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+<article id="content">
+<header>
+<h1 class="title">Module <code>szyfrow.railfence</code></h1>
+</header>
+<section id="section-intro">
+<p><a href="https://en.wikipedia.org/wiki/Rail_fence_cipher">Railfence transposition cipher</a>.</p>
+<p>Works by splitting the text into sections, then reading across them to
+generate the rows in the cipher. The rows are then combined to form the
+ciphertext.</p>
+<p>Example: the plaintext "hellotherefriends", with a height of four, written
+out in the railfence as
+h h i
+etere*
+lorfns
+l e d
+(with the * showing the one character to finish the last section).
+Each 'section' is two columns, but unfolded. In the example, the first
+section is 'hellot'.</p>
+<details class="source">
+<summary>
+<span>Expand source code</span>
+</summary>
+<pre><code class="python">"""[Railfence transposition cipher](https://en.wikipedia.org/wiki/Rail_fence_cipher).
+
+Works by splitting the text into sections, then reading across them to
+generate the rows in the cipher. The rows are then combined to form the
+ciphertext.
+
+Example: the plaintext "hellotherefriends", with a height of four, written
+out in the railfence as
+ h h i
+ etere*
+ lorfns
+ l e d
+(with the * showing the one character to finish the last section).
+Each 'section' is two columns, but unfolded. In the example, the first
+section is 'hellot'.
+"""
+import math
+from enum import Enum
+from itertools import starmap, zip_longest
+from szyfrow.support.utilities import *
+from szyfrow.support.language_models import *
+
+
+def railfence_encipher(message, height, fillvalue=''):
+ """Railfence cipher.
+ Works by splitting the text into sections, then reading across them to
+ generate the rows in the cipher. The rows are then combined to form the
+ ciphertext.
+
+ Example: the plaintext "hellotherefriends", with a height of four, written
+ out in the railfence as
+ h h i
+ etere*
+ lorfns
+ l e d
+ (with the * showing the one character to finish the last section).
+ Each 'section' is two columns, but unfolded. In the example, the first
+ section is 'hellot'.
+
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 2, fillvalue='!')
+ 'hlohraateerishsslnpeefetotsigaleccpeselteevsmhatetiiaogicotxfretnrifneihr!'
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 3, fillvalue='!')
+ 'horaersslpeeosglcpselteevsmhatetiiaogicotxfretnrifneihr!!lhateihsnefttiaece!'
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 5, fillvalue='!')
+ 'hresleogcseeemhetaocofrnrner!!lhateihsnefttiaece!!ltvsatiigitxetifih!!oarspeslp!'
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 10, fillvalue='!')
+ 'hepisehagitnr!!lernesge!!lmtocerh!!otiletap!!tseaorii!!hassfolc!!evtitffe!!rahsetec!!eixn!'
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 3)
+ 'horaersslpeeosglcpselteevsmhatetiiaogicotxfretnrifneihrlhateihsnefttiaece'
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 5)
+ 'hresleogcseeemhetaocofrnrnerlhateihsnefttiaeceltvsatiigitxetifihoarspeslp'
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 7)
+ 'haspolsevsetgifrifrlatihnettaeelemtiocxernhorersleesgcptehaiaottneihesfic'
+ """
+ sections = chunks(message, (height - 1) * 2, fillvalue=fillvalue)
+ n_sections = len(sections)
+ # Add the top row
+ rows = [cat([s[0] for s in sections])]
+ # process the middle rows of the grid
+ for r in range(1, height-1):
+ rows += [cat([s[r:r+1] + s[height*2-r-2:height*2-r-1] for s in sections])]
+ # process the bottom row
+ rows += [cat([s[height - 1:height] for s in sections])]
+ # rows += [wcat([s[height - 1] for s in sections])]
+ return cat(rows)
+
+def railfence_decipher(message, height, fillvalue=''):
+ """Railfence decipher.
+ Works by reconstructing the grid used to generate the ciphertext, then
+ unfolding the sections so the text can be concatenated together.
+
+ Example: given the ciphertext 'hhieterelorfnsled' and a height of 4, first
+ work out that the second row has a character missing, find the rows of the
+ grid, then split the section into its two columns.
+
+ 'hhieterelorfnsled' is split into
+ h h i
+ etere
+ lorfns
+ l e d
+ (spaces added for clarity), which is stored in 'rows'. This is then split
+ into 'down_rows' and 'up_rows':
+
+ down_rows:
+ hhi
+ eee
+ lrn
+ led
+
+ up_rows:
+ tr
+ ofs
+
+ These are then zipped together (after the up_rows are reversed) to recover
+ the plaintext.
+
+ Most of the procedure is about finding the correct lengths for each row then
+ splitting the ciphertext into those rows.
+
+ >>> railfence_decipher('hlohraateerishsslnpeefetotsigaleccpeselteevsmhatetiiaogicotxfretnrifneihr!', 2).strip('!')
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ >>> railfence_decipher('horaersslpeeosglcpselteevsmhatetiiaogicotxfretnrifneihr!!lhateihsnefttiaece!', 3).strip('!')
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ >>> railfence_decipher('hresleogcseeemhetaocofrnrner!!lhateihsnefttiaece!!ltvsatiigitxetifih!!oarspeslp!', 5).strip('!')
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ >>> railfence_decipher('hepisehagitnr!!lernesge!!lmtocerh!!otiletap!!tseaorii!!hassfolc!!evtitffe!!rahsetec!!eixn!', 10).strip('!')
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ >>> railfence_decipher('horaersslpeeosglcpselteevsmhatetiiaogicotxfretnrifneihrlhateihsnefttiaece', 3)
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ >>> railfence_decipher('hresleogcseeemhetaocofrnrnerlhateihsnefttiaeceltvsatiigitxetifihoarspeslp', 5)
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ >>> railfence_decipher('haspolsevsetgifrifrlatihnettaeelemtiocxernhorersleesgcptehaiaottneihesfic', 7)
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ """
+ # find the number and size of the sections, including how many characters
+ # are missing for a full grid
+ n_sections = math.ceil(len(message) / ((height - 1) * 2))
+ padding_to_add = n_sections * (height - 1) * 2 - len(message)
+ # row_lengths are for the both up rows and down rows
+ row_lengths = [n_sections] * (height - 1) * 2
+ for i in range((height - 1) * 2 - 1, (height - 1) * 2 - (padding_to_add + 1), -1):
+ row_lengths[i] -= 1
+ # folded_rows are the combined row lengths in the middle of the railfence
+ folded_row_lengths = [row_lengths[0]]
+ for i in range(1, height-1):
+ folded_row_lengths += [row_lengths[i] + row_lengths[-i]]
+ folded_row_lengths += [row_lengths[height - 1]]
+ # find the rows that form the railfence grid
+ rows = []
+ row_start = 0
+ for i in folded_row_lengths:
+ rows += [message[row_start:row_start + i]]
+ row_start += i
+ # split the rows into the 'down_rows' (those that form the first column of
+ # a section) and the 'up_rows' (those that ofrm the second column of a
+ # section).
+ down_rows = [rows[0]]
+ up_rows = []
+ for i in range(1, height-1):
+ down_rows += [cat([c for n, c in enumerate(rows[i]) if n % 2 == 0])]
+ up_rows += [cat([c for n, c in enumerate(rows[i]) if n % 2 == 1])]
+ down_rows += [rows[-1]]
+ up_rows.reverse()
+ return cat(c for r in zip_longest(*(down_rows + up_rows), fillvalue='') for c in r)
+
+
+def railfence_break(message, max_key_length=20,
+ fitness=Pbigrams, chunksize=500):
+ """Breaks a railfence cipher using a range of lengths and
+ n-gram frequency analysis
+
+ >>> railfence_break(railfence_encipher(sanitise( \
+ "It is a truth universally acknowledged, that a single man in \
+ possession of a good fortune, must be in want of a wife. However \
+ little known the feelings or views of such a man may be on his \
+ first entering a neighbourhood, this truth is so well fixed in \
+ the minds of the surrounding families, that he is considered the \
+ rightful property of some one or other of their daughters."), \
+ 7)) # doctest: +ELLIPSIS
+ (7, -709.46467226...)
+ >>> railfence_break(railfence_encipher(sanitise( \
+ "It is a truth universally acknowledged, that a single man in \
+ possession of a good fortune, must be in want of a wife. However \
+ little known the feelings or views of such a man may be on his \
+ first entering a neighbourhood, this truth is so well fixed in \
+ the minds of the surrounding families, that he is considered the \
+ rightful property of some one or other of their daughters."), \
+ 7), \
+ fitness=Ptrigrams) # doctest: +ELLIPSIS
+ (7, -997.0129085...)
