AC_AuthCompute
» Table of Contents |  | | » Glossary | | | » Index | | |
| | |
| ||
| ||
SYNOPSIS
# include <cssm.h>
|
|
|
PARAMETERS
| ACHandle (input) | The handle that describes the authorization computation module used to perform this function. | |
| BaseAuthorizations (input) | ||
A pointer to a CSSM_TUPLEGROUP containing at least one ACL certificate, specifying the authorization granted to certain root keys, named entities or combinations thereof. A NULL group of BaseAuthorizations always results in a NULL AuthorizationResult. | ||
| Credentials (input/optional) | ||
A pointer to a CSSM_TUPLEGROUP containing a group of certificates, in TUPLE form. The tuple-certificates define the delegation of authorizations from the BaseAuthorizations to the Requestors. If no additional authorization-granting tuples are provided, then this value is NULL and the BaseAuthorizations are the only source of trusted authorizations used as input to the authorization computation. | ||
| NumberOfRequestors (input) | ||
The number of entries in the Requestors array. | ||
| Requestors (input) | ||
A pointer to a list of requestors that define the "who" portion of the request. The list can be of type CSSM_LIST_TYPE_SEXPR. Typical exhibits include:
| ||
| RequestedAuthorizationPeriod (input/optional) | ||
A list defining a validity period or NULL (implying "all time"). This is the "when" portion of the request. If the list is of type CSSM_LIST_TYPE_SEXPR, then the validity interval is specified as a two-element list containing the values ((not-before <date1>)(not-after <date2 >)). Note that each element is a two-element sublist. The <date> is represented by an ASCII byte-string, in the format (for example) "1998-11-24_15:06:16" and is assumed to be GMT. Open-ended time intervals are specified by omitting either of the interval ends. For example, ((not-before 1997-1-1_00:00:0)) specifies all dates and times beginning on January 1, 1997 going forward indefinitely. For programming convenience, when testing for authorization at a single point in time, the date is represented by a one-element list containing (<date>). | ||
| RequestedAuthorization (input) | ||
A list defining the "what" portion of the authorization being requested. If the list is of type CSSM_LIST_TYPE_SEXPR, then the list presents an authorization request in SPKI format. If a specific authorization is being requested, then this input is a two-element SEXPR list containing (tag <req>). The valid values for <req> are application-specific. If this is a request to derive all possible authorizations based on the BaseAuthorizations, Credentials, and Requestors, then this input value must be the two-element list containing (tag (*)). This list corresponds to "all authorizations". With this input, the function tests the provided ACL and certificates against the Requestors (and possibly RequestedAuthorizationPeriod) to yield all authorizations for which the provided Exhibits qualify. | ||
| AuthorizationResult (output) | ||
A CSSM_TUPLEGROUP structure, giving the result of the authorization computation. Typically there will be one result, but there could be as many as there are entries in the BaseAuthorizations. Each of these results says, in effect: "for this machine, under this ACL and the provided certificates, relative to the specified Requestors, the following authorizations have been deduced". Those authorizations are available only on the current platform (and possibly only for the application providing the ACL), and are therefore in the form of an ACL. They are not intended to be used by any other machine or application instance, necessarily, and need to be converted into certificates signed by some private key available to the caller if they are to be so used. | ||
DESCRIPTION
This function performs an authorization computation and returns the results as a group of tuple certificates. The computation is based on the following input values:
| Requestors | One or more items that identify the requestor. These items are matched against subject fields in BaseAuthorizations or Credentials. These will be of any form that occurs in an ACL or certificate, and the class of entries is extensible. AuthCompute uses these fields to compare against Subject fields of TUPLES but does not interpret them, so it does not need to be aware of these extensions. Requestors, taken together with RequestedAuthorization and RequestedAuthorizationPeriod, form request tuples of the form "who requests what, when." Requestors can be public keys that verify some signed request, hashes of objects submitted for proof of permission, etc. In general, there will be only one Requestor, typically the public key of some keyholder signing a request or authenticating a connection. | |||||||
| RequestedAuthorization | ||||||||
The authorization against which the Requestors are being tested in this computation. | ||||||||
| RequestedAuthorizationPeriod | ||||||||
The time range of an authorization computation. | ||||||||
| BaseAuthorizations | ||||||||
The group of ACL entries (unsigned certificates) provided as the basis for this computation. | ||||||||
| Credentials | A group of tuple-certificates used with the BaseAuthorizations to grant authorizations to the Requestors.
| |||||||
The most likely Requestor is a public key that signs a request. In common practice there will be one Requestor per computation, but it is possible for an ACL or certificate to require multiple signatures or other forms of identification before an action is authorized. In that case, there must be multiple Requestors. This function can be used in the following modes:
To verify the authorization of a specific request, backed up by specific Requestors
To compute the set of authorizations that a particular set of Requestors has been granted by the BaseAuthorizations and Credentials.
When using this function to verify an authorization, the RequestedAuthorization is the specific authorization being requested and the RequestedAuthorizationPeriod gives the date and time of that request (typically the current date and time) using both NOT_BEFORE and NOT_AFTER dates. The result, if any, should be an ACL entry with the same authorization that was requested. If such an ACL entry is produced by the computation, then the request is authorized.
| Requested Authorization Example |
| (http http://private.cdsa.hp.com/local-data.html ) |
| (ftp ftp://private.cdsa.hp.com/users/cme/private/test.txt write) |
| Requested Authorization Period Example |
| (valid (not-before "1999-07-28_17:00:44") (not-after "1999-07-28_17:00:44")) |
When using this function to compute the full set of possible authorizations from a set of credentials, rather than to verify a specific access request, the inputs should be of the following form:
RequestedAuthorizationPeriod is either an empty list or the list "valid", indicating "all time".
RequestedAuthorization is the list "*", indicating all possible authorizations.
The result of this computation, if any, will be one or more ACL entries representing all the granted authorizations for the indicated requestor.
The scope of ACLs output from this function is limited to the local system. Each ACL should be interpreted to mean: "for this machine, under these base authorization ACLs and the provided certificates, relative to the specified requestors, the following authorizations have been deduced". Those authorizations are available only on the current platform (and possibly only for the application providing the ACL) and are therefore in the form of an ACL. They are not intended to be used by any other machine or application instance. However, the resulting ACLs can be transferred and used outside of the local scope by an entity with authority in the target scope/environment. The transfer and use is a three-step process:
Convert the ACL into one or more certificates. The certificates must be signed by some private key with appropriate authority in the target scope/environment.
Transfer the certificates to the target environment.
Use the signed certificates as input Credentials to this function in the target scope/environment.
If the function is successful, check (*AuthorizationResult)->NumCerts to determine the precise number of authorizations granted by this computation. If 0, then the requestors were not authorized.
RETURN VALUE
A CSSM_RETURN value indicating success or specifying a particular error condition. The value CSSM_OK indicates success. All other values represent an error condition.