"enc -bf-ofb" Command Summary

A quick summary is provided to list major features of the OpenSSL 'enc -bf-ofb' command. Blowfish algorithm in OFB operation mode with a random salt and PKCS#5 padding, or Blowfish/OFB/Salted/PKCS5Padding, is the recommended way to use Blowfish in OFB mode.

As a summary, we should remember the following about the OpenSSL "enc -bf-ofb" command:

OpenSSL "enc -bf-ofb" command allows us to run Blowfish algorithm in OFB (Output FeedBack) operation mode.

OFB (Output FeedBack) operation mode does not encrypt the plaintext block directly. It encrypts the IV block recursively. The encryption output at each iteration is XORed with the plaintext block to give the ciphertext.

OpenSSL allows us to run cipher operations in 3 ways: Literal Key, Salted Key and Random Salt.

"Literal Key" means the secret key and the IV are specified literally using "-K" and "-iv" options.

"Salted Key" means the secret key and the IV are derived from a passphrase and a salt given in "-pass" and "-S" options.

"Random Key" means the secret key and the IV are derived from a passphrase and a random salt using "-pass" and "-salt" options.

OpenSSL allows us to pad plaintext with the standard PKCS#5 padding algorithm, which uses an integer byte as the padding byte with value equal to the number of bytes to be padded.

With all options mentioned above, we have many choices to run Blowfish OFB mode encryption. But the recommended way is to:

Note that some of these points are not discussed in this chapter directly. But they are covered in the OpenSSL "enc -bf-ecb" command chapter.

Last update: 2015.

Table of Contents

 About This Book

 Blowfish Cipher Algorithm

 Perl Crypt::Blowfish Module

 Perl Crypt::ECB Perl Module

 Perl Crypt::CBC Module

 Perl Crypt::CFB Perl Module

 OpenSSL "enc -bf-ecb" for Blowfish/ECB Encryption

 OpenSSL "enc -bf-cbc" for Blowfish/CBC Encryption

 OpenSSL "enc -bf-cfb" for Blowfish/CFB Encryption

OpenSSL "enc -bf-ofb" for Blowfish/OFB Encryption

 "bf-ofb" Cipher with Literal Key

 "bf-ofb" Cipher on Multiple Blocks

 "bf-ofb" Encryption Verification

 "bf-ofb" 2-Block Test Vectors

 "bf-ofb" Cipher with Salted Key

 "bf-ofb" Cipher with Random Salt

"enc -bf-ofb" Command Summary

 References

 PDF Printing Version