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I have to use an encryption algorithm using Base64 but when I researched online I find forums state it is an encoding algorithm. This has me confused. :(

Is Base64 an encryption or encoding algorithm? How do we differentiate between the two except for the fact that one is publicly decipherable while the other needs a key for that?

Ahmed Faisal
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It's an encoding algorithm (hence "Base64 encoding") to allow people to move data in an ASCII friendly environment (i.e. no control characters or anything non-printable). It should give you good portability with XML and JSON etc.

The encoding is entirely well known, the algorithm is simple and as it has not "mutability" of the algorithm or concept of keys etc. it is not considered as "encryption".

In summary, anybody can Base64 decode your content, so it's not encryption. At least not useful as encryption. It may keep a four year old stumped, but that's it.

Jeff Watkins
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An encoding algorithm merely presents data in an alternative format. It does not in any way attempt to hide data, it merely expresses the same data in an alternative syntax. Base64 is such an encoding algorithm. It merely encodes arbitrary data using only ASCII characters, which is useful in many situations in which non-ASCII characters may not be handled correctly. You can encode and decode Base64 back and forth all day long; there's no secret, no protection, no encryption.

deceze
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  • If one encodes a byte array on machine A and decodes the string on machine B will the byte array still be identical? – John Mc Jan 22 '20 at 22:24
  • If the algorithm defines a stable procedure and both machines follow that procedure correctly, yes. For base 64 that’s generally a yes. – deceze Jan 23 '20 at 05:42
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The difference between encoding and encrypting is in whether you need to know a secret in order to get back the original form. base64 is an encoding because all you need to know is the algorithm to encode/decode.

When something is encrypted, there's a secret key that's used, and you need to know the key in order to decrypt it. There's two general types of encryption:

  • symmetric encryption = the same key is used to encrypt and decrypt. The correspondents using this encryption both need to know this key.
  • asymmetric encryption = different keys are used to encrypt and decrypt. This is also called public key encryption because you can make one of the keys well known (public), while keeping the other one secret (private). This allows anyone to encrypt a message that using the public key, while only the person who knows the private key can decrypt it, or vice versa.
Barmar
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  • Can you clarify why *asymmetric encryption* is relevant to the discussion? If anything, base64 can be regarded as a symmetric cipher. – Artjom B. Mar 03 '15 at 16:38
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One can certainly see Base64 as a substitution cipher with a pre-set/fixed key which also blows up the ciphertext by roughly 4/3, but this is not a very useful thought process. The main property of it is that it transforms some data into another format without some additional information. So it is an encoding algorithm.

Note that there are different variants of Base64 with different alphabets such as the one that is URL-safe (table 2 of the RFC4648). If you can set the alphabet with positions, then it will be an encryption algorithm, but it shouldn't be called Base64 anymore.

Artjom B.
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