (ef.exists()) {
val encLines = File(encFile).readLines().drop(1) // exclude comment line
val nLines = encLines.size
if (keyLines2.size >= nLines) {
val encrypted = encLines.joinToString("").toAlpha()
val key = keyLines2.take(nLines).joinToString("").toAlpha()
val decrypted = vigenere(encrypted, key, false)
val decFile = keyFile.dropLast(3) + "dec"
File(decFile).writeText(decrypted)
println("\n'$decFile' has been created in the current directory.")
for (i in first until first + nLines) {
keyLines[i] = "-" + keyLines[i].drop(1)
}
File(keyFile).writeText(keyLines.joinToString("\n"))
if (DEMO) {
println("\nThe contents of the decrypted file are :\n")
println(decrypted)
}
}
else println("Not enough lines left in that file to do decryption")
}
else println("\n'$encFile' is missing.")
}
else println("\nThat file does not exist.")
}
else -> return // Quit
}
}
}</lang>
- Output:
Input/output for a sample session. In the interests of brevity, --<menu>-- indicates the re-display of the menu after the previous choice has been processed:
1. Create one time pad file. 2. Delete one time pad file. 3. List one time pad files. 4. Encrypt plain text. 5. Decrypt cipher text. 6. Quit program. Your choice (1 to 6) : 1 Note that encrypted lines always contain 48 characters. OTP file name to create (without extension) : user1 Number of lines in OTP (max 1000) : 4 'user1.1tp' has been created in the current directory. 'user1.1tp_cpy' has been created in the current directory. The contents of these files are : # OTP file MZSAVH VHJLRS YLFXZB JWAHSN AHPCSE RUJMFX ZZPMFB QTTNLM LDANXY LGJEBV IRKDTR NHKOPG ZDUBDC KOOWZC HEBKWC YAHOFY DYPCXG TGCBXC VFETFM VOTHNI ZCGKNL QONXYE IDCROZ LHLWMN YWSGDO YYSNNV QMOJFM AHVOGP CDFAKM HZCWEX CEAXXV INKAEO --<menu>-- Your choice (1 to 6) : 3 The OTP (and related) files in the current directory are: user1.1tp user1.1tp_cpy --<menu>-- Your choice (1 to 6) : 4 OTP file name to use (without extension) : user1 Text to encrypt :- Beware the Jabberwock, my son! The jaws that bite, the claws that catch! 'user1.1tp_enc' has been created in the current directory. The contents of the encrypted file are : # Encrypted file NDOAML OONURT ZPWTND TIYZGA TOTLSA JNQMYY HSTFMF SETJDF SDTPXR NNHVAO YSCVZU UTLAFM PEWGRH OJRCTF IOVEHK ZKETBQ --<menu>-- Your choice (1 to 6) : 5 OTP file name to use (without extension) : user1 'user1.1tp_dec' has been created in the current directory. The contents of the decrypted file are : # Decrypted file BEWARE THEJAB BERWOC KMYSON THEJAW STHATB ITETHE CLAWST HATCAT CHYRZT QBSSGD HMBMQG QBCFOF EVDGUD BKUULI BKXFWS --<menu>- Your choice (1 to 6) : 2 Note that this will also delete ALL associated files. OTP file name to delete (without extension) : user1 'user1.1tp' has been deleted from the current directory. 'user1.1tp_cpy' has been deleted from the current directory. 'user1.1tp_enc' has been deleted from the current directory. 'user1.1tp_dec' has been deleted from the current directory. --<menu>-- Your choice (1 to 6) : 6
Nim
<lang Nim>import os, re, sequtils, strformat, strutils import nimcrypto
- One-time pad file signature.
const Magic = "#one-time pad"
- Suffix for pad files.
const Suffix = ".1tp"
proc log(msg: string) =
## Log a message. stderr.write msg stderr.write '\n'
proc makeKeys(n, size: Positive): seq[string] =
## Generate "n" secure, random keys of "size" bytes.
# We're generating and storing keys in their hexadecimal form to make
# one-time pad files a little more human readable and to ensure a key
# can not start with a hyphen.
var bytes = newSeq[byte](size)
for _ in 1..n:
if randomBytes(bytes) != size:
raise newException(ValueError, "unable to build keys.")
result.add bytes.mapIt(it.toHex).join()
proc makePad(name: string; padSize, keySize: Positive): string =
## Create a new one-time pad identified by the given name. ## Args: ## name: unique one-time pad identifier. ## padSize: the number of keys (or pages) in the pad. ## keySize: the number of bytes per key. ## Returns: ## the new one-time pad as a string.
