{"id":16449,"date":"2026-08-31T10:44:07","date_gmt":"2026-08-31T07:44:07","guid":{"rendered":"https:\/\/www.ihs.com.tr\/blog\/?p=16449"},"modified":"2026-08-31T10:44:07","modified_gmt":"2026-08-31T07:44:07","slug":"cipher-block-chaining-cbc-nedir","status":"publish","type":"post","link":"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/","title":{"rendered":"Cipher Block Chaining (CBC) Nedir? Eski Nesil Blok \u015eifreleme Modlar\u0131 Neden Zafiyet Ta\u015f\u0131yor?"},"content":{"rendered":"<p>Dijital verilerin g\u00fcvenli\u011fi, g\u00fcn\u00fcm\u00fcz teknoloji d\u00fcnyas\u0131n\u0131n en temel yap\u0131 ta\u015flar\u0131ndan biridir. Bilgiyi yetkisiz eri\u015fimden korumak i\u00e7in kulland\u0131\u011f\u0131m\u0131z en g\u00fc\u00e7l\u00fc ara\u00e7lardan biri olan \u015fifreleme, verileri okunamaz hale getirerek gizlili\u011fi sa\u011flar. Bu s\u00fcrecin kalbinde ise blok \u015fifreleme algoritmalar\u0131 ve onlar\u0131n nas\u0131l uyguland\u0131\u011f\u0131n\u0131 belirleyen &#8220;\u00e7al\u0131\u015fma modlar\u0131&#8221; yer al\u0131r. Bu modlar, tek bir veri blo\u011funu \u015fifrelemek i\u00e7in tasarlanm\u0131\u015f algoritmalar\u0131n, b\u00fcy\u00fck boyutlu verileri g\u00fcvenli bir \u015fekilde nas\u0131l i\u015fleyece\u011fini tan\u0131mlar. Ancak, \u00f6zellikle Cipher Block Chaining (CBC) gibi eski nesil modlar, modern siber tehditler kar\u015f\u0131s\u0131nda art\u0131k yetersiz kalmakta ve ciddi g\u00fcvenlik zafiyetleri bar\u0131nd\u0131rmaktad\u0131r. Bu makalede, blok \u015fifrelemenin temellerinden ba\u015flayarak CBC modunun \u00e7al\u0131\u015fma prensibini, bar\u0131nd\u0131rd\u0131\u011f\u0131 riskleri ve neden modern alternatifler olan AEAD modlar\u0131n\u0131n tercih edilmesi gerekti\u011fini derinlemesine inceleyece\u011fiz.<\/p>\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_77 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">\u0130\u00e7erik Tablosu<\/p>\n<label for=\"ez-toc-cssicon-toggle-item-6a9584fb7347e\" class=\"ez-toc-cssicon-toggle-label\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/label><input type=\"checkbox\" id=\"ez-toc-cssicon-toggle-item-6a9584fb7347e\" aria-label=\"Toggle\" \/><nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Blok-Sifrelemenin-Temelleri-ve-Calisma-Modlari\" >Blok \u015eifrelemenin Temelleri ve \u00c7al\u0131\u015fma Modlar\u0131<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Simetrik-Sifreleme-Nedir\" >Simetrik \u015eifreleme Nedir?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Blok-Sifre-Kavrami-ve-Sabit-Blok-Boyutlari\" >Blok \u015eifre Kavram\u0131 ve Sabit Blok Boyutlar\u0131<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Sifreleme-Calisma-Modlari-Modes-of-Operation-Neden-Gereklidir\" >\u015eifreleme \u00c7al\u0131\u015fma Modlar\u0131 (Modes of Operation) Neden Gereklidir?<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Electronic-Codebook-ECB-En-Temel-ve-En-Guvensiz-Mod\" >Electronic Codebook (ECB): En Temel ve En G\u00fcvensiz Mod<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#ECB-Modu-Nasil-Calisir\" >ECB Modu Nas\u0131l \u00c7al\u0131\u015f\u0131r?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#ECBnin-Yapisal-Zafiyeti-Ayni-Duz-Metin-Ayni-Sifreli-Metin\" >ECB&#8217;nin Yap\u0131sal Zafiyeti: Ayn\u0131 D\u00fcz Metin, Ayn\u0131 \u015eifreli Metin<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Gorsel-Kriptanaliz-%E2%80%9CTux-Pengueni%E2%80%9D-Problemi\" >G\u00f6rsel Kriptanaliz: &#8220;Tux Pengueni&#8221; Problemi<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#ECB-Modunun-Kullanilmamasi-Gereken-Senaryolar\" >ECB Modunun Kullan\u0131lmamas\u0131 Gereken Senaryolar<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Cipher-Block-Chaining-CBC-Moduna-Derinlemesine-Bakis\" >Cipher Block Chaining (CBC) Moduna Derinlemesine Bak\u0131\u015f<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#CBC-Modu-Nedir-ve-Nasil-Calisir\" >CBC Modu Nedir ve Nas\u0131l \u00c7al\u0131\u015f\u0131r?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Baslatma-Vektorunun-Initialization-Vector-%E2%80%93-IV-Rolu-ve-Onemi\" >Ba\u015flatma Vekt\u00f6r\u00fcn\u00fcn (Initialization Vector &#8211; IV) Rol\u00fc ve \u00d6nemi<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Zincirleme-Mekanizmasi-Bir-Onceki-Blogun-Etkisi\" >Zincirleme Mekanizmas\u0131: Bir \u00d6nceki Blo\u011fun Etkisi<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#CBC-Sifreleme-Surecinin-Adimlari\" >CBC \u015eifreleme S\u00fcrecinin Ad\u0131mlar\u0131<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#CBC-Sifre-Cozme-Surecinin-Adimlari\" >CBC \u015eifre \u00c7\u00f6zme S\u00fcrecinin Ad\u0131mlar\u0131<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-16\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#CBCnin-ECBye-Gore-Sagladigi-Temel-Guvenlik-Avantajlari\" >CBC&#8217;nin ECB&#8217;ye G\u00f6re Sa\u011flad\u0131\u011f\u0131 Temel G\u00fcvenlik Avantajlar\u0131<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-17\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Eski-Nesil-Modlarin-Guvenlik-Zafiyetleri-ve-Saldiri-Vektorleri\" >Eski Nesil Modlar\u0131n G\u00fcvenlik Zafiyetleri ve Sald\u0131r\u0131 Vekt\u00f6rleri<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-18\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#CBC-Modundaki-Zafiyetler\" >CBC Modundaki Zafiyetler<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-19\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Diger-Eski-Modlardaki-Problemler-CFB-OFB\" >Di\u011fer Eski Modlardaki Problemler (CFB, OFB)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-20\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Tekrarlanan-Anahtar-Akisi-Keystream-Reuse-Zafiyeti\" >Tekrarlanan Anahtar Ak\u0131\u015f\u0131 (Keystream Reuse) Zafiyeti<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-21\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Modern-Kriptografide-Cozum-Kimlik-Dogrulamali-Sifreleme-AEAD\" >Modern Kriptografide \u00c7\u00f6z\u00fcm: Kimlik Do\u011frulamal\u0131 \u015eifreleme (AEAD)<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-22\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Sifrelemenin-Yetersizligi-Butunluk-ve-Kimlik-Dogrulama-Ihtiyaci\" >\u015eifrelemenin Yetersizli\u011fi: B\u00fct\u00fcnl\u00fck ve Kimlik Do\u011frulama \u0130htiyac\u0131<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-23\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#AEAD-Modlari-Nedir\" >AEAD Modlar\u0131 Nedir?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-24\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#GaloisCounter-Mode-GCM-ve-Calisma-Prensibi\" >Galois\/Counter Mode (GCM) ve \u00c7al\u0131\u015fma Prensibi<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-25\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Counter-with-CBC-MAC-CCM-ve-Calisma-Prensibi\" >Counter with CBC-MAC (CCM) ve \u00c7al\u0131\u015fma Prensibi<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-26\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#AEAD-Modlarinin-CBC-ve-Diger-Eski-Modlara-Gore-Ustunlukleri\" >AEAD Modlar\u0131n\u0131n CBC ve Di\u011fer Eski Modlara G\u00f6re \u00dcst\u00fcnl\u00fckleri<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-27\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Guvenli-Bir-Sistem-Icin-Dogru-Sifreleme-Modunu-Secme\" >G\u00fcvenli Bir Sistem \u0130\u00e7in Do\u011fru \u015eifreleme Modunu Se\u00e7me<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-28\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Hangi-Durumlarda-Hangi-Mod-Tercih-Edilmelidir\" >Hangi Durumlarda Hangi Mod Tercih Edilmelidir?