pwd

    OpenVMS usage: char_string
    type:          character-coded text string
    access:        read only
    mechanism:     by descriptor-fixed-length string descriptor
    ASCII password string to be encrypted. The pwd argument is the
    address of a character string descriptor pointing to the ASCII
    password. The password string can contain between 1 and 32
    characters and use the uppercase characters A through Z, the
    numbers 0 through 9, the dollar sign ($),  and the underscore
    (_).

    The caller must validate the password string before calling
    $HASH_PASSWORD to ensure that only permitted characters are
    included.

 alg

    OpenVMS usage: byte_unsigned
    type:          byte (unsigned)
    access:        read only
    mechanism:     by value
    Algorithm used to hash the ASCII password string. The alg
    argument is an unsigned byte specifying the hash algorithm.

    Refer to the HP OpenVMS System Services Reference Manual to view
    the table of recognized algorithms.

    Values ranging from 128 to 255 are reserved for customer use; the
    constant UAI$K_CUST_ALGORITHM defines the start of this range.

    You can use the UAI$_ENCRYPT and UAI$_ENCRYPT2 item codes with
    the $GETUAI system service to retrieve the primary and secondary
    password hash algorithms for a user.

 salt

    OpenVMS usage: word_unsigned
    type:          word (unsigned)
    access:        read only
    mechanism:     by value
    Value used to increase the effectiveness of the hash. The salt
    argument is an unsigned word containing 16 bits of data that is
    used by the hash algorithms when encrypting a password for the
    associated user name. The $GETUAI item code UAI$_SALT is used to
    retrieve the SALT value for a given user. If you do not specify a
    SALT value, $HASH_PASSWORD uses the value of 0.

 usrnam

    OpenVMS usage:char_string
    type:         character-coded text string
    access:       read only
    mechanism:    by descriptor-fixed-length string descriptor
    Name of the user associated with the password. The usrnam
    argument is the address of a descriptor pointing to a character
    text string containing the user name. The current password
    encryption algorithm (UAI$C_PURDY_S) folds the user name into
    the ASCII password string to ensure that different users with the
    same password produce different hash values. This argument must
    be supplied for all calls to $HASH_PASSWORD but is ignored when
    using the CRC algorithm (UAI$C_AD_II).

 hash

    OpenVMS usage:quadword_unsigned
    type:         quadword (unsigned)
    access:       write only
    mechanism:    by reference
    Output hash value representing the encrypted password. The hash
    argument is the address of an unsigned quadword to which $HASH_
    PASSWORD writes the output of the hash. If you use the UAI$C_AD_
    II algorithm, the second longword of the hash is always set to 0.