+ """
+ def worker(message, height, fitness):
+ plaintext = railfence_decipher(message, height)
+ fit = fitness(plaintext)
+ return height, fit
+
+ sanitised_message = sanitise(message)
+ results = starmap(worker, [(sanitised_message, i, fitness)
+ for i in range(2, max_key_length+1)])
+ return max(results, key=lambda k: k[1])</code></pre>
+</details>
+</section>
+<section>
+</section>
+<section>
+</section>
+<section>
+<h2 class="section-title" id="header-functions">Functions</h2>
+<dl>
+<dt id="szyfrow.railfence.cat"><code class="name flex">
+<span>def <span class="ident">cat</span></span>(<span>iterable, /)</span>
+</code></dt>
+<dd>
+<div class="desc"><p>Concatenate any number of strings.</p>
+<p>The string whose method is called is inserted in between each given string.
+The result is returned as a new string.</p>
+<p>Example: '.'.join(['ab', 'pq', 'rs']) -> 'ab.pq.rs'</p></div>
+</dd>
+<dt id="szyfrow.railfence.lcat"><code class="name flex">
+<span>def <span class="ident">lcat</span></span>(<span>iterable, /)</span>
+</code></dt>
+<dd>
+<div class="desc"><p>Concatenate any number of strings.</p>
+<p>The string whose method is called is inserted in between each given string.
+The result is returned as a new string.</p>
+<p>Example: '.'.join(['ab', 'pq', 'rs']) -> 'ab.pq.rs'</p></div>
+</dd>
+<dt id="szyfrow.railfence.railfence_break"><code class="name flex">
+<span>def <span class="ident">railfence_break</span></span>(<span>message, max_key_length=20, fitness=<function Pbigrams>, chunksize=500)</span>
+</code></dt>
+<dd>
+<div class="desc"><p>Breaks a railfence cipher using a range of lengths and
+n-gram frequency analysis</p>
+<pre><code class="language-python-repl">>>> railfence_break(railfence_encipher(sanitise( "It is a truth universally acknowledged, that a single man in possession of a good fortune, must be in want of a wife. However little known the feelings or views of such a man may be on his first entering a neighbourhood, this truth is so well fixed in the minds of the surrounding families, that he is considered the rightful property of some one or other of their daughters."), 7)) # doctest: +ELLIPSIS
+(7, -709.46467226...)
+>>> railfence_break(railfence_encipher(sanitise( "It is a truth universally acknowledged, that a single man in possession of a good fortune, must be in want of a wife. However little known the feelings or views of such a man may be on his first entering a neighbourhood, this truth is so well fixed in the minds of the surrounding families, that he is considered the rightful property of some one or other of their daughters."), 7), fitness=Ptrigrams) # doctest: +ELLIPSIS
+(7, -997.0129085...)
+</code></pre></div>
+<details class="source">
+<summary>
+<span>Expand source code</span>
+</summary>
+<pre><code class="python">def railfence_break(message, max_key_length=20,
+ fitness=Pbigrams, chunksize=500):
+ """Breaks a railfence cipher using a range of lengths and
+ n-gram frequency analysis
+
+ >>> railfence_break(railfence_encipher(sanitise( \
+ "It is a truth universally acknowledged, that a single man in \
+ possession of a good fortune, must be in want of a wife. However \
+ little known the feelings or views of such a man may be on his \
+ first entering a neighbourhood, this truth is so well fixed in \
+ the minds of the surrounding families, that he is considered the \
+ rightful property of some one or other of their daughters."), \
+ 7)) # doctest: +ELLIPSIS
+ (7, -709.46467226...)
+ >>> railfence_break(railfence_encipher(sanitise( \
+ "It is a truth universally acknowledged, that a single man in \
+ possession of a good fortune, must be in want of a wife. However \
+ little known the feelings or views of such a man may be on his \
+ first entering a neighbourhood, this truth is so well fixed in \
+ the minds of the surrounding families, that he is considered the \
+ rightful property of some one or other of their daughters."), \
+ 7), \
+ fitness=Ptrigrams) # doctest: +ELLIPSIS
+ (7, -997.0129085...)
