ice.cert
Class X509Certificate

java.lang.Object
  ice.cert.X509Certificate

All Implemented Interfaces:

Serializable

public class X509Certificate

extends Object

implements Serializable

Implementation of the jdk 1.2 java.security.cert.X509Certificates class. In order to keep the downward compatibility with jdk 1.1, this class does not extend the jdk 1.2 class. However all the functionality are implemented.

This class provides a standard way to access all the attributes of an X.509 certificate. It does not however implement certificate extensions.

The basic X.509 v3 format 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.

A good decription and profiling is provided in the IETF PKIX WG draft, Part I: X.509 Certificate and CRL Profile, <draft-ietf-pkix-ipki-part1-07.txt>.

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,
     issuerUniqueID  [1]  IMPLICIT UniqueIdentifier OPTIONAL,
                          -- If present, version must be v2 or v3
     subjectUniqueID [2]  IMPLICIT UniqueIdentifier OPTIONAL,
                          -- If present, version must be v2 or v3
     extensions      [3]  EXPLICIT Extensions OPTIONAL
                          -- If present, version must be v3
     }
 

Certificates are instantiated using a certificate factory. The following is an example of how to instantiate a ice-specific X.509 certificate:

 
 InputStream inStream = new FileInputStream("fileName-of-cert");
 ice.cert.X509CertificateFactory cf = new ice.cert.X509CertificateFactory();
 ice.cert.X509Certificate cert = cf.generateCertificate(inStream);
 inStream.close();
 

This implementation is compliant to the specifications given in jdk1.2's java.security.cert.X509Certificate. However few differences can be noticed:

• For compatibility with jdk1.1, this class does not subclass any of the jdk1.2 classes
• This class has been designed for internet-type certificates, specifically SSL certificates. It may or may not be compatible with PEM, SET or other certificates.
• This class implements methods for conviently saving certificates in binary or base64 (text) format, as well as static methods to do the same with certificate chains.

Since:

ICEsecure 1.1

Author:

Jerome Bugnet

See Also:

X509CertificateFactory, Serialized Form

Method Summary

void	checkValidity() Checks that the certificate is currently valid.
void	checkValidity(Date date) Checks that the given date is within the certificate's validity period.
boolean	equals(Object other) Compares this certificate for equality with the specified object.
int	getBasicConstraints() Gets the certificate constraints path length from the critical BasicConstraints extension, (OID = 2.5.29.19).
byte[]	getEncoded() Returns the encoded form of this certificate.
X500Name	getIssuer() Returns the distinguished name of the certificate issuer
Principal	getIssuerDN() Gets the issuer (issuer distinguished name) value from the certificate.
boolean[]	getIssuerUniqueID() Gets the issuerUniqueID value from the certificate.
boolean[]	getKeyUsage() Gets a boolean array representing bits of the KeyUsage extension, (OID = 2.5.29.15).
Date	getNotAfter() Gets the notAfter date from the validity period of the certificate.
Date	getNotBefore() Gets the notBefore date from the validity period of the certificate.
PublicKey	getPublicKey() Gets the public key from this certificate.
BigInteger	getSerialNumber() Gets the serialNumber value from the certificate.
String	getSigAlgName() Gets the signature algorithm name for the certificate signature algorithm.
String	getSigAlgOID() Gets the signature algorithm OID string from the certificate.
byte[]	getSigAlgParams() Gets the DER-encoded signature algorithm parameters from this certificate's signature algorithm.
byte[]	getSignature() Gets the signature value (the raw signature bits) from the certificate.
X500Name	getSubject() Returns the distinguished name of the certificate's owner
Principal	getSubjectDN() Gets the subject (subject distinguished name) value from the certificate.
boolean[]	getSubjectUniqueID() Gets the subjectUniqueID value from the certificate.
byte[]	getTBSCertificate() Gets the DER-encoded certificate information, the tbsCertificate from this certificate.
String	getType() Returns the type of this certificate.
int	getVersion() Gets the version (version number) value from the certificate.
int	hashCode() Returns a hashcode value for this certificate from its encoded form.
void	save(OutputStream out) Save this certificate in binary form.
void	saveAsText(OutputStream out) Save this certificate in text form.
static void	saveChain(X509Certificate[] chain, OutputStream out) Saves a certificate chain in binary form.
static void	saveChainAsText(X509Certificate[] chain, OutputStream out) Saves a certificate chain in text form.
String	toString()
void	verify(PublicKey key) Verifies that this certificate was signed using the private key that corresponds to the specified public key.
void	verify(PublicKey key, String sigProvider) Verifies that this certificate was signed using the private key that corresponds to the specified public key.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Method Detail

checkValidity

public void checkValidity()
                   throws CertificateExpiredException,
                          CertificateNotYetValidException

Checks that the certificate is currently valid. It is if the current date and time are within the validity period given in the certificate.

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 }
 

Throws:

CertificateExpiredException - if the certificate has expired.

CertificateNotYetValidException - if the certificate is not yet valid.

checkValidity

public void checkValidity(Date date)
                   throws CertificateExpiredException,
                          CertificateNotYetValidException

Checks that the given date is within the certificate's validity period. In other words, this determines whether the certificate would be valid at the given date/time.