let pad = @[Magic, &"#name={name}", &"#size={padSize}"] & makeKeys(padSize, keySize)
result = pad.join("\n")
proc `xor`(message, key: string): string =
## Return "message" XOR-ed with "key". ## ## Args: ## message: plaintext or cyphertext to be encrypted or decrypted. ## key: encryption and decryption key. ## Returns: ## plaintext or cyphertext as a string.
if key.len < message.len:
quit("Key size is too short to encrypt/decrypt the message.", QuitFailure)
result = newStringOfCap(message.len)
var keyIndex = 0
for msgChar in message:
result.add chr(ord(msgChar) xor ord(key[keyIndex]))
inc keyIndex
proc useKey(pad: var string): string =
## Use the next available key from the given one-time pad. ## ## Args: ## pad: a one-time pad, updated. ## Returns: ## the key.
var matches: array[1, string]
let pos = pad.find(re"(?m)(^[A-F0-9]+$)", matches)
if pos < 0:
quit("Pad is all used up.", QuitFailure)
pad.insert("-", pos)
result = matches[0]
proc writePad(path: string; padSize, keySize: Positive) =
## Write a new one-time pad to the given path. ## ## Args: ## path: path to write one-time pad to. ## padSize: the number of keys (or pages) in the pad. ## keySize: the number of bytes per key.
if fileExists(path):
quit("Pad " & path & " already exists", QuitFailure)
try:
path.writeFile(makePad(path.extractFilename(), padSize, keySize))
except IOError:
quit("Unable to write file " & path, QuitFailure)
log("New one-time pad written to " & path)
proc process(pad, message: string; outfile: File) =
## Encrypt or decrypt "message" using the given pad. ## ## Args: ## pad: path to one-time pad. ## message: plaintext or ciphertext message to encrypt or decrypt. ## outfile: file-like object to write to.
if not fileExists(pad):
quit("No such pad: " & pad, QuitFailure)
let start = pad.readLines(1)
if start.len == 0 or start[0] != Magic:
quit(&"file '{pad}' does not look like a one-time pad", QuitFailure)
# Rewrites the entire one-time pad every time var padData = pad.readFile() let key = padData.useKey().parseHexStr() pad.writeFile(padData)
outfile.write(message xor key)
when isMainModule:
import parseopt
proc printUsage() =
echo "Usage: ", getAppFilename().lastPathPart,
" [-h] [--length LENGTH] [--key-size KEY_SIZE] [-o OUTFILE]"
echo " [--encrypt FILE | --decrypt FILE] pad"
echo ""
echo """One-time pad.
positional arguments:
pad Path to one-time pad. If neither --encrypt or --decrypt
are given, will create a new pad.
optional arguments:
-h, --help show this help message and exit
--length LENGTH Pad size. Ignored if --encrypt or --decrypt are given.
Defaults to 10.
--key-size KEY_SIZE Key size in bytes. Ignored if --encrypt or --decrypt
are given. Defaults to 64.
--outfile OUTFILE Write encoded/decoded message to a file. Ignored if
--encrypt or --decrypt is not given. Defaults to
stdout.
--encrypt FILE Encrypt FILE using the next available key from pad.
--decrypt FILE Decrypt FILE using the next available key from pad.
"""
var
parser = initOptParser(shortNoVal = {'h'}, longNoval = @["help"])
padPath: string
length = 10
outpath = ""
encryptPath = ""
decryptPath = ""
keySize = 64
encrypt = false
decrypt = false
for kind, key, val in parser.getopt(): case kind
of cmdShortOption:
printUsage()
if key != "h":
quit("Wrong option: " & key, QuitFailure)
elif val.len != 0:
quit("Wrong value for option -h", QuitFailure)
else:
quit(QuitSuccess)
of cmdLongOption:
case key
of "help":
printUsage()
quit(QuitSuccess)
of "length":
try:
length = parseInt(val)
if length < 2: raise newException(ValueError, "")
except ValueError:
quit("Wrong length: " & val, QuitFailure)
of "encrypt":
encryptPath = val
encrypt = true
of "decrypt":
decryptPath = val
decrypt = true
of "outfile":
outPath = val
of "key-size":
try:
keySize = parseInt(val)
if length < 2: raise newException(ValueError, "")
except ValueError:
quit("Wrong key size: " & val, QuitFailure)
else:
quit("Invalid option: " & key, QuitFailure)
of cmdArgument:
padPath = if key.endsWith(Suffix): key else: key & Suffix
of cmdEnd:
discard # Cannot not occur.
