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What is Blowfish encryption, and how does it work?

What is Blowfish encryption, and how does it work?


Blowfish encryption is a symmetric-key block cipher usually used in file encryption, VPNs, and
password hashing. It was introduced in 1993 and became a go-to encryption method because of its
efficient encryption and decryption processes. However, Blowfish is slowly being replaced by
newer, more secure algorithms such as AES. This article will look at the Blowfish encryption
processes, main features, and safety.

Contents What is Blowfish encryption?

Main features of Blowfish

How does Blowfish encryption work?

Advantages and disadvantages of Blowfish encryption

Blowfish encryption examples

Is Blowfish encryption safe to use?

What is Blowfish encryption?


Blowfish is a symmetric encryption method, a 64-bit block cipher that uses a key up to 448 bits
long. It was created by Bruce Schneier in 1993 as an alternative to the aging Data Encryption
Standard (DES) and the International Data Encryption Algorithm (IDEA) encryption algorithms.
Although Blowfish is known for its speed and simplicity, its usage has declined recently. It is
being replaced by newer and more secure encryption methods such as the Advanced Encryption
Standard (AES).

Main features of Blowfish

Here are some of the main features of the Blowfish algorithm: Block cipher. A block cipher in Blowfish encrypts data in 64-bit blocks. Symmetric key algorithm. The Blowfish algorithm uses the same symmetric
encryption key to encrypt and decrypt data.
Variable length key. Blowfish offers different key lengths, from 32 bits to
448 bits. The longer the key, the safer the data. However, longer keys usually require more
processing time and resources.
Feistel cipher. The Feistel cipher structure splits the plaintext into two
halves and scrambles each half separately using a chain of mathematical operations.

How does Blowfish encryption work?


Blowfish is a symmetric key block cipher that uses the same key to encrypt and decrypt data.
Compared to other{‘ ‘} cryptography methods,
Blowfish is considered pretty simple, which contributes to its speed and efficiency. However, it
has some potential vulnerabilities that cannot be overlooked when seeking maximum data security.

Here’s a broader explanation of the Blowfish encryption process: Key expansion. Blowfish begins with a secret key, which can be from 32 bits
to 448 bits long. The encryption key is then prepared and stretched out using the P-array and
S-boxes precomputation to generate a series of subkeys.
Subkeys generation. The stretched-out key is divided into smaller parts: the
64-bit blocks are divided into two 32-bit chunks. These pieces are mixed with some predefined
values to create a new set of subkeys.
Data encryption. Here comes the main part. Those two 32-bit halves pass
through 16 rounds of encryption. Each round involves a complex sequence of substitutions and
transpositions (XOR operations, additions, and lookups in the S-boxes).
Post-processing. After the 16 rounds, the scrambled pieces of 32-bits are
rejoined to form 64-bit ciphertext blocks.
Decryption. Decryption in Blowfish uses the same process as encryption but in
reverse. So it all goes backward until the ciphertext is reversed into plaintext.

This Blowfish encryption process secures your data using your private key. The best thing about
Blowfish is that it’s quite challenging to recover the data without the original key once it is
encrypted. However, such technology, created in the 90s, is now slightly outdated and is being
replaced by more sophisticated and safer encryption methods, such as AES or Blowfish’s
successor, Twofish.

Advantages and disadvantages of Blowfish encryption


Besides being fast and efficient, the Blowfish encryption algorithm may not be as safe for your
data encryption process as expected. So look at the main advantages and disadvantages of
Blowfish yourself and consider the specific needs for your application.


The Blowfish encryption algorithm, providing speed, flexibility, and simplicity, is a viable
option for specific applications. However, the small block size, slow encryption key setup, and
lack of built-in authentication make it less suitable for many modern applications. While
Blowfish was groundbreaking in the 90s, it is essential to consider its limitations when
considering an encryption algorithm. Modern algorithms like AES provide more robust encryption
solutions than Blowfish.

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Blowfish encryption examples


Wondering where you might bump into Blowfish? This speedy cipher is used in zipping up your
data, safeguarding your passwords, and email messages. Blowfish has done a little bit of
everything, so let’s look at some of this encryption method’s most popular use cases.
Network protocols. The Blowfish algorithm has been used in network{‘ ‘} protocols like Secure Shell (SSH) and
IPSec to secure internet communications.
Password hashing. Some{‘ ‘} password managers use the{‘ ‘} bcrypt password hashing function
based on Blowfish.
File encryption. Certain file encryption software provides the option to use
Blowfish for encryption to prevent unauthorized access.
Disk encryption. Some disk encryption software uses Blowfish to safeguard
your sensitive data from digital pirates and snoops.
Embedded systems. Due to its simplicity and speed, Blowfish has been used in
some embedded systems, such as devices with limited processing power.
Email encryption. Blowfish has been used in some email encryption software to
keep your messages under wraps.

For quite some time, Blowfish has been a digital hero. However, modern encryption methods are
slowly pushing it out of the market. Although Blowfish does the job in data encryption, today’s
cyberspace is rife with threats that require modern and advanced solutions.

Is Blowfish encryption safe to use?


Blowfish has been a trusty lock for your sensitive data for years. It’s speedy, efficient, and
offers variable length encryption, which helps protect your digital assets from brute force
attacks. But it’s not all sunshine and rainbows. The 64-bit block size can be an obstacle when
dealing with heaps of data. So leave these resource-intensive encryption jobs for more modern
encryption solutions like AES, offering a block size of 128, 192, and 256 bits.


The Blowfish algorithm can still be the way to go for some tasks. But you might want to adopt
AES when it comes to large chunks of data or top-tier security. As always, assessing your needs
is the key to picking the right encryption algorithm.

The post What is Blowfish encryption, and how does it work? first appeared on NordVPN.

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