blowfish(3) OpenSSL blowfish(3) NNAAMMEE blowfish, BF_set_key, BF_encrypt, BF_decrypt, BF_ecb_encrypt, BF_cbc_encrypt, BF_cfb64_encrypt, BF_ofb64_encrypt, BF_options - Blow- fish encryption SSYYNNOOPPSSIISS #include 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); DDEESSCCRRIIPPTTIIOONN This library implements the Blowfish cipher, which was invented and described by Counterpane (see http://www.counterpane.com/blowfish.html ). Blowfish is a block cipher that operates on 64 bit (8 byte) blocks of data. It 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 _d_e_s___m_o_d_e_s(7)). Blowfish is currently one of the faster block ciphers. It is quite a bit faster than DES, and much faster than IDEA or RC2. Blowfish consists of a key setup phase and the actual encryption or decryption phase. _B_F___s_e_t___k_e_y_(_) sets up the BBFF__KKEEYY kkeeyy using the lleenn bytes long key at ddaattaa. _B_F___e_c_b___e_n_c_r_y_p_t_(_) is the basic Blowfish encryption and decryption func- tion. It encrypts or decrypts the first 64 bits of iinn using the key kkeeyy, putting the result in oouutt. eenncc decides if encryption (BBFF__EENNCCRRYYPPTT) or decryption (BBFF__DDEECCRRYYPPTT) shall be performed. The vector pointed at by iinn and oouutt must be 64 bits in length, no less. If they are larger, everything after the first 64 bits is ignored. The mode functions _B_F___c_b_c___e_n_c_r_y_p_t_(_), _B_F___c_f_b_6_4___e_n_c_r_y_p_t_(_) and _B_F___o_f_b_6_4___e_n_c_r_y_p_t_(_) all operate on variable length data. They all take an initialization vector iivveecc which needs to be passed along into the next call of the same function for the same message. iivveecc may be ini- tialized with anything, but the recipient needs to know what it was initialized with, or it won't be able to decrypt. Some programs and protocols simplify this, like SSH, where iivveecc is simply initialized to zero. _B_F___c_b_c___e_n_c_r_y_p_t_(_) operates on data that is a multiple of 8 bytes long, while _B_F___c_f_b_6_4___e_n_c_r_y_p_t_(_) and _B_F___o_f_b_6_4___e_n_c_r_y_p_t_(_) are used to encrypt an 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 nnuumm, which is a pointer to an integer where the current offset in iivveecc is stored between calls. This integer must be initialized to zero when iivveecc is initialized. _B_F___c_b_c___e_n_c_r_y_p_t_(_) is the Cipher Block Chaining function for Blowfish. It encrypts or decrypts the 64 bits chunks of iinn using the key sscchheedd-- uullee, putting the result in oouutt. eenncc decides if encryption (BF_ENCRYPT) or decryption (BF_DECRYPT) shall be performed. iivveecc must point at an 8 byte long initialization vector. _B_F___c_f_b_6_4___e_n_c_r_y_p_t_(_) is the CFB mode for Blowfish with 64 bit feedback. It encrypts or decrypts the bytes in iinn using the key sscchheedduullee, putting the result in oouutt. eenncc decides if encryption (BBFF__EENNCCRRYYPPTT) or decryp- tion (BBFF__DDEECCRRYYPPTT) shall be performed. iivveecc must point at an 8 byte long initialization vector. nnuumm must point at an integer which must be initially zero. _B_F___o_f_b_6_4___e_n_c_r_y_p_t_(_) is the OFB mode for Blowfish with 64 bit feedback. It uses the same parameters as _B_F___c_f_b_6_4___e_n_c_r_y_p_t_(_), which must be ini- tialized the same way. _B_F___e_n_c_r_y_p_t_(_) and _B_F___d_e_c_r_y_p_t_(_) are the lowest level functions for Blow- fish encryption. They encrypt/decrypt the first 64 bits of the vector pointed by ddaattaa, using the key kkeeyy. These functions should not be used unless you implement 'modes' of Blowfish. The alternative is to use _B_F___e_c_b___e_n_c_r_y_p_t_(_). 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. RREETTUURRNN VVAALLUUEESS None of the functions presented here return any value. NNOOTTEE Applications should use the higher level functions _E_V_P___E_n_c_r_y_p_t_I_n_i_t(3) etc. instead of calling the blowfish functions directly. SSEEEE AALLSSOO _d_e_s___m_o_d_e_s(7) HHIISSTTOORRYY The Blowfish functions are available in all versions of SSLeay and OpenSSL. 1.0.1u 2016-09-22 blowfish(3)