BF_ENCRYPT(3ossl)

📦
version 15.1 · 2 versions
, in freebsd 15.1

💅 BF_ENCRYPT — the Blowfish page, but make it make sense 🐡

okay so bestie, welcome to the 3ossl corner of the OpenSSL man pages ✨ this one's all about Blowfish, and yes, she's a little vintage, and yes, we're gonna talk about it.

🌸 NAME 🌸

BF_set_key, BF_encrypt, BF_decrypt, BF_ecb_encrypt, BF_cbc_encrypt, BF_cfb64_encrypt, BF_ofb64_encrypt, BF_options — literally all of them are Blowfish encryption 🐡💖

✨ SYNOPSIS ✨

#include <openssl/blowfish.h>
🚨 heads up bestie, this is the important part: the following functions have been deprecated since OpenSSL 3.0, and you can hide them entirely by defining OPENSSL_API_COMPAT with a suitable version value — see openssl_user_macros(7) for the deets 👀
 void BF_set_key(BF_KEY *key, int len, const unsigned char *data);

 void BF_ecb_encrypt(const unsigned char *in, unsigned char *out,
                     BF_KEY *key, int enc);
 void BF_cbc_encrypt(const unsigned char *in, unsigned char *out,
                     long length, BF_KEY *schedule,
                     unsigned char *ivec, int enc);
 void BF_cfb64_encrypt(const unsigned char *in, unsigned char *out,
                       long length, BF_KEY *schedule,
                       unsigned char *ivec, int *num, int enc);
 void BF_ofb64_encrypt(const unsigned char *in, unsigned char *out,
                       long length, BF_KEY *schedule,
                       unsigned char *ivec, int *num);
 const char *BF_options(void);

 void BF_encrypt(BF_LONG *data, const BF_KEY *key);
 void BF_decrypt(BF_LONG *data, const BF_KEY *key);

🦋 DESCRIPTION 🦋

so. first thing first. all of the functions described on this page are deprecated. like, every single one. no cap 😭 applications should instead use EVP_EncryptInit_ex(3), EVP_EncryptUpdate(3) and EVP_EncryptFinal_ex(3) — or the equivalently named decrypt functions, iykyk.

This library implements the Blowfish cipher, which was invented and described by Counterpane (see <http://www.counterpane.com/blowfish.html> — yes the link is in the original, go look, it's giving vintage web 🎀).

Blowfish is a block cipher that operates on 64 bit (8 byte) blocks of data. She uses a variable size key, but typically, 128 bit (16 byte) keys are considered good for strong encryption 💪 Blowfish can be used in the same modes as DES (see des_modes(7)). Blowfish is currently one of the faster block ciphers — quite a bit faster than DES, and much faster than IDEA or RC2. she ate, honestly ⚡

Blowfish consists of a key setup phase and the actual encryption or decryption phase. two-phase queen 👑

BF_set_key() sets up the BF_KEY key using the len bytes long key at data.

BF_ecb_encrypt() is the basic Blowfish encryption and decryption function. It encrypts or decrypts the first 64 bits of in using the key key, putting the result in out. enc decides if encryption (BF_ENCRYPT) or decryption (BF_DECRYPT) shall be performed. The vector pointed at by in and out must be 64 bits in length, no less. If they are larger, everything after the first 64 bits is ignored 🙈 (rude, but okay).

The mode functions BF_cbc_encrypt(), BF_cfb64_encrypt() and BF_ofb64_encrypt() all operate on variable length data. They all take an initialization vector ivec which needs to be passed along into the next call of the same function for the same message. ivec may be initialized with anything, but the recipient needs to know what it was initialized with, or it won't be able to decrypt — communication is key, bestie 🫶 Some programs and protocols simplify this, like SSH, where ivec is simply initialized to zero. BF_cbc_encrypt() operates on data that is a multiple of 8 bytes long, while BF_cfb64_encrypt() and BF_ofb64_encrypt() are used to encrypt a variable number of bytes (the amount does not have to be an exact multiple of 8). The purpose of the latter two is to simulate stream ciphers, and therefore, they need the parameter num, which is a pointer to an integer where the current offset in ivec is stored between calls. This integer must be initialized to zero when ivec is initialized. no skipping that step ⚠️

BF_cbc_encrypt() is the Cipher Block Chaining function for Blowfish. It encrypts or decrypts the 64 bits chunks of in using the key schedule, putting the result in out. enc decides if encryption (BF_ENCRYPT) or decryption (BF_DECRYPT) shall be performed. ivec must point at an 8 byte long initialization vector.

BF_cfb64_encrypt() is the CFB mode for Blowfish with 64 bit feedback. It encrypts or decrypts the bytes in in using the key schedule, putting the result in out. enc decides if encryption (BF_ENCRYPT) or decryption (BF_DECRYPT) shall be performed. ivec must point at an 8 byte long initialization vector. num must point at an integer which must be initially zero. (yes, again. zero. always zero. 🎯)

BF_ofb64_encrypt() is the OFB mode for Blowfish with 64 bit feedback. It uses the same parameters as BF_cfb64_encrypt(), which must be initialized the same way.

BF_encrypt() and BF_decrypt() are the lowest level functions for Blowfish encryption. They encrypt/decrypt the first 64 bits of the vector pointed by data, using the key key. These functions should not be used unless you implement 'modes' of Blowfish. The alternative is to use BF_ecb_encrypt(). If you still want to use these functions, you should be aware that they take each 32-bit chunk in host-byte order, which is little-endian on little-endian platforms and big-endian on big-endian ones 😵‍💫 so like… mind the endianness, okay?

🔥 RETURN VALUES 🔥

literally none of the functions presented here return any value. void queens. they do the thing and they leave 💅

🌈 NOTE 🌈

Applications should use the higher level functions EVP_EncryptInit(3) etc. instead of calling these functions directly. (yes, we said it in DESCRIPTION too. we're saying it again. that's how much we mean it 💀)

🎀 SEE ALSO 🎀

🧚 HISTORY 🧚

All of these functions were deprecated in OpenSSL 3.0. that's the whole tea ☕

Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.

and that's the whole page, bestie 🫶 mwah 💋 — this was OpenSSL 3.5.6, dated 2026-04-07, signing off as BF_ENCRYPT(3ossl) 🐡✨ don't call these directly, use EVP, and stay endian-aware 💖

📦 where this page comes from