State v. Levie
The main purpose of encryption is to change any data to a humanly unreadable form. Nowadays, encryption is seen as one of the key solutions to prevent the unauthorized disclosure of information. 
Companies and governmental entities have been spending time and money implementing ways to fight cybercrime and increase awareness between internet users and general public with the purpose to reduce the occurrence of crimes such as Identity theft. 
Mainly, one can say that encryption is about privacy. The right to a "safety zone" and privacy exists in the First and Fourth Amendment rights in the USA where a remarkable and recent privacy-based law has been approved, the Gramm-Leach-Bliley Act. In Europe the Lisbon Treaty describes the protection of fundamental data as fundamental human right. 
While achieving privacy through the use of encryption seems to provide everyone with answers to decrease the disclosure of personal information, it benefits the possibility to conceal from authorities acts of terrorism, child pornography and others.
The use of encryption tools is becoming more and more disseminated; states are starting to make a crime "to use encryption". States like Illinois in USA are creating specific laws to handle this matter : "A person shall not knowingly use or attempt to use encryption, directly or indirectly, to:
Block cipher
A block cipher consists of two paired algorithms, one for encryption, "E", and the other for decryption, "D". Both algorithms accept two inputs: an input block of size "n" bits and a key of size "k" bits; and both yield an "n"-bit output block. The decryption algorithm "D" is defined to be the inverse function of encryption, i.e., "D" = "E". More formally, a block cipher is specified by an encryption function
which takes as input a key "K" of bit length "k", called the "key size", and a bit string "P" of length "n", called the "block size", and returns a string "C" of "n" bits. "P" is called the plaintext, and "C" is termed the ciphertext. For each "K", the function "E"("P") is required to be an invertible mapping on {0,1}. The inverse for "E" is defined as a function
taking a key "K" and a ciphertext "C" to return a plaintext value "P", such that