keynote - a trust-management system library
struct environment *env_next;
struct keynote_keylist *key_next;
int keynote_errno ;
kn_add_assertion(int sessid, char *assertion, int len, int flags);
kn_remove_assertion(int sessid, int assertid);
kn_add_action(int sessid, char *name, char *value, int flags);
kn_remove_action(int sessid, char *name);
kn_add_authorizer(int sessid, char *principal);
kn_remove_authorizer(int sessid, char *principal);
kn_do_query(int sessid, char **returnvalues, int numvalues);
kn_get_failed(int sessid, int type, int seq);
kn_query(struct environment *env, char **returnvalues, int numvalues,
char **trusted, int *trustedlen, int numtrusted,
char **untrusted, int *untrustedlen, int numuntrusted,
char **authorizers, int numauthauthorizers);
kn_read_asserts(char *array, int arraylen, int *numassertions);
kn_keycompare(void *key1, void *key2, int algorithm);
kn_get_authorizer(int sessid, int assertid, int *algorithm);
struct keynote_keylist *
kn_get_licensees(int sessid, int assertid);
kn_encode_base64(unsigned char const *src, unsigned int srclen,
char *dst, unsigned int dstlen);
kn_decode_base64(char const *src, unsigned char *dst,
unsigned int dstlen);
kn_encode_hex(unsigned char *src, char **dst, int srclen);
kn_decode_hex(char *src, char **dst);
kn_encode_key(struct keynote_deckey *dc, int iencoding, int encoding,
kn_decode_key(struct keynote_deckey *dc, char *key, int keytype);
kn_sign_assertion(char *assertion, int len, char *key, char *algorithm,
kn_verify_assertion(char *assertion, int len);
kn_free_key(struct keynote_deckey *);
Link options: -lkeynote -lm -lcrypto
For more details on KeyNote, see RFC 2704.
keynote_errno contains an error code if some library call failed. Failed
calls return -1 (if their return value is integer), or NULL (if their
return value is a pointer) and set keynote_errno. The defined error
ERROR_MEMORY Some memory allocation or usage error was
ERROR_SYNTAX Some syntactic or logical error was encountered.
ERROR_NOTFOUND One of the arguments referred to a nonexistent
structure or entry.
If no errors were encountered, keynote_errno will be set to 0. This
variable should be reset to 0 if an error was encountered, prior to
calling other library routines.
The main interface to KeyNote is centered around the concept of a
session. A session describes a collection of policies, assertions, action
authorizers, return values, and action attributes that the KeyNote system
uses to evaluate a query. Information is not shared between sessions.
Policies, credentials, action authorizers, and action attributes can be
added or deleted at any point during the lifetime of a session.
Furthermore, an application can discover which assertions failed to be
evaluated, and in what way, during a query.
For those applications that only need to do a simple query, there exists
a single call that takes as arguments all the necessary information and
performs all the necessary steps. This is essentially a wrapper that
calls the session API functions as necessary.
Finally, there exist functions for doing ASCII to hexadecimal and Base64
encoding (and vice versa), for encoding/decoding keys between ASCII and
binary formats, and for signing and verifying assertions.
The description of all KeyNote library functions follows.
kn_init() creates a new KeyNote session, and performs any necessary
initializations. On success, this function returns the new session ID,
which is used by all subsequent calls with a sessid argument. On
failure, it returns -1 and sets keynote_errno to ERROR_MEMORY.
kn_add_assertion() adds the assertion pointed to by the array assertion,
of length len in the session identified by sessid. The first argument
can be discarded after the call to this function. The following flags
ASSERT_FLAG_LOCAL Mark this assertion as ultimately trusted.
Trusted assertions need not be signed, and the
Authorizer and Licensees fields can have non-key
At least one (trusted) assertion should have POLICY as the Authorizer.
On success, this function will return an assertion ID which can be used
to remove the assertion from the session, by using
kn_remove_assertion(3). On failure, -1 is returned, and keynote_errno is
set to ERROR_NOTFOUND if the session was not found, ERROR_SYNTAX if the
assertion was syntactically incorrect, or ERROR_MEMORY if necessary
memory could not be allocated.
kn_remove_assertion() removes the assertion identified by assertid from
the session identified by sessid. On success, this function returns 0.
On failure, it returns -1 and sets keynote_errno to ERROR_NOTFOUND.
kn_add_action() inserts the variable name in the action environment of
session sessid, with the value value. The same attribute may be added
more than once, but only the last instance will be used (memory resources
are consumed however).
