update readme

Author: Allenem

README.md

@@ -2,13 +2,7 @@
 
 This is just a repository about 《Introduction of Information Security》 experiments
 
-## DES
-
-[DES](./DES)
-
->The Data Encryption Standard (DES /ˌdiːˌiːˈɛs, dɛz/) is a symmetric-key algorithm for the encryption of electronic data. Although its short key length of 56 bits, criticized from the beginning, makes it too insecure for most current applications, it was highly influential in the advancement of modern cryptography.
-
-From Wikipedia, the free encyclopedia (https://en.wikipedia.org/wiki/Data_Encryption_Standard)
+RSA branch
 
 ## RSA