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<title data-rh="true">5th and 6th seminar | mf</title><meta data-rh="true" name="viewport" content="width=device-width,initial-scale=1"><meta data-rh="true" name="twitter:card" content="summary_large_image"><meta data-rh="true" property="og:url" content="https://blog.mfocko.xyz/c/bonuses/seminar-05-06/"><meta data-rh="true" property="og:locale" content="en"><meta data-rh="true" name="docusaurus_locale" content="en"><meta data-rh="true" name="docsearch:language" content="en"><meta data-rh="true" name="docusaurus_version" content="current"><meta data-rh="true" name="docusaurus_tag" content="docs-c-current"><meta data-rh="true" name="docsearch:version" content="current"><meta data-rh="true" name="docsearch:docusaurus_tag" content="docs-c-current"><meta data-rh="true" property="og:title" content="5th and 6th seminar | mf"><meta data-rh="true" name="description" content="200IQ encryption.
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<script>!function(){function t(t){document.documentElement.setAttribute("data-theme",t)}var e=function(){try{return new URLSearchParams(window.location.search).get("docusaurus-theme")}catch(t){}}()||function(){try{return localStorage.getItem("theme")}catch(t){}}();t(null!==e?e:"light")}(),function(){try{const c=new URLSearchParams(window.location.search).entries();for(var[t,e]of c)if(t.startsWith("docusaurus-data-")){var a=t.replace("docusaurus-data-","data-");document.documentElement.setAttribute(a,e)}}catch(t){}}()</script><div id="__docusaurus"><div role="region" aria-label="Skip to main content"><a class="skipToContent_fXgn" href="#__docusaurus_skipToContent_fallback">Skip to main content</a></div><nav aria-label="Main" class="navbar navbar--fixed-top"><div class="navbar__inner"><div class="navbar__items"><button aria-label="Toggle navigation bar" aria-expanded="false" class="navbar__toggle clean-btn" type="button"><svg width="30" height="30" viewBox="0 0 30 30" aria-hidden="true"><path stroke="currentColor" stroke-linecap="round" stroke-miterlimit="10" stroke-width="2" d="M4 7h22M4 15h22M4 23h22"></path></svg></button><a class="navbar__brand" href="/"><b class="navbar__title text--truncate">mf</b></a><div class="navbar__item dropdown dropdown--hoverable"><a href="#" aria-haspopup="true" aria-expanded="false" role="button" class="navbar__link">Additional FI MU materials</a><ul class="dropdown__menu"><li><a class="dropdown__link" href="/algorithms/">Algorithms</a></li><li><a aria-current="page" class="dropdown__link dropdown__link--active" href="/c/">C</a></li><li><a class="dropdown__link" href="/cpp/">C++</a></li></ul></div><a class="navbar__item navbar__link" href="/contributions/">Contributions</a><a class="navbar__item navbar__link" href="/talks/">Talks</a></div><div class="navbar__items navbar__items--right"><a class="navbar__item navbar__link" href="/blog/">Blog</a><div class="toggle_vylO colorModeToggle_DEke"><button class="clean-btn toggleButton_gllP toggleButtonDisabled_aARS" type="button" disabled="" title="Switch between dark and light mode (currently light mode)" aria-label="Switch between dark and light mode (currently light mode)" aria-live="polite"><svg viewBox="0 0 24 24" width="24" height="24" class="lightToggleIcon_pyhR"><path fill="currentColor" d="M12,9c1.65,0,3,1.35,3,3s-1.35,3-3,3s-3-1.35-3-3S10.35,9,12,9 M12,7c-2.76,0-5,2.24-5,5s2.24,5,5,5s5-2.24,5-5 S14.76,7,12,7L12,7z M2,13l2,0c0.55,0,1-0.45,1-1s-0.45-1-1-1l-2,0c-0.55,0-1,0.45-1,1S1.45,13,2,13z M20,13l2,0c0.55,0,1-0.45,1-1 s-0.45-1-1-1l-2,0c-0.55,0-1,0.45-1,1S19.45,13,20,13z M11,2v2c0,0.55,0.45,1,1,1s1-0.45,1-1V2c0-0.55-0.45-1-1-1S11,1.45,11,2z M11,20v2c0,0.55,0.45,1,1,1s1-0.45,1-1v-2c0-0.55-0.45-1-1-1C11.45,19,11,19.45,11,20z M5.99,4.58c-0.39-0.39-1.03-0.39-1.41,0 c-0.39,0.39-0.39,1.03,0,1.41l1.06,1.06c0.39,0.39,1.03,0.39,1.41,0s0.39-1.03,0-1.41L5.99,4.58z M18.36,16.95 c-0.39-0.39-1.03-0.39-1.41,0c-0.39,0.39-0.39,1.03,0,1.41l1.06,1.06c0.39,0.39,1.03,0.39,1.41,0c0.39-0.39,0.39-1.03,0-1.41 L18.36,16.95z M19.42,5.99c0.39-0.39,0.39-1.03,0-1.41c-0.39-0.39-1.03-0.39-1.41,0l-1.06,1.06c-0.39,0.39-0.39,1.03,0,1.41 s1.03,0.39,1.41,0L19.42,5.99z M7.05,18.36c0.39-0.39,0.39-1.03,0-1.41c-0.39-0.39-1.03-0.39-1.41,0l-1.06,1.06 c-0.39,0.39-0.39,1.03,0,1.41s1.03,0.39,1.41,0L7.05,18.36z"></path></svg><svg viewBox="0 0 24 24" width="24" height="24" class="darkToggleIcon_wfgR"><path fill="currentColor" d="M9.37,5.51C9.19,6.15,9.1,6.82,9.1,7.5c0,4.08,3.32,7.4,7.4,7.4c0.68,0,1.35-0.09,1.99-0.27C17.45,17.19,14.93,19,12,19 c-3.86,0-7-3.14-7-7C5,9.07,6.81,6.55,9.37,5.51z M12,3c-4.97,0-9,4.03-9,9s4.03,9,9,9s9-4.03,9-9c0-0.46-0.04-0.92-0.1-1.36 c-0.98,1.37-2.58,2.26-4.4,2.26c-2.98,0-5.4-2.42-5.4-5.4c0-1.81,0.89-3.42,2.26-4.4C12.92,3.04,12.46,3,12,3L12,3z"></path></svg></button></div><div class="navbarSearchContainer_Bca1"><button type="button" class="DocSearch DocSearch-Button" aria-label="Search"><span class="DocSearch-Button-Container"><svg width="20" height="20" class="DocSearch-Search-Icon" viewBox="0 0 20 20"><path d="M14.386 14.386l4.0877 4.0877-4.0877-4.0877c-2.
