DES_ofb_encrypt (3)
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NAME
DES_random_key, DES_set_key, DES_key_sched, DES_set_key_checked, DES_set_key_unchecked, DES_set_odd_parity, DES_is_weak_key, DES_ecb_encrypt, DES_ecb2_encrypt, DES_ecb3_encrypt, DES_ncbc_encrypt, DES_cfb_encrypt, DES_ofb_encrypt, DES_pcbc_encrypt, DES_cfb64_encrypt, DES_ofb64_encrypt, DES_xcbc_encrypt, DES_ede2_cbc_encrypt, DES_ede2_cfb64_encrypt, DES_ede2_ofb64_encrypt, DES_ede3_cbc_encrypt, DES_ede3_cbcm_encrypt, DES_ede3_cfb64_encrypt, DES_ede3_ofb64_encrypt, DES_cbc_cksum, DES_quad_cksum, DES_string_to_key, DES_string_to_2keys, DES_fcrypt, DES_crypt, DES_enc_read, DES_enc_write - DES encryptionSYNOPSIS
#include <openssl/des.h> void DES_random_key(DES_cblock *ret); int DES_set_key(const_DES_cblock *key, DES_key_schedule *schedule); int DES_key_sched(const_DES_cblock *key, DES_key_schedule *schedule); int DES_set_key_checked(const_DES_cblock *key, DES_key_schedule *schedule); void DES_set_key_unchecked(const_DES_cblock *key, DES_key_schedule *schedule); void DES_set_odd_parity(DES_cblock *key); int DES_is_weak_key(const_DES_cblock *key); void DES_ecb_encrypt(const_DES_cblock *input, DES_cblock *output, DES_key_schedule *ks, int enc); void DES_ecb2_encrypt(const_DES_cblock *input, DES_cblock *output, DES_key_schedule *ks1, DES_key_schedule *ks2, int enc); void DES_ecb3_encrypt(const_DES_cblock *input, DES_cblock *output, DES_key_schedule *ks1, DES_key_schedule *ks2, DES_key_schedule *ks3, int enc); void DES_ncbc_encrypt(const unsigned char *input, unsigned char *output, long length, DES_key_schedule *schedule, DES_cblock *ivec, int enc); void DES_cfb_encrypt(const unsigned char *in, unsigned char *out, int numbits, long length, DES_key_schedule *schedule, DES_cblock *ivec, int enc); void DES_ofb_encrypt(const unsigned char *in, unsigned char *out, int numbits, long length, DES_key_schedule *schedule, DES_cblock *ivec); void DES_pcbc_encrypt(const unsigned char *input, unsigned char *output, long length, DES_key_schedule *schedule, DES_cblock *ivec, int enc); void DES_cfb64_encrypt(const unsigned char *in, unsigned char *out, long length, DES_key_schedule *schedule, DES_cblock *ivec, int *num, int enc); void DES_ofb64_encrypt(const unsigned char *in, unsigned char *out, long length, DES_key_schedule *schedule, DES_cblock *ivec, int *num); void DES_xcbc_encrypt(const unsigned char *input, unsigned char *output, long length, DES_key_schedule *schedule, DES_cblock *ivec, const_DES_cblock *inw, const_DES_cblock *outw, int enc); void DES_ede2_cbc_encrypt(const unsigned char *input, unsigned char *output, long length, DES_key_schedule *ks1, DES_key_schedule *ks2, DES_cblock *ivec, int enc); void DES_ede2_cfb64_encrypt(const unsigned char *in, unsigned char *out, long length, DES_key_schedule *ks1, DES_key_schedule *ks2, DES_cblock *ivec, int *num, int enc); void DES_ede2_ofb64_encrypt(const unsigned char *in, unsigned char *out, long length, DES_key_schedule *ks1, DES_key_schedule *ks2, DES_cblock *ivec, int *num); void DES_ede3_cbc_encrypt(const unsigned char *input, unsigned char *output, long length, DES_key_schedule *ks1, DES_key_schedule *ks2, DES_key_schedule *ks3, DES_cblock *ivec, int enc); void DES_ede3_cbcm_encrypt(const unsigned char *in, unsigned char *out, long length, DES_key_schedule *ks1, DES_key_schedule *ks2, DES_key_schedule *ks3, DES_cblock *ivec1, DES_cblock *ivec2, int enc); void DES_ede3_cfb64_encrypt(const unsigned char *in, unsigned char *out, long length, DES_key_schedule *ks1, DES_key_schedule *ks2, DES_key_schedule *ks3, DES_cblock *ivec, int *num, int enc); void DES_ede3_ofb64_encrypt(const unsigned char *in, unsigned char *out, long length, DES_key_schedule *ks1, DES_key_schedule *ks2, DES_key_schedule *ks3, DES_cblock *ivec, int *num); DES_LONG DES_cbc_cksum(const unsigned char *input, DES_cblock *output, long length, DES_key_schedule *schedule, const_DES_cblock *ivec); DES_LONG DES_quad_cksum(const unsigned char *input, DES_cblock output[], long length, int out_count, DES_cblock *seed); void DES_string_to_key(const char *str, DES_cblock *key); void DES_string_to_2keys(const char *str, DES_cblock *key1, DES_cblock *key2); char *DES_fcrypt(const char *buf, const char *salt, char *ret); char *DES_crypt(const char *buf, const char *salt); int DES_enc_read(int fd, void *buf, int len, DES_key_schedule *sched, DES_cblock *iv); int DES_enc_write(int fd, const void *buf, int len, DES_key_schedule *sched, DES_cblock *iv);
DESCRIPTION
This library contains a fast implementation of theThere are two phases to the use of
DES_random_key() generates a random key. The
Before a
DES_set_key_checked() will check that the key passed is of odd parity and is not a week or semi-weak key. If the parity is wrong, then -1 is returned. If the key is a weak key, then -2 is returned. If an error is returned, the key schedule is not generated.