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-29\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Kriptografik-Protokollerde-Mod-Seciminin-Kritik-Rolu\" >Kriptografik Protokollerde Mod Se\u00e7iminin Kritik Rol\u00fc<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-30\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Mevcut-Sistemlerde-CBCden-Modern-Modlara-Gecis-Stratejileri\" >Mevcut Sistemlerde CBC&#8217;den Modern Modlara Ge\u00e7i\u015f Stratejileri<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-31\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Veri-Guvenligi-ve-Modern-Sifreleme-Standartlari-Icin-Neden-IHS-Telekomu-Tercih-Etmelisiniz\" >Veri G\u00fcvenli\u011fi ve Modern \u015eifreleme Standartlar\u0131 \u0130\u00e7in Neden \u0130HS Telekom&#8217;u Tercih Etmelisiniz?<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-32\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Guclu-Kriptografik-Protokolleri-Destekleyen-Altyapi\" >G\u00fc\u00e7l\u00fc Kriptografik Protokolleri Destekleyen Altyap\u0131<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-33\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Veri-Gizliligi-ve-Butunlugunu-Saglayan-Guvenlik-Katmanlari\" >Veri Gizlili\u011fi ve B\u00fct\u00fcnl\u00fc\u011f\u00fcn\u00fc Sa\u011flayan G\u00fcvenlik Katmanlar\u0131<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-34\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Endustri-Standartlarina-Uygun-Guvenli-Veri-Saklama-ve-Iletim-Cozumleri\" >End\u00fcstri Standartlar\u0131na Uygun G\u00fcvenli Veri Saklama ve \u0130letim \u00c7\u00f6z\u00fcmleri<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-35\" href=\"https:\/\/www.ihs.com.tr\/blog\/cipher-block-chaining-cbc-nedir\/#Guvenlik-Konularinda-Uzman-Teknik-Destek-ve-Danismanlik\" >G\u00fcvenlik Konular\u0131nda Uzman Teknik Destek ve Dan\u0131\u015fmanl\u0131k<\/a><\/li><\/ul><\/li><\/ul><\/nav><\/div>\n<h2><span class=\"ez-toc-section\" id=\"Blok-Sifrelemenin-Temelleri-ve-Calisma-Modlari\"><\/span>Blok \u015eifrelemenin Temelleri ve \u00c7al\u0131\u015fma Modlar\u0131<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Veri \u015fifreleme, bilginin gizlili\u011fini ve b\u00fct\u00fcnl\u00fc\u011f\u00fcn\u00fc koruma prati\u011finin merkezindedir. Bu alandaki en yayg\u0131n y\u00f6ntemlerden biri, veriyi belirli boyutlardaki par\u00e7alara ay\u0131rarak i\u015fleyen blok \u015fifreleme algoritmalar\u0131d\u0131r. Ancak bu algoritmalar\u0131n tek ba\u015flar\u0131na b\u00fcy\u00fck veri setlerini g\u00fcvenli bir \u015fekilde \u015fifrelemesi m\u00fcmk\u00fcn de\u011fildir. \u0130\u015fte bu noktada &#8220;\u00e7al\u0131\u015fma modlar\u0131&#8221; devreye girer ve \u015fifreleme s\u00fcrecini y\u00f6neterek g\u00fcvenli\u011fi art\u0131r\u0131r.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Simetrik-Sifreleme-Nedir\"><\/span>Simetrik \u015eifreleme Nedir?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Simetrik \u015fifreleme, kriptografinin en temel prensiplerinden biridir. Bu y\u00f6ntemde, veriyi \u015fifrelemek (encrypt) ve \u015fifresini \u00e7\u00f6zmek (decrypt) i\u00e7in ayn\u0131 anahtar kullan\u0131l\u0131r. Bu nedenle &#8220;tek anahtarl\u0131&#8221; veya &#8220;payla\u015f\u0131ml\u0131 anahtarl\u0131&#8221; \u015fifreleme olarak da bilinir. G\u00f6nderici, d\u00fcz metni (plaintext) payla\u015f\u0131lan gizli anahtarla \u015fifreleyerek \u015fifreli metin (ciphertext) olu\u015fturur. Al\u0131c\u0131 ise ayn\u0131 gizli anahtar\u0131 kullanarak \u015fifreli metni tekrar okunabilir d\u00fcz metne d\u00f6n\u00fc\u015ft\u00fcr\u00fcr. H\u0131zl\u0131 ve verimli olmas\u0131 nedeniyle b\u00fcy\u00fck veri hacimlerinin \u015fifrelenmesinde yayg\u0131n olarak tercih edilir. AES (Advanced Encryption Standard) ve DES (Data Encryption Standard) gibi pop\u00fcler \u015fifreleme standartlar\u0131 simetrik \u015fifreleme algoritmalar\u0131d\u0131r.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Blok-Sifre-Kavrami-ve-Sabit-Blok-Boyutlari\"><\/span>Blok \u015eifre Kavram\u0131 ve Sabit Blok Boyutlar\u0131<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Blok \u015fifre, simetrik \u015fifrelemenin bir alt t\u00fcr\u00fcd\u00fcr ve veriyi &#8220;blok&#8221; ad\u0131 verilen sabit boyutlu par\u00e7alara ay\u0131rarak \u00e7al\u0131\u015f\u0131r. Algoritma, her seferinde yaln\u0131zca bir blo\u011fu i\u015fler. \u00d6rne\u011fin, yayg\u0131n olarak kullan\u0131lan AES algoritmas\u0131 128 bit (16 byte) blok boyutuna sahiptir. Bu, \u015fifrelenecek verinin 128 bitlik par\u00e7alara b\u00f6l\u00fcnd\u00fc\u011f\u00fc ve her bir par\u00e7an\u0131n ayr\u0131 ayr\u0131 \u015fifrelendi\u011fi anlam\u0131na gelir. E\u011fer \u015fifrelenecek veri bu blok boyutundan k\u00fc\u00e7\u00fckse veya tam kat\u0131 de\u011filse, son blo\u011fun boyutunu tamamlamak i\u00e7in &#8220;doldurma&#8221; (padding) ad\u0131 verilen bir teknik kullan\u0131l\u0131r. Sabit blok boyutu, algoritmalar\u0131n donan\u0131m ve yaz\u0131l\u0131m \u00fczerinde verimli bir \u015fekilde uygulanmas\u0131n\u0131 sa\u011flar.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Sifreleme-Calisma-Modlari-Modes-of-Operation-Neden-Gereklidir\"><\/span>\u015eifreleme \u00c7al\u0131\u015fma Modlar\u0131 (Modes of Operation) Neden Gereklidir?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Bir blok \u015fifreleme algoritmas\u0131, tan\u0131m\u0131 gere\u011fi yaln\u0131zca tek bir sabit boyutlu blo\u011fu nas\u0131l \u015fifreleyece\u011fini bilir. Ancak ger\u00e7ek d\u00fcnyada \u015fifrelenmesi gereken veriler (e-postalar, dosyalar, veritabanlar\u0131 vb.) genellikle tek bir bloktan \u00e7ok daha b\u00fcy\u00fckt\u00fcr. \u0130\u015fte bu noktada \u00e7al\u0131\u015fma modlar\u0131 devreye girer. \u00c7al\u0131\u015fma modlar\u0131, bir blok \u015fifreleme algoritmas\u0131n\u0131n birden \u00e7ok veri blo\u011funu g\u00fcvenli ve tutarl\u0131 bir \u015fekilde nas\u0131l \u015fifreleyece\u011fini belirleyen kurallar ve prosed\u00fcrler b\u00fct\u00fcn\u00fcd\u00fcr. Farkl\u0131 modlar, g\u00fcvenlik, paralelle\u015ftirme yetene\u011fi ve hata yay\u0131l\u0131m\u0131 gibi konularda farkl\u0131 \u00f6zellikler sunar. Do\u011fru \u00e7al\u0131\u015fma modunu se\u00e7mek, \u015fifrelemenin genel g\u00fcvenli\u011fi i\u00e7in en az g\u00fc\u00e7l\u00fc bir <a href=\"https:\/\/www.ihs.com.tr\/blog\/web-sitesi-nasil-yapilir\/\" target=\"_blank\">web sitesi<\/a> algoritmas\u0131 se\u00e7mek kadar kritiktir.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Electronic-Codebook-ECB-En-Temel-ve-En-Guvensiz-Mod\"><\/span>Electronic Codebook (ECB): En Temel ve En G\u00fcvensiz Mod<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Blok \u015fifreleme \u00e7al\u0131\u015fma modlar\u0131 aras\u0131nda en basit olan\u0131 Electronic Codebook (ECB) modudur. Anla\u015f\u0131lmas\u0131 ve uygulanmas\u0131 kolay olsa da bar\u0131nd\u0131rd\u0131\u011f\u0131 yap\u0131sal zafiyetler nedeniyle modern kriptografide kesinlikle kullan\u0131lmamas\u0131 gereken bir y\u00f6ntem olarak kabul edilir. ECB&#8217;nin neden g\u00fcvensiz oldu\u011funu anlamak, daha karma\u015f\u0131k ve g\u00fcvenli modlar\u0131n \u00f6nemini kavramak i\u00e7in iyi bir ba\u015flang\u0131\u00e7 noktas\u0131d\u0131r.