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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_read_password,
       des_read_2passwords, des_read_pw_string, 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);

26/Feb/2001		      0.9.6				1

des(3)			     OpenSSL			   des(3)

	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);

	int des_read_password(des_cblock *key, const char *prompt, int verify);
	int des_read_2passwords(des_cblock *key1, des_cblock *key2,
	       const char *prompt, int verify);
	int des_read_pw_string(char *buf, int length, const char *prompt,
	       int verify);

26/Feb/2001		      0.9.6				2

des(3)			     OpenSSL			   des(3)

	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);
	char *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); for
       backward compatibility the function des_random_seed() is
       available as well).  If the PRNG could not generate a
       secure key, 0 is returned.  In earlier versions of the
       library, des_random_key() did not generate secure keys.

       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() (called des_key_sched() in the MIT library)
       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.

26/Feb/2001		      0.9.6				3

des(3)			     OpenSSL			   des(3)

       des_set_odd_parity() (called des_fixup_key_parity() in the
       MIT library) 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 (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 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 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.

26/Feb/2001		      0.9.6				4

des(3)			     OpenSSL			   des(3)

       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

26/Feb/2001		      0.9.6				5

des(3)			     OpenSSL			   des(3)

       for compatibility with the MIT Kerberos library.
       des_read_pw_string() is also available under the name
       EVP_read_pw_string().

       des_read_pw_string() writes the string specified by prompt
       to standard output, turns echo off and reads in input
       string from the terminal.  The string is returned in buf,
       which must have space for at least length bytes.	 If
       verify is set, the user is asked for the password twice
       and unless the two copies match, an error is returned.  A
       return code of -1 indicates a system error, 1 failure due
       to use interaction, and 0 is success.

       des_read_password() does the same and converts the
       password to a DES key by calling des_string_to_key();
       des_read_2password() operates in the same way as
       des_read_password() except that it generates two keys by
       using the des_string_to_2key() function.
       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().

       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

26/Feb/2001		      0.9.6				6

des(3)			     OpenSSL			   des(3)

       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
       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 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_read_pw_string() is the most machine/OS dependent

26/Feb/2001		      0.9.6				7

des(3)			     OpenSSL			   des(3)

       function and normally generates the most problems when
       porting this code.

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(3), evp(3), rand(3)

HISTORY
       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(), des_read_password()
       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_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 MIT library.

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

       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_read_password, des_read_2passwords,
       des_read_pw_string, 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"

26/Feb/2001		      0.9.6				8

des(3)			     OpenSSL			   des(3)

26/Feb/2001		      0.9.6				9

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