if padPath.len == 0:
quit("Missing pad file.", QuitFailure)
if encrypt and decrypt:
quit("Incompatible options: encrypt and decrypt", QuitFailure)
if encrypt or decrypt:
var outfile: File
if outpath.len == 0:
outfile = stdout
else:
try:
outfile = outpath.open(fmWrite)
except IOError:
quit("Unable to open output file.", QuitFailure)
let message = try:
if encrypt: encryptPath.readFile()
else: decryptPath.readFile()
except IOError:
quit("Unable to open file to encrypt or decrypt.", QuitFailure)
padPath.process(message, outfile) if outfile != stdout: outfile.close()
else: padPath.writePad(length, keySize)</lang>
- Output:
Show the help message and exit:
$ ./one_time_pad --help
Usage: one_time_pad [-h] [--length LENGTH] [--key-size KEY_SIZE] [-o OUTFILE]
[--encrypt FILE | --decrypt FILE] pad
One-time pad.
positional arguments:
pad Path to one-time pad. If neither --encrypt or --decrypt
are given, will create a new pad.
optional arguments:
-h, --help show this help message and exit
--length LENGTH Pad size. Ignored if --encrypt or --decrypt are given.
Defaults to 10.
--key-size KEY_SIZE Key size in bytes. Ignored if --encrypt or --decrypt
are given. Defaults to 64.
--outfile OUTFILE Write encoded/decoded message to a file. Ignored if
--encrypt or --decrypt is not given. Defaults to
stdout.
--encrypt FILE Encrypt FILE using the next available key from pad.
--decrypt FILE Decrypt FILE using the next available key from pad.
Create a new one-time pad in the current working directory:
$ ./one_time_pad --length 5 --key-size 128 mypad New one-time pad written to mypad.1tp $ head mypad.1tp #one-time pad #name=mypad.1tp #size=5 73BA79D1E6E153...
Distribute our new one-time pad and use it to encrypt a message:
$ cp mypad.1tp shared.1tp $ echo "like all shared secrets, the pad has to be at least as long as the message" > message.txt $ ./one_time_pad --encrypt message.txt --outfile secret.dat mypad
Decrypt the message using the shared copy of the one-time pad:
$ ./one_time_pad --decrypt secret.dat --outfile plaintext.txt shared.1tp $ cat plaintext.txt like all shared secrets, the pad has to be at least as long as the message
Perl
<lang Perl># 20200814 added Perl programming solution
use strict; use warnings;
use Crypt::OTP; use Bytes::Random::Secure qw( random_bytes );
print "Message : ", my $message = "show me the monKey", "\n";
my $otp = random_bytes(length $message); print "Ord(OTP) : ", ( map { ord($_).' ' } (split //, $otp) ) , "\n";
my $cipher = OTP( $otp, $message, 1 ); print "Ord(Cipher) : ", ( map { ord($_).' ' } (split //, $cipher) ) , "\n";
print "Decoded : ", OTP( $otp, $cipher, 1 ), "\n";</lang>
- Output:
Message : show me the monKey Ord(OTP) : 133 61 239 52 182 60 169 161 33 153 142 106 128 43 55 44 224 7 Ord(Cipher) : 246 85 128 67 150 81 204 129 85 241 235 74 237 68 89 103 133 126 Decoded : show me the monKey
Phix
Python
<lang python> """One-time pad using an XOR cipher. Requires Python >=3.6."""
import argparse import itertools import pathlib import re import secrets import sys
- One-time pad file signature.
MAGIC = "#one-time pad"
def make_keys(n, size):
"""Generate ``n`` secure, random keys of ``size`` bytes.""" # We're generating and storing keys in their hexadecimal form to make # one-time pad files a little more human readable and to ensure a key # can not start with a hyphen. return (secrets.token_hex(size) for _ in range(n))
def make_pad(name, pad_size, key_size):
"""Create a new one-time pad identified by the given name.
Args:
name (str): Unique one-time pad identifier.
pad_size (int): The number of keys (or pages) in the pad.
key_size (int): The number of bytes per key.
Returns:
The new one-time pad as a string.
"""
pad = [
MAGIC,
f"#name={name}",
f"#size={pad_size}",
*make_keys(pad_size, key_size),
]
return "\n".join(pad)
def xor(message, key):
"""Return ``message`` XOR-ed with ``key``.
Args:
message (bytes): Plaintext or cyphertext to be encrypted or decrypted.
key (bytes): Encryption and decryption key.
Returns:
Plaintext or cyphertext as a byte string.
"""
return bytes(mc ^ kc for mc, kc in zip(message, itertools.cycle(key)))
def use_key(pad):
"""Use the next available key from the given one-time pad.
Args:
pad (str): A one-time pad.
Returns:
(str, str) A two-tuple of updated pad and key.
