Obfuscation by encryption is done by crypters. Packers compress the sections while crypters encrypt the sections. Similar to packers, crypters have a stub used to decrypt encrypted code and data. As a result, crypters may instead increase the file size of the host. 

The following image shows a file crypted by Yoda Crypter:  

The section offsets and sizes have been retained but encrypted. The stub was placed in a newly added section named yC. If we compare how the original opcode bytes look with the encrypted bytes, we'll notice that opcode bytes have zero bytes spread out. This is a trait that can be used to identify encrypted bytes. ...

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