add crypto and zlib chapters

Sascha Schulz

2024-09-16 179755d7782c2ef18fb19b30dda0a538bfb5823e

 index.html

@@ -4239,6 +4239,77 @@
                     </code>
                  </pre>
               </section>
               <section>
                  <h3>Kryptographie</h3>
               </section>
               <section>
                  Mithilfe des nativen <code>crypto</code>-Moduls ist es möglich, moderne sichere kryptografische Verfahren zu verwenden:
                  <pre>
                     <code class="js" data-trim data-line-numbers>
                        const crypto = require("crypto");
                     </code>
                  </pre>
                  Hierzu nutzt NodeJS selber die weit verbreitete OpenSSL-Bibliothek
               </section>
               <section>
                  Einen MD5-Hash erzeugen:
                  <pre>
                     <code class="js" data-trim data-line-numbers>
                        const crypto = require("crypto");

                        const hash = crypto.createHash("md5");
                        const md5 = hash.update("abcdefg")
                           .digest(); // Buffer (default)
                           // .digest("hex") // Hexadezimal
                           // .digest("utf8") // Bytes forciert als Chars
								
                        console.log(md5);
                     </code>
                  </pre>
               </section>
               <section>
                  <p>Aufgabe</p>
                  <p>Erzeuge jeweils den md5- und den sha256-Hash als Hex-Wert der beiden Texte in der Datei <code>text-examples.txt</code> und vergleiche jeweils ihren md5- und sha256-Hash miteinander</p>
               </section>
               <section>
                  <h3>Zippen</h3>
               </section>
               <section>
                  Mit dem nativen Modul <code>zlib</code> ist es möglich, Kompression in seinen Anwendungen zu nutzen.
                  <pre>
                     <code class="js" data-trim data-line-numbers>
                        const zlib = require("zlib");

                        // Komprimieren
                        zlib.deflate("abc" /* buffer | string */, (err, compressed) => {});
								
                        // Dekomprimieren
                        zlib.inflate(compressed /* buffer */, (err, decompressed) => {});
								
                        // Als Stream
                        const zipper = zlib.createDeflate();
                        const unzipper = zlib.createInflate();
								
                        source.pipe(zipper).pipe(target);
                        source.pipe(unzipper).pipe(target);
                     </code>
                  </pre>
               </section>
               <section>
                  <p>Aufgabe</p>
                  <p>Nutze die einfachen Varianten <code>zlib.deflate</code> und <code>zlib.inflate</code>, um einen beliebigen Text zu komprimieren und anschließend wieder zu dekomprimieren</p>
               </section>
               <section>
                  <p>Aufgabe</p>
                  <p>Nutze die Stream-Varianten <code>zlib.createDeflate</code> und <code>zlib.createInflate</code>, um jeweils ein getrenntes Programm für die Kompression und Dekompression mit <code>process.stdin</code> und <code>process.stdout</code> zu machen, sodass in der Konsole folgende Nutzung möglich ist:</p>
                  <pre>
                     <code class="bash" data-trim data-line-numbers>
                        echo "abc" | node compress.js | node decompress.js
                        cat file.txt | node compress.js > file.zipped
                        cat file.zipped | node decompress.js > file.txt
                     </code>
                  </pre>
               </section>
            </section>
         </div>
      </div>