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"ECB-Modu-Nasil-Calisir\"><\/span>ECB Modu Nas\u0131l \u00c7al\u0131\u015f\u0131r?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>ECB modunun \u00e7al\u0131\u015fma prensibi son derece basittir. \u015eifrelenecek olan d\u00fcz metin, \u015fifreleme algoritmas\u0131n\u0131n blok boyutuna (\u00f6rne\u011fin AES i\u00e7in 128 bit) e\u015fit par\u00e7alara b\u00f6l\u00fcn\u00fcr. Ard\u0131ndan, her bir blok, di\u011fer bloklardan tamamen ba\u011f\u0131ms\u0131z bir \u015fekilde, ayn\u0131 \u015fifreleme anahtar\u0131 kullan\u0131larak \u015fifrelenir. \u015eifre \u00e7\u00f6zme i\u015flemi de ayn\u0131 mant\u0131kla i\u015fler; her \u015fifreli blok, yine di\u011ferlerinden ba\u011f\u0131ms\u0131z olarak ayn\u0131 anahtarla \u00e7\u00f6z\u00fcl\u00fcr. Bu ba\u011f\u0131ms\u0131zl\u0131k, ECB&#8217;nin en temel \u00f6zelli\u011fi ve ayn\u0131 zamanda en b\u00fcy\u00fck zay\u0131fl\u0131\u011f\u0131d\u0131r.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"ECBnin-Yapisal-Zafiyeti-Ayni-Duz-Metin-Ayni-Sifreli-Metin\"><\/span>ECB&#8217;nin Yap\u0131sal Zafiyeti: Ayn\u0131 D\u00fcz Metin, Ayn\u0131 \u015eifreli Metin<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>ECB&#8217;nin en kritik zafiyeti, deterministik (belirleyici) yap\u0131s\u0131d\u0131r. Bu, ayn\u0131 anahtar kullan\u0131ld\u0131\u011f\u0131 s\u00fcrece, birbirinin ayn\u0131 olan iki d\u00fcz metin blo\u011funun \u015fifrelendi\u011finde her zaman birbirinin ayn\u0131 olan iki \u015fifreli metin blo\u011fu \u00fcretece\u011fi anlam\u0131na gelir. \u00d6rne\u011fin, bir belgede &#8220;SALDIRI&#8221; kelimesi 10 farkl\u0131 yerde ge\u00e7iyorsa, ECB ile \u015fifrelendi\u011finde bu 10 kelimeye kar\u015f\u0131l\u0131k gelen \u015fifreli bloklar\u0131n hepsi ayn\u0131 olacakt\u0131r. Bu durum, sald\u0131rgan\u0131n \u015fifreli metni \u00e7\u00f6zemese bile, veri i\u00e7indeki desenleri ve tekrarlar\u0131 analiz ederek \u00f6nemli bilgiler \u00e7\u0131karmas\u0131na olanak tan\u0131r. Bu zafiyet, veri gizlili\u011fini temelden ihlal eder.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Gorsel-Kriptanaliz-%E2%80%9CTux-Pengueni%E2%80%9D-Problemi\"><\/span>G\u00f6rsel Kriptanaliz: &#8220;Tux Pengueni&#8221; Problemi<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>ECB&#8217;nin desen koruma zafiyetini en \u00e7arp\u0131c\u0131 \u015fekilde g\u00f6steren \u00f6rnek, &#8220;Tux Pengueni&#8221; problemidir. Bu \u00f6rnekte, Linux&#8217;un maskotu olan Tux pengueninin bir resim dosyas\u0131 (bitmap) ECB modu kullan\u0131larak \u015fifrelenir. Bitmap resimler, piksellerin renk verilerinden olu\u015fur ve genellikle ayn\u0131 renkteki geni\u015f alanlar (\u00f6rne\u011fin, penguenin siyah g\u00f6vdesi veya beyaz karn\u0131) birbirini tekrar eden veri bloklar\u0131 olu\u015fturur. ECB modu, bu tekrar eden bloklar\u0131 ayn\u0131 \u015fifreli bloklara d\u00f6n\u00fc\u015ft\u00fcrd\u00fc\u011f\u00fc i\u00e7in, \u015fifrelenmi\u015f resimde penguenin ana hatlar\u0131 ve deseni b\u00fcy\u00fck \u00f6l\u00e7\u00fcde korunur. Ortaya \u00e7\u0131kan g\u00f6r\u00fcnt\u00fc anlams\u0131z piksellerden olu\u015fsa da, orijinal resmin sil\u00fceti net bir \u015fekilde g\u00f6r\u00fclebilir. Bu, ECB&#8217;nin veri i\u00e7eri\u011fini de\u011fil, yaln\u0131zca verinin kendisini gizledi\u011fini, desenleri ise a\u00e7\u0131kta b\u0131rakt\u0131\u011f\u0131n\u0131 kan\u0131tlar.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"ECB-Modunun-Kullanilmamasi-Gereken-Senaryolar\"><\/span>ECB Modunun Kullan\u0131lmamas\u0131 Gereken Senaryolar<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Yap\u0131sal zafiyetleri nedeniyle ECB modu, neredeyse hi\u00e7bir senaryoda kullan\u0131lmamal\u0131d\u0131r. \u00d6zellikle a\u015fa\u011f\u0131dakiler gibi durumlarda kullan\u0131m\u0131 felaketle sonu\u00e7lanabilir:<\/p>\n<ul>\n<li>B\u00fcy\u00fck ve yap\u0131sal verilerin \u015fifrelenmesi (resimler, metin belgeleri, protokol mesajlar\u0131).<\/li>\n<li>Tekrar eden desenler i\u00e7erme olas\u0131l\u0131\u011f\u0131 y\u00fcksek olan her t\u00fcrl\u00fc veri.<\/li>\n<li>Veri gizlili\u011finin kritik oldu\u011fu t\u00fcm uygulamalar.<\/li>\n<\/ul>\n<p>ECB, yaln\u0131zca tamamen rastgele ve tek bir bloktan daha uzun olmayan verilerin (\u00f6rne\u011fin, ba\u015fka bir \u015fifreleme anahtar\u0131n\u0131n \u015fifrelenmesi) \u015fifrelenmesi gibi \u00e7ok ni\u015f durumlarda teorik olarak d\u00fc\u015f\u00fcn\u00fclebilir. Ancak pratikte, daha g\u00fcvenli alternatifler her zaman mevcuttur ve tercih edilmelidir. \u015eifreleme i\u015flemleri, genellikle g\u00fcvenli bir <a href=\"https:\/\/www.ihs.com.tr\/sunucu-kiralama\/\" target=\"_blank\">sunucu<\/a> \u00fczerinde ger\u00e7ekle\u015ftirilerek verinin korunmas\u0131 sa\u011flan\u0131r.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Cipher-Block-Chaining-CBC-Moduna-Derinlemesine-Bakis\"><\/span>Cipher Block Chaining (CBC) Moduna Derinlemesine Bak\u0131\u015f<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Electronic Codebook (ECB) modunun belirgin zafiyetlerini gidermek amac\u0131yla geli\u015ftirilen Cipher Block Chaining (CBC), blok \u015fifreleme modlar\u0131 aras\u0131nda en bilinen ve ge\u00e7mi\u015fte en yayg\u0131n kullan\u0131lanlardan biridir. CBC, \u015fifreleme s\u00fcrecine bir &#8220;zincirleme&#8221; mekanizmas\u0131 ekleyerek, ayn\u0131 d\u00fcz metin bloklar\u0131n\u0131n farkl\u0131 \u015fifreli metin bloklar\u0131 \u00fcretmesini sa\u011flar ve b\u00f6ylece desen analizini zorla\u015ft\u0131r\u0131r.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"CBC-Modu-Nedir-ve-Nasil-Calisir\"><\/span>CBC Modu Nedir ve Nas\u0131l \u00c7al\u0131\u015f\u0131r?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>CBC modu, ad\u0131ndan da anla\u015f\u0131laca\u011f\u0131 gibi, \u015fifreleme bloklar\u0131n\u0131 birbirine zincirler. Her bir d\u00fcz metin blo\u011fu, \u015fifrelenmeden \u00f6nce bir \u00f6nceki blo\u011fun \u015fifreli metni ile bir XOR (\u00f6zel veya) i\u015flemine tabi tutulur. Bu i\u015flem, her blo\u011fun \u015fifrelenme sonucunu, kendisinden \u00f6nceki t\u00fcm bloklara ba\u011f\u0131ml\u0131 hale getirir. B\u00f6ylece, d\u00fcz metin i\u00e7indeki iki blok ayn\u0131 olsa bile, zincirdeki konumlar\u0131 farkl\u0131 oldu\u011fu i\u00e7in \u00fcretilen \u015fifreli metin bloklar\u0131 tamamen farkl\u0131 olacakt\u0131r. Bu mekanizma, ECB&#8217;nin en b\u00fcy\u00fck zafiyeti olan desen koruma sorununu etkili bir \u015fekilde \u00e7\u00f6zer.