crypt(3X)                  DG/UX 4.30                   crypt(3X)



     NAME
          crypt - password and file encryption functions

     SYNOPSIS
          cc [flag ...] file ... -lcrypt

          char *crypt (key, salt)
          char *key, *salt;

          void setkey (key)
          char *key;

          void encrypt (block, flag)
          char *block;
          int flag;

          char *descrypt (key, salt)
          char *key, *salt;

          void dessetkey (key)
          char *key;

          void desencrypt (block, flag)
          char *block;
          int flag;

          int runsetkey (p, key)
          int p[2];
          char *key;

          int runcrypt (offset, buffer, count, p)
          long offset;
          char *buffer;
          unsigned int count;
          int p[2];

          int cryptclose(p)
          int p[2];

     DESCRIPTION
          des_crypt is the password encryption function.  It is based
          on a one way hashing encryption algorithm with variations
          intended (among other things) to frustrate use of hardware
          implementations of a key search.

          Key is a user's typed password.  Salt is a two-character
          string chosen from the set [a-zA-Z0-9./]; this string is
          used to perturb the hashing algorithm in one of 4096
          different ways, after which the password is used as the key
          to encrypt repeatedly a constant string.  The returned value
          points to the encrypted password.  The first two characters
          are the salt itself.



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     crypt(3X)                  DG/UX 4.30                   crypt(3X)



          The des_setkey and des_encrypt entries provide (rather
          primitive) access to the actual hashing algorithm.  The
          argument of des_setkey is a character array of length 64
          containing only the characters with numerical value 0 and 1.
          If this string is divided into groups of 8, the low-order
          bit in each group is ignored; this gives a 56-bit key which
          is set into the machine.  This is the key that will be used
          with the hashing algorithm to encrypt the string block with
          the function des_encrypt.

          The argument to the des_encrypt entry is a character array
          of length 64 containing only the characters with numerical
          value 0 and 1.  The argument array is modified in place to a
          similar array representing the bits of the argument after
          having been subjected to the hashing algorithm using the key
          set by des_setkey.  If edflag is zero, the argument is
          encrypted; if non-zero, it is decrypted.

          Note that decryption is not provided in the international
          version of crypt(3X).

          Crypt, setkey, and encrypt are front-end routines that
          invoke des_crypt, des_setkey, and des_encrypt respectively.

          The routines run_setkey and run_crypt are designed for use
          by applications that need cryptographic capabilities [such
          as ed(1) and vi(1)] that must be compatible with the
          crypt(1) user-level utility.  Run_setkey establishes a two-
          way pipe connection with crypt(1), using key as the password
          argument.  Run_crypt takes a block of characters and
          transforms the cleartext or ciphertext into their ciphertext
          or cleartext using crypt(1). Offset is the relative byte
          position from the beginning of the file that the block of
          text provided in block is coming from.  Count is the number
          of characters in block, and p is an array containing input
          and output descriptors.  When encryption is finished,
          crypt_close is used to terminate the connection with
          crypt(1).

          Run_setkey returns -1 if a connection with crypt(1) cannot
          be established.  This will occur on international versions
          of DG/UX where crypt(1) is not available. If a null key is
          passed to run_setkey, 0 is returned.  Otherwise, 1 is
          returned.  Run_crypt returns -1 if it cannot write output or
          read input from the pipe attached to crypt. Otherwise it
          returns 0.

     DIAGNOSTICS
          In the international version of crypt(3X), a flag argument
          of 1 to des_encrypt is not accepted, and an error message is
          printed.




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     crypt(3X)                  DG/UX 4.30                   crypt(3X)



     SEE ALSO
          getpass(3C), passwd(4).
          crypt(1), login(1), passwd(1) in the User's Reference for
          the DG/UX System.

     CAVEAT
          The return value in crypt points to static data that are
          overwritten by each call.















































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