Wiki sécurité informatique

Crypto 100 - OMG_SO_ENCRYPTED

Le texte fournit lors du challenge nous laisse penser à un chiffrement de césar.

Après analyse sur le site dcode on s'aperçoit que le chiffrement est du rot13 (13ème position du chiffre de césar)

Le texte décodé en rot13 :

This text is here to simulate a sementic analysis.
 It means that when you get a corporate document,
 you usually have to read it and analyse it before you get the useful information. 
The flag starts with 'ndh2k16_'. 
After that, there is the hash. 


very first letter of the hash seems to be 1. 
second letter of the hash seems to be 8.
third letter of the hash seems to be 0.
fourth letter of the hash was set to 4.
fifth letter of the hash was set to 9.
sixth letter of the hash seems to be 5.
seventh letter of the hash should be 6.
eighth letter of the hash was set to 2.
ninth letter of the hash is a.
tenth letter of the hash seems to be f.
eleventh letter of the hash appears to be 5. 
twelfth letter of the hash appears to be a.
thirteenth letter of the hash was set to 1.
fourteenth letter of the hash should be c.
fifteenth letter of the hash should be b.
sixteenth letter of the hash is 0.
seventeenth letter of the hash appears to be 4. 
eighteenth letter of the hash will have the value of e.
nineteenth letter of the hash seems to be c.
twentieth letter of the hash will have the value of 1.
twenty-first letter of the hash was set to c.
twenty- second letter of the hash will have the value of f.
twenty-third letter of the hash should be c.
twenty-fourth letter of the hash will have the value of b.
twenty-fifth letter of the hash should be 5.
twenty-sixth letter of the hash will have the value of 0.
twenty-seventh letter of the hash was set to f.
twenty-eighth letter of the hash seems to be e.
twenty-ninth letter of the hash seems to be 0.
thirtieth letter of the hash was set to 9.
thirty-first letter of the hash should be 6.
thirty-second letter of the hash should be d.

J'ai remis les lettres dans l'ordre de lecture pour que cela soit plus simple à lire.

flag : ndh2k16_18049562af5a1cb04ec1cfcb50fe096d