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Baslatma-Vektorunun-Initialization-Vector-%E2%80%93-IV-Rolu-ve-Onemi\"><\/span>Ba\u015flatma Vekt\u00f6r\u00fcn\u00fcn (Initialization Vector &#8211; IV) Rol\u00fc ve \u00d6nemi<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Zincirleme mekanizmas\u0131 bir soru ortaya \u00e7\u0131kar\u0131r: \u0130lk d\u00fcz metin blo\u011fu, kendisinden \u00f6nce bir \u015fifreli metin blo\u011fu olmad\u0131\u011f\u0131 i\u00e7in ne ile XOR&#8217;lanacakt\u0131r? \u0130\u015fte bu noktada <b>Ba\u015flatma Vekt\u00f6r\u00fc (Initialization Vector &#8211; IV)<\/b> devreye girer. IV, \u015fifreleme algoritmas\u0131n\u0131n blok boyutuna e\u015fit, rastgele ve tahmin edilemez bir veri blo\u011fudur. \u0130lk d\u00fcz metin blo\u011fu, \u015fifrelenmeden \u00f6nce bu IV ile XOR&#8217;lan\u0131r. IV&#8217;nin en \u00f6nemli g\u00f6revi, ayn\u0131 d\u00fcz metin ayn\u0131 anahtarla birden \u00e7ok kez \u015fifrelense bile, her seferinde tamamen farkl\u0131 bir \u015fifreli metin dizisi \u00fcretilmesini sa\u011flamakt\u0131r. G\u00fcvenli bir CBC uygulamas\u0131 i\u00e7in IV&#8217;nin her \u015fifreleme i\u015flemi i\u00e7in benzersiz ve kriptografik olarak rastgele olmas\u0131 hayati \u00f6nem ta\u015f\u0131r. IV, genellikle \u015fifreli metnin ilk blo\u011fu olarak, \u015fifresi \u00e7\u00f6z\u00fclmemi\u015f bir \u015fekilde metne eklenir.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Zincirleme-Mekanizmasi-Bir-Onceki-Blogun-Etkisi\"><\/span>Zincirleme Mekanizmas\u0131: Bir \u00d6nceki Blo\u011fun Etkisi<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>CBC&#8217;nin kalbinde yer alan zincirleme mekanizmas\u0131, bir &#8220;yay\u0131lma&#8221; (diffusion) etkisi yarat\u0131r. D\u00fcz metindeki tek bir bitte meydana gelen bir de\u011fi\u015fiklik, o bloktaki XOR i\u015flemi ve \u015fifreleme sonucunda ilgili \u015fifreli metin blo\u011funun tamamen de\u011fi\u015fmesine neden olur. Daha da \u00f6nemlisi, bu de\u011fi\u015fen \u015fifreli metin blo\u011fu, bir sonraki blo\u011fun \u015fifrelemesinde kullan\u0131laca\u011f\u0131 i\u00e7in, takip eden t\u00fcm \u015fifreli metin bloklar\u0131 da bu de\u011fi\u015fiklikten etkilenir. Bu \u00f6zellik, veri \u00fczerinde yap\u0131lan k\u00fc\u00e7\u00fck de\u011fi\u015fikliklerin bile \u015fifreli metin boyunca yay\u0131lmas\u0131n\u0131 sa\u011flayarak g\u00fcvenli\u011fi art\u0131r\u0131r.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"CBC-Sifreleme-Surecinin-Adimlari\"><\/span>CBC \u015eifreleme S\u00fcrecinin Ad\u0131mlar\u0131<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>CBC modu ile \u015fifreleme ad\u0131mlar\u0131 a\u015fa\u011f\u0131daki gibidir:<\/p>\n<ol>\n<li>Rastgele ve benzersiz bir Ba\u015flatma Vekt\u00f6r\u00fc (IV) olu\u015fturulur.<\/li>\n<li>\u0130lk d\u00fcz metin blo\u011fu (P1), IV ile XOR&#8217;lan\u0131r.<\/li>\n<li>XOR i\u015fleminin sonucu, anahtar kullan\u0131larak \u015fifrelenir ve ilk \u015fifreli metin blo\u011fu (C1) elde edilir.<\/li>\n<li>\u0130kinci d\u00fcz metin blo\u011fu (P2), bir \u00f6nceki \u015fifreli metin blo\u011fu (C1) ile XOR&#8217;lan\u0131r.<\/li>\n<li>Bu sonu\u00e7 anahtarla \u015fifrelenir ve ikinci \u015fifreli metin blo\u011fu (C2) elde edilir.<\/li>\n<li>Bu i\u015flem, t\u00fcm d\u00fcz metin bloklar\u0131 bitene kadar tekrarlan\u0131r.<\/li>\n<\/ol>\n<h3><span class=\"ez-toc-section\" id=\"CBC-Sifre-Cozme-Surecinin-Adimlari\"><\/span>CBC \u015eifre \u00c7\u00f6zme S\u00fcrecinin Ad\u0131mlar\u0131<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>CBC modu ile \u015fifre \u00e7\u00f6zme i\u015flemi, \u015fifreleme ad\u0131mlar\u0131n\u0131n tersine \u00e7evrilmesiyle ger\u00e7ekle\u015ftirilir:<\/p>\n<ol>\n<li>\u015eifreli metnin ba\u015f\u0131ndaki IV al\u0131n\u0131r.<\/li>\n<li>\u0130lk \u015fifreli metin blo\u011fu (C1), anahtar kullan\u0131larak \u00e7\u00f6z\u00fcl\u00fcr.<\/li>\n<li>\u00c7\u00f6z\u00fclen blo\u011fun sonucu, IV ile XOR&#8217;lanarak ilk d\u00fcz metin blo\u011fu (P1) elde edilir.<\/li>\n<li>\u0130kinci \u015fifreli metin blo\u011fu (C2), anahtar kullan\u0131larak \u00e7\u00f6z\u00fcl\u00fcr.<\/li>\n<li>\u00c7\u00f6z\u00fclen blo\u011fun sonucu, bir \u00f6nceki \u015fifreli metin blo\u011fu (C1) ile XOR&#8217;lanarak ikinci d\u00fcz metin blo\u011fu (P2) elde edilir.<\/li>\n<li>Bu i\u015flem, t\u00fcm \u015fifreli metin bloklar\u0131 bitene kadar tekrarlan\u0131r.<\/li>\n<\/ol>\n<h3><span class=\"ez-toc-section\" id=\"CBCnin-ECBye-Gore-Sagladigi-Temel-Guvenlik-Avantajlari\"><\/span>CBC&#8217;nin ECB&#8217;ye G\u00f6re Sa\u011flad\u0131\u011f\u0131 Temel G\u00fcvenlik Avantajlar\u0131<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>CBC&#8217;nin ECB&#8217;ye k\u0131yasla en b\u00fcy\u00fck avantaj\u0131, zincirleme mekanizmas\u0131 sayesinde desenleri gizlemesidir. Ayn\u0131 d\u00fcz metin bloklar\u0131, zincirdeki farkl\u0131 konumlar\u0131na ba\u011fl\u0131 olarak tamamen farkl\u0131 \u015fifreli metin bloklar\u0131 \u00fcretir. Ayr\u0131ca, rastgele bir IV kullan\u0131m\u0131, ayn\u0131 mesaj\u0131n ayn\u0131 anahtarla tekrar \u015fifrelenmesi durumunda bile farkl\u0131 bir sonu\u00e7 elde edilmesini garanti eder. Bu \u00f6zellikler, CBC&#8217;yi ECB&#8217;ye g\u00f6re \u00e7ok daha g\u00fcvenli bir se\u00e7enek haline getirir ve veri gizlili\u011fini \u00f6nemli \u00f6l\u00e7\u00fcde art\u0131r\u0131r. Bu t\u00fcr g\u00fcvenlik mekanizmalar\u0131, \u00f6zellikle <a href=\"https:\/\/www.ihs.com.tr\/web-hosting\/\" target=\"_blank\">hosting<\/a> hizmetlerinde depolanan verilerin korunmas\u0131nda temel bir rol oynar.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Eski-Nesil-Modlarin-Guvenlik-Zafiyetleri-ve-Saldiri-Vektorleri\"><\/span>Eski Nesil Modlar\u0131n G\u00fcvenlik Zafiyetleri ve Sald\u0131r\u0131 Vekt\u00f6rleri<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Cipher Block Chaining (CBC) ve benzeri eski nesil \u015fifreleme modlar\u0131, ortaya \u00e7\u0131kt\u0131klar\u0131 d\u00f6nemde \u00f6nemli bir g\u00fcvenlik ad\u0131m\u0131 olsalar da, modern kriptanaliz teknikleri kar\u015f\u0131s\u0131nda \u00e7e\u015fitli zafiyetler bar\u0131nd\u0131rd\u0131klar\u0131 kan\u0131tlanm\u0131\u015ft\u0131r. Bu zafiyetler, sadece veri gizlili\u011fini de\u011fil, ayn\u0131 zamanda veri b\u00fct\u00fcnl\u00fc\u011f\u00fcn\u00fc de tehdit eden ciddi sald\u0131r\u0131 vekt\u00f6rlerine kap\u0131 a\u00e7maktad\u0131r. Bu sald\u0131r\u0131lar, \u015fifreleme mekanizmalar\u0131n\u0131n nas\u0131l k\u00f6t\u00fcye kullan\u0131labilece\u011fini ve neden modern alternatiflere ihtiya\u00e7 duyuldu\u011funu g\u00f6stermektedir.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"CBC-Modundaki-Zafiyetler\"><\/span>CBC Modundaki Zafiyetler<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>CBC, ECB&#8217;nin desen analizi sorununu \u00e7\u00f6zse de, kendi yap\u0131s\u0131ndan kaynaklanan \u00f6nemli g\u00fcvenlik a\u00e7\u0131klar\u0131 i\u00e7erir. Bu a\u00e7\u0131klar genellikle \u015fifre \u00e7\u00f6zme s\u00fcrecinin ve veri yap\u0131s\u0131n\u0131n tahmin edilebilir \u00f6zelliklerinden kaynaklan\u0131r.