Java Doc for X509Certificate.java in  » 6.0-JDK-Core » security » javax » security » cert » Java Source Code / Java DocumentationJava Source Code and Java Documentation

The basic X.509 format was defined by ISO/IEC and ANSI X9 and is described below in ASN.1:

 Certificate  ::=  SEQUENCE  {
 tbsCertificate       TBSCertificate,
 signatureAlgorithm   AlgorithmIdentifier,
 signature            BIT STRING  }
 

These certificates are widely used to support authentication and other functionality in Internet security systems. Common applications include Privacy Enhanced Mail (PEM), Transport Layer Security (SSL), code signing for trusted software distribution, and Secure Electronic Transactions (SET).

These certificates are managed and vouched for by Certificate Authorities (CAs). CAs are services which create certificates by placing data in the X.509 standard format and then digitally signing that data. CAs act as trusted third parties, making introductions between principals who have no direct knowledge of each other. CA certificates are either signed by themselves, or by some other CA such as a "root" CA.

The ASN.1 definition of tbsCertificate is:

 TBSCertificate  ::=  SEQUENCE  {
 version         [0]  EXPLICIT Version DEFAULT v1,
 serialNumber         CertificateSerialNumber,
 signature            AlgorithmIdentifier,
 issuer               Name,
 validity             Validity,
 subject              Name,
 subjectPublicKeyInfo SubjectPublicKeyInfo,
 }
 

Here is sample code to instantiate an X.509 certificate:

 
 InputStream inStream = new FileInputStream("fileName-of-cert");
 X509Certificate cert = X509Certificate.getInstance(inStream);
 inStream.close();
 

 byte[] certData = <certificate read from a file, say>
 X509Certificate cert = X509Certificate.getInstance(certData);
 

In either case, the code that instantiates an X.509 certificate consults the Java security properties file to locate the actual implementation or instantiates a default implementation.

The Java security properties file is located in the file named <JAVA_HOME>/lib/security/java.security. <JAVA_HOME> refers to the value of the java.home system property, and specifies the directory where the JRE is installed. In the Security properties file, a default implementation for X.509 v1 may be given such as:

 cert.provider.x509v1=com.sun.security.cert.internal.x509.X509V1CertImpl
 

The value of this cert.provider.x509v1 property has to be changed to instatiate another implementation. If this security property is not set, a default implementation will be used. Currently, due to possible security restrictions on access to Security properties, this value is looked up and cached at class initialization time and will fallback on a default implementation if the Security property is not accessible.

Note: The classes in the package javax.security.cert exist for compatibility with earlier versions of the Java Secure Sockets Extension (JSSE). New applications should instead use the standard Java SE certificate classes located in java.security.cert.

Note: Only one DER-encoded certificate is expected to be in the input stream. Also, all X509Certificate subclasses must provide a constructor of the form:

 public <subClass>(InputStream inStream) ...
 

Note: All X509Certificate subclasses must provide a constructor of the form:

 public <subClass>(InputStream inStream) ...
 

The validity period consists of two date/time values: the first and last dates (and times) on which the certificate is valid. It is defined in ASN.1 as:

 validity             Validity

 Validity ::= SEQUENCE {
 notBefore      CertificateValidityDate,
 notAfter       CertificateValidityDate }

 CertificateValidityDate ::= CHOICE {
 utcTime        UTCTime,
 generalTime    GeneralizedTime }
 

Note: Only one DER-encoded certificate is expected to be in the input stream. Also, all X509Certificate subclasses must provide a constructor of the form:

 public <subClass>(InputStream inStream) ...
 

Note: All X509Certificate subclasses must provide a constructor of the form:

 public <subClass>(InputStream inStream) ...
 

The issuer name field contains an X.500 distinguished name (DN). The ASN.1 definition for this is:

 issuer    Name

 Name ::= CHOICE { RDNSequence }
 RDNSequence ::= SEQUENCE OF RelativeDistinguishedName
 RelativeDistinguishedName ::=
 SET OF AttributeValueAssertion
 AttributeValueAssertion ::= SEQUENCE {
 AttributeType,
 AttributeValue }
 AttributeType ::= OBJECT IDENTIFIER
 AttributeValue ::= ANY
 

 validity             Validity

 Validity ::= SEQUENCE {
 notBefore      CertificateValidityDate,
 notAfter       CertificateValidityDate }

 CertificateValidityDate ::= CHOICE {
 utcTime        UTCTime,
 generalTime    GeneralizedTime }
 

 serialNumber     CertificateSerialNumber

 CertificateSerialNumber  ::=  INTEGER
 

 signatureAlgorithm   AlgorithmIdentifier

 AlgorithmIdentifier  ::=  SEQUENCE  {
 algorithm               OBJECT IDENTIFIER,
 parameters              ANY DEFINED BY algorithm OPTIONAL  }
 -- contains a value of the type
 -- registered for use with the
 -- algorithm object identifier value
 

The algorithm name is determined from the algorithm OID string. the signature algorithm name.

See getSigAlgName for relevant ASN.1 definitions. the signature algorithm OID string.

See getSigAlgName for relevant ASN.1 definitions. the DER-encoded signature algorithm parameters, ornull if no parameters are present.

 subject    Name
 

See getIssuerDN for Name and other relevant definitions. a Principal whose name is the subject name.
See Also:   X509Certificate.getIssuerDN()

 version         [0]  EXPLICIT Version DEFAULT v1

 Version  ::=  INTEGER  {  v1(0), v2(1), v3(2)  }