DES_set_key() works like DES_set_key_checked() if the DES_check_key flag is non-zero, otherwise like DES_set_key_unchecked(). These functions are available for compatibility; it is recommended to use a function that does not depend on a global variable.
DES_set_odd_parity() sets the parity of the passed key to odd.
DES_is_weak_key() returns 1 if the passed key is a weak key, 0 if it is ok.
The following routines mostly operate on an input and output stream of DES_cblocks.
DES_ecb_encrypt() is the basic
DES_ecb3_encrypt() encrypts/decrypts the input block by using three-key Triple-DES encryption in
The macro DES_ecb2_encrypt() is provided to perform two-key Triple-DES encryption by using ks1 for the final encryption.
DES_ncbc_encrypt() encrypts/decrypts using the cipher-block-chaining (
DES_xcbc_encrypt() is
DES_ede3_cbc_encrypt() implements outer triple
The DES_ede2_cbc_encrypt() macro implements two-key Triple-DES by reusing ks1 for the final encryption. "C=E(ks1,D(ks2,E(ks1,M)))". This form of Triple-DES is used by the
DES_pcbc_encrypt() encrypt/decrypts using the propagating cipher block chaining mode used by Kerberos v4. Its parameters are the same as DES_ncbc_encrypt().
DES_cfb_encrypt() encrypt/decrypts using cipher feedback mode. This method takes an array of characters as input and outputs and array of characters. It does not require any padding to 8 character groups. Note: the ivec variable is changed and the new changed value needs to be passed to the next call to this function. Since this function runs a complete
DES_cfb64_encrypt() implements
DES_ede3_cfb64_encrypt() and DES_ede2_cfb64_encrypt() is the same as DES_cfb64_encrypt() except that Triple-DES is used.
DES_ofb_encrypt() encrypts using output feedback mode. This method takes an array of characters as input and outputs and array of characters. It does not require any padding to 8 character groups. Note: the ivec variable is changed and the new changed value needs to be passed to the next call to this function. Since this function runs a complete
DES_ofb64_encrypt() is the same as DES_cfb64_encrypt() using Output Feed Back mode.
DES_ede3_ofb64_encrypt() and DES_ede2_ofb64_encrypt() is the same as DES_ofb64_encrypt(), using Triple-DES.
The following functions are included in the
DES_cbc_cksum() produces an 8 byte checksum based on the input stream (via
DES_quad_cksum() is a Kerberos v4 function. It returns a 4 byte checksum from the input bytes. The algorithm can be iterated over the input, depending on out_count, 1, 2, 3 or 4 times. If output is non-NULL, the 8 bytes generated by each pass are written into output.
The following are DES-based transformations:
DES_fcrypt() is a fast version of the Unix crypt(3) function. This version takes only a small amount of space relative to other fast crypt() implementations. This is different to the normal crypt in that the third parameter is the buffer that the return value is written into. It needs to be at least 14 bytes long. This function is thread safe, unlike the normal crypt.
DES_crypt() is a faster replacement for the normal system crypt(). This function calls DES_fcrypt() with a static array passed as the third parameter. This emulates the normal non-thread safe semantics of crypt(3).
DES_enc_write() writes len bytes to file descriptor fd from buffer buf. The data is encrypted via pcbc_encrypt (default) using sched for the key and iv as a starting vector. The actual data send down fd consists of 4 bytes (in network byte order) containing the length of the following encrypted data. The encrypted data then follows, padded with random data out to a multiple of 8 bytes.
DES_enc_read() is used to read len bytes from file descriptor fd into buffer buf. The data being read from fd is assumed to have come from DES_enc_write() and is decrypted using sched for the key schedule and iv for the initial vector.
Warning: The data format used by DES_enc_write() and DES_enc_read() has a cryptographic weakness: When asked to write more than
DES_rw_mode is used to specify the encryption mode to use with DES_enc_read() and DES_end_write(). If set to
NOTES
Single-keyThe evp(3) library provides higher-level encryption functions.
BUGS
DES_3cbc_encrypt() is flawed and must not be used in applications.DES_cbc_encrypt() does not modify ivec; use DES_ncbc_encrypt() instead.
DES_cfb_encrypt() and DES_ofb_encrypt() operates on input of 8 bits. What this means is that if you set numbits to 12, and length to 2, the first 12 bits will come from the 1st input byte and the low half of the second input byte. The second 12 bits will have the low 8 bits taken from the 3rd input byte and the top 4 bits taken from the 4th input byte. The same holds for output. This function has been implemented this way because most people will be using a multiple of 8 and because once you get into pulling bytes input bytes apart things get ugly!
DES_string_to_key() is available for backward compatibility with the
CONFORMING TO
The des library was written to be source code compatible with the
SEE ALSO
crypt(3), des_modes(7), evp(3), rand(3)HISTORY
In OpenSSL 0.9.7, all des_ functions were renamed todes_cbc_cksum(), des_cbc_encrypt(), des_ecb_encrypt(), des_is_weak_key(), des_key_sched(), des_pcbc_encrypt(), des_quad_cksum(), des_random_key() and des_string_to_key() are available in the
des_set_key_checked() and des_set_key_unchecked() were added in OpenSSL 0.9.5.
des_generate_random_block(), des_init_random_number_generator(), des_new_random_key(), des_set_random_generator_seed() and des_set_sequence_number() and des_rand_data() are used in newer versions of Kerberos but are not implemented here.
des_random_key() generated cryptographically weak random data in SSLeay and in OpenSSL prior version 0.9.5, as well as in the original