+ """
+ def worker(message, height, fitness):
+ plaintext = railfence_decipher(message, height)
+ fit = fitness(plaintext)
+ return height, fit
+
+ sanitised_message = sanitise(message)
+ results = starmap(worker, [(sanitised_message, i, fitness)
+ for i in range(2, max_key_length+1)])
+ return max(results, key=lambda k: k[1])</code></pre>
+</details>
+</dd>
+<dt id="szyfrow.railfence.railfence_decipher"><code class="name flex">
+<span>def <span class="ident">railfence_decipher</span></span>(<span>message, height, fillvalue='')</span>
+</code></dt>
+<dd>
+<div class="desc"><p>Railfence decipher.
+Works by reconstructing the grid used to generate the ciphertext, then
+unfolding the sections so the text can be concatenated together.</p>
+<p>Example: given the ciphertext 'hhieterelorfnsled' and a height of 4, first
+work out that the second row has a character missing, find the rows of the
+grid, then split the section into its two columns.</p>
+<p>'hhieterelorfnsled' is split into
+h h i
+etere
+lorfns
+l e d
+(spaces added for clarity), which is stored in 'rows'. This is then split
+into 'down_rows' and 'up_rows':</p>
+<p>down_rows:
+hhi
+eee
+lrn
+led</p>
+<p>up_rows:
+tr
+ofs</p>
+<p>These are then zipped together (after the up_rows are reversed) to recover
+the plaintext.</p>
+<p>Most of the procedure is about finding the correct lengths for each row then
+splitting the ciphertext into those rows.</p>
+<pre><code class="language-python-repl">>>> railfence_decipher('hlohraateerishsslnpeefetotsigaleccpeselteevsmhatetiiaogicotxfretnrifneihr!', 2).strip('!')
+'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+>>> railfence_decipher('horaersslpeeosglcpselteevsmhatetiiaogicotxfretnrifneihr!!lhateihsnefttiaece!', 3).strip('!')
+'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+>>> railfence_decipher('hresleogcseeemhetaocofrnrner!!lhateihsnefttiaece!!ltvsatiigitxetifih!!oarspeslp!', 5).strip('!')
+'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+>>> railfence_decipher('hepisehagitnr!!lernesge!!lmtocerh!!otiletap!!tseaorii!!hassfolc!!evtitffe!!rahsetec!!eixn!', 10).strip('!')
+'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+>>> railfence_decipher('horaersslpeeosglcpselteevsmhatetiiaogicotxfretnrifneihrlhateihsnefttiaece', 3)
+'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+>>> railfence_decipher('hresleogcseeemhetaocofrnrnerlhateihsnefttiaeceltvsatiigitxetifihoarspeslp', 5)
+'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+>>> railfence_decipher('haspolsevsetgifrifrlatihnettaeelemtiocxernhorersleesgcptehaiaottneihesfic', 7)
+'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+</code></pre></div>
+<details class="source">
+<summary>
+<span>Expand source code</span>
+</summary>
+<pre><code class="python">def railfence_decipher(message, height, fillvalue=''):
+ """Railfence decipher.
+ Works by reconstructing the grid used to generate the ciphertext, then
+ unfolding the sections so the text can be concatenated together.
+
+ Example: given the ciphertext 'hhieterelorfnsled' and a height of 4, first
+ work out that the second row has a character missing, find the rows of the
+ grid, then split the section into its two columns.
+
+ 'hhieterelorfnsled' is split into
+ h h i
+ etere
+ lorfns
+ l e d
+ (spaces added for clarity), which is stored in 'rows'. This is then split
+ into 'down_rows' and 'up_rows':
+
+ down_rows:
+ hhi
+ eee
+ lrn
+ led
+
+ up_rows:
+ tr
+ ofs
+
+ These are then zipped together (after the up_rows are reversed) to recover
+ the plaintext.
+
+ Most of the procedure is about finding the correct lengths for each row then
+ splitting the ciphertext into those rows.
+
+ >>> railfence_decipher('hlohraateerishsslnpeefetotsigaleccpeselteevsmhatetiiaogicotxfretnrifneihr!', 2).strip('!')
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ >>> railfence_decipher('horaersslpeeosglcpselteevsmhatetiiaogicotxfretnrifneihr!!lhateihsnefttiaece!', 3).strip('!')
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ >>> railfence_decipher('hresleogcseeemhetaocofrnrner!!lhateihsnefttiaece!!ltvsatiigitxetifih!!oarspeslp!', 5).strip('!')
