{"id":10227,"date":"2022-11-23T15:18:39","date_gmt":"2022-11-23T15:18:39","guid":{"rendered":"https:\/\/mdr.foobrdigital.com\/?p=10227"},"modified":"2022-11-23T15:18:39","modified_gmt":"2022-11-23T15:18:39","slug":"round-function","status":"publish","type":"post","link":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/2022\/11\/23\/round-function\/","title":{"rendered":"Round Function"},"content":{"rendered":"\n<p>The heart of this cipher is the DES function,&nbsp;<em>f<\/em>. The DES function applies a 48-bit key to the rightmost 32 bits to produce a 32-bit output.<\/p>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.tutorialspoint.com\/cryptography\/images\/round_function.jpg\" alt=\"Round Function\"\/><\/figure>\n\n\n\n<ul>\n<li><strong>Expansion Permutation Box<\/strong>&nbsp;\u2212 Since right input is 32-bit and round key is a 48-bit, we first need to expand right input to 48 bits. Permutation logic is graphically depicted in the following illustration \u2212<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.tutorialspoint.com\/cryptography\/images\/permutation_logic.jpg\" alt=\"Permutation Logic\"\/><\/figure>\n\n\n\n<ul>\n<li>The graphically depicted permutation logic is generally described as table in DES specification illustrated as shown \u2212<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.tutorialspoint.com\/cryptography\/images\/des_specification.jpg\" alt=\"DES Specification\"\/><\/figure>\n\n\n\n<ul>\n<li><strong>XOR (Whitener).<\/strong>&nbsp;\u2212 After the expansion permutation, DES does XOR operation on the expanded right section and the round key. The round key is used only in this operation.<\/li>\n\n\n\n<li><strong>Substitution Boxes.<\/strong>&nbsp;\u2212 The S-boxes carry out the real mixing (confusion). DES uses 8 S-boxes, each with a 6-bit input and a 4-bit output. Refer the following illustration \u2212<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.tutorialspoint.com\/cryptography\/images\/s-boxes.jpg\" alt=\"S-boxes\"\/><\/figure>\n\n\n\n<ul>\n<li>The S-box rule is illustrated below \u2212<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.tutorialspoint.com\/cryptography\/images\/s_box_rule.jpg\" alt=\"S-box Rule\"\/><\/figure>\n\n\n\n<ul>\n<li>There are a total of eight S-box tables. The output of all eight s-boxes is then combined in to 32 bit section.<\/li>\n\n\n\n<li><strong>Straight Permutation<\/strong>&nbsp;\u2212 The 32 bit output of S-boxes is then subjected to the straight permutation with rule shown in the following illustration:<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.tutorialspoint.com\/cryptography\/images\/straight_permutation.jpg\" alt=\"Straight Permutation\"\/><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>The heart of this cipher is the DES function,&nbsp;f. The DES function applies a 48-bit key to the rightmost 32 bits to produce a 32-bit output.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[590],"tags":[],"_links":{"self":[{"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/posts\/10227"}],"collection":[{"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/comments?post=10227"}],"version-history":[{"count":0,"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/posts\/10227\/revisions"}],"wp:attachment":[{"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/media?parent=10227"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/categories?post=10227"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/tags?post=10227"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}