Blowfish is a symmetric block cipher algorithm that was developed by Bruce Schneier in 1993. It is a fast and secure encryption algorithm that uses a variable-length key, ranging from 32 bits to 448 bits, to encrypt data. The key is used to generate subkeys that are then used to encrypt the data.

Blowfish uses a Feistel structure, which means that it divides the input data into two equal-sized blocks and then applies a series of operations to these blocks in order to encrypt them. It uses a simple but effective key expansion algorithm and a complex series of operations to perform the encryption.

One of the key features of Blowfish is that it is resistant to differential and linear cryptanalysis, which are techniques used to break encryption algorithms by analyzing the patterns in the encrypted data. This makes it a secure choice for protecting sensitive information.

Blowfish has been widely used in a variety of applications, including secure communications, password storage, and data encryption. It is also one of the encryption algorithms supported by OpenVPN. In addition, Blowfish has been widely analyzed and tested by the cryptography community, and no significant vulnerabilities have been found to date. This makes it a secure choice for protecting sensitive information.

At this point, though, I’m amazed it’s still being used. If people ask, I recommend Twofish instead.

-Bruce Schneier, 2007[1]

Is AES better than blowfish?

In general, AES is considered to be more secure than Blowfish due to its larger key size and more complex design. AES uses a 128-bit, 192-bit, or 256-bit key to encrypt data, while Blowfish uses a key ranging from 32 bits to 448 bits. AES is also faster and more efficient than Blowfish, making it a more practical choice for many applications.

However, Blowfish is still a secure encryption algorithm and is widely used in a variety of applications. It has the advantage of being relatively simple to implement and has a relatively fast encryption and decryption speed.

However, it is important to note that no cryptographic algorithm is completely secure, and it is always possible that new vulnerabilities may be discovered in the future. It is important to carefully consider the security requirements of your application and to use cryptographic algorithms that are appropriate for the level of security you need.