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ >>> railfence_decipher('hepisehagitnr!!lernesge!!lmtocerh!!otiletap!!tseaorii!!hassfolc!!evtitffe!!rahsetec!!eixn!', 10).strip('!')
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ >>> railfence_decipher('horaersslpeeosglcpselteevsmhatetiiaogicotxfretnrifneihrlhateihsnefttiaece', 3)
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ >>> railfence_decipher('hresleogcseeemhetaocofrnrnerlhateihsnefttiaeceltvsatiigitxetifihoarspeslp', 5)
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ >>> railfence_decipher('haspolsevsetgifrifrlatihnettaeelemtiocxernhorersleesgcptehaiaottneihesfic', 7)
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ """
+ # find the number and size of the sections, including how many characters
+ # are missing for a full grid
+ n_sections = math.ceil(len(message) / ((height - 1) * 2))
+ padding_to_add = n_sections * (height - 1) * 2 - len(message)
+ # row_lengths are for the both up rows and down rows
+ row_lengths = [n_sections] * (height - 1) * 2
+ for i in range((height - 1) * 2 - 1, (height - 1) * 2 - (padding_to_add + 1), -1):
+ row_lengths[i] -= 1
+ # folded_rows are the combined row lengths in the middle of the railfence
+ folded_row_lengths = [row_lengths[0]]
+ for i in range(1, height-1):
+ folded_row_lengths += [row_lengths[i] + row_lengths[-i]]
+ folded_row_lengths += [row_lengths[height - 1]]
+ # find the rows that form the railfence grid
+ rows = []
+ row_start = 0
+ for i in folded_row_lengths:
+ rows += [message[row_start:row_start + i]]
+ row_start += i
+ # split the rows into the 'down_rows' (those that form the first column of
+ # a section) and the 'up_rows' (those that ofrm the second column of a
+ # section).
+ down_rows = [rows[0]]
+ up_rows = []
+ for i in range(1, height-1):
+ down_rows += [cat([c for n, c in enumerate(rows[i]) if n % 2 == 0])]
+ up_rows += [cat([c for n, c in enumerate(rows[i]) if n % 2 == 1])]
+ down_rows += [rows[-1]]
+ up_rows.reverse()
+ return cat(c for r in zip_longest(*(down_rows + up_rows), fillvalue='') for c in r)</code></pre>
+</details>
+</dd>
+<dt id="szyfrow.railfence.railfence_encipher"><code class="name flex">
+<span>def <span class="ident">railfence_encipher</span></span>(<span>message, height, fillvalue='')</span>
+</code></dt>
+<dd>
+<div class="desc"><p>Railfence cipher.
+Works by splitting the text into sections, then reading across them to
+generate the rows in the cipher. The rows are then combined to form the
+ciphertext.</p>
+<p>Example: the plaintext "hellotherefriends", with a height of four, written
+out in the railfence as
+h h i
+etere*
+lorfns
+l e d
+(with the * showing the one character to finish the last section).
+Each 'section' is two columns, but unfolded. In the example, the first
+section is 'hellot'.</p>
+<pre><code class="language-python-repl">>>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 2, fillvalue='!')
+'hlohraateerishsslnpeefetotsigaleccpeselteevsmhatetiiaogicotxfretnrifneihr!'
+>>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 3, fillvalue='!')
+'horaersslpeeosglcpselteevsmhatetiiaogicotxfretnrifneihr!!lhateihsnefttiaece!'
+>>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 5, fillvalue='!')
+'hresleogcseeemhetaocofrnrner!!lhateihsnefttiaece!!ltvsatiigitxetifih!!oarspeslp!'
+>>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 10, fillvalue='!')
+'hepisehagitnr!!lernesge!!lmtocerh!!otiletap!!tseaorii!!hassfolc!!evtitffe!!rahsetec!!eixn!'
+>>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 3)
+'horaersslpeeosglcpselteevsmhatetiiaogicotxfretnrifneihrlhateihsnefttiaece'
+>>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 5)
+'hresleogcseeemhetaocofrnrnerlhateihsnefttiaeceltvsatiigitxetifihoarspeslp'
+>>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 7)
+'haspolsevsetgifrifrlatihnettaeelemtiocxernhorersleesgcptehaiaottneihesfic'
+</code></pre></div>
+<details class="source">
+<summary>
+<span>Expand source code</span>
+</summary>
+<pre><code class="python">def railfence_encipher(message, height, fillvalue=''):
+ """Railfence cipher.