"""
match = re.search(r"^[a-f0-9]+$", pad, re.MULTILINE)
if not match:
error("pad is all used up")
key = match.group() pos = match.start()
return (f"{pad[:pos]}-{pad[pos:]}", key)
def log(msg):
"""Log a message."""
sys.stderr.write(msg)
sys.stderr.write("\n")
def error(msg):
"""Exit with an error message."""
sys.stderr.write(msg)
sys.stderr.write("\n")
sys.exit(1)
def write_pad(path, pad_size, key_size):
"""Write a new one-time pad to the given path.
Args:
path (pathlib.Path): Path to write one-time pad to.
length (int): Number of keys in the pad.
"""
if path.exists():
error(f"pad '{path}' already exists")
with path.open("w") as fd:
fd.write(make_pad(path.name, pad_size, key_size))
log(f"New one-time pad written to {path}")
def main(pad, message, outfile):
"""Encrypt or decrypt ``message`` using the given pad.
Args:
pad (pathlib.Path): Path to one-time pad.
message (bytes): Plaintext or ciphertext message to encrypt or decrypt.
outfile: File-like object to write to.
"""
if not pad.exists():
error(f"no such pad '{pad}'")
with pad.open("r") as fd:
if fd.readline().strip() != MAGIC:
error(f"file '{pad}' does not look like a one-time pad")
# Rewrites the entire one-time pad every time
with pad.open("r+") as fd:
updated, key = use_key(fd.read())
fd.seek(0)
fd.write(updated)
outfile.write(xor(message, bytes.fromhex(key)))
if __name__ == "__main__":
# Command line interface parser = argparse.ArgumentParser(description="One-time pad.")
parser.add_argument(
"pad",
help=(
"Path to one-time pad. If neither --encrypt or --decrypt "
"are given, will create a new pad."
),
)
parser.add_argument(
"--length",
type=int,
default=10,
help="Pad size. Ignored if --encrypt or --decrypt are given. Defaults to 10.",
)
parser.add_argument(
"--key-size",
type=int,
default=64,
help="Key size in bytes. Ignored if --encrypt or --decrypt are given. Defaults to 64.",
)
parser.add_argument(
"-o",
"--outfile",
type=argparse.FileType("wb"),
default=sys.stdout.buffer,
help=(
"Write encoded/decoded message to a file. Ignored if --encrypt or "
"--decrypt is not given. Defaults to stdout."
),
)
group = parser.add_mutually_exclusive_group()
group.add_argument(
"--encrypt",
metavar="FILE",
type=argparse.FileType("rb"),
help="Encrypt FILE using the next available key from pad.",
)
group.add_argument(
"--decrypt",
metavar="FILE",
type=argparse.FileType("rb"),
help="Decrypt FILE using the next available key from pad.",
)
args = parser.parse_args()
if args.encrypt:
message = args.encrypt.read()
elif args.decrypt:
message = args.decrypt.read()
else:
message = None
# Sometimes necessary if message came from stdin
if isinstance(message, str):
message = message.encode()
pad = pathlib.Path(args.pad).with_suffix(".1tp")
if message:
main(pad, message, args.outfile)
else:
write_pad(pad, args.length, args.key_size)
</lang>
- Output:
Command line interface. Show the help message and exit
$ python otp.py --help
usage: otp.py [-h] [--length LENGTH] [--key-size KEY_SIZE] [-o OUTFILE]
[--encrypt FILE | --decrypt FILE]
pad
One-time pad.
positional arguments:
pad Path to one-time pad. If neither --encrypt or --decrypt
are given, will create a new pad.
optional arguments:
-h, --help show this help message and exit
--length LENGTH Pad size. Ignored if --encrypt or --decrypt are given.
Defaults to 10.
--key-size KEY_SIZE Key size in bytes. Ignored if --encrypt or --decrypt
are given. Defaults to 64.
-o OUTFILE, --outfile OUTFILE
Write encoded/decoded message to a file. Ignored if
--encrypt or --decrypt is not given. Defaults to
stdout.
--encrypt FILE Encrypt FILE using the next available key from pad.
--decrypt FILE Decrypt FILE using the next available key from pad.
Create a new one-time pad in the current working directory.
$ python otp.py mypad --length 5 --key-size 128 $ $ head mypad.1tp #one-time pad #name=mypad.1tp #size=5 8522ecc603a492693c04a19e55a3340601e3 ...
Distribute our new one-time pad and use it to encrypt a message.
$ cp mypad.1tp shared.1tp $ $ echo "like all shared secrets, the pad has to be at least as long as the message" > message.txt $ python otp.py mypad.1tp --encrypt message.txt -o secret.dat
And decrypt the message using the shared copy of the one-time pad.
$ python otp.py shared.1tp --decrypt secret.dat -o plaintext.txt
Racket
Raku
(formerly Perl 6)
The task is somewhat under-specified, especially the third (optional) section so I'm skipping that for now. Each sub-task has it's own code.
