NAME
RC2_set_key,
RC2_encrypt, RC2_decrypt,
RC2_cbc_encrypt,
RC2_ecb_encrypt,
RC2_cfb64_encrypt,
RC2_ofb64_encrypt —
low-level functions for Rivest Cipher
2
SYNOPSIS
#include
<openssl/rc2.h>
void
RC2_set_key(RC2_KEY
*expanded_key, int len, const
unsigned char *user_key, int
effective_bits);
void
RC2_encrypt(unsigned long *data,
RC2_KEY *expanded_key);
void
RC2_decrypt(unsigned long *data,
RC2_KEY *expanded_key);
void
RC2_cbc_encrypt(const unsigned char
*in, unsigned char *out, long
length, RC2_KEY *expanded_key,
unsigned char *iv, int
encrypt);
void
RC2_ecb_encrypt(const unsigned char
*in, unsigned char *out, RC2_KEY
*expanded_key, int encrypt);
void
RC2_cfb64_encrypt(const unsigned char
*in, unsigned char *out, long
length, RC2_KEY *expanded_key,
unsigned char *iv, int *num,
int encrypt);
void
RC2_ofb64_encrypt(const unsigned char
*in, unsigned char *out, long
length, RC2_KEY *expanded_key,
unsigned char *iv, int
*num);
DESCRIPTION
RC2 is a block cipher operating on blocks of
RC2_BLOCK = 8 bytes,
equivalent to 64 bits, using a variable key length with an additional
parameter called “effective key bits” or “effective key
length”. The maximum effective key kength is 1024 bits.
If using RC2 cannot be avoided, it is recommended that application programs use the EVP_rc2_cbc(3) family of functions instead of the functions documented in the present manual page, to ease later migration to less outdated encryption algorithms.
RC2_set_key()
expands the first len bytes of
user_key into the RC2_KEY
structure *expanded_key. The storage for the expanded
key has to be provided by the calling code. If the len
argument exceeds 128, only the first 128 bytes are used.
Optionally, if the effective_bits argument is positive and less than 1024, the effective key length of *expanded_key is reduced to effective_bits. Reducing the effective key length is not cryptographically useful. This option was originally designed to conform to US export regulations valid at the time, which were designed to allow the US government to spy on foreign encrypted communications. Unless interoperability requires otherwise, setting effective_bits to 1024 is recommended.
RC2_encrypt()
and
RC2_decrypt()
interpret data as an array of two 32 bit integers and
encrypt or decrypt that single block in place, respectively, using the
expanded_key.
The remaining functions encode or decode
length bytes starting at in to
length bytes starting at out in
various modes of operation using the expanded_key.
Both arrays need to be long enough to hold length
bytes rounded up to the next multiple of 8. The iv
argument points to an array of 8 bytes used as the initialization vector. If
the encrypt argument is
RC2_ENCRYPT or another non-zero value, encryption is
performed; if it is RC2_DECRYPT =
0, decryption is performed.
RC2_cbc_encrypt()
operates in cipher block chaining mode.
RC2_ecb_encrypt()
encodes or decodes eight bytes at in to eight bytes at
out in electronic codebook mode.
RC2_cfb64_encrypt()
and
RC2_ofb64_encrypt()
operate in cipher feedback mode and output feedback mode, respectively, with
64 bit blocks. The number of bytes used from the last 8 byte block is kept
track of in *num.
SEE ALSO
HISTORY
RC2_set_key(),
RC2_encrypt(),
RC2_cbc_encrypt(),
RC2_ecb_encrypt(),
RC2_cfb64_encrypt(), and
RC2_ofb64_encrypt() first appeared in SSLeay 0.5.2.
RC2_decrypt() first appeared in SSLeay 0.9.0. All
these functions have been available since OpenBSD
2.4.