#Defcamp CTF Qualification 2015##No Crypto (Crypto 200)
The folowing plaintext has been encrypted using an unknown key, with AES-128 CBC:
 - Original: Pass: sup3r31337. Don't loose it! - Encrypted: 4f3a0e1791e8c8e5fefe93f50df4d8061fee884bcc5ea90503b6ac1422bda2b2b7e6a975bfc555f44f7dbcc30aa1fd5e - IV: 19a9d10c3b155b55982a54439cb05dce
How would you modify it so that it now decrypts to: "Pass: notAs3cre7. Don't loose it!" 
This challenge does not have a specific flag format.
####풀이 방법 * 메시지를 바꾸고 싶다는 문제  - Original 메시지와 바꾸려는 메시지의 차이가 첫 블록만 다름  - IV + plaintext를 처음 주어진 문제와 같게 맞추면 암호문이 같아짐
 * IV xor Original = IV' xor NewMsg * IV' = IV xor Original xor NewMsg