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<p><a href="/files/c/bonuses/05-06.tar.gz" target="_blank" rel="noopener noreferrer">Source</a></p>
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<h2 class="anchor anchorWithStickyNavbar_LWe7" id="introduction">Introduction<a href="#introduction" class="hash-link" aria-label="Direct link to Introduction" title="Direct link to Introduction"></a></h2>
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<p>In this bonus you will implement few functions that will be used together for
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implementing a very special cipher.</p>
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<h3 class="anchor anchorWithStickyNavbar_LWe7" id="task-no-1-reverse-05-k">Task no. 1: Reverse (0.5 K₡)<a href="#task-no-1-reverse-05-k" class="hash-link" aria-label="Direct link to Task no. 1: Reverse (0.5 K₡)" title="Direct link to Task no. 1: Reverse (0.5 K₡)"></a></h3>
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<p>Write a function <code>char* reverse(const char* text)</code> that returns copy of the input
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string in reversed order (also uppercase).</p>
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<p>In case you are given <code>NULL</code>, return <code>NULL</code>.</p>
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<p>Example (more in tests):</p>
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<div class="language-c codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#000000;--prism-background-color:#ffffff"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-c codeBlock_bY9V thin-scrollbar" style="color:#000000;background-color:#ffffff"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#000000"><span class="token keyword" style="color:rgb(0, 0, 255)">char</span><span class="token operator" style="color:rgb(0, 0, 0)">*</span><span class="token plain"> reversed </span><span class="token operator" style="color:rgb(0, 0, 0)">=</span><span class="token plain"> </span><span class="token function" style="color:rgb(0, 0, 255)">reverse</span><span class="token punctuation" style="color:rgb(4, 81, 165)">(</span><span class="token string" style="color:rgb(163, 21, 21)">"Hello world!"</span><span class="token punctuation" style="color:rgb(4, 81, 165)">)</span><span class="token punctuation" style="color:rgb(4, 81, 165)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain"></span><span class="token function" style="color:rgb(0, 0, 255)">printf</span><span class="token punctuation" style="color:rgb(4, 81, 165)">(</span><span class="token string" style="color:rgb(163, 21, 21)">"%s\n"</span><span class="token punctuation" style="color:rgb(4, 81, 165)">,</span><span class="token plain"> reversed</span><span class="token punctuation" style="color:rgb(4, 81, 165)">)</span><span class="token punctuation" style="color:rgb(4, 81, 165)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain"></span><span class="token comment" style="color:rgb(0, 128, 0)">// "!DLROW OLLEH"</span><span class="token plain"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain"></span><span class="token keyword" style="color:rgb(0, 0, 255)">if</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(4, 81, 165)">(</span><span class="token plain">reversed </span><span class="token operator" style="color:rgb(0, 0, 0)">!=</span><span class="token plain"> </span><span class="token constant" style="color:rgb(129, 31, 63)">NULL</span><span class="token punctuation" style="color:rgb(4, 81, 165)">)</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(4, 81, 165)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain"> </span><span class="token function" style="color:rgb(0, 0, 255)">free</span><span class="token punctuation" style="color:rgb(4, 81, 165)">(</span><span class="token plain">reversed</span><span class="token punctuation" style="color:rgb(4, 81, 165)">)</span><span class="token punctuation" style="color:rgb(4, 81, 165)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain"></span><span class="token punctuation" style="color:rgb(4, 81, 165)">}</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div>
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<h3 class="anchor anchorWithStickyNavbar_LWe7" id="task-no-2-vigenère-05-k">Task no. 2: Vigenère (0.5 K₡)<a href="#task-no-2-vigenère-05-k" class="hash-link" aria-label="Direct link to Task no. 2: Vigenère (0.5 K₡)" title="Direct link to Task no. 2: Vigenère (0.5 K₡)"></a></h3>
