.TH CBIT 3X
.SH NAME
cbit, cbitread, cbitlookup, cbitparse, cbitcert \(mi security category manipulation
.SH SYNOPSIS
.nf
.PP
.B #include <cbit.h>
.PP
.B "struct cbit *cbitparse(char **fields, struct cbit *cb);"
.PP
.B "struct cbit *cbitread(char *file);"
.PP
.B "struct cbit *cbitlookup(char *name, struct cbit *cb);"
.PP
.B "char *cbitcert(struct cbit *p);"
.fi
.SH DESCRIPTION
These functions manipulate
certificates entitling computers to handle
compartmented security categories.
Each security compartment is represented by a structure of form:
.EX
.ta 8n +25n
.nf
\fLstruct cbit {
	\fLchar *name;\fR		official name of category
	\fLint floor;\fR		default value (only bottom bit used)
	\fLchar *owner;\fR		public name of issuing authority
	\fLchar *nickname;\fR		our version of category name
	\fLint bitslot;\fR		where we store it
	\fLchar *exerciser;\fR		who we are
	\fLchar *certificate;\fR	owner's signature
\fL}
.fi
.EE
which describes the meaning of the
.IR bitslot -th
bit in a computer's label space.
By convention, the lines of the file
.F /etc/cbits
contain (in ASCII colon-separated form) the compartments currently
held on the local computer.
.PP
.I Cbitparse
fills in and returns a
cbit
in the obvious way from a vector of seven strings.
If the second argument is zero
.I cbitparse
allots a new structure using
.IR malloc (3).
.PP
.I "Cbitread"
reads and parses an ASCII file of
cbits,
returning an array of
filled in structures.
The last entry in the array is a dummy; it is signalled by having
a zero value of
.IR name .
.PP
.IR Cbitlookup ,
when fed a category name and an array of
cbits
(such as returned by
.IR cbitread ),
returns a pointer to the unique entry whose category name is
.IR name ,
or returns zero.
.PP
.IR Cbitcert
composes a certificate granting
.I exerciser
the right to hold files with the given security category.
The output of
.I cbitcert
depends only on
.IR name ,
.IR floor ,
.IR owner ,
and
.IR exerciser .
The output
must be signed by
.I owner
with
.IR xs
(see
.IR notary (3))
to produce
the checksum value in
.IR certificate .
Third parties may check validity of a cbit
by calling
.EX
.B "verify(p->exerciser, p->certificate, cbitcert(p), strlen(cbitcert(p)))"
.EE
.SH FILES
.F /etc/cbits
.SH SEE ALSO
.IR notary (3).
.SH DIAGNOSTICS
These routines all return 0
on error.