{"id":563,"date":"2011-03-05T12:30:20","date_gmt":"2011-03-05T10:30:20","guid":{"rendered":"https:\/\/bob-team.de\/wordpress\/?p=563"},"modified":"2011-03-23T10:17:01","modified_gmt":"2011-03-23T08:17:01","slug":"symetrische-verschlusselung","status":"publish","type":"post","link":"https:\/\/bob-team.de\/wordpress\/2011\/03\/05\/symetrische-verschlusselung\/","title":{"rendered":"Symetrische Verschl\u00fcsselung"},"content":{"rendered":"

Bei Symmetrisches Kryptosystemen<\/a> nutzen Sender und Empf\u00e4nger den selben Schl\u00fcssel um ihre Nachricht vor den Blicken Dritter zu sch\u00fctzen. Folgendes Beispiel zeigt dieses Verfahren mit ein paar Zeilen in Java.<\/p>\n

[code lang=“java“]import java.security.spec.AlgorithmParameterSpec; <\/p>\n

import javax.crypto.Cipher;
\nimport javax.crypto.KeyGenerator;
\nimport javax.crypto.SecretKey;
\nimport javax.crypto.spec.IvParameterSpec; <\/p>\n

public class SimpleCipher {
\n public static void main(String[] args) {
\n String data = „This have I thought good to deliver thee“;
\n \/\/ —————Encryption ———————————
\n byte[] encrypted = null;
\n byte[] iv = null;
\n SecretKey key = null;
\n try {
\n KeyGenerator keygen = KeyGenerator.getInstance(„DES“);
\n key = keygen.generateKey(); \/\/ the secret key
\n \/*
\n * get cipher engine instance. DES algorithm is used and
\n * it requires the input data to be 8-byte sized blocks.
\n * To encrypt a plain text message that is not multiples
\n * of 8-byte blocks, the text message must be padded
\n * with additional bytes to make the text message to
\n * be multiples of 8-byte blocks.PKCS5Padding has used
\n * for that purpose. note that CBC is a block cipher
\n * mode therefore we need an initialization vector to
\n * chain blocks.
\n *\/
\n Cipher cipher = Cipher.getInstance(„DES\/CBC\/PKCS5Padding“);
\n cipher.init(Cipher.ENCRYPT_MODE, key);
\n encrypted = cipher.doFinal(data.getBytes());
\n \/*
\n * save the initialization vector, remember that
\n * we need this only when we are using cipher
\n * block chaining mode for encryption
\n *\/
\n iv = cipher.getIV();
\n } catch (Exception e) {
\n e.printStackTrace();
\n }
\n \/\/ —————Decryption ———————————
\n try {
\n Cipher cipher = Cipher.getInstance(„DES\/CBC\/PKCS5Padding“);
\n AlgorithmParameterSpec param = new IvParameterSpec(iv);\/*
\n * set the
\n * vector
\n * value
\n *\/
\n cipher.init(Cipher.DECRYPT_MODE, key, param);
\n byte[] decrypted = cipher.doFinal(encrypted);
\n System.out.println(new String(decrypted));
\n } catch (Exception e) {
\n e.printStackTrace();
\n }
\n }
\n}[\/code]<\/p>\n","protected":false},"excerpt":{"rendered":"

Bei Symmetrisches Kryptosystemen nutzen Sender und Empf\u00e4nger den selben Schl\u00fcssel um ihre Nachricht vor den Blicken Dritter zu sch\u00fctzen. Folgendes Beispiel zeigt dieses Verfahren mit ein paar Zeilen in Java.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-563","post","type-post","status-publish","format-standard","hentry","category-java","entry"],"_links":{"self":[{"href":"https:\/\/bob-team.de\/wordpress\/wp-json\/wp\/v2\/posts\/563","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/bob-team.de\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/bob-team.de\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/bob-team.de\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/bob-team.de\/wordpress\/wp-json\/wp\/v2\/comments?post=563"}],"version-history":[{"count":2,"href":"https:\/\/bob-team.de\/wordpress\/wp-json\/wp\/v2\/posts\/563\/revisions"}],"predecessor-version":[{"id":623,"href":"https:\/\/bob-team.de\/wordpress\/wp-json\/wp\/v2\/posts\/563\/revisions\/623"}],"wp:attachment":[{"href":"https:\/\/bob-team.de\/wordpress\/wp-json\/wp\/v2\/media?parent=563"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/bob-team.de\/wordpress\/wp-json\/wp\/v2\/categories?post=563"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/bob-team.de\/wordpress\/wp-json\/wp\/v2\/tags?post=563"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}