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<p>Vigenère cipher is similar to the Caesar cipher, but you also have a key that is
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used for encrypting (or decrypting).</p>
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<p>Your task is to write two functions:</p>
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<ul>
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<li><code>char* vigenere_encrypt(const char* key, const char* text)</code> for encrypting</li>
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<li><code>char* vigenere_decrypt(const char* key, const char* text)</code> for decrypting</li>
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</ul>
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<p>In both of those you should return uppercase characters.</p>
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<p>Meaning of the parameters you are given:</p>
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<ul>
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<li><code>key</code> - String that represents key that is used for *crypting. It consists of
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one word and can have only characters of the alphabet. Does not matter if they
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are uppercase or lowercase.</li>
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<li><code>text</code> - String that is to be *crypted.</li>
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</ul>
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<p>Function returns address of the encrypted (or decrypted) string. Or <code>NULL</code> in case
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error occurs.</p>
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<p>Example:</p>
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<div class="language-c codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#000000;--prism-background-color:#ffffff"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-c codeBlock_bY9V thin-scrollbar" style="color:#000000;background-color:#ffffff"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#000000"><span class="token keyword" style="color:rgb(0, 0, 255)">char</span><span class="token plain"> </span><span class="token operator" style="color:rgb(0, 0, 0)">*</span><span class="token plain">encrypted </span><span class="token operator" style="color:rgb(0, 0, 0)">=</span><span class="token plain"> </span><span class="token function" style="color:rgb(0, 0, 255)">vigenere_encrypt</span><span class="token punctuation" style="color:rgb(4, 81, 165)">(</span><span class="token string" style="color:rgb(163, 21, 21)">"CoMPuTeR"</span><span class="token punctuation" style="color:rgb(4, 81, 165)">,</span><span class="token plain"> </span><span class="token string" style="color:rgb(163, 21, 21)">"Hello world!"</span><span class="token punctuation" style="color:rgb(4, 81, 165)">)</span><span class="token punctuation" style="color:rgb(4, 81, 165)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain"></span><span class="token function" style="color:rgb(0, 0, 255)">printf</span><span class="token punctuation" style="color:rgb(4, 81, 165)">(</span><span class="token string" style="color:rgb(163, 21, 21)">"%s\n"</span><span class="token punctuation" style="color:rgb(4, 81, 165)">,</span><span class="token plain"> encrypted</span><span class="token punctuation" style="color:rgb(4, 81, 165)">)</span><span class="token punctuation" style="color:rgb(4, 81, 165)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain"></span><span class="token comment" style="color:rgb(0, 128, 0)">// "JSXAI PSINR!"</span><span class="token plain"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain"></span><span class="token keyword" style="color:rgb(0, 0, 255)">if</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(4, 81, 165)">(</span><span class="token plain">encrypted </span><span class="token operator" style="color:rgb(0, 0, 0)">!=</span><span class="token plain"> </span><span class="token constant" style="color:rgb(129, 31, 63)">NULL</span><span class="token punctuation" style="color:rgb(4, 81, 165)">)</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(4, 81, 165)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain"> </span><span class="token function" style="color:rgb(0, 0, 255)">free</span><span class="token punctuation" style="color:rgb(4, 81, 165)">(</span><span class="token plain">encrypted</span><span class="token punctuation" style="color:rgb(4, 81, 165)">)</span><span class="token plain"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain"></span><span class="token punctuation" style="color:rgb(4, 81, 165)">}</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.1