+ Works by splitting the text into sections, then reading across them to
+ generate the rows in the cipher. The rows are then combined to form the
+ ciphertext.
+
+ Example: the plaintext "hellotherefriends", with a height of four, written
+ out in the railfence as
+ h h i
+ etere*
+ lorfns
+ l e d
+ (with the * showing the one character to finish the last section).
+ Each 'section' is two columns, but unfolded. In the example, the first
+ section is 'hellot'.
+
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 2, fillvalue='!')
+ 'hlohraateerishsslnpeefetotsigaleccpeselteevsmhatetiiaogicotxfretnrifneihr!'
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 3, fillvalue='!')
+ 'horaersslpeeosglcpselteevsmhatetiiaogicotxfretnrifneihr!!lhateihsnefttiaece!'
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 5, fillvalue='!')
+ 'hresleogcseeemhetaocofrnrner!!lhateihsnefttiaece!!ltvsatiigitxetifih!!oarspeslp!'
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 10, fillvalue='!')
+ 'hepisehagitnr!!lernesge!!lmtocerh!!otiletap!!tseaorii!!hassfolc!!evtitffe!!rahsetec!!eixn!'
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 3)
+ 'horaersslpeeosglcpselteevsmhatetiiaogicotxfretnrifneihrlhateihsnefttiaece'
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 5)
+ 'hresleogcseeemhetaocofrnrnerlhateihsnefttiaeceltvsatiigitxetifihoarspeslp'
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 7)
+ 'haspolsevsetgifrifrlatihnettaeelemtiocxernhorersleesgcptehaiaottneihesfic'
+ """
+ sections = chunks(message, (height - 1) * 2, fillvalue=fillvalue)
+ n_sections = len(sections)
+ # Add the top row
+ rows = [cat([s[0] for s in sections])]
+ # process the middle rows of the grid
+ for r in range(1, height-1):
+ rows += [cat([s[r:r+1] + s[height*2-r-2:height*2-r-1] for s in sections])]
+ # process the bottom row
+ rows += [cat([s[height - 1:height] for s in sections])]
+ # rows += [wcat([s[height - 1] for s in sections])]
+ return cat(rows)</code></pre>
+</details>
+</dd>
+<dt id="szyfrow.railfence.wcat"><code class="name flex">
+<span>def <span class="ident">wcat</span></span>(<span>iterable, /)</span>
+</code></dt>
+<dd>
+<div class="desc"><p>Concatenate any number of strings.</p>
+<p>The string whose method is called is inserted in between each given string.
+The result is returned as a new string.</p>
+<p>Example: '.'.join(['ab', 'pq', 'rs']) -> 'ab.pq.rs'</p></div>
+</dd>
+</dl>
+</section>
+<section>
+</section>
+</article>
+<nav id="sidebar">
+<h1>Index</h1>
+<div class="toc">
+<ul></ul>
+</div>
+<ul id="index">
+<li><h3>Super-module</h3>
+<ul>
+<li><code><a title="szyfrow" href="index.html">szyfrow</a></code></li>
+</ul>
+</li>
+<li><h3><a href="#header-functions">Functions</a></h3>
+<ul class="two-column">
+<li><code><a title="szyfrow.railfence.cat" href="#szyfrow.railfence.cat">cat</a></code></li>
+<li><code><a title="szyfrow.railfence.lcat" href="#szyfrow.railfence.lcat">lcat</a></code></li>
+<li><code><a title="szyfrow.railfence.railfence_break" href="#szyfrow.railfence.railfence_break">railfence_break</a></code></li>
+<li><code><a title="szyfrow.railfence.railfence_decipher" href="#szyfrow.railfence.railfence_decipher">railfence_decipher</a></code></li>
+<li><code><a title="szyfrow.railfence.railfence_encipher" href="#szyfrow.railfence.railfence_encipher">railfence_encipher</a></code></li>
+<li><code><a title="szyfrow.railfence.wcat" href="#szyfrow.railfence.wcat">wcat</a></code></li>
+</ul>
+</li>
+</ul>
+</nav>
+</main>
+<footer id="footer">
+<p>Generated by <a href="https://pdoc3.github.io/pdoc"><cite>pdoc</cite> 0.9.2</a>.</p>
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projects / szyfrow.git / blobdiff