Why is AES encrypted cipher of the same string with the same key always different?

Question

I have a file called plain.txt. Inside the file I have:

Hello Hello Hello Hello

I am using this command to encrypt it:

openssl          


        

Answer 1

The reason you are getting different encrypted string is " enc -aes-128-cbc". CBC stands for Cipher Block Chaining. So, for 2nd block, the encrypted output of first block acts ac IV, so each time you get different string. for more details google "AES in CBC mode"