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<h4 class="anchor anchorWithStickyNavbar_LWe7" id="bonus-part-05-k">Bonus part (0.5 K₡)<a href="#bonus-part-05-k" class="hash-link" aria-label="Direct link to Bonus part (0.5 K₡)" title="Direct link to Bonus part (0.5 K₡)"></a></h4>
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<p>If you can utilize helper function that would do both encrypting and decrypting,
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you can gain 0.5 K₡.</p>
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<p>Usage of <code>true</code>/<code>false</code> to decide path in code is prohibited. It leads to merging
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of both functions into one. Point of this part is to discover a way to do this
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generically in such way that there are no separate paths for one or the other. One
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function with no branching for both of them, parametrization is your friend :)</p>
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<h3 class="anchor anchorWithStickyNavbar_LWe7" id="task-no-3-bit-madness-05-k">Task no. 3: Bit madness (0.5 K₡)<a href="#task-no-3-bit-madness-05-k" class="hash-link" aria-label="Direct link to Task no. 3: Bit madness (0.5 K₡)" title="Direct link to Task no. 3: Bit madness (0.5 K₡)"></a></h3>
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<p>This is a state of the art crypto. Please do not share :)</p>
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<p>For encrypting:</p>
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<ol>
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<li>Split the character that is to be encrypted in halves (4 and 4 bits each).</li>
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<li>Bits in 1st half are to be split into pairs. Swap bits in those pairs.</li>
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<li>Then use the 4 bits that you created in the 2nd step for <code>XOR</code> with the other
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4 bits.</li>
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</ol>
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<p>This simple and ingenious principle will be illustrated on the following example.
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String we want to encrypt is <code>Hello world!</code>. We need to encrypt each letter separately,
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so we will demonstrate on letter <code>H</code>:</p>
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<ol>
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<li>
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<p>Letter <code>H</code> is represented in ASCII as <code>72</code>.</p>
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<p><code>72</code> represented in binary is: <code>01001000</code>. So first 4 bits are: <code>0100</code> and last
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4 bits are <code>1000</code>.</p>
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</li>
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<li>
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<p>First half of bits (<code>0100</code>) consists of 2 pairs (<code>01</code> and <code>00</code>) which we swap
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(<code>01 ~> 10</code> and <code>00 ~> 00</code>). That way we get <code>1000</code>.</p>
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</li>
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<li>
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<p>That half is used for xor with the other 4 bits:</p>
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<div class="codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#000000;--prism-background-color:#ffffff"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-text codeBlock_bY9V thin-scrollbar" style="color:#000000;background-color:#ffffff"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#000000"><span class="token plain"> 1000 // second half</span><br></span><span class="token-line" style="color:#000000"><span class="token plain">XOR 1000 // first half after 2nd step</span><br></span><span class="token-line" style="color:#000000"><span class="token plain">--------</span><br></span><span class="token-line" style="color:#000000"><span class="token plain"> 0000</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div>
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</li>
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<li>
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<p>Now we combine both halves (first one is <code>1000</code>, which we got from the 2nd step