Sub-task one: generate one-time-pad files.
This is a fairly basic otp file generator. Uses Crypt::Random for decently high quality random numbers. (Random bytes are drawn from /dev/urandom on Unix-like systems, and CryptGenRandom() on Windows.) It will ask for a file name to save to, and the number of lines you want. Each line can be used to encode up to 48 characters of data. Default is 1000 lines, Only generating 4 lines here for demonstration purposes. Saving the file to 'rosettacode.1tp'.
<lang perl6>sub MAIN {
put "Generate data for one time pad encryption.\n" ~
"File will have .1tp extension.";
my $fn;
loop {
$fn = prompt 'Filename for one time pad data: ';
if $fn !~~ /'.1tp' $/ { $fn ~= '.1tp' }
if $fn.IO.e {
my $ow = prompt "$fn aready exists, over-write? y/[n] ";
last if $ow ~~ m:i/'y'/;
redo;
}
last;
}
put 'Each line will contain 48 characters of encyption data.'; my $lines = prompt 'How many lines of data to generate? [1000] '; $lines ||= 1000; generate($fn, $lines); say "One-time-pad data saved to: ", $fn.IO.absolute;
sub generate ( $fn, $lines) {
use Crypt::Random;
$fn.IO.spurt: "# one-time-pad encryption data\n" ~
((sprintf(" %s %s %s %s %s %s %s %s\n",
((('A'..'Z')[crypt_random_uniform(26)] xx 6).join) xx 8))
xx $lines).join;
}
}</lang>
- Output:
Generate data for one time pad encryption. File wile have .1tp extension. Filename for one time pad data: rosettacode Each line will contain 48 characters of encyption data. How many lines of data to generate? [1000] 4 One-time-pad data saved to: /home/myhome/mydirectory/rosettacode.1tp
Sample file generated by above code:
# one-time-pad encryption data DSUJOU UUWDZD VHFWRR AJDMDC ERZDGD WWKLHJ YITCML FORXCV BXGFCL ANGCGY VTAEUG UYAIPK FXWMNI INDLOR JIDZQL BOFFQD JISNOS CMLRPW TFGELQ HPTMRN SHBBDP AIVDAC CEWIFH TRLQVK FRBUUC GDCQHQ CEEURS RGVWVT JZIQLP NQCABF BWUPUI UDTZAF
Sub-task two: encrypt/decrypt text using the otp files generated by part one.
One-time-pad encryption gets it's security from the fact that the pads are used one time. As a line is used in the otp file, it needs to be marked as used, or removed so it doesn't get reused. Theoretically, you would make a copy of rosettacode.1tp and send it by secure means to the receiver of your encrypted text so that they can use it to decrypt. Since we are encrypting and decrypting on the same computer, we'll make a copy of the otp file named rosettacopy.1tp and use that for decryption so the encrypt and decrypt functions don't conflict.
<lang perl6>sub s2v ($s) { $s.uc.comb(/ <[ A..Z ]> /)».ord »-» 65 } sub v2s (@v) { (@v »%» 26 »+» 65)».chr.join }
sub hide ($secret, $otp) { v2s(s2v($secret) »+» s2v($otp)) } sub reveal ($hidden, $otp) { v2s(s2v($hidden) »-» s2v($otp)) }
sub otp-data ($fn, $lines) {
my $fh = $fn.IO.open :rw;
my $data;
my $count = 0;
repeat {
my $pos = $fh.tell;
my $line = $fh.get;
if $line.substr(0,1) ne '-'|'#' {
$data ~= $line;
$fh.seek($pos);
$fh.put: '-' ~ $line.substr(1);
$count++;
}
} until $count == $lines or $fh.eof;
note "Insufficient lines of data remaining in $fn" if $count != $lines;
$data;
}
sub otp-size (Str $string) { ceiling $string.uc.comb(/ <[ A..Z ]> /) / 48 }
sub otp-encrypt ( $secret, $fn ) {
