=== Buoc 1: meo dau cach (doc duoc phan lon) ===
#e mu't never ever re!se a &o<ce since doi g  hat leaks the whole key tre m
 he p5ssword for the 'tagin/ !erver sits i si0e a locked vault that i  of'l
$leas1 come meet me a  the 'l6 stone bridg+ t;night when the clock st!ike2 
7rypt;graphy is the s udy o. !ecure commun'ca ion in the presence of 2dve3s
5lway' authenticate t<e cip e text or an a:ta7ker is completely free 'o m.d
 he q!ick brown fox j!mps o>e  the lazy do) a:d then it runs along a "uie5 
 he s olen key you wa:ted i; 4lag{n0nce_re;seis_tw0_time_pad} keep i' se"r
'end  he reinforcemen s ove: &o the easter  g5te well before the morn:ng 2u
5 str1am cipher is re5lly j=s& a fancy key=tr1am that you xor with th6 pl i
?eep  he plaintext ra her s o t and the ke7 m5terial truly hard for a=yon$ 
0o no  ever trust a c;mmuni+a&ion channel :ha  you are unable to veri5y e/d
 he w1ekly staff meet=ng ha; <ow been move* d;wn to the second baseme=t o' 
=== Buoc 2: known-plaintext tren cau da nhan ra -> full keystream ===
we must never ever reuse a nonce since doing that leaks the whole keystream
the password for the staging server sits inside a locked vault that is offl
please come meet me at the old stone bridge tonight when the clock strikes 
cryptography is the study of secure communication in the presence of advers
always authenticate the ciphertext or an attacker is completely free to mod
the quick brown fox jumps over the lazy dog and then it runs along a quiet 
the stolen key you wanted is flag{n0nce_reuse_is_tw0_time_pad} keep it secr
send the reinforcements over to the eastern gate well before the morning su
a stream cipher is really just a fancy keystream that you xor with the plai
keep the plaintext rather short and the key material truly hard for anyone 
do not ever trust a communication channel that you are unable to verify end
the weekly staff meeting has now been moved down to the second basement of 
FLAG: flag{n0nce_reuse_is_tw0_time_pad}
