des(3)                      OpenSSL                      des(3)





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 encryption

SYNOPSIS
        #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 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() func-
       tion.

       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
       electronic 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 (cleart-
       ext) 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 two-
       key 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 argu-
       ment 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 sched-
       ule argument, and initialization vector provided by the
       ivec argument.  If the length argument is not an inte-
       gral 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 bet-
       ter 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 propagat-
       ing 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 num-
       ber of bytes, no 8 byte padding.  Each call to this rou-
       tine 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 vari-
       able 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 sys-
       tem crypt().  This function calls DES_fcrypt() with a
       static array passed as the third parameter.  This emu-
       lates 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 func-
       tions unless you are sure you know what you do (in which
       case you might not want to use them anyway).  They can-
       not 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
       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
       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 out-
       put.  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 compati-
       bility with the MIT library.  New applications should
       use a cryptographic hash function.  The same applies for
       DES_string_to_2key().

CONFORMING TO
       ANSI X3.106

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

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

HISTORY
       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_random_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 com-
       patibility 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_gen-
       erator(), 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
       Eric Young (eay@cryptsoft.com). Modified for the OpenSSL
       project (http://www.openssl.org).



0.9.7c                     2001-10-25                    des(3)