|
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and second one is <code>0000</code>, which we got from the 3rd step) and get <code>10000000</code>,
|
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which is encrypted character <code>H</code> using this method.</p>
|
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</li>
|
|||
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</ol>
|
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<p>In case of decryption, reverse those steps.</p>
|
|||
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<p>Your task is to implement functions:</p>
|
|||
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<ul>
|
|||
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<li><code>unsigned char* bit_encrypt(const char* text)</code></li>
|
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|
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<li><code>char* bit_decrypt(const unsigned char* text)</code></li>
|
|||
|
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</ul>
|
|||
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<p>Example:</p>
|
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<div class="language-c codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#000000;--prism-background-color:#ffffff"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-c codeBlock_bY9V thin-scrollbar" style="color:#000000;background-color:#ffffff"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#000000"><span class="token keyword" style="color:rgb(0, 0, 255)">unsigned</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(0, 0, 255)">char</span><span class="token operator" style="color:rgb(0, 0, 0)">*</span><span class="token plain"> encrypted </span><span class="token operator" style="color:rgb(0, 0, 0)">=</span><span class="token plain"> </span><span class="token function" style="color:rgb(0, 0, 255)">bit_encrypt</span><span class="token punctuation" style="color:rgb(4, 81, 165)">(</span><span class="token string" style="color:rgb(163, 21, 21)">"Hello world!"</span><span class="token punctuation" style="color:rgb(4, 81, 165)">)</span><span class="token punctuation" style="color:rgb(4, 81, 165)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain"></span><span class="token keyword" style="color:rgb(0, 0, 255)">for</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(4, 81, 165)">(</span><span class="token keyword" style="color:rgb(0, 0, 255)">int</span><span class="token plain"> i </span><span class="token operator" style="color:rgb(0, 0, 0)">=</span><span class="token plain"> </span><span class="token number" style="color:rgb(9, 134, 88)">0</span><span class="token punctuation" style="color:rgb(4, 81, 165)">;</span><span class="token plain"> i </span><span class="token operator" style="color:rgb(0, 0, 0)"><</span><span class="token plain"> </span><span class="token number" style="color:rgb(9, 134, 88)">12</span><span class="token punctuation" style="color:rgb(4, 81, 165)">;</span><span class="token plain">i</span><span class="token operator" style="color:rgb(0, 0, 0)">++</span><span class="token punctuation" style="color:rgb(4, 81, 165)">)</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(4, 81, 165)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain"> </span><span class="token function" style="color:rgb(0, 0, 255)">printf</span><span class="token punctuation" style="color:rgb(4, 81, 165)">(</span><span class="token string" style="color:rgb(163, 21, 21)">"%x "</span><span class="token punctuation" style="color:rgb(4, 81, 165)">,</span><span class="token plain"> encrypted</span><span class="token punctuation" style="color:rgb(4, 81, 165)">[</span><span class="token plain">i</span><span class="token punctuation" style="color:rgb(4, 81, 165)">]</span><span class="token punctuation" style="color:rgb(4, 81, 165)">)</span><span class="token punctuation" style="color:rgb(4, 81, 165)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain"> </span><span class="token comment" style="color:rgb(0, 128, 0)">//80 9c 95 95 96 11 bc 96 b9 95 9d 10</span><span class="token plain"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain"></span><span class="token punctuation" style="color:rgb(4, 81, 165)">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#000000"><span class="token plain"></span><span class="token keyword" style="color:rgb(0, 0, 255)">if</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(4, 81, 165)">(</span><span class="token plain">encrypted </span><span class="token
|
|||
|
|
<h3 class="anchor anchorWithStickyNavbar_LWe7" id="task-no-4-all-combined-to-bmp-05-k">Task no. 4: All combined to BMP (0.5 K₡)<a href="#task-no-4-all-combined-to-bmp-05-k" class="hash-link" aria-label="Direct link to Task no. 4: All combined to BMP (0.5 K₡)" title="Direct link to Task no. 4: All combined to BMP (0.5 K₡)"></a></h3>