my $otp-size = otp-size $secret;
my $otp-data = otp-data($fn, $otp-size);
my $encrypted = hide $secret, $otp-data;
# pad encryted text out to a full line with random text
$encrypted ~= ('A'..'Z').roll while $encrypted.chars % 48;
join "\n", $encrypted.comb(6).rotor(8, :partial).map:
{ sprintf "{ join ' ', "%s" xx $_ }", $_ };
}
sub otp-decrypt ( $secret, $fn ) {
my $otp-size = otp-size $secret;
my $otp-data = otp-data($fn, $otp-size);
my $plain-text = reveal $secret, $otp-data;
join "\n", $plain-text.comb(6).rotor(8, :partial).map:
{ sprintf "{ join ' ', "%s" xx $_ }", $_ };
}
my $otp-encrypt-fn = 'rosettacode.1tp'; my $otp-decrypt-fn = 'rosettacopy.1tp';
my $secret = "Beware the Jabberwock, my son! The jaws that bite, the claws that catch!";
say "Secret:\n$secret\n\nEncrypted:"; say my $encrypted = otp-encrypt $secret, $otp-encrypt-fn; say "\nDecrypted:\n", otp-decrypt $encrypted, $otp-decrypt-fn;</lang>
- Output:
Secret: Beware the Jabberwock, my son! The jaws that bite, the claws that catch! Encrypted: EWQJFY NBAMZE WLWSFT KVBERP XYDMGZ OPRLAK GBXVTP HZRTUO IXZHCE CUUORL THOFDI DCXRLG JQICPI ZEREHP RLOEAE PRMVJH Decrypted: BEWARE THEJAB BERWOC KMYSON THEJAW STHATB ITETHE CLAWST HATCAT CHOMLN YOOBJC JEXJWW ETMQCA RROTTY IDLFKT ODHQTE
Contents of rosettacode.1tp after encryption / rosettacopy.1tp after decryption:
# one-time-pad encryption data -DSUJOU UUWDZD VHFWRR AJDMDC ERZDGD WWKLHJ YITCML FORXCV -BXGFCL ANGCGY VTAEUG UYAIPK FXWMNI INDLOR JIDZQL BOFFQD JISNOS CMLRPW TFGELQ HPTMRN SHBBDP AIVDAC CEWIFH TRLQVK FRBUUC GDCQHQ CEEURS RGVWVT JZIQLP NQCABF BWUPUI UDTZAF
Tcl
Part 1: random strings
Get true random numbers, and turn them into strings.
With "randInt" from Tcl'ers wiki Cryptographically secure random numbers using /dev/urandom
<lang Tcl>puts "# True random chars for one-time pad"
proc randInt { min max } {
set randDev [open /dev/urandom rb]
set random [read $randDev 8]
binary scan $random H16 random
set random [expr {([scan $random %x] % (($max-$min) + 1) + $min)}]
close $randDev
return $random
}
proc randStr { sLen grp alfa } {
set aLen [string length $alfa]; incr aLen -1
set rs ""
for {set i 0} {$i < $sLen} {incr i} {
if { [expr {$i % $grp} ] == 0} { append rs " " }
set r [randInt 0 $aLen]
set char [string index $alfa $r]
append rs $char
##puts "$i: $r $char"
}
return $rs
}
set alfa "ABCDEFGHIJKLMNOPQRSTUVWXYZ" set len 48 set lines 4 set fn "test.1tp"
- Write file:
set fh [open $fn w] puts $fh "# OTP" for {set ln 0} {$ln < $lines} {incr ln} {
set line [randStr $len 6 $alfa] ##puts "$ln :$line." puts $fh $line
} close $fh
- Read file:
puts "# File $fn:" set fh [open $fn] puts [read $fh [file size $fn]] close $fh
puts "# Done."</lang>
- Output:
# True random chars for one-time pad # File test.1tp: # OTP OWCTEL SGDQEA UKEWCU PUTDEA XICBOL VVMJHD OHAXSE ZFAGDE QHDHKQ CCJBYF CMRCMC IXXPVM IOHQDA XIDTPX FGRIJC NPDOAT MYYQUV ZVKGDF ZLYKSX MBPLON RMQKQT QDYJVO LNKUFV DNKIQP NQOZKU MQOWHS VOQFWL EQWBFA HZQAMG JWNHGZ QERNNV GBKQTM # Done.
Part 2: Encrypt/Decrypt
See Tcl'ers wiki: vignere Vigenere ...
Part 3: Management
- list padfiles in directory
- list lines / blocks between "comment"-lines in padfile (i.e. remaining usable data)
...
