hacktricks/cryptography/hash-length-extension-attack.md

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# Muhtasari wa shambulio

Fikiria server ambayo ina **kutilia sahihi** baadhi ya **data** kwa **kuongeza** **siri** kwa baadhi ya data dhahiri inayojulikana kisha kuhakiki data hiyo. Ikiwa unajua:

* **Urefu wa siri** (hii inaweza pia kufanywa kwa nguvu kutoka kwa safu ya urefu uliopewa)
* **Data dhahiri**
* **Algoritimu (na ni dhaifu kwa shambulio hili)**
* **Kujaza inajulikana**
* Kawaida moja ya msingi hutumiwa, hivyo ikiwa mahitaji mengine 3 yanakidhiwa, hii pia inafaa
* Kujaza hubadilika kulingana na urefu wa siri+data, ndio maana urefu wa siri unahitajika

Basi, ni rahisi kwa **mshambuliaji** kuongeza **data** na **kuzalisha** sahihi **ya awali + data iliyongezwa**.

## Vipi?

Kimsingi, algorithm dhaifu huzalisha hashes kwa kwanza **kutia hash kibodi cha data**, na kisha, **kutoka** kwa **hash iliyoundwa awali** (hali), wan **ongeza kibodi inayofuata ya data** na **kuitia hash**.

Kisha, fikiria kwamba siri ni "siri" na data ni "data", MD5 ya "secretdata" ni 6036708eba0d11f6ef52ad44e8b74d5b.\
Ikiwa mshambuliaji anataka kuongeza herufi "ongeza" anaweza:

* Kuzalisha MD5 ya 64 "A"s
* Badilisha hali ya hash iliyoundwa awali kuwa 6036708eba0d11f6ef52ad44e8b74d5b
* Ongeza herufi "ongeza"
* Maliza hash na hash inayotokana itakuwa **sahihi kwa "siri" + "data" + "kujaza" + "ongeza"**

## **Zana**

{% embed url="https://github.com/iagox86/hash_extender" %}

## Marejeo

Unaweza kupata shambulio hili limeelezewa vizuri katika [https://blog.skullsecurity.org/2012/everything-you-need-to-know-about-hash-length-extension-attacks](https://blog.skullsecurity.org/2012/everything-you-need-to-know-about-hash-length-extension-attacks)


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