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• Encoding

• Encryption

• Hashing

• Obfuscation

• Summary

There is often
significant confusion
around the differences between encryption, encoding, hashing, and
obfuscation.

Get the TL;DR

Let’s take a look at each one:

Encoding

Encoding transforms data into another format using a scheme
that is publicly available so that it can easily be reversed. It does
not require a key as the only thing required to decode it is the algorithm
that was used to encode it.

Examples:
ASCII,
Unicode, URL Encoding,
Base64

Encryption

The purpose of encryption is to transform data in order to keep it
secret from others, e.g. sending someone a secret letter that only they
should be able to read, or securely sending a password over the Internet.
Rather than focusing on usability, the goal is to ensure the data cannot be
consumed by anyone other than the intended recipient(s).

Encryption transforms data into another format in such a way that
only specific individual(s) can reverse the transformation. It uses a
key, which is kept secret, in conjunction with the plaintext and the
algorithm, in order to perform the encryption operation. As such, the
ciphertext, algorithm, and key are all required to return to the plaintext.

Examples:
AES,
Blowfish,
RSA

Hashing

Hashing serves the purpose of ensuring integrity, i.e. making it so
that if something is changed you can know that it’s changed. Technically,
hashing takes arbitrary input and produce a fixed-length string that has the
following attributes:

1. The same input will always produce the same output.

2. Multiple disparate inputs should not produce the same output.

3. It should not be possible to go from the output to the input.

4. Any modification of a given input should result in drastic change to the
   hash.

Hashing is used in conjunction with authentication to produce strong
evidence that a given message has not been modified. This is accomplished by
taking a given input, hashing it, and then signing the hash with the
sender’s private key.

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When the recipient opens the message, they can then validate the signature
of the hash with the sender’s public key and then hash the message
themselves and compare it to the hash that was signed by the sender. If they
match it is an unmodified message, sent by the correct person.

Examples:
SHA-3,
MD5 (Now obsolete),
etc.

Obfuscation

The purpose of obfuscation is to make something harder to understand,
usually for the purposes of making it more difficult to attack or to copy.

One common use is the the obfuscation of source code so that it’s harder to
replicate a given product if it is reverse engineered.

It’s important to note that obfuscation is not a strong control (like
properly employed encryption) but rather an obstacle. It, like encoding, can
often be reversed by using the same technique that obfuscated it. Other
times it is simply a manual process that takes time to work through.

Another key thing to realize about obfuscation is that there is a limitation
to how obscure the code can become, depending on the content being obscured.
If you are obscuring computer code, for example, the limitation is that the
result must still be consumable by the computer or else the application will
cease to function.

Examples:
JavaScript Obfuscator,
ProGuard

Summary

• Encoding is for maintaining data usability and can be
  reversed by employing the same algorithm that encoded the content, i.e.
  no key is used.

• Encryption is for maintaining data confidentiality and
  requires the use of a key (kept secret) in order to return to plaintext.

• Hashing is for validating the integrity of content by
  detecting all modification thereof via obvious changes to the hash
  output.

• Obfuscation is used to
  prevent people from understanding the meaning of something, and
  is often used with computer code to help prevent successful reverse
  engineering and/or theft of a product’s functionality.

Notes

1. One might ask when obfuscation would be used instead of encryption, and
   the answer is that obfuscation is used to make it harder for one entity
   to understand (like a human) while still being easy to consume for
   something else (like a computer). With encryption, neither a human or a
   computer could read the content without a key.