Playfair cipher: Difference between revisions
Added Kotlin
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(Added Kotlin) |
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}
}</lang>
=={{header|Kotlin}}==
{{trans|FreeBASIC}}
<lang scala>// version 1.0.5-2
enum class PlayfairOption {
NO_Q,
I_EQUALS_J
}
class Playfair(val keyword: String, val pfo: PlayfairOption) {
private val table: Array<CharArray> = Array(5, { CharArray(5) }) // 5 x 5 char array
init {
// build table
val used = BooleanArray(26) // all elements false
if (pfo == PlayfairOption.NO_Q)
used[16] = true // Q used
else
used[9] = true // J used
val alphabet = keyword.toUpperCase() + "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
var i = 0
var j = 0
var c: Char
var d: Int
for (k in 0 until alphabet.length) {
c = alphabet[k]
if (c !in 'A'..'Z') continue
d = c.toInt() - 65
if (!used[d]) {
table[i][j] = c
used[d] = true
if (++j == 5) {
if (++i == 5) break // table has been filled
j = 0
}
}
}
}
private fun getCleanText(plainText: String): String {
val plainText2 = plainText.toUpperCase() // ensure everything is upper case
// get rid of any non-letters and insert X between duplicate letters
var cleanText = ""
var prevChar = '\u0000' // safe to assume null character won't be present in plainText
var nextChar: Char
for (i in 0 until plainText2.length) {
nextChar = plainText2[i]
// It appears that Q should be omitted altogether if NO_Q option is specified - we assume so anyway
if (nextChar !in 'A'..'Z' || (nextChar == 'Q' && pfo == PlayfairOption.NO_Q)) continue
// If I_EQUALS_J option specified, replace J with I
if (nextChar == 'J' && pfo == PlayfairOption.I_EQUALS_J) nextChar = 'I'
if (nextChar != prevChar)
cleanText += nextChar
else
cleanText += "X" + nextChar
prevChar = nextChar
}
val len = cleanText.length
if (len % 2 == 1) { // dangling letter at end so add another letter to complete digram
if (cleanText[len - 1] != 'X')
cleanText += 'X'
else
cleanText += 'Z'
}
return cleanText
}
private fun findChar(c: Char): Pair<Int, Int> {
for (i in 0..4)
for (j in 0..4)
if (table[i][j] == c) return Pair(i, j)
return Pair(-1, -1)
}
public fun encode(plainText: String): String {
val cleanText = getCleanText(plainText)
var cipherText = ""
var length = cleanText.length
for (i in 0 until length step 2) {
val (row1, col1) = findChar(cleanText[i])
val (row2, col2) = findChar(cleanText[i + 1])
cipherText += when {
row1 == row2 -> table[row1][(col1 + 1) % 5].toString() + table[row2][(col2 + 1) % 5]
col1 == col2 -> table[(row1 + 1) % 5][col1].toString() + table[(row2 + 1) % 5][col2]
else -> table[row1][col2].toString() + table[row2][col1]
}
if (i < length - 1) cipherText += " "
}
return cipherText
}
public fun decode(cipherText: String): String {
var decodedText = ""
var length = cipherText.length
for (i in 0 until length step 3) { // cipherText will include spaces so we need to skip them
val (row1, col1) = findChar(cipherText[i])
val (row2, col2) = findChar(cipherText[i + 1])
decodedText += when {
row1 == row2 -> table[row1][if (col1 > 0) col1 - 1 else 4].toString() + table[row2][if (col2 > 0) col2 - 1 else 4]
col1 == col2 -> table[if (row1 > 0) row1- 1 else 4][col1].toString() + table[if (row2 > 0) row2 - 1 else 4][col2]
else -> table[row1][col2].toString() + table[row2][col1]
}
if (i < length - 1) decodedText += " "
}
return decodedText
}
public fun printTable() {
println("The table to be used is :\n")
for (i in 0..4) {
for (j in 0..4) print(table[i][j] + " ")
println()
}
}
}
fun main(args: Array<String>) {
print("Enter Playfair keyword : ")
val keyword: String = readLine()!!
var ignoreQ: String
do {
print("Ignore Q when buiding table y/n : ")
ignoreQ = readLine()!!.toLowerCase()
}
while (ignoreQ != "y" && ignoreQ != "n")
val pfo = if (ignoreQ == "y") PlayfairOption.NO_Q else PlayfairOption.I_EQUALS_J
val playfair = Playfair(keyword, pfo)
playfair.printTable()
print("\nEnter plain text : ")
val plainText: String = readLine()!!
val encodedText = playfair.encode(plainText)
println("\nEncoded text is : $encodedText")
val decodedText = playfair.decode(encodedText)
println("Decoded text is : $decodedText")
}</lang>
{{out}}
<pre>
Enter Playfair keyword : Playfair example
Ignore Q when buiding table y/n : n
The table to be used is :
P L A Y F
I R E X M
B C D G H
K N O Q S
T U V W Z
Enter plain text : Hide the gold...in the TREESTUMP!!!!
Encoded text is : BM OD ZB XD NA BE KU DM UI XM MO UV IF
Decoded text is : HI DE TH EG OL DI NT HE TR EX ES TU MP
</pre>
=={{header|NetRexx}}==
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