Parameters:

date - the Date to check against to see if this certificate is valid at that date/time.

Throws:

CertificateExpiredException - if the certificate has expired with respect to the date supplied.

CertificateNotYetValidException - if the certificate is not yet valid with respect to the date supplied.

See Also:

checkValidity()

getBasicConstraints

public int getBasicConstraints()

Gets the certificate constraints path length from the critical BasicConstraints extension, (OID = 2.5.29.19).

The basic constraints extension identifies whether the subject of the certificate is a Certificate Authority (CA) and how deep a certification path may exist through that CA. The pathLenConstraint field (see below) is meaningful only if cA is set to TRUE. In this case, it gives the maximum number of CA certificates that may follow this certificate in a certification path. A value of zero indicates that only an end-entity certificate may follow in the path.

Note that for the PKIX profile this extension is always marked critical if cA is TRUE, meaning this certificate belongs to a Certificate Authority.

The ASN.1 definition for this is:

 BasicConstraints ::= SEQUENCE {
     cA                  BOOLEAN DEFAULT FALSE,
     pathLenConstraint   INTEGER (0..MAX) OPTIONAL }
 

Returns:

the length of the constraint if the BasicConstraints extension is present in the certificate and the cA value is TRUE. Otherwise returns -1.

getIssuerDN

public Principal getIssuerDN()

Gets the issuer (issuer distinguished name) value from the certificate. The issuer name identifies the entity that signed (and issued) the certificate.

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
 

The Name describes a hierarchical name composed of attributes, such as country name, and corresponding values, such as US. The type of the AttributeValue component is determined by the AttributeType; in general it will be a directoryString. A directoryString is usually one of PrintableString, TeletexString or UniversalString.

Returns:

a Principal whose name is the issuer distinguished name. This implementation returns a ice.cert.X500Name

See Also:

X500Name

getIssuerUniqueID

public boolean[] getIssuerUniqueID()

Gets the issuerUniqueID value from the certificate. The issuer unique identifier is present in the certificate to handle the possibility of reuse of issuer names over time. The PKIX Part I recommends that names not be reused and that conforming certificates not make use of unique identifiers. Applications conforming to that profile should be capable of parsing unique identifiers and making comparisons.

The ASN.1 definition for this is:

 issuerUniqueID  [1]  IMPLICIT UniqueIdentifier OPTIONAL

 UniqueIdentifier  ::=  BIT STRING
 

Returns:

the issuer unique identifier or null if it is not present in the certificate.

getKeyUsage

public boolean[] getKeyUsage()

Gets a boolean array representing bits of the KeyUsage extension, (OID = 2.5.29.15). The key usage extension defines the purpose (e.g., encipherment, signature, certificate signing) of the key contained in the certificate. The ASN.1 definition for this is:

 KeyUsage ::= BIT STRING {
     digitalSignature        (0),
     nonRepudiation          (1),
     keyEncipherment         (2),
     dataEncipherment        (3),
     keyAgreement            (4),
     keyCertSign             (5),
     cRLSign                 (6),
     encipherOnly            (7),
     decipherOnly            (8) }
 

The PKIX part I draft recommends that when used, this be marked as a critical extension.

Returns:

the bit values of the KeyUsage extension as an array of booleans, or null if the KeyUsage extension is not present in the certificate.

getNotAfter

public Date getNotAfter()

Gets the notAfter date from the validity period of the certificate. See getNotBefore() for relevant ASN.1 definitions.

Returns:

the end date of the validity period.

See Also:

checkValidity()

getNotBefore

public Date getNotBefore()

Gets the notBefore date from the validity period of the certificate. The relevant ASN.1 definitions are:

 validity             Validity

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

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

Returns:

the start date of the validity period.

See Also:

checkValidity()

getSerialNumber

public BigInteger getSerialNumber()

Gets the serialNumber value from the certificate. The serial number is an integer assigned by the certification authority to each certificate. It must be unique for each certificate issued by a given CA (i.e., the issuer name and serial number identify a unique certificate). The ASN.1 definition for this is:

 serialNumber     CertificateSerialNumber

 
 CertificateSerialNumber  ::=  INTEGER
 

Returns:

the serial number.

getSigAlgName

public String getSigAlgName()

Gets the signature algorithm name for the certificate signature algorithm. An example is the string "SHA-1/DSA". The ASN.1 definition for this is:

 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.

Returns:

the signature algorithm name.

getSigAlgOID

public String getSigAlgOID()

Gets the signature algorithm OID string from the certificate. An OID is represented by a set of positive whole numbers separated by periods. For example, the string "1.2.840.10040.4.3" identifies the SHA-1 with DSA signature algorithm, as per the PKIX part I.

See getSigAlgName() for relevant ASN.1 definitions.

Returns:

the signature algorithm OID string.

getSigAlgParams

public byte[] getSigAlgParams()

Gets the DER-encoded signature algorithm parameters from this certificate's signature algorithm. In most cases, the signature algorithm parameters are null; the parameters are usually supplied with the certificate's public key.

See getSigAlgName() for relevant ASN.1 definitions.