Wren
<lang ecmascript>import "random" for Random import "io" for File, Directory import "/ioutil" for FileUtil, Input import "/dynamic" for Enum import "/str" for Char, Str
var CHARS_PER_LINE = 48 var CHUNK_SIZE = 6 var COLS = 8 var DEMO = true // would normally be set to false
var FileType = Enum.create("FileType", ["OTP", "ENC", "DEC"])
var toAlpha = Fn.new { |s| s.where { |c| Char.isAsciiUpper(c) }.join() }
var isOtpRelated = Fn.new { |s|
return s.endsWith(".1tp") || s.endsWith(".1tp_cpy") ||
s.endsWith(".1tp_enc") || s.endsWith(".1tp_dec")
}
var inChunks = Fn.new { |s, nLines, ft|
var chunks = Str.chunks(s, CHUNK_SIZE)
var sb = ""
for (i in 0...nLines) {
var j = i * COLS
var ch = chunks[j...j+COLS].join(" ")
sb = sb + " " + ch + "\n"
}
sb = " file\n" + sb
return (ft == FileType.OTP) ? "# OTP" + sb :
(ft == FileType.ENC) ? "# Encrypted" + sb :
(ft == FileType.DEC) ? "# Decrypted" + sb : ""
}
var makePad = Fn.new { |nLines|
var nChars = nLines * CHARS_PER_LINE var r = Random.new() var sb = "" /* generate random upper case letters */ for (i in 0...nChars) sb = sb + String.fromByte(r.int(65, 91)) return inChunks.call(sb, nLines, FileType.OTP)
}
var vigenere = Fn.new { |text, key, encrypt|
var sb = ""
var i = 0
for (c in text) {
var ci = encrypt ? (c.bytes[0] + key[i].bytes[0] - 130) % 26 :
(c.bytes[0] - key[i].bytes[0] + 26) % 26
sb = sb + String.fromByte(ci + 65)
i = i + 1
}
var temp = sb.count % CHARS_PER_LINE
if (temp > 0) { // pad with random characters so each line is a full one
var r = Random.new()
for (i in temp...CHARS_PER_LINE) sb = sb + String.fromByte(r.int(65, 91))
}
var ft = encrypt ? FileType.ENC : FileType.DEC
return inChunks.call(sb, (sb.count / CHARS_PER_LINE).floor, ft)
}
var menu = Fn.new {
System.print("""
1. Create one time pad file.
2. Delete one time pad file.
3. List one time pad files.
4. Encrypt plain text.
5. Decrypt cipher text.
6. Quit program.
""")
return Input.integer("Your choice (1 to 6) : ", 1, 6)
}
while (true) {
var choice = menu.call()
System.print()
if (choice == 1) { // Create OTP
System.print("Note that encrypted lines always contain 48 characters.\n")
var fileName = Input.text("OTP file name to create (without extension) : ", 1) + ".1tp"
var nLines = Input.integer("Number of lines in OTP (max 1000) : ", 1, 1000)
var key = makePad.call(nLines)
File.create(fileName) { |f| f.writeBytes(key) }
System.print("\n'%(fileName)' has been created in the current directory.")
if (DEMO) {
// a copy of the OTP file would normally be on a different machine
var fileName2 = fileName + "_cpy" // copy for decryption
File.create(fileName2) { |f| f.writeBytes(key) }
System.print("'%(fileName2)' has been created in the current directory.")
System.print("\nThe contents of these files are :\n")
System.print(key)
}
} else if (choice == 2) { // Delete OTP
System.print("Note that this will also delete ALL associated files.\n")
var toDelete1 = Input.text("OTP file name to delete (without extension) : ", 1) + ".1tp"
var toDelete2 = toDelete1 + "_cpy"
var toDelete3 = toDelete1 + "_enc"
var toDelete4 = toDelete1 + "_dec"
var allToDelete = [toDelete1, toDelete2, toDelete3, toDelete4]
var deleted = 0
System.print()
for (name in allToDelete) {
if (File.exists(name)) {
File.delete(name)
deleted = deleted + 1
System.print("'%(name)' has been deleted from the current directory.")
}
}
if (deleted == 0) System.print("There are no files to delete.")
} else if (choice == 3) { // List OTPs
System.print("The OTP (and related) files in the current directory are:\n")
var otpFiles = Directory.list("./").where { |f| File.exists(f) && isOtpRelated.call(f) }.toList
System.print(otpFiles.join("\n")) // already sorted
} else if (choice == 4) { // Encrypt
var keyFile = Input.text("OTP file name to use (without extension) : ", 1) + ".1tp"
if (File.exists(keyFile)) {
var lines = FileUtil.readLines(keyFile)
var first = lines.count
for (i in 0...lines.count) {
if (lines[i].startsWith(" ")) {
first = i
break
}
}
if (first == lines.count) {
System.print("\nThat file has no unused lines.")
continue
}
var lines2 = lines.skip(first).toList // get rid of comments and used lines
var text = toAlpha.call(Str.upper(Input.text("Text to encrypt :-\n\n", 1)))
var len = text.count
var nLines = (len / CHARS_PER_LINE).floor
if (len % CHARS_PER_LINE > 0) nLines = nLines + 1
if (lines2.count >= nLines) {
var key = toAlpha.call(lines2.take(nLines).join(""))
var encrypted = vigenere.call(text, key, true)
var encFile = keyFile + "_enc"
File.create(encFile) { |f| f.writeBytes(encrypted) }
System.print("\n'%(encFile)' has been created in the current directory.")
for (i in first...first + nLines) {
lines[i] = "-" + lines[i][1..-1]
}
File.create(keyFile) { |f| f.writeBytes(lines.join("\n")) }
if (DEMO) {
System.print("\nThe contents of the encrypted file are :\n")
System.print(encrypted)
}
} else System.print("Not enough lines left in that file to do encryption")
} else System.print("\nhat file does not exist.")
