Bifid cipher: Difference between revisions

=={{header|EMal}}==

<syntaxhighlight lang="emal">

type PolybiusSquare

model

Map map

List grid

new by int side, text symbols

me.map ← text%Pair[]

me.grid ← List[].with(side, <int y|text[].with(side, <int x|""))

int y, x ← 0

for each text symbol in symbols

me.grid[y][x] ← symbol

me.map[symbol] ← int%int(y => x).named("y", "x")

x++

if x æ side

x ← 0

y++

end

end

end

fun asText = text by block

text result = ""

for int y ← 0; y < me.grid.length; y++

for int x ← 0; x < me.grid[y].length; x++

result.append(" " + me.grid[y][x])

end

result.appendLine()

end

return result

end

end

type BifidCipher

model

PolybiusSquare square

new by PolybiusSquare ←square do end

fun encrypt ← text by text value

List row ← int[].with(value.length * 2)

int y ← 0

int x ← value.length

for each text char in value

Pair p ← me.square.map[char]

row[y++] ← p.y

row[x++] ← p.x

end

text encrypted

for int i ← 0; i < row.length; i += 2

encrypted.append(me.square.grid[row[i]][row[i + 1]])

end

return encrypted

end

fun decrypt ← text by text value

List row ← int[]

for each text char in value

Pair p ← me.square.map[char]

row.append(p.y)

row.append(p.x)

end

int y ← 0

int x ← value.length

text decrypted

for int i ← 0; i < value.length; i++

decrypted.append(me.square.grid[row[y++]][row[x++]])

end

return decrypted

end

end

type Main

List pairs ← Pair[

text%PolybiusSquare("ATTACKATDAWN" => PolybiusSquare(5, "ABCDEFGHIKLMNOPQRSTUVWXYZ")).named("sample", "square"),

text%PolybiusSquare("FLEEATONCE" => PolybiusSquare(5, "BGWKZQPNDSIOAXEFCLUMTHYVR")).named("sample", "square"),

text%PolybiusSquare("The invasion will start on the first of January".upper().replace(" ", "") =>

PolybiusSquare(6, "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")).named("sample", "square")]

for each Pair pair in pairs

writeLine("Using Polybius square:")

write(pair.square)

BifidCipher cipher ← BifidCipher(pair.square)

write("Encrypting '" + pair.sample + "'")

text encrypted ← cipher.encrypt(pair.sample)

write(" => '" + encrypted + "'")

text decrypted ← cipher.decrypt(encrypted)

writeLine(" => '" + decrypted + "'")

writeLine()

end

</syntaxhighlight>

{{ out }}

<pre>

Using Polybius square:

A B C D E

F G H I K

L M N O P

Q R S T U

V W X Y Z

Encrypting 'ATTACKATDAWN' => 'DQBDAXDQPDQH' => 'ATTACKATDAWN'

Using Polybius square:

B G W K Z

Q P N D S

I O A X E

F C L U M

T H Y V R

Encrypting 'FLEEATONCE' => 'UAEOLWRINS' => 'FLEEATONCE'

Using Polybius square:

A B C D E F

G H I J K L

M N O P Q R

S T U V W X

Y Z 0 1 2 3

4 5 6 7 8 9

Encrypting 'THEINVASIONWILLSTARTONTHEFIRSTOFJANUARY' => 'TBPDIPHJSPOTAIVMGPCZKNSCN09BFIHK64I7BM4' => 'THEINVASIONWILLSTARTONTHEFIRSTOFJANUARY'

</pre>