*nix Documentation Project
·  Home
 +   man pages
·  Linux HOWTOs
·  FreeBSD Tips
·  *niX Forums

  man pages->OpenBSD man pages -> des_cfb_encrypt (3)              
Title
Content
Arch
Section
 

DES_RANDOM_KEY(3)

Contents


NAME    [Toc]    [Back]

       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 encryption

SYNOPSIS    [Toc]    [Back]

        #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    [Toc]    [Back]

       This library contains a fast implementation of the DES
       encryption algorithm.

       There are two phases to the use of DES encryption.  The
       first is the generation of a DES_key_schedule from a key,
       the second is the actual encryption.  A DES key is of type
       DES_cblock. This type is consists of 8 bytes with odd parity.
  The least significant bit in each byte is the parity
       bit.  The key schedule is an expanded form of the key; it
       is used to speed the encryption process.

       DES_random_key() generates a random key.  The PRNG must be
       seeded prior to using this function (see rand(3)).  If the
       PRNG could not generate a secure key, 0 is returned.

       Before a DES key can be used, it must be converted into
       the architecture dependent DES_key_schedule via the
       DES_set_key_checked() or DES_set_key_unchecked() function.

       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 is the passed key is a weak
       key, 0 if it is ok.  The probability that a randomly
       generated key is weak is 1/2^52, so it is not really worth
       checking for them.

       The following routines mostly operate on an input and output
 stream of DES_cblocks.

       DES_ecb_encrypt() is the basic DES encryption routine that
       encrypts or decrypts a single 8-byte DES_cblock in elec-
       tronic code book (ECB) mode.  It always transforms the
       input data, pointed to by input, into the output data,
       pointed to by the output argument.  If the encrypt argument
 is non-zero (DES_ENCRYPT), the input (cleartext) is
       encrypted in to the output (ciphertext) using the
       key_schedule specified by the schedule argument, previously
 set via DES_set_key. If encrypt is zero
       (DES_DECRYPT), the input (now ciphertext) is decrypted
       into the output (now cleartext).  Input and output may
       overlap.  DES_ecb_encrypt() does not return a value.

       DES_ecb3_encrypt() encrypts/decrypts the input block by
       using three-key Triple-DES encryption in ECB mode.  This
       involves encrypting the input with ks1, decrypting with
       the key schedule ks2, and then encrypting with ks3.  This
       routine greatly reduces the chances of brute force breaking
 of DES and has the advantage of if ks1, ks2 and ks3
       are the same, it is equivalent to just encryption using
       ECB mode and ks1 as the key.

       The macro DES_ecb2_encrypt() is provided to perform twokey
 Triple-DES encryption by using ks1 for the final
       encryption.

       DES_ncbc_encrypt() encrypts/decrypts using the cipher-
       block-chaining (CBC) mode of DES.  If the encrypt argument
       is non-zero, the routine cipher-block-chain encrypts the
       cleartext data pointed to by the input argument into the
       ciphertext pointed to by the output argument, using the
       key schedule provided by the schedule argument, and initialization
 vector provided by the ivec argument.  If the
       length argument is not an integral multiple of eight
       bytes, the last block is copied to a temporary area and
       zero filled.  The output is always an integral multiple of
       eight bytes.

       DES_xcbc_encrypt() is RSA's DESX mode of DES.  It uses inw
       and outw to 'whiten' the encryption.  inw and outw are
       secret (unlike the iv) and are as such, part of the key.
       So the key is sort of 24 bytes.  This is much better than
       CBC DES.

       DES_ede3_cbc_encrypt() implements outer triple CBC DES
       encryption with three keys. This means that each DES operation
 inside the CBC mode is really an
       "C=E(ks3,D(ks2,E(ks1,M)))".  This mode is used by SSL.
       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 RSAREF library.

       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 ECB encryption per numbits,
       this function is only suggested for use when sending small
       numbers of characters.