<\/p>\n<h4>Doldurma (Padding) Kavram\u0131 ve Padding Oracle Sald\u0131r\u0131lar\u0131<\/h4>\n<p>Blok \u015fifrelemeler sabit boyutlu bloklarla \u00e7al\u0131\u015f\u0131r. E\u011fer son d\u00fcz metin blo\u011fu tam boyutta de\u011filse, blo\u011fu tamamlamak i\u00e7in &#8220;doldurma&#8221; (padding) eklenir. \u00d6rne\u011fin, PKCS#7 standard\u0131nda, eksik olan N byte&#8217;\u0131 tamamlamak i\u00e7in her biri N de\u011ferini i\u00e7eren N adet byte eklenir. \u015eifre \u00e7\u00f6zme taraf\u0131nda, uygulama bu doldurmay\u0131 kontrol eder ve ge\u00e7erli de\u011filse bir hata d\u00f6nd\u00fcr\u00fcr. <b>Padding Oracle Sald\u0131r\u0131s\u0131<\/b> tam olarak bu hata mesaj\u0131n\u0131 s\u00f6m\u00fcr\u00fcr. Sald\u0131rgan, manip\u00fcle etti\u011fi \u015fifreli metin bloklar\u0131n\u0131 sunucuya g\u00f6nderir. Sunucunun &#8220;ge\u00e7erli doldurma&#8221; ya da &#8220;ge\u00e7ersiz doldurma&#8221; \u015feklinde verdi\u011fi (veya vermedi\u011fi) tepkileri analiz ederek, \u015fifreli metnin i\u00e7eri\u011fi hakk\u0131nda bayt bayt bilgi s\u0131zd\u0131rabilir. Bu, sald\u0131rgan\u0131n anahtar\u0131 bilmeden \u015fifreli metni tamamen \u00e7\u00f6zmesine olanak tan\u0131yabilir.<\/p>\n<h4>Bit Flipping Sald\u0131r\u0131lar\u0131 ve Veri B\u00fct\u00fcnl\u00fc\u011f\u00fcn\u00fcn Bozulmas\u0131<\/h4>\n<p>CBC&#8217;nin en \u00f6nemli zafiyetlerinden biri de veri b\u00fct\u00fcnl\u00fc\u011f\u00fcn\u00fc (integrity) sa\u011flamamas\u0131d\u0131r. \u015eifreleme, verinin gizlili\u011fini korurken, onun de\u011fi\u015ftirilip de\u011fi\u015ftirilmedi\u011fini garanti etmez. <b>Bit Flipping Sald\u0131r\u0131s\u0131<\/b>, bu zafiyetten faydalan\u0131r. CBC&#8217;nin \u015fifre \u00e7\u00f6zme mekanizmas\u0131nda (P[i] = Decrypt(C[i]) XOR C[i-1]), sald\u0131rgan bir \u00f6nceki \u015fifreli metin blo\u011fundaki (C[i-1]) bitleri de\u011fi\u015ftirerek bir sonraki d\u00fcz metin blo\u011funda (P[i]) \u00f6ng\u00f6r\u00fclebilir de\u011fi\u015fiklikler yapabilir. \u00d6rne\u011fin, &#8220;user=guest&#8221; verisini &#8220;user=admin&#8221; olarak de\u011fi\u015ftirmek isteyen bir sald\u0131rgan, &#8220;guest&#8221; kelimesine denk gelen \u015fifreli blo\u011fun bir \u00f6nceki blo\u011fundaki ilgili bitleri manip\u00fcle ederek bu de\u011fi\u015fikli\u011fi ger\u00e7ekle\u015ftirebilir. \u015eifre \u00e7\u00f6zme s\u0131ras\u0131nda manip\u00fcle edilen C[i-1] blo\u011fu anlams\u0131z bir veriye d\u00f6n\u00fc\u015fse de, P[i] blo\u011fu sald\u0131rgan\u0131n istedi\u011fi gibi de\u011fi\u015fmi\u015f olur.<\/p>\n<h4>Tahmin Edilebilir IV Kullan\u0131m\u0131n\u0131n Riskleri<\/h4>\n<p>CBC&#8217;nin g\u00fcvenli\u011fi, her \u015fifreleme i\u015flemi i\u00e7in kullan\u0131lan Ba\u015flatma Vekt\u00f6r\u00fcn\u00fcn (IV) benzersiz ve kriptografik olarak tahmin edilemez olmas\u0131na ba\u011fl\u0131d\u0131r. E\u011fer bir sald\u0131rgan IV&#8217;yi tahmin edebilir veya kontrol edebilirse, ciddi g\u00fcvenlik sorunlar\u0131 ortaya \u00e7\u0131kar. Sabit bir IV kullanmak veya basit bir saya\u00e7 gibi tahmin edilebilir bir y\u00f6ntemle IV \u00fcretmek, iki farkl\u0131 d\u00fcz metnin ayn\u0131 \u00f6nekle ba\u015flamas\u0131 durumunda, \u00fcretilen \u015fifreli metinlerin de ayn\u0131 \u00f6nekle ba\u015flamas\u0131na neden olabilir. Bu durum, sald\u0131rgan\u0131n metinler aras\u0131ndaki ili\u015fkileri analiz etmesine ve gizli bilgiler s\u0131zd\u0131rmas\u0131na olanak tan\u0131r.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Diger-Eski-Modlardaki-Problemler-CFB-OFB\"><\/span>Di\u011fer Eski Modlardaki Problemler (CFB, OFB)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>CBC d\u0131\u015f\u0131ndaki di\u011fer eski modlar olan Cipher Feedback (CFB) ve Output Feedback (OFB) de benzer sorunlar ta\u015f\u0131r. Bu modlar, blok \u015fifrelemeyi bir ak\u0131\u015f \u015fifreleyici gibi \u00e7al\u0131\u015facak \u015fekilde d\u00f6n\u00fc\u015ft\u00fcr\u00fcr. Veri, \u015fifreleme algoritmas\u0131ndan \u00fcretilen bir anahtar ak\u0131\u015f\u0131 (keystream) ile XOR&#8217;lanarak \u015fifrelenir. Bu yap\u0131lar\u0131 nedeniyle, bit flipping sald\u0131r\u0131lar\u0131na kar\u015f\u0131 savunmas\u0131zd\u0131rlar. Ayr\u0131ca, her iki modda da g\u00fcvenlik, kullan\u0131lan IV&#8217;nin veya noncenin (number used once) benzersizli\u011fine kritik derecede ba\u011fl\u0131d\u0131r.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Tekrarlanan-Anahtar-Akisi-Keystream-Reuse-Zafiyeti\"><\/span>Tekrarlanan Anahtar Ak\u0131\u015f\u0131 (Keystream Reuse) Zafiyeti<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>CFB ve OFB gibi ak\u0131\u015f \u015fifreleyici modlar\u0131ndaki en \u00f6l\u00fcmc\u00fcl hata, anahtar ak\u0131\u015f\u0131n\u0131n (keystream) yeniden kullan\u0131lmas\u0131d\u0131r. E\u011fer ayn\u0131 anahtar ve ayn\u0131 IV\/nonce ile iki farkl\u0131 mesaj \u015fifrelenirse, her iki mesaj da ayn\u0131 anahtar ak\u0131\u015f\u0131yla XOR&#8217;lan\u0131r. Sald\u0131rgan bu iki \u015fifreli metni (C1 = P1 \u2295 K, C2 = P2 \u2295 K) ele ge\u00e7irirse, ikisini birbirleriyle XOR&#8217;layarak anahtar ak\u0131\u015f\u0131n\u0131 ortadan kald\u0131rabilir (C1 \u2295 C2 = P1 \u2295 P2). Bu sonu\u00e7, iki d\u00fcz metnin XOR&#8217;lanm\u0131\u015f halini verir. E\u011fer d\u00fcz metinler hakk\u0131nda (\u00f6rne\u011fin standart bir HTTP ba\u015fl\u0131\u011f\u0131 gibi) k\u0131smi bilgi varsa, sald\u0131rgan her iki metni de kolayca elde edebilir. Bu nedenle, bu modlarda IV\/nonce&#8217;nin asla tekrarlanmamas\u0131 esast\u0131r.<\/p>\n<div class=\"karsilastirma\">\n<table>\n<caption>Eski Nesil \u015eifreleme Modlar\u0131 ve Zafiyetleri<\/caption>\n<thead>\n<tr>\n<th>Mod<\/th>\n<th>Temel \u00c7al\u0131\u015fma Prensibi<\/th>\n<th>Ba\u015fl\u0131ca Zafiyet(ler)<\/th>\n<th>Sald\u0131r\u0131 Vekt\u00f6r\u00fc \u00d6rne\u011fi<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td><b>ECB<\/b> (Electronic Codebook)<\/td>\n<td>Her blok ba\u011f\u0131ms\u0131z \u015fifrelenir.<\/td>\n<td>Desenleri korur, deterministiktir.<\/td>\n<td>Tux Pengueni (G\u00f6rsel Kriptanaliz)<\/td>\n<\/tr>\n<tr>\n<td><b>CBC<\/b> (Cipher Block Chaining)<\/td>\n<td>Her blok, \u00f6nceki \u015fifreli blokla zincirlenir.<\/td>\n<td>B\u00fct\u00fcnl\u00fck korumas\u0131 yoktur, doldurma hatalar\u0131n\u0131 s\u00f6m\u00fcr\u00fcr.<\/td>\n<td>Padding Oracle, Bit Flipping<\/td>\n<\/tr>\n<tr>\n<td><b>CFB\/OFB<\/b> (Cipher\/Output Feedback)<\/td>\n<td>Blok \u015fifreyi ak\u0131\u015f \u015fifreleyiciye d\u00f6n\u00fc\u015ft\u00fcr\u00fcr.<\/td>\n<td>Anahtar ak\u0131\u015f\u0131n\u0131n yeniden kullan\u0131m\u0131na kar\u015f\u0131 savunmas\u0131zd\u0131r.<\/td>\n<td>Keystream Reuse Attack<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<h2><span class=\"ez-toc-section\" id=\"Modern-Kriptografide-Cozum-Kimlik-Dogrulamali-Sifreleme-AEAD\"><\/span>Modern Kriptografide \u00c7\u00f6z\u00fcm: Kimlik Do\u011frulamal\u0131 \u015eifreleme (AEAD)<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Eski nesil \u015fifreleme modlar\u0131n\u0131n bar\u0131nd\u0131rd\u0131\u011f\u0131 zafiyetler, modern siber g\u00fcvenlik ihtiya\u00e7lar\u0131 i\u00e7in sadece veri gizlili\u011finin (confidentiality) yeterli olmad\u0131\u011f\u0131n\u0131 a\u00e7\u0131k\u00e7a ortaya koymu\u015ftur. Bir verinin \u015fifrelenmi\u015f olmas\u0131, onun yolculuk s\u0131ras\u0131nda de\u011fi\u015ftirilmedi\u011fi (integrity) veya ger\u00e7ekten beklenen kaynaktan geldi\u011fi (authenticity) anlam\u0131na gelmez. Bu eksiklikleri gidermek i\u00e7in geli\u015ftirilen Kimlik Do\u011frulamal\u0131 \u015eifreleme (AEAD) modlar\u0131, g\u00fcn\u00fcm\u00fcz\u00fcn g\u00fcvenlik standartlar\u0131n\u0131 belirlemektedir.