Module java.base
Package java.security.cert

# Class Certificate

java.lang.Object
java.security.cert.Certificate

All Implemented Interfaces:
  `Serializable`

Direct Known Subclasses:
  `X509Certