1. Overview

The terms encryption and encoding are often mistakenly used interchangeably, and hashing is sometimes misrepresented as a form of encryption. These misconceptions can lead to significant errors in implementing security measures. To address this, let’s delve into a high-level overview of these concepts and clarify their distinct purposes and differences.

Understanding the differences between encryption, encoding, and hashing is critical in data security and software development. While all three processes transform data, they serve fundamentally different purposes.

2. Key Differences Between Encryption, Encoding, and Hashing

Aspect	Encryption	Encoding	Hashing
Purpose	Protect data confidentiality by making it unreadable to unauthorized users.	Transform data to make it consumable or transferable in a different format.	Verify data integrity by producing a fixed-length hash from input data.
Reversibility	Reversible only with the correct key (decryption key).	Always reversible with a known algorithm (e.g., Base64 decoding).	Irreversible; cannot retrieve original data from the hash.
Security	Designed for secure communication, protecting data from unauthorized access.	Not secure; intended for data integrity, not confidentiality.	Designed for data integrity, password storage, and digital signatures.
Key Requirement	Requires encryption and decryption keys for the process.	Does not require keys; uses predefined algorithms for encoding and decoding.	No keys required; uses hashing algorithms to generate hashes.
Use Case	Encrypting sensitive data like passwords, financial transactions, and emails.	Encoding URLs, transforming binary data for email attachments, or data storage.	Password storage, verifying data integrity, or file comparison.
Output Format	Typically appears as scrambled or unreadable data.	Often appears as human-readable (e.g., Base64, ASCII).	Fixed-length alphanumeric string (e.g., 64-character hash for SHA-256).
Algorithms	Examples: AES, RSA, DES, Blowfish.	Examples: Base64, URL encoding, ASCII, UTF-8.	Examples: MD5, SHA-1, SHA-256, BCrypt.
Focus	Focuses on protecting data from unauthorized access.	Focuses on data compatibility and standardization.	Focuses on ensuring data integrity and authentication.

3. Encoding

Encoding can be described as a method of converting data into a different format to ensure it is compatible and easily processed by various systems. Encoding is all about information representation. For example, consider the text “This is some information”. This is in human readable form. But computers understand only binary data like the following:

01010100 01101000 01101001 01110011 00100000 01101001 01110011 00100000 01110011 01101111 01101101 01100101 00100000 01101001 01101110 01100110 01101111 01110010 01101101 01100001 01110100 01101001 01101111 01101110

So now we have two representations of the same information. You can say that the sequence of characters is encoded to sequence of bits. So, encoding is just a transformation from one data representation to another, keeping the same information. Typically, this process relies on a mapping system, like an ASCII table in our example, which links each representation in one system to its corresponding representation in another. In the realm of character encoding, beyond the familiar ASCII, there are several noteworthy alternatives:

• Unicode: Enables the representation of a wide range of characters, including complex symbols and emojis.
• Base64: Allows binary data, such as images, to be expressed as text.
• URL Encoding: Facilitates the inclusion of arbitrary data in URLs by encoding reserved or unusable characters, such as spaces or colons.

Take JSON Web Tokens (JWT) as an example. The three components of a token are encoded using Base64-URL, which combines Base64 encoding with URL encoding. Here’s an example of an encoded JWT:

eyJhbGciOiAiSFMyNTYiLCAidHlwIjogIkpXVCJ9.eyJzdWIiOiAiMTIzNDU2Nzg5MCIsICJuYW1lIjogIkpvaG4gRG9lIiwgImlhdCI6IDE1MTYyMzkwMjJ9.dummy_signature

This encoding mechanism allows the token to be easily passed in HTML and HTTP environments without fear of clashes with reserved or unrepresentable characters. Encoding ensures interoperability between systems. Encoding has no security purpose. Encoding is a reversible process.

4. Encryption

Encryption (more specifically, encoding) is the process of transforming information in a way that, ideally, only authorized parties can decode. Encryption makes your data unreadable and hard to decode for an unauthorized user. The main goal of encryption is to ensure data confidentiality, i.e., protecting data from being accessed by unauthorized parties. In a way, encryption is a form of encoding.

Encryption is designed to render data unreadable and difficult to decode by unauthorized individuals. In contrast, encoding has the opposite objective: to make data easily interpretable and compatible across systems. While encoding focuses on facilitating understanding and accessibility, encryption emphasizes confidentiality and ensures that only authorized parties can decipher the data.

The most effective methods for encrypting data rely on mathematical algorithms that can only be deciphered with a specific key or significant computational effort. These encryption algorithms are broadly categorized into two families:

• Symmetric-key algorithms: These algorithms utilize the same key for both encryption and decryption. The Advanced Encryption Standard (AES) is a widely used example of this type.
• Asymmetric-key algorithms: These algorithms employ a pair of keys — one for encryption and another for decryption. The keys are mathematically linked, making it impossible to deduce one from the other. An example of this family is the RSA algorithm.

Encryption is also a reversible process, but only for those with proper authorization. Authorized individuals possess the necessary decryption key, enabling them to convert the encrypted data back to its original, readable form.

5. Hashing

Hashing is a method used to produce a unique, fixed-length string (known as a hash) that is directly derived from the given input data. The hash is uniquely tied to the specific input, ensuring consistency and reliability.

Since a hash is derived from the unique input data, even a minor modification in the input results in a completely different hash. Therefore, by comparing the hash of a piece of data with a pre-existing hash, you can determine if the data has been modified. Essentially, hashing guarantees the integrity of the data.

Following is the hash of text “This is some information” using SHA-256:

fb0560e80a616867e6ffcb2ed3fbbc8d2cbbbe0d8e7ba24f4c51d5874a50d69a

A good hashing algorithm should possess these qualities:

• Fixed Length Output: The generated hash should always be of a uniform size.
• Deterministic Output: The same input should consistently generate the same hash.
• Unique Outputs: Different inputs should not lead to the same hash value.
• Non-Reversible: It should be impossible to deduce the original input from the produced hash.
• Sensitive to Changes: Any alteration in the input should lead to a completely different hash.

Following are few well-known hashing algorithms:

• MD5
• SHA-1
• SHA-256
• SHA-3
• Blowfish
• RIPEMD
• Tiger