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Sifrelemenin-Yetersizligi-Butunluk-ve-Kimlik-Dogrulama-Ihtiyaci\"><\/span>\u015eifrelemenin Yetersizli\u011fi: B\u00fct\u00fcnl\u00fck ve Kimlik Do\u011frulama \u0130htiyac\u0131<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>CBC gibi modlar, veriyi okunamaz hale getirerek gizlili\u011fi sa\u011flar. Ancak bir sald\u0131rgan, \u015fifreli veriyi (ciphertext) manip\u00fcle ederek al\u0131c\u0131ya ula\u015ft\u0131\u011f\u0131nda, al\u0131c\u0131n\u0131n bu de\u011fi\u015fikli\u011fi fark etmesi i\u00e7in ek bir mekanizma yoktur. Bit-flipping sald\u0131r\u0131s\u0131 bunun en net \u00f6rne\u011fidir. Sald\u0131rgan, \u015fifreli veriyi de\u011fi\u015ftirerek al\u0131c\u0131n\u0131n eline ge\u00e7en \u00e7\u00f6z\u00fclm\u00fc\u015f metnin anlam\u0131n\u0131 tamamen de\u011fi\u015ftirebilir. Bu nedenle, modern kriptografik sistemler \u00fc\u00e7 temel hedefi sa\u011flamal\u0131d\u0131r:<\/p>\n<ul>\n<li><b>Gizlilik:<\/b> Veri, yetkisiz ki\u015filer taraf\u0131ndan okunamaz olmal\u0131d\u0131r.<\/li>\n<li><b>B\u00fct\u00fcnl\u00fck:<\/b> Verinin aktar\u0131m s\u0131ras\u0131nda de\u011fi\u015ftirilmedi\u011fi garanti edilmelidir.<\/li>\n<li><b>Kimlik Do\u011frulama:<\/b> Verinin ger\u00e7ekten iddia edilen kaynaktan geldi\u011fi do\u011frulanmal\u0131d\u0131r.<\/li>\n<\/ul>\n<p>\u0130\u015fte AEAD, bu \u00fc\u00e7 hedefi tek bir entegre operasyonda birle\u015ftiren \u00e7\u00f6z\u00fcmd\u00fcr.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"AEAD-Modlari-Nedir\"><\/span>AEAD Modlar\u0131 Nedir?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>AEAD (Authenticated Encryption with Associated Data), yani &#8220;\u0130li\u015fkili Veri ile Kimlik Do\u011frulamal\u0131 \u015eifreleme&#8221;, hem \u015fifreleme hem de kimlik do\u011frulama i\u015flemlerini ayn\u0131 anda ger\u00e7ekle\u015ftiren bir \u00e7al\u0131\u015fma modudur. Bu modlar, \u015fifrelenmi\u015f verinin yan\u0131 s\u0131ra bir de &#8220;kimlik do\u011frulama etiketi&#8221; (authentication tag) veya MAC (Message Authentication Code) \u00fcretir. Bu etiket, hem \u015fifrelenen verinin hem de anahtar\u0131n bir kriptografik \u00f6zetidir. Al\u0131c\u0131 taraf\u0131, verinin \u015fifresini \u00e7\u00f6zmeden \u00f6nce bu etiketi do\u011frular. E\u011fer etikette en ufak bir uyumsuzluk varsa (yani veri veya etiket yolda de\u011fi\u015ftirilmi\u015fse), \u015fifre \u00e7\u00f6zme i\u015flemi tamamen iptal edilir ve veri reddedilir. Bu, Padding Oracle gibi sald\u0131r\u0131lar\u0131 da imkans\u0131z hale getirir, \u00e7\u00fcnk\u00fc manip\u00fcle edilmi\u015f veri hi\u00e7bir zaman i\u015fleme al\u0131nmaz.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"GaloisCounter-Mode-GCM-ve-Calisma-Prensibi\"><\/span>Galois\/Counter Mode (GCM) ve \u00c7al\u0131\u015fma Prensibi<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>GCM, g\u00fcn\u00fcm\u00fczde en yayg\u0131n kullan\u0131lan AEAD modlar\u0131ndan biridir. Y\u00fcksek performans\u0131 ve paralelle\u015ftirilebilir yap\u0131s\u0131 sayesinde \u00f6zellikle a\u011f protokollerinde (TLS 1.2 ve 1.3 gibi) ve donan\u0131m h\u0131zland\u0131rmal\u0131 sistemlerde tercih edilir. GCM, iki temel bile\u015fenden olu\u015fur:<\/p>\n<ul>\n<li><b>CTR (Counter Mode):<\/b> Verinin \u015fifrelenmesi i\u00e7in saya\u00e7 modunu kullan\u0131r. Bu mod, bir saya\u00e7 (nonce) ve anahtardan bir anahtar ak\u0131\u015f\u0131 (keystream) \u00fcretir ve d\u00fcz metin bu ak\u0131\u015fla XOR&#8217;lanarak \u015fifrelenir. Bu yap\u0131, \u015fifreleme i\u015fleminin paralel olarak yap\u0131labilmesini sa\u011flar.<\/li>\n<li><b>GHASH:<\/b> Kimlik do\u011frulama etiketini (MAC) olu\u015fturmak i\u00e7in Galois alanlar\u0131 \u00fczerinde \u00e7al\u0131\u015fan \u00f6zel bir hash fonksiyonudur. Hem \u015fifreli metni hem de iste\u011fe ba\u011fl\u0131 olarak \u015fifrelenmemi\u015f &#8220;ili\u015fkili veriyi&#8221; (\u00f6rne\u011fin, IP ba\u015fl\u0131klar\u0131) i\u015fleme katarak etiketi \u00fcretir.<\/li>\n<\/ul>\n<p>GCM, h\u0131z\u0131 ve verimlili\u011fi sayesinde modern sistemler i\u00e7in standart haline gelmi\u015ftir. \u0130nternet trafi\u011finin g\u00fcvenli\u011fini sa\u011flayan <a href=\"https:\/\/www.ihs.com.tr\/ssl\/\" target=\"_blank\">SSL<\/a> sertifikalar\u0131, genellikle GCM gibi AEAD modlar\u0131n\u0131 kullanan \u015fifreleme tak\u0131mlar\u0131na dayan\u0131r.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Counter-with-CBC-MAC-CCM-ve-Calisma-Prensibi\"><\/span>Counter with CBC-MAC (CCM) ve \u00c7al\u0131\u015fma Prensibi<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>CCM, bir di\u011fer pop\u00fcler AEAD modudur ve \u00f6zellikle kablosuz a\u011f g\u00fcvenli\u011fi gibi (\u00f6rne\u011fin, WPA2\/3) daha k\u0131s\u0131tl\u0131 kaynaklara sahip ortamlar i\u00e7in tasarlanm\u0131\u015ft\u0131r. GCM gibi, CCM de iki bile\u015feni birle\u015ftirir:<\/p>\n<ul>\n<li><b>CTR (Counter Mode):<\/b> Veri \u015fifrelemesi i\u00e7in GCM ile ayn\u0131 \u015fekilde saya\u00e7 modunu kullan\u0131r.<\/li>\n<li><b>CBC-MAC:<\/b> Kimlik do\u011frulama i\u00e7in CBC moduna dayal\u0131 bir Mesaj Kimlik Do\u011frulama Kodu (MAC) algoritmas\u0131 kullan\u0131r.<\/li>\n<\/ul>\n<p>CCM, GCM&#8217;ye g\u00f6re genellikle biraz daha yava\u015ft\u0131r ve GCM gibi tamamen paralelle\u015ftirilemez. Ancak basitli\u011fi ve g\u00fcvenilirli\u011fi sayesinde g\u00f6m\u00fcl\u00fc sistemler ve belirli standartlar i\u00e7in \u00f6nemli bir alternatiftir.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"AEAD-Modlarinin-CBC-ve-Diger-Eski-Modlara-Gore-Ustunlukleri\"><\/span>AEAD Modlar\u0131n\u0131n CBC ve Di\u011fer Eski Modlara G\u00f6re \u00dcst\u00fcnl\u00fckleri<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>AEAD modlar\u0131n\u0131n eski nesil modlara g\u00f6re \u00fcst\u00fcnl\u00fckleri nettir:<\/p>\n<ul>\n<li><b>Entegre G\u00fcvenlik:<\/b> Gizlilik, b\u00fct\u00fcnl\u00fck ve kimlik do\u011frulamay\u0131 tek bir ad\u0131mda sunarak &#8220;\u015fifrele ve sonra MAC&#8217;le&#8221; (encrypt-then-MAC) gibi karma\u015f\u0131k ve hataya a\u00e7\u0131k yap\u0131lar\u0131 ortadan kald\u0131r\u0131r.<\/li>\n<li><b>Sald\u0131r\u0131lara Kar\u015f\u0131 Diren\u00e7:<\/b> Padding Oracle ve Bit Flipping gibi CBC&#8217;yi hedef alan klasik sald\u0131r\u0131 vekt\u00f6rlerine kar\u015f\u0131 do\u011fas\u0131 gere\u011fi ba\u011f\u0131\u015f\u0131kl\u0131d\u0131r. Manip\u00fcle edilmi\u015f herhangi bir veri, etiket do\u011frulamas\u0131ndan ge\u00e7emeyece\u011fi i\u00e7in an\u0131nda reddedilir.<\/li>\n<li><b>Kullan\u0131m Kolayl\u0131\u011f\u0131:<\/b> Geli\u015ftiricilere, g\u00fcvenli\u011fi do\u011fru bir \u015fekilde uygulamalar\u0131 i\u00e7in daha basit ve daha az hataya a\u00e7\u0131k bir aray\u00fcz sunar. Bu da uygulama katman\u0131ndaki hatalar\u0131 azalt\u0131r.<\/li>\n<\/ul>\n<p>Bu nedenlerle, yeni geli\u015ftirilen t\u00fcm sistemlerde ve protokollerde AEAD modlar\u0131n\u0131n (\u00f6zellikle AES-GCM) kullan\u0131lmas\u0131 \u015fiddetle tavsiye edilmektedir.