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Certificate Functions

 


Chapter 5
Certificate Functions

This chapter describes the functions and related types used to work with a certificate database such as the cert7.db database provided with Communicator.

Validating Certificates
Manipulating Certificates
Getting Certificate Information
Comparing SecItem Objects

 

Validating Certificates

CERT_VerifyCertNow
CERT_VerifyCertName
CERT_CheckCertValidTimes
NSS_CmpCertChainWCANames

CERT_VerifyCertNow

Checks that the current date is within the certificate's validity period and that the CA signature on the certificate is valid.

Syntax
#include <cert.h> 
SECStatus CERT_VerifyCertNow(
   CERTCertDBHandle *handle, 
   CERTCertificate *cert,
   PRBool checkSig, 
   SECCertUsage certUsage, 
   void *wincx);
Parameters

This function has the following parameters:

handle

A pointer to the certificate database handle.

cert

A pointer to the certificate to be checked.

checkSig

Indicates whether certificate signatures are to be checked. PR_TRUE means certificate signatures are to be checked. PR_FALSE means certificate signatures will not be checked.

certUsage

One of these values:

wincx

The PIN argument value to pass to PK11 functions. See description below for more information.

Returns

The function returns one of these values:

Description

The CERT_VerifyCertNow function must call one or more PK11 functions to obtain the services of a PKCS #11 module. Some of the PK11 functions require a PIN argument (see SSL_SetPKCS11PinArg for details), which must be specified in the wincx parameter. To obtain the value to pass in the wincx parameter, call SSL_RevealPinArg.

 

CERT_VerifyCertName

Compares the common name specified in the subject DN for a certificate with a specified hostname.

Syntax
#include <cert.h>
SECStatus CERT_VerifyCertName(
   CERTCertificate *cert, 
   char *hostname);
Parameters

This function has the following parameters:

cert

A pointer to the certificate against which to check the hostname referenced by hostname.

hostname

The hostname to be checked.

Returns

The function returns one of these values:

Description

The comparison performed by CERT_VerifyCertName is not a simple string comparison. Instead, it takes account of the following rules governing the construction of common names in SSL server certificates:

CERT_CheckCertValidTimes

Checks whether a specified time is within a certificate's validity period.

Syntax
#include <cert.h>
#include <certt.h>
SECCertTimeValidity CERT_CheckCertValidTimes(
   CERTCertificate *cert,
   int64 t);
Parameters

This function has the following parameters:

cert

A pointer to the certificate whose validity period you want to check against.

t

The time to check against the certificate's validity period. For more information, see the NSPR header pr_time.h.

Returns

The function returns an enumerator of type SECCertTimeValidity:

typedef enum {
   secCertTimeValid,
   secCertTimeExpired,
   secCertTimeNotValidYet
} SECCertTimeValidity;

NSS_CmpCertChainWCANames

Determines whether any of the signers in the certificate chain for a specified certificate are on a specified list of CA names.

Syntax
#include <nss.h>
SECStatus NSS_CmpCertChainWCANames(
   CERTCertificate *cert, 
   CERTDistNames *caNames);
Parameters

This function has the following parameters:

cert

A pointer to the certificate structure for the certificate whose certificate chain is to be checked.

caNames

A pointer to a structure that contains a list of distinguished names (DNs) against which to check the DNs for the signers in the certificate chain.

Returns

The function returns one of these values:

Manipulating Certificates

CERT_DupCertificate
CERT_DestroyCertificate

CERT_DupCertificate

Makes a shallow copy of a specified certificate.

Syntax
#include <cert.h>
CERTCertificate *CERT_DupCertificate(CERTCertificate *c)
Parameter

This function has the following parameter:

c

A pointer to the certificate object to be duplicated.

Returns

If successful, the function returns a pointer to a certificate object of type CERTCertificate.

Description

The CERT_DupCertificate function increments the reference count for the certificate passed in the c parameter.

 

CERT_DestroyCertificate

Destroys a certificate object.

