Bacon cipher: Difference between revisions

=={{header|Python}}==

This deviates from the Bacon method as it encodes to different capitalisation of text rather than differences in font.

<lang python>import string

sometext = """All children, except one, grow up. They soon know that they will grow

up, and the way Wendy knew was this. One day when she was two years old

she was playing in a garden, and she plucked another flower and ran with

it to her mother. I suppose she must have looked rather delightful, for

Mrs. Darling put her hand to her heart and cried, "Oh, why can't you

remain like this for ever!" This was all that passed between them on

the subject, but henceforth Wendy knew that she must grow up. You always

know after you are two. Two is the beginning of the end.

Of course they lived at 14 [their house number on their street], and

until Wendy came her mother was the chief one. She was a lovely lady,

with a romantic mind and such a sweet mocking mouth. Her romantic

mind was like the tiny boxes, one within the other, that come from the

puzzling East, however many you discover there is always one more; and

her sweet mocking mouth had one kiss on it that Wendy could never get,

though there it was, perfectly conspicuous in the right-hand corner.""".lower()

lc2bin = {ch: '{:05b}'.format(i)

for i, ch in enumerate(string.ascii_lowercase + ' .')}

bin2lc = {val: key for key, val in lc2bin.items()}

phrase = 'Rosetta code Bacon cipher example secret phrase to encode in the capitalisation of peter pan'.lower()

def to_5binary(msg):

return ( ch == '1' for ch in ''.join(lc2bin.get(ch, '') for ch in msg.lower()))

def encrypt(message, text):

bin5 = to_5binary(message)

textlist = list(text.lower())

out = []

for capitalise in bin5:

while textlist:

ch = textlist.pop(0)

if ch.isalpha():

if capitalise:

ch = ch.upper()

out.append(ch)

break

else:

out.append(ch)

else:

raise Exception('ERROR: Ran out of characters in sometext')

return ''.join(out) + '...'

def decrypt(bacontext):

binary = []

bin5 = []

out = []

for ch in bacontext:

if ch.isalpha():

binary.append('1' if ch.isupper() else '0')

if len(binary) == 5:

bin5 = ''.join(binary)

out.append(bin2lc[bin5])

binary = []

return ''.join(out)

print('PLAINTEXT = \n%s\n' % phrase)

encrypted = encrypt(phrase, sometext)

print('ENCRYPTED = \n%s\n' % encrypted)

decrypted = decrypt(encrypted)

print('DECRYPTED = \n%s\n' % decrypted)

assert phrase == decrypted, 'Round-tripping error'</lang>

{{out}}

<pre>PLAINTEXT =

rosetta code bacon cipher example secret phrase to encode in the capitalisation of peter pan

ENCRYPTED =

All cHiLDReN, exCept One, GroW UP. thEY soon kNOw That tHey WILl groW

Up, aNd tHE wAy wendY knew was tHis. ONE daY WhEN ShE was tWo yEars oLD

SHe wAS PlaYinG in a GARdEn, anD shE pLUCked anoTHer fLOWEr AnD Ran WitH

It To Her MothEr. i supPoSe shE muSt hAve LOOKeD raTHER deLIGHtfuL, for

mrS. daRlinG puT HeR hAnd TO hER HeARt And cRied, "OH, wHy caN't yOU

RemaiN LikE thIS fOr eVer!" thIS wAS AlL tHat PAssED BetWeeN ThEm on

tHe subjecT, BUT hEnceForTH wendy kNeW ThAt shE muSt grow uP. yoU AlWays

kNOW afTEr YOU aRe tWO. Two iS tHE BeGinNING of The End.

OF coUrsE theY LIvEd aT 14 [THEir housE NuM...

DECRYPTED =

rosetta code bacon cipher example secret phrase to encode in the capitalisation of peter pan</pre>