<\/p>\n<div class=\"karsilastirma\">\n<table>\n<caption>\u015eifreleme Modlar\u0131n\u0131n Kar\u015f\u0131la\u015ft\u0131rmas\u0131: CBC vs. AEAD (GCM)<\/caption>\n<thead>\n<tr>\n<th>\u00d6zellik<\/th>\n<th>CBC (Cipher Block Chaining)<\/th>\n<th>GCM (Galois\/Counter Mode) &#8211; AEAD<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td><b>Gizlilik (Confidentiality)<\/b><\/td>\n<td>Evet<\/td>\n<td>Evet<\/td>\n<\/tr>\n<tr>\n<td><b>B\u00fct\u00fcnl\u00fck (Integrity)<\/b><\/td>\n<td>Hay\u0131r (Ek bir MAC mekanizmas\u0131 gerektirir)<\/td>\n<td>Evet (Entegre)<\/td>\n<\/tr>\n<tr>\n<td><b>Kimlik Do\u011frulama (Authenticity)<\/b><\/td>\n<td>Hay\u0131r<\/td>\n<td>Evet (Entegre)<\/td>\n<\/tr>\n<tr>\n<td><b>Paralelle\u015ftirme<\/b><\/td>\n<td>\u015eifreleme seri, \u015fifre \u00e7\u00f6zme paralel olabilir.<\/td>\n<td>Hem \u015fifreleme hem \u015fifre \u00e7\u00f6zme paralel yap\u0131labilir.<\/td>\n<\/tr>\n<tr>\n<td><b>Bilinen Zafiyetler<\/b><\/td>\n<td>Padding Oracle, Bit Flipping<\/td>\n<td>Nonce\/IV&#8217;nin yeniden kullan\u0131m\u0131na kar\u015f\u0131 hassas.<\/td>\n<\/tr>\n<tr>\n<td><b>\u00d6nerilen Kullan\u0131m<\/b><\/td>\n<td>Sadece mevcut eski sistemlerde (legacy systems). Yeni sistemlerde ka\u00e7\u0131n\u0131lmal\u0131d\u0131r.<\/td>\n<td>T\u00fcm yeni sistemler ve protokoller i\u00e7in standart se\u00e7im.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<h2><span class=\"ez-toc-section\" id=\"Guvenli-Bir-Sistem-Icin-Dogru-Sifreleme-Modunu-Secme\"><\/span>G\u00fcvenli Bir Sistem \u0130\u00e7in Do\u011fru \u015eifreleme Modunu Se\u00e7me<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Bir kriptografik sistemin genel g\u00fcvenli\u011fi, yaln\u0131zca se\u00e7ilen \u015fifreleme algoritmas\u0131n\u0131n g\u00fcc\u00fcne de\u011fil, ayn\u0131 zamanda bu algoritman\u0131n nas\u0131l uyguland\u0131\u011f\u0131n\u0131 belirleyen \u00e7al\u0131\u015fma modunun do\u011frulu\u011funa da kritik derecede ba\u011fl\u0131d\u0131r. Yanl\u0131\u015f mod se\u00e7imi, en g\u00fc\u00e7l\u00fc algoritmay\u0131 bile etkisiz hale getirebilir ve sistemi ciddi sald\u0131r\u0131lara a\u00e7\u0131k b\u0131rakabilir. Bu nedenle, geli\u015ftiricilerin ve sistem y\u00f6neticilerinin, projelerinin ihtiya\u00e7lar\u0131na en uygun ve en g\u00fcvenli modu bilin\u00e7li bir \u015fekilde se\u00e7mesi hayati \u00f6nem ta\u015f\u0131r.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Hangi-Durumlarda-Hangi-Mod-Tercih-Edilmelidir\"><\/span>Hangi Durumlarda Hangi Mod Tercih Edilmelidir?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Do\u011fru modu se\u00e7mek i\u00e7in temel kural \u015fudur: <b>Yeni geli\u015ftirilen t\u00fcm sistemlerde, varsay\u0131lan tercih her zaman bir AEAD (Authenticated Encryption with Associated Data) modu olmal\u0131d\u0131r.<\/b><\/p>\n<ul>\n<li><b>Genel Ama\u00e7l\u0131 ve Y\u00fcksek Performansl\u0131 Sistemler:<\/b> A\u011f trafi\u011fi (TLS\/SSL), disk \u015fifreleme, API g\u00fcvenli\u011fi gibi y\u00fcksek performans gerektiren uygulamalar i\u00e7in <b>AES-GCM<\/b> (Galois\/Counter Mode) en iyi se\u00e7enektir. Paralelle\u015ftirilebilir yap\u0131s\u0131 sayesinde modern i\u015flemcilerde y\u00fcksek h\u0131zlara ula\u015fabilir.<\/li>\n<li><b>Kaynak K\u0131s\u0131tl\u0131 Ortamlar:<\/b> G\u00f6m\u00fcl\u00fc sistemler, IoT cihazlar\u0131 veya belirli kablosuz ileti\u015fim standartlar\u0131 (\u00f6rne\u011fin WPA2) gibi daha az i\u015flem g\u00fcc\u00fcne sahip ortamlar i\u00e7in <b>AES-CCM<\/b> (Counter with CBC-MAC) uygun bir alternatiftir.<\/li>\n<li><b>Eski (Legacy) Sistemlerle Uyumluluk:<\/b> E\u011fer mevcut bir sistemle uyumluluk zorunluysa ve bu sistem yaln\u0131zca eski modlar\u0131 destekliyorsa, <b>CBC<\/b> modu kullan\u0131labilir. Ancak bu durumda, veri b\u00fct\u00fcnl\u00fc\u011f\u00fcn\u00fc sa\u011flamak i\u00e7in mutlaka ayr\u0131 bir MAC (Mesaj Kimlik Do\u011frulama Kodu) mekanizmas\u0131 (\u00f6rne\u011fin, HMAC) ile birlikte &#8220;Encrypt-then-MAC&#8221; (\u00d6nce \u015eifrele, Sonra MAC&#8217;le) yakla\u015f\u0131m\u0131 kullan\u0131lmal\u0131d\u0131r.<\/li>\n<li><b>Asla Kullan\u0131lmamas\u0131 Gereken Mod:<\/b> <b>ECB<\/b> (Electronic Codebook) modu, yap\u0131sal zafiyetleri nedeniyle hi\u00e7bir modern uygulamada kullan\u0131lmamal\u0131d\u0131r.<\/li>\n<\/ul>\n<p>Do\u011fru bir <a href=\"https:\/\/www.ihs.com.tr\/domain\/alan-adi-domain-tescili.html\" target=\"_blank\">domain<\/a> se\u00e7imi kadar, do\u011fru \u015fifreleme modunu se\u00e7mek de dijital varl\u0131klar\u0131n\u0131z\u0131n temel g\u00fcvenli\u011fini sa\u011flar.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Kriptografik-Protokollerde-Mod-Seciminin-Kritik-Rolu\"><\/span>Kriptografik Protokollerde Mod Se\u00e7iminin Kritik Rol\u00fc<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>TLS (Transport Layer Security) gibi internetin temelini olu\u015fturan g\u00fcvenlik protokollerinde mod se\u00e7imi, &#8220;\u015fifreleme tak\u0131m\u0131&#8221; (cipher suite) ad\u0131 verilen bir yap\u0131yla belirlenir. Bir \u015fifreleme tak\u0131m\u0131; anahtar de\u011fi\u015fim algoritmas\u0131n\u0131, \u015fifreleme algoritmas\u0131n\u0131, \u00e7al\u0131\u015fma modunu ve MAC algoritmas\u0131n\u0131 tan\u0131mlar. \u00d6rne\u011fin, modern ve g\u00fcvenli bir TLS 1.3 \u015fifreleme tak\u0131m\u0131 `TLS_AES_256_GCM_SHA384` \u015feklinde belirtilir. Bu, ana \u015fifreleme i\u00e7in AES-256 algoritmas\u0131n\u0131n GCM modu ile kullan\u0131laca\u011f\u0131n\u0131 ifade eder. Sunucu ve istemci aras\u0131ndaki ilk el s\u0131k\u0131\u015fma (handshake) s\u0131ras\u0131nda, her iki taraf\u0131n da destekledi\u011fi en g\u00fcvenli \u015fifreleme tak\u0131m\u0131 \u00fczerinde anla\u015f\u0131l\u0131r. Zay\u0131f veya eski modlar\u0131 (CBC gibi) destekleyen \u015fifreleme tak\u0131mlar\u0131n\u0131 sunucu yap\u0131land\u0131rmas\u0131ndan kald\u0131rmak, sistemi &#8220;downgrade&#8221; sald\u0131r\u0131lar\u0131na kar\u015f\u0131 korumak i\u00e7in \u00f6nemli bir g\u00fcvenlik ad\u0131m\u0131d\u0131r.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Mevcut-Sistemlerde-CBCden-Modern-Modlara-Gecis-Stratejileri\"><\/span>Mevcut Sistemlerde CBC&#8217;den Modern Modlara Ge\u00e7i\u015f Stratejileri<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Mevcut (legacy) sistemlerde CBC&#8217;den AEAD modlar\u0131na ge\u00e7i\u015f yapmak, g\u00fcvenli\u011fi art\u0131rmak i\u00e7in at\u0131lmas\u0131 gereken \u00f6nemli bir ad\u0131md\u0131r. Ancak bu ge\u00e7i\u015fin dikkatli bir \u015fekilde planlanmas\u0131 gerekir:<\/p>\n<ol>\n<li><b>Analiz ve De\u011ferlendirme:<\/b> \u0130lk olarak, sistemin hangi bile\u015fenlerinin CBC modu kulland\u0131\u011f\u0131 ve bu bile\u015fenlerin hangi di\u011fer sistemlerle etkile\u015fimde oldu\u011fu tespit edilmelidir.<\/li>\n<li><b>Kademeli Ge\u00e7i\u015f:<\/b> M\u00fcmk\u00fcnse, ge\u00e7i\u015f bir anda yap\u0131lmamal\u0131d\u0131r. Sisteme hem CBC hem de GCM deste\u011fi eklenerek, \u00f6nce yeni verilerin GCM ile \u015fifrelenmesi sa\u011flanabilir. Bu s\u0131rada, eski veriler okunurken CBC deste\u011fi korunur.<\/li>\n<li><b>Veri Migrasyonu:<\/b> Depolanan eski verilerin (at-rest data) yeniden \u015fifrelenmesi gerekebilir. Bu, arka planda \u00e7al\u0131\u015fan bir s\u00fcre\u00e7le, CBC ile \u015fifrelenmi\u015f verileri okuyup GCM ile yeniden \u015fifreleyerek yap\u0131labilir.<\/li>\n<li><b>Test ve Do\u011frulama:<\/b> Ge\u00e7i\u015f tamamland\u0131ktan sonra, sistemin t\u00fcm bile\u015fenlerinin yeni mod ile sorunsuz \u00e7al\u0131\u015ft\u0131\u011f\u0131ndan emin olmak i\u00e7in kapsaml\u0131 testler yap\u0131lmal\u0131d\u0131r.