} else if (choice == 5) { // Decrypt
var keyFile = Input.text("OTP file name to use (without extension) : ", 1) + ".1tp_cpy"
if (File.exists(keyFile)) {
var keyLines = FileUtil.readLines(keyFile)
var first = keyLines.count
for (i in 0...keyLines.count) {
if (keyLines[i].startsWith(" ")) {
first = i
break
}
}
if (first == keyLines.count) {
System.print("\nThat file has no unused lines.")
continue
}
var keyLines2 = keyLines[first..-1] // get rid of comments and used lines
var encFile = keyFile[0..-4] + "enc"
if (File.exists(encFile)) {
var encLines = FileUtil.readLines(encFile)[1..-1] // exclude comment line
var nLines = encLines.count
if (keyLines2.count >= nLines) {
var encrypted = toAlpha.call(encLines.join(""))
var key = toAlpha.call(keyLines2.take(nLines).join(""))
var decrypted = vigenere.call(encrypted, key, false)
var decFile = keyFile[0..-4] + "dec"
File.create(decFile) { |f| f.writeBytes(decrypted) }
System.print("\n'%(decFile)' has been created in the current directory.")
for (i in first...first + nLines) {
keyLines[i] = "-" + keyLines[i][1..-1]
}
File.create(keyFile) { |f| f.writeBytes(keyLines.join("\n")) }
if (DEMO) {
System.print("\nThe contents of the decrypted file are :\n")
System.print(decrypted)
}
} else System.print("Not enough lines left in that file to do decryption")
} else System.print("\n'%(encFile)' is missing.")
} else System.print("\nThat file does not exist.")
} else {
return // Quit
}
}</lang>
- Output:
Input/output for a sample session. In the interests of brevity, --<menu>-- indicates the re-display of the menu after the previous choice has been processed:
1. Create one time pad file. 2. Delete one time pad file. 3. List one time pad files. 4. Encrypt plain text. 5. Decrypt cipher text. 6. Quit program. Your choice (1 to 6) : 1 Note that encrypted lines always contain 48 characters. OTP file name to create (without extension) : user1 Number of lines in OTP (max 1000) : 4 'user1.1tp' has been created in the current directory. 'user1.1tp_cpy' has been created in the current directory. The contents of these files are : # OTP file JRTAGR LQKYMI NADNZW XAVCEX RYLONG UODMBF XZAAFE LWLCGT BGNPAT CJYIDS UDRWOD QMJMYI SYDRWV PQEXLI AXJWSI GMUTRR KIUSZH XFNRCF NKJLYU IDJXIQ GHSSAN MLSHVU AMKIFV MVXAZT QSOLCZ RXYLMS QOLAMJ JJGAHS IROKWS ZARISI TIKXHC GCPPSB --<menu>-- Your choice (1 to 6) : 3 The OTP (and related) files in the current directory are: user1.1tp user1.1tp_cpy --<menu>-- Your choice (1 to 6) : 4 OTP file name to use (without extension) : user1 Text to encrypt :- Beware the Jabberwock, my son! The jaws that bite, the claws that catch! 'user1.1tp_enc' has been created in the current directory. The contents of the encrypted file are : # Encrypted file KVPAXV EXOHMJ OEUJNY HMTUSK KFPXNC MHKMUG FSETMI NHLYYM IGGRAM EQLTCZ VNUYHO CYRHKU GTRZAZ UUDTDL DEDXRL DMAVDA --<menu>-- Your choice (1 to 6) : 5 OTP file name to use (without extension) : user1 'user1.1tp_dec' has been created in the current directory. The contents of the decrypted file are : # Decrypted file BEWARE THEJAB BERWOC KMYSON THEJAW STHATB ITETHE CLAWST HATCAT CHNLZH BKDCTL MMIVMM OVOIEE FEZWSD DHUBZD XAGCMJ --<menu>-- Your choice (1 to 6) : 2 Note that this will also delete ALL associated files. OTP file name to delete (without extension) : user1 'user1.1tp' has been deleted from the current directory. 'user1.1tp_cpy' has been deleted from the current directory. 'user1.1tp_enc' has been deleted from the current directory. 'user1.1tp_dec' has been deleted from the current directory. --<menu>-- Your choice (1 to 6) : 6