Returns:

the DER-encoded signature algorithm parameters, or null if no parameters are present.

getSignature

public byte[] getSignature()

Gets the signature value (the raw signature bits) from the certificate. The ASN.1 definition for this is:

 signature     BIT STRING  
 

Returns:

the signature.

getSubjectDN

public Principal getSubjectDN()

Gets the subject (subject distinguished name) value from the certificate. The ASN.1 definition for this is:

 subject    Name
 

See getIssuerDN() for Name and other relevant definitions.

Returns:

a Principal whose name is the subject name. This implementation returns a ice.cert.X500Name

See Also:

X500Name

getSubjectUniqueID

public boolean[] getSubjectUniqueID()

Gets the subjectUniqueID value from the certificate.

The ASN.1 definition for this is:

 subjectUniqueID  [2]  IMPLICIT UniqueIdentifier OPTIONAL

 UniqueIdentifier  ::=  BIT STRING
 

Returns:

the subject unique identifier or null if it is not present in the certificate.

getTBSCertificate

public byte[] getTBSCertificate()
                         throws CertificateEncodingException

Gets the DER-encoded certificate information, the tbsCertificate from this certificate. This can be used to verify the signature independently.

Returns:

the DER-encoded certificate information.

Throws:

CertificateEncodingException - if an encoding error occurs.

getVersion

public int getVersion()

Gets the version (version number) value from the certificate. The ASN.1 definition for this is:

 version  [0] EXPLICIT Version DEFAULT v1

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

Returns:

the version number, i.e. 1, 2 or 3.

getEncoded

public byte[] getEncoded()
                  throws CertificateEncodingException

Returns the encoded form of this certificate. For X.509 certificates it is encoded as ASN.1 DER.

Throws:

CertificateEncodingException - if an encoding error occurs.

getPublicKey

public PublicKey getPublicKey()

Gets the public key from this certificate.

Returns:

the public key.

getSubject

public X500Name getSubject()

Returns the distinguished name of the certificate's owner

Returns:

the X500Name of the owner

getIssuer

public X500Name getIssuer()

Returns the distinguished name of the certificate issuer

Returns:

the X500Name of the issuer

verify

public void verify(PublicKey key)
            throws CertificateException,
                   NoSuchAlgorithmException,
                   InvalidKeyException,
                   NoSuchProviderException,
                   SignatureException

Verifies that this certificate was signed using the private key that corresponds to the specified public key.

Parameters:

key - the PublicKey used to carry out the verification.

Throws:

NoSuchAlgorithmException - on unsupported signature algorithms.

InvalidKeyException - on incorrect key.

NoSuchProviderException - if there's no default provider.

SignatureException - on signature errors.

CertificateException - on encoding errors.

verify

public void verify(PublicKey key,
                   String sigProvider)
            throws CertificateException,
                   NoSuchAlgorithmException,
                   InvalidKeyException,
                   NoSuchProviderException,
                   SignatureException

Verifies that this certificate was signed using the private key that corresponds to the specified public key. This method uses the signature verification engine supplied by the specified provider.

Parameters:

key - the PublicKey used to carry out the verification.

sigProvider - the name of the signature provider.

Throws:

NoSuchAlgorithmException - on unsupported signature algorithms.

InvalidKeyException - on incorrect key.

NoSuchProviderException - on incorrect provider.

SignatureException - on signature errors.

CertificateException - on encoding errors.

save

public void save(OutputStream out)
          throws IOException

Save this certificate in binary form.

Throws:

IOException

saveAsText

public void saveAsText(OutputStream out)
                throws IOException

Save this certificate in text form. The format used to save the certificate is a base 64 encoding of the binary form of the certificate with the markers

-----BEGIN CERTIFICATE-----
 -----END CERTIFICATE-----

Throws:

IOException

saveChain

public static void saveChain(X509Certificate[] chain,
                             OutputStream out)
                      throws IOException

Saves a certificate chain in binary form. This method saves a certificate chain in PKCS7 format. Be aware that this method does not check if the chain is valid.

See RSA Security site for the PKCS#7 format.

Throws:

IOException

saveChainAsText

public static void saveChainAsText(X509Certificate[] chain,
                                   OutputStream out)
                            throws IOException

Saves a certificate chain in text form. This method saves a certificate chain in Base64 encoded PKCS7 format. The markers are

 -----BEGIN PKCS #7 SIGNED DATA-----
 -----END PKCS #7 SIGNED DATA-----

Be aware that this method does not check if the chain is valid.

See RSA Security site for the PKCS#7 format.

Throws:

IOException

getType

public String getType()

Returns the type of this certificate.

Returns:

"X.509" for this implementation.

equals

public boolean equals(Object other)

Compares this certificate for equality with the specified object. If the other object is an instanceof X509Certificate, then its encoded form is retrieved and compared with the encoded form of this certificate.

Parameters:

other - the object to test for equality with this certificate.

Returns:

true iff the encoded forms of the two certificates match, false otherwise.

hashCode

public int hashCode()

Returns a hashcode value for this certificate from its encoded form.

Returns:

the hashcode value.

toString

public String toString()