       DES_cfb64_encrypt() implements CFB mode of DES with 64bit
       feedback.  Why is this useful you ask?  Because this routine
 will allow you to encrypt an arbitrary number of
       bytes, no 8 byte padding.  Each call to this routine will
       encrypt the input bytes to output and then update ivec and
       num.  num contains 'how far' we are though ivec.  If this
       does not make much sense, read more about cfb mode of DES
       :-).

       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 ECB encryption per numbits, this function
       is only suggested for use when sending small numbers of
       characters.

       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 library
       for compatibility with the MIT Kerberos library.

       DES_cbc_cksum() produces an 8 byte checksum based on the
       input stream (via CBC encryption).  The last 4 bytes of
       the checksum are returned and the complete 8 bytes are
       placed in output. This function is used by Kerberos v4.
       Other applications should use EVP_DigestInit(3) etc.
       instead.

       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 MAXWRITE bytes, DES_enc_write() will split
       the data into several chunks that are all encrypted using
       the same IV.  So don't use these functions unless you are
       sure you know what you do (in which case you might not
       want to use them anyway).  They cannot handle non-blocking
       sockets.  DES_enc_read() uses an internal state and thus
       cannot be used on multiple files.

       DES_rw_mode is used to specify the encryption mode to use
       with DES_enc_read() and DES_end_write().  If set to
       DES_PCBC_MODE (the default), DES_pcbc_encrypt is used.  If
       set to DES_CBC_MODE DES_cbc_encrypt is used.

NOTES    [Toc]    [Back]

       Single-key DES is insecure due to its short key size.  ECB
       mode is not suitable for most applications; see
       des_modes(7).

       The evp(3) library provides higher-level encryption functions.

BUGS    [Toc]    [Back]

       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 MIT library.  New applications should use a
       cryptographic hash function.  The same applies for
       DES_string_to_2key().

CONFORMING TO    [Toc]    [Back]

       ANSI X3.106

       The des library was written to be source code compatible
       with the MIT Kerberos library.

SEE ALSO    [Toc]    [Back]

      
      
       crypt(3), des_modes(7), evp(3), rand(3)

HISTORY    [Toc]    [Back]

       In OpenSSL 0.9.7, all des_ functions were renamed to DES_
       to avoid clashes with older versions of libdes.  Compatibility
 des_ functions are provided for a short while, as
       well as crypt().  Declarations for these are in
       <openssl/des_old.h>. There is no DES_ variant for des_ran-
       dom_seed().  This will happen to other functions as well
       if they are deemed redundant (des_random_seed() just calls
       RAND_seed() and is present for backward compatibility
       only), buggy or already scheduled for removal.

       des_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 MIT Kerberos library;
       des_check_key_parity(), des_fixup_key_parity() and
       des_is_weak_key() are available in newer versions of that
       library.

       des_set_key_checked() and des_set_key_unchecked() were
       added in OpenSSL 0.9.5.

       des_generate_random_block(), des_init_random_number_gener-
       ator(), des_new_random_key(), des_set_random_genera-
       tor_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 MIT library.

AUTHOR    [Toc]    [Back]

       Eric Young (eay@cryptsoft.com). Modified for the OpenSSL
       project (http://www.openssl.org).


OpenBSD 3.6                 2004-04-08                          8
[ Back ]
 Similar pages
Name OS Title
des_key_sched Tru64 Data Encryption Standard (DES) encryption library routines (Auth)
des_is_weak_key Tru64 Data Encryption Standard (DES) encryption library routines (Auth)
des_quad_cksum Tru64 Data Encryption Standard (DES) encryption library routines (Auth)
des_string_to_key Tru64 Data Encryption Standard (DES) encryption library routines (Auth)
des_crypt Tru64 Data Encryption Standard (DES) encryption library routines (Auth)
des_3ecb_encrypt OpenBSD (non USA) DES encryption
des_cbc_encrypt OpenBSD (non USA) DES encryption
des_3cbc_encrypt OpenBSD (non USA) DES encryption
RC4 Tru64 RC4 encryption
RC4_set_key Tru64 RC4 encryption
Copyright © 2004-2005 DeniX Solutions SRL
newsletter delivery service