Update crypto.md

This commit is contained in:
vin01 2017-10-14 00:52:24 +05:30 committed by GitHub
parent 4afc061af6
commit 5d838b2160

View file

@ -47,3 +47,23 @@
```
0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345
```
**Length extension attack**
In cryptography and computer security, a length extension attack is a type of attack where an attacker can use `Hash(message1)` and the length of message1 to calculate `Hash(message1 ∥ message2)` for an attacker-controlled message2.
```
http://example.com/download?file=report.pdf&mac=563162c9c71a17367d44c165b84b85ab59d036f9
```
```
http://example.com/download?file=report.pdf%80%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00
%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00
%00%00%A8/../../../../../../../etc/passwd&mac=ee40aa8ec0cfafb7e2ec4de20943b673968857a5
```
https://www.whitehatsec.com/blog/hash-length-extension-attacks/
https://blog.skullsecurity.org/2012/everything-you-need-to-know-about-hash-length-extension-attacks