Syntax
#include <cert.h>
#include <certt.h>
void CERT_DestroyCertificate(CERTCertificate *cert);
Parameters

This function has the following parameter:

cert

A pointer to the certificate to destroy.

Description

Certificate and key structures are shared objects. When an application makes a copy of a particular certificate or key structure that already exists in memory, SSL makes a shallow copy--that is, it increments the reference count for that object rather than making a whole new copy. When you call CERT_DestroyCertificate or SECKEY_DestroyPrivateKey, the function decrements the reference count and, if the reference count reaches zero as a result, both frees the memory and sets all the bits to zero. The use of the word "destroy" in function names or in the description of a function implies reference counting.

Never alter the contents of a certificate or key structure. If you attempt to do so, the change affects all the shallow copies of that structure and can cause severe problems.

 

Getting Certificate Information

CERT_FindCertByName
CERT_GetCertNicknames
CERT_FreeNicknames
CERT_GetDefaultCertDB
NSS_FindCertKEAType

 

CERT_FindCertByName

Finds the certificate in the certificate database with a specified DN.

Syntax
#include <cert.h>
CERTCertificate *CERT_FindCertByName (
   CERTCertDBHandle *handle, 
   SECItem *name);
Parameters

This function has the following parameters:

handle

A pointer to the certificate database handle.

name

The subject DN of the certificate you wish to find.

Returns

If successful, the function returns a certificate object of type CERTCertificate.

 

CERT_GetCertNicknames

Returns the nicknames of the certificates in a specified certificate database.

Syntax
#include <cert.h>
#include <certt.h>
CERTCertNicknames *CERT_GetCertNicknames (
   CERTCertDBHandle *handle,
   int what, 
   void *wincx);
Parameters

This function has the following parameters:

handle

A pointer to the certificate database handle.

what

One of these values:

wincx

The PIN argument value to pass to PK11 functions. See description below for more information.

Returns

The function returns a CERTCertNicknames object containing the requested nicknames.

Description

CERT_GetCertNicknames must call one or more PK11 functions to obtain the services of a PKCS #11 module. Some of the PK11 functions require a PIN argument (see SSL_SetPKCS11PinArg for details), which must be specified in the wincx parameter. To obtain the value to pass in the wincx parameter, call SSL_RevealPinArg.

 

CERT_FreeNicknames

Frees a CERTCertNicknames structure. This structure is returned by CERT_GetCertNicknames.

Syntax
#include <cert.h>
void CERT_FreeNicknames(CERTCertNicknames *nicknames);
Parameters

This function has the following parameter:

nicknames

A pointer to the CERTCertNicknames structure to be freed.

 

CERT_GetDefaultCertDB

Returns a handle to the default certificate database.

Syntax
#include <cert.h>
CERTCertDBHandle *CERT_GetDefaultCertDB(void);
Returns

The function returns the CERTCertDBHandle for the default certificate database.

Description

This function is useful for determining whether the default certificate database has been opened.

 

NSS_FindCertKEAType

Returns key exchange type of the keys in an SSL server certificate.

Syntax
#include <nss.h>
SSLKEAType NSS_FindCertKEAType(CERTCertificate * cert);
Parameter

This function has the following parameter:

a

The certificate to check.

Returns

The function returns one of these values:

Comparing SecItem Objects

SECITEM_CompareItem

Compares two SECItem objects and returns a SECComparison enumerator that shows the difference between them.

Syntax
#include <secitem.h>
#include <seccomon.h>
SECComparison SECITEM_CompareItem(
   SECItem *a, 
   SECItem *b);
Parameters

This function has the following parameters:

a

A pointer to one of the items to be compared.

b

A pointer to one of the items to be compared.

Returns

The function returns an enumerator of type SECComparison.

typedef enum _SECComparison {
   SECLessThan                = -1,
   SECEqual                = 0,
   SECGreaterThan = 1
} SECComparison;

 

Document Tags and Contributors

 Contributors to this page: Sheppy, kwilson
 Last updated by: Sheppy,