<\/li>\n<li><b>Eski Modlar\u0131 Devre D\u0131\u015f\u0131 B\u0131rakma:<\/b> T\u00fcm sistem GCM&#8217;ye tamamen ge\u00e7ti\u011finde ve art\u0131k CBC&#8217;ye ihtiya\u00e7 kalmad\u0131\u011f\u0131nda, g\u00fcvenlik zafiyetlerine kap\u0131 aralamamak i\u00e7in CBC destekleyen \u015fifreleme tak\u0131mlar\u0131 ve k\u00fct\u00fcphaneler tamamen devre d\u0131\u015f\u0131 b\u0131rak\u0131lmal\u0131d\u0131r.<\/li>\n<\/ol>\n<p>Bu stratejiler, \u00f6zellikle <a href=\"https:\/\/www.ihs.com.tr\/sunucu-kiralama\/vds-sunucu.html\" target=\"_blank\">VDS<\/a> gibi sanal sunucu ortamlar\u0131nda \u00e7al\u0131\u015fan uygulamalar\u0131n g\u00fcvenli\u011fini modern standartlara ta\u015f\u0131mak i\u00e7in kritik \u00f6neme sahiptir.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Veri-Guvenligi-ve-Modern-Sifreleme-Standartlari-Icin-Neden-IHS-Telekomu-Tercih-Etmelisiniz\"><\/span>Veri G\u00fcvenli\u011fi ve Modern \u015eifreleme Standartlar\u0131 \u0130\u00e7in Neden \u0130HS Telekom&#8217;u Tercih Etmelisiniz?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Dijital d\u00fcnyada veri g\u00fcvenli\u011fi, sadece g\u00fc\u00e7l\u00fc algoritmalar ve do\u011fru \u015fifreleme modlar\u0131n\u0131 se\u00e7mekle s\u0131n\u0131rl\u0131 de\u011fildir; ayn\u0131 zamanda bu teknolojileri destekleyen, g\u00fcvenilir ve modern bir altyap\u0131ya sahip olmay\u0131 gerektirir. IHS Telekom, sundu\u011fu hizmetlerde en g\u00fcncel g\u00fcvenlik standartlar\u0131n\u0131 temel alarak m\u00fc\u015fterilerinin verilerini en \u00fcst d\u00fczeyde korumay\u0131 hedefler.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Guclu-Kriptografik-Protokolleri-Destekleyen-Altyapi\"><\/span>G\u00fc\u00e7l\u00fc Kriptografik Protokolleri Destekleyen Altyap\u0131<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u0130nternet \u00fczerinden ger\u00e7ekle\u015fen her veri al\u0131\u015fveri\u015finin g\u00fcvenli\u011fi, TLS gibi g\u00fc\u00e7l\u00fc kriptografik protokollere ba\u011fl\u0131d\u0131r. IHS Telekom, sunucu altyap\u0131s\u0131n\u0131 her zaman en g\u00fcncel ve g\u00fcvenli TLS s\u00fcr\u00fcmlerini (\u00f6rne\u011fin, TLS 1.3) ve AES-GCM gibi modern AEAD \u015fifreleme tak\u0131mlar\u0131n\u0131 destekleyecek \u015fekilde yap\u0131land\u0131r\u0131r. Bu, web siteniz ile ziyaret\u00e7ileriniz aras\u0131ndaki ileti\u015fimin sadece gizli kalmas\u0131n\u0131 de\u011fil, ayn\u0131 zamanda manip\u00fclasyona kar\u015f\u0131 da korunmas\u0131n\u0131 sa\u011flar. \u00d6zellikle <a href=\"https:\/\/www.ihs.com.tr\/web-hosting\/wordpress-hosting.html\" target=\"_blank\">WordPress hosting<\/a> hizmetlerimizde bu standartlar, sitenizin g\u00fcvenli\u011fini temelden sa\u011flamla\u015ft\u0131r\u0131r.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Veri-Gizliligi-ve-Butunlugunu-Saglayan-Guvenlik-Katmanlari\"><\/span>Veri Gizlili\u011fi ve B\u00fct\u00fcnl\u00fc\u011f\u00fcn\u00fc Sa\u011flayan G\u00fcvenlik Katmanlar\u0131<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Veri, hem aktar\u0131m s\u0131ras\u0131nda (in-transit) hem de depoland\u0131\u011f\u0131 yerde (at-rest) korunmal\u0131d\u0131r. IHS Telekom, sundu\u011fu <a href=\"https:\/\/www.ihs.com.tr\/sunucu-kiralama\/vps-server.html\" target=\"_blank\">VPS<\/a> ve di\u011fer sunucu \u00e7\u00f6z\u00fcmlerinde, verilerinizi korumak i\u00e7in \u00e7ok katmanl\u0131 bir g\u00fcvenlik yakla\u015f\u0131m\u0131 benimser. G\u00fc\u00e7l\u00fc g\u00fcvenlik duvarlar\u0131 (firewall), d\u00fczenli g\u00fcvenlik taramalar\u0131 ve modern \u015fifreleme standartlar\u0131na uygun depolama \u00e7\u00f6z\u00fcmleri ile verilerinizin hem gizlili\u011fi hem de b\u00fct\u00fcnl\u00fc\u011f\u00fc garanti alt\u0131na al\u0131n\u0131r. Bu sayede, bu makalede bahsedilen bit-flipping veya yetkisiz veri de\u011fi\u015ftirme gibi tehditlere kar\u015f\u0131 g\u00fc\u00e7l\u00fc bir savunma hatt\u0131 olu\u015fturulur.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Endustri-Standartlarina-Uygun-Guvenli-Veri-Saklama-ve-Iletim-Cozumleri\"><\/span>End\u00fcstri Standartlar\u0131na Uygun G\u00fcvenli Veri Saklama ve \u0130letim \u00c7\u00f6z\u00fcmleri<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Hassas verilerle \u00e7al\u0131\u015fan i\u015fletmeler i\u00e7in end\u00fcstri standartlar\u0131na (PCI DSS, GDPR vb.) uyumluluk kritik \u00f6neme sahiptir. IHS Telekom, bu standartlar\u0131n gerektirdi\u011fi teknik ve operasyonel g\u00fcvenlik \u00f6nlemlerini kar\u015f\u0131layan hizmetler sunar. Verilerinizin saklanmas\u0131 ve iletilmesi s\u00fcre\u00e7lerinde, en iyi kriptografik uygulamalar benimsenerek yasal ve teknolojik uyumluluk en \u00fcst d\u00fczeyde tutulur.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Guvenlik-Konularinda-Uzman-Teknik-Destek-ve-Danismanlik\"><\/span>G\u00fcvenlik Konular\u0131nda Uzman Teknik Destek ve Dan\u0131\u015fmanl\u0131k<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Do\u011fru \u015fifreleme teknolojilerini se\u00e7mek ve uygulamak karma\u015f\u0131k olabilir. IHS Telekom, sadece g\u00fcvenli bir altyap\u0131 sunmakla kalmaz, ayn\u0131 zamanda g\u00fcvenlik konular\u0131nda uzman teknik destek ekibiyle de yan\u0131n\u0131zda olur. Sunucunuzun g\u00fcvenlik yap\u0131land\u0131rmas\u0131, <a href=\"https:\/\/www.ihs.com.tr\/ssl\/rapidssl.html\" target=\"_blank\">RapidSSL<\/a> sertifikas\u0131 kurulumu veya en do\u011fru hosting \u00e7\u00f6z\u00fcm\u00fcn\u00fcn se\u00e7imi gibi konularda ihtiya\u00e7 duydu\u011funuz profesyonel dan\u0131\u015fmanl\u0131\u011f\u0131 alarak dijital varl\u0131klar\u0131n\u0131z\u0131 g\u00f6n\u00fcl rahatl\u0131\u011f\u0131yla koruyabilirsiniz.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Dijital verilerin g\u00fcvenli\u011fi, g\u00fcn\u00fcm\u00fcz teknoloji d\u00fcnyas\u0131n\u0131n en temel yap\u0131 ta\u015flar\u0131ndan biridir. Bilgiyi yetkisiz eri\u015fimden korumak i\u00e7in kulland\u0131\u011f\u0131m\u0131z en g\u00fc\u00e7l\u00fc ara\u00e7lardan biri olan&hellip;<\/p>\n","protected":false},"author":3,"featured_media":16450,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[400],"tags":[],"class_list":["post-16449","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-ssl-sertifikasi"],"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/www.ihs.com.tr\/blog\/wp-json\/wp\/v2\/posts\/16449","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ihs.com.tr\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ihs.com.tr\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ihs.com.tr\/blog\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ihs.com.tr\/blog\/wp-json\/wp\/v2\/comments?post=16449"}],"version-history":[{"count":1,"href":"https:\/\/www.ihs.com.tr\/blog\/wp-json\/wp\/v2\/posts\/16449\/revisions"}],"predecessor-version":[{"id":16451,"href":"https:\/\/www.ihs.com.tr\/blog\/wp-json\/wp\/v2\/posts\/16449\/revisions\/16451"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.ihs.com.tr\/blog\/wp-json\/wp\/v2\/media\/16450"}],"wp:attachment":[{"href":"https:\/\/www.ihs.com.tr\/blog\/wp-json\/wp\/v2\/media?parent=16449"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ihs.com.tr\/blog\/wp-json\/wp\/v2\/categories?post=16449"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ihs.com.tr\/blog\/wp-json\/wp\/v2\/tags?post=16449"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}