The flags specified are formed by or’ing the following values:
ENVIRONMENT_FLAG_FUNC In this case, value is a pointer to a
function that takes as argument a string
and returns a string. This is used to
implement callbacks for getting action
attribute values. The argument passed to
such a callback function is a string
identifying the action attribute whose
value is requested, and should return a
pointer to string containing that value
(this pointer will not be freed by the
library), the empty string if the value was
not found, or a NULL to indicate an error
(and may set keynote_errno appropriately).
Prior to first use (currently, at the time
the attribute is added to the session
environment), such functions are called
with KEYNOTE_CALLBACK_INITIALIZE as the
argument (defined in keynote.h) so that
they can perform any special
initializations. Furthermore, when the
session is deleted, all such functions will
be called with KEYNOTE_CALLBACK_CLEANUP to
perform any special cleanup (such as free
any allocated memory). A function may be
called with either of these arguments more
than once, if it has been defined as the
callback function for more than one
ENVIRONMENT_FLAG_REGEX In this case, name is a regular expression
that may match more than one attribute. In
case of conflict between a regular
expression and a ‘‘simple’’ attribute, the
latter will be given priority. In case of
conflict between two regular expression
attributes, the one added later will be
given priority. A callback function should
never change the current KeyNote session,
start/invoke/operate on another session, or
call one of the session-API functions.
The combination of the two flags may be used to specify callback
functions that handle large sets of attributes (even to the extent of
having one callback function handling all attribute references). This is
particularly useful when the action attribute set is particularly large.
On success, keynote_add_action(3) returns 0. On failure, it returns -1
and sets keynote_errno to ERROR_NOTFOUND if the session was not found,
ERROR_SYNTAX if the name was invalid (e.g., started with an underscore
character) or was NULL, or ERROR_MEMORY if necessary memory could not be
kn_remove_action() removes action attribute name from the environment of
session sessid. Notice that if more than one instances of name exist,
only the one added last will be deleted. On success, this function
returns 0. On failure, it returns -1 and keynote_errno is set to
ERROR_NOTFOUND if the session or the attribute were not found, or
ERROR_SYNTAX if the name was invalid. If the attribute value was a
callback, that function will be called with the define
KEYNOTE_CALLBACK_CLEANUP as the argument.
kn_add_authorizer() adds the principal pointed to by principal to the
action authorizers list of session sessid. The principal is typically an
ASCII-encoded key. On success, this function will return 0. On failure,
it returns -1 and sets keynote_errno to ERROR_NOTFOUND if the session was
not found, ERROR_SYNTAX if the encoding was invalid, or ERROR_MEMORY if
necessary memory could not be allocated.
kn_remove_authorizer() removes principal from the action authorizer list
of session sessid. On success, this function returns 0. On failure, it
returns -1 and sets keynote_errno to ERROR_NOTFOUND if the session was
kn_do_query() evaluates the request based on the assertions, action
attributes, and action authorizers added to session sessid. returnvalues
is an ordered array of strings that contain the return values. The
lowest-ordered return value is contained in returnvalues, and the
highest-ordered value is returnvalues[numvalues - 1]. If returnvalues is
NULL, the returnvalues from the previous call to kn_do_query(3) will be
used. The programmer SHOULD NOT free returnvalues after the call to
kn_do_query(3) if this feature is used, as the array is not replicated
internally. On success, this function returns an index into the
returnvalues array. On failure, it returns -1 and sets keynote_errno to
ERROR_NOTFOUND if the session was not found or the authorizers list was
empty, ERROR_SYNTAX if no returnvalues have been specified, or
ERROR_MEMORY if necessary memory could not be allocated.
kn_get_failed() returns the assertion ID of the numth assertion
(starting from zero) in session sessid that was somehow invalid during
evaluation. This function is typically called after kn_do_query(3) is
used to evaluate a request. type specifies the type of failure the
application is interested in. It can be set to:
KEYNOTE_ERROR_ANY to indicate interest in any error.
KEYNOTE_ERROR_SYNTAX for syntactic or semantic errors.
KEYNOTE_ERROR_MEMORY for memory-related problems.