|
|||
|
|
<p>Authors of the BMP cipher are non-disclosed :)</p>
|
|||
|
|
<p>Create pair of functions:</p>
|
|||
|
|
<ul>
|
|||
|
|
<li><code>unsigned char* bmp_encrypt(const char* key, const char* text)</code></li>
|
|||
|
|
<li><code>char* bmp_decrypt(const char* key, const unsigned char* text)</code></li>
|
|||
|
|
</ul>
|
|||
|
|
<p>BMP cipher consists of following steps for encrypting:</p>
|
|||
|
|
<ol>
|
|||
|
|
<li>Reverse the input string</li>
|
|||
|
|
<li>Use Vigenere on the string you got from step #1</li>
|
|||
|
|
<li>Use bit madness on the string you got from step #2</li>
|
|||
|
|
</ol>
|
|||
|
|
<p>For decrypting, reverse the steps.</p>
|
|||
|
|
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="submitting">Submitting<a href="#submitting" class="hash-link" aria-label="Direct link to Submitting" title="Direct link to Submitting"></a></h2>
|
|||
|
|
<p>In case you have any questions, feel free to reach out to me.</p>
|
|||
|
|
<hr></div><footer class="theme-doc-footer docusaurus-mt-lg"><div class="theme-doc-footer-edit-meta-row row"><div class="col"><a href="https://github.com/mfocko/blog/tree/main/c/bonuses/05-06.md" target="_blank" rel="noopener noreferrer" class="theme-edit-this-page"><svg fill="currentColor" height="20" width="20" viewBox="0 0 40 40" class="iconEdit_Z9Sw" aria-hidden="true"><g><path d="m34.5 11.7l-3 3.1-6.3-6.3 3.1-3q0.5-0.5 1.2-0.5t1.1 0.5l3.9 3.9q0.5 0.4 0.5 1.1t-0.5 1.2z m-29.5 17.1l18.4-18.5 6.3 6.3-18.4 18.4h-6.3v-6.2z"></path></g></svg>Edit this page</a></div><div class="col lastUpdated_vwxv"><span class="theme-last-updated">Last updated<!-- --> on <b><time datetime="2023-11-24T15:53:49.000Z">Nov 24, 2023</time></b></span></div></div></footer></article><nav class="pagination-nav docusaurus-mt-lg" aria-label="Docs pages"><a class="pagination-nav__link pagination-nav__link--prev" href="/c/bonuses/seminar-04/"><div class="pagination-nav__sublabel">Previous</div><div class="pagination-nav__label">4th seminar</div></a><a class="pagination-nav__link pagination-nav__link--next" href="/c/bonuses/seminar-08/"><div class="pagination-nav__sublabel">Next</div><div class="pagination-nav__label">8th seminar</div></a></nav></div></div><div class="col col--3"><div class="tableOfContents_bqdL thin-scrollbar theme-doc-toc-desktop"><ul class="table-of-contents table-of-contents__left-border"><li><a href="#introduction" class="table-of-contents__link toc-highlight">Introduction</a><ul><li><a href="#task-no-1-reverse-05-k" class="table-of-contents__link toc-highlight">Task no. 1: Reverse (0.5 K₡)</a></li><li><a href="#task-no-2-vigenère-05-k" class="table-of-contents__link toc-highlight">Task no. 2: Vigenère (0.5 K₡)</a></li><li><a href="#task-no-3-bit-madness-05-k" class="table-of-contents__link toc-highlight">Task no. 3: Bit madness (0.5 K₡)</a></li><li><a href="#task-no-4-all-combined-to-bmp-05-k" class="table-of-contents__link toc-highlight">Task no. 4: All combined to BMP (0.5 K₡)</a></li></ul></li><li><a href="#submitting" class="table-of-contents__link toc-highlight">Submitting</a></li></ul></div></div></div></div></main></div></div></div><footer class="footer footer--dark"><div class="container container-fluid"><div class="row footer__links"><div class="col footer__col"><div class="footer__title">Git</div><ul class="footer__items clean-list"><li class="footer__item"><a href="https://github.com/mfocko" target="_blank" rel="noopener noreferrer" class="footer__link-item">GitHub<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPIU"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></a></li><li class="footer__item"><a href="https://gitlab.com/mfocko" target="_blank" rel="noopener noreferrer" class="footer__link-item">GitLab<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPIU"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></a></li><li class="footer__item"><a href="https://git.mfocko.xyz/mfocko" target="_blank" rel="noopener noreferrer" class="footer__link-item">Gitea (self-hosted)<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPIU"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></a></li></ul></div><div class="col footer__col"><div class="footer__title">Social #1</div><ul class="footer__items clean-list"><li class="footer__item"><a href="https://www.linkedin.com/in/mfocko/" target="_blank" rel="noopener noreferrer" class="footer__link-item">LinkedIn<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPIU"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125
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</body>
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</html>
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