KEYNOTE_ERROR_SIGNATURE if the assertion could not be
These values are defined in keynote.h. An application can then delete the
offending assertion using kn_remove_assertion(3). For example, to remove
all assertion whose signature failed, an application could do something
while ((assertid = kn_get_failed(sessid, KEYNOTE_ERROR_SIGNATURE, 0)
On success, kn_get_failed(3) returns an assertion ID. On failure, or when
no assertion matching the given criteria is found, it returns -1 and set
keynote_errno to ERROR_NOTFOUND.
kn_cleanup_action_environment() removes all action attributes from the
action environment of session sessid. It returns 0 on success.
kn_close() closes session sessid and frees all related resources,
deleting action attributes, action authorizers, and assertions. On
success, this function returns 0. On failure, it returns -1 and sets
keynote_errno to ERROR_NOTFOUND if the session was not found.
kn_read_asserts() parses the string array of length arraylen and returns
an array of pointers to strings containing copies of the assertions found
in array. Both the array of pointers and the strings are allocated by
kn_read_asserts() dynamically, and thus should be freed by the programmer
when they are no longer needed. numassertions contains the number of
assertions (and thus strings in the returned array) found in array. On
failure, this function returns NULL and sets keynote_errno to
ERROR_MEMORY if necessary memory could not be allocated, or ERROR_SYNTAX
if array was NULL. Note that if there were no assertions found in array,
a valid pointer will be returned, but numassertions will contain the
value zero on return. The returned pointer should be freed by the
kn_keycompare() compares key1 and key2 (which must be of the same
algorithm) and returns 1 if equal and 0 otherwise.
kn_get_authorizer() returns the authorizer key (in binary format) for
assertion assertid in session sessid. It also sets the algorithm
argument to the algorithm of the authorizer key. On failure,
kn_get_authorizer() returns NULL, and sets keynote_errno to
kn_get_licensees() returns the licensee key(s) for assertion assertid in
session sessid. The keys are returned in a linked list of struct
keynote_keylist structures. On failure, kn_get_licensees() returns NULL.
and sets keynote_errno to ERROR_NOTFOUND.
kn_query() takes as arguments a list of action attributes in env, a list
of return values in returnvalues (the number of returnvalues in indicated
by numvalues), a number (numtrusted) of locally-trusted assertions in
trusted (the length of each assertion is given by the respective element
of trustedlen), a number (numuntrusted) of assertions that need to be
cryptographically verified in untrusted (the length of each assertion is
given by the respective element of untrustedlen), and a number
(numauthorizers) of action authorizers in authorizers. env is a linked
list of struct environment structures. The env_name, env_value, and
env_flags fields correspond to the name, value, and flags arguments to
kn_add_assertion(3) respectively. env_regex is not used. On success,
this function returns an index in returnvalues indicating the returned
value to the query. On failure, it returns -1 and sets keynote_errno to
the same values as kn_do_query(3), or to ERROR_MEMORY if a trusted or
untrusted assertion could not be added to the session due to lack of
memory resources. Syntax errors in assertions will not be reported by
kn_encode_base64() converts the data of length srclen contained in src in
Base64 encoding and stores them in dst which is of length dstlen. The
actual length of the encoding stored in dst is returned. dst should be
long enough to also contain the trailing string terminator. If srclen is
not a multiple of 4, or dst is not long enough to contain the encoded
data, this function returns -1 and sets keynote_errno to ERROR_SYNTAX.
kn_decode_base64() decodes the Base64-encoded data stored in src and
stores the result in dst, which is of length dstlen. The actual length
of the decoded data is returned on success. On failure, this function
returns -1 and sets keynote_errno to ERROR_SYNTAX, denoting either an
invalid Base64 encoding or insufficient space in dst.
kn_encode_hex() encodes in ASCII-hexadecimal format the data of length
srclen contained in src. This function allocates a chunk of memory to
store the result, which is returned in dst. Thus, this function should
be used as follows:
kn_encode_hex(src, &dst, srclen);
The length of the allocated buffer will be (2 * srclen + 1). On success,
this function returns 0. On failure, it returns -1 and sets keynote_errno
to ERROR_MEMORY if it failed to allocate enough memory, ERROR_SYNTAX if
dst was NULL.
kn_decode_hex() decodes the ASCII hex-encoded string in src and stores
the result in a memory chunk allocated by the function. A pointer to that
memory is stored in dst. The length of the allocated memory will be
(strlen(src) / 2). On success, this function returns 0. On failure, it
returns -1 and sets keynote_errno to ERROR_MEMORY if it could not
allocate enough memory, or ERROR_SYNTAX if dst was NULL, or the length of
src is not even.
kn_encode_key() ASCII-encodes a cryptographic key. The binary
representation of the key is contained in dc. The field dec_key in that
structure is a pointer to some cryptographic algorithm dependent
information describing the key. In this implementation, this pointer
should be a DSA * or RSA * for DSA or RSA keys respectively, as used in
the SSL library, or a keynote_binary * for cryptographic keys whose
algorithm KeyNote does not know about but the application wishes to
include in the action authorizers (and thus need to be canonicalized).
The field dec_algorithm describes the cryptographic algorithm, and may be
one of KEYNOTE_ALGORITHM_DSA, KEYNOTE_ALGORITHM_RSA, or
KEYNOTE_ALGORITHM_BINARY in this implementation.
iencoding describes how the key should be binary-encoded. This
implementation supports INTERNAL_ENC_PKCS1 for RSA keys,
INTERNAL_ENC_ASN1 for DSA keys, and INTERNAL_ENC_NONE for BINARY keys.
encoding describes what ASCII encoding should be applied to the key.
Valid values are ENCODING_HEX and ENCODING_BASE64, for hexadecimal and
Base64 encoding respectively. keytype is one of KEYNOTE_PUBLIC_KEY or
KEYNOTE_PRIVATE_KEY to indicate whether the key is public or private.
Private keys have the string KEYNOTE_PRIVATE_KEY_PREFIX (defined in
keynote.h) prefixed to the algorithm name. On success, this function
returns a string containing the encoded key. On failure, it returns NULL
and sets keynote_errno to ERROR_NOTFOUND if the dc argument was invalid,
ERROR_MEMORY if it failed to allocate the necessary memory, or
ERROR_SYNTAX if the key to be converted was invalid.
kn_decode_key() decodes the ASCII-encoded string contained in key. The
result is placed in dc, with dec_algorithm describing the algorithm (see
kn_encode_key(3)), and dec_key pointing to an algorithm-dependent
structure. In this implementation, this is an SSLeay/OpenSSL-defined DSA
* for DSA keys, RSA * for RSA and X509-based keys, and a keynote_binary *
for BINARY keys. keytype takes the values KEYNOTE_PUBLIC_KEY or
KEYNOTE_PRIVATE_KEY to specify a public or private key, where applicable.
On success, this function returns 0. On failure, it returns -1 and sets
keynote_errno to ERROR_MEMORY if necessary memory could not be allocated,
or ERROR_SYNTAX if the key or the ASCII encoding was malformed.
kn_sign_assertion() produces the cryptographic signature for the
assertion of length len stored in assertion, using the ASCII-encoded
cryptographic key contained in key. The type of signature to be produced
is described by the string algorithm. Possible values for this string
are SIG_RSA_SHA1_HEX SIG_RSA_SHA1_BASE64, SIG_RSA_MD5_HEX, and
SIG_RSA_MD5_HEX for RSA keys, SIG_DSA_SHA1_HEX and SIG_DSA_SHA1_BASE64
for DSA keys, SIG_X509_SHA1_HEX, and SIG_X509_SHA1_BASE64 for X509-based
keys. No other cryptographic signatures are currently supported by this
implementation. If vflag is set to 1, then the generated signature will
also be verified. On success, this function returns a string containing
the ASCII-encoded signature, without modifying the assertion. On
failure, it returns NULL and sets keynote_errno to ERROR_NOTFOUND if one
of the arguments was NULL, ERROR_MEMORY if necessary memory could not be
allocated, or ERROR_SYNTAX if the algorithm, the key, or the assertion
(if signature verification was requested) was invalid.
kn_verify_assertion() verifies the cryptographic signature on the
assertion of length len contained in string assertion. On success, this
function returns SIGRESULT_TRUE if the signature could be verified, or
SIGRESULT_FALSE otherwise. On failure, this function returns -1 and sets
keynote_errno to ERROR_MEMORY if necessary memory could not be allocated,
or ERROR_SYNTAX if the assertion contained a syntactic error, or the
cryptographic algorithm was not supported.
kn_free_key() frees a cryptographic key.
kn_get_string() parses the argument, treating it as a keynote(4) (quoted)
string. This is useful for parsing key files.
keynote(1), keynote(4), keynote(5)
‘‘The KeyNote Trust-Management System, Version 2’’
M. Blaze, J. Feigenbaum, A. D. Keromytis, Internet Drafts, RFC
‘‘Decentralized Trust Management’’
M. Blaze, J. Feigenbaum, J. Lacy, 1996 IEEE Conference on
Privacy and Security
‘‘Compliance-Checking in the PolicyMaker Trust Management System’’
M. Blaze, J. Feigenbaum, M. Strauss, 1998 Financial Crypto
Angelos D. Keromytis (email@example.com)
The return values of all the functions have been given along with the
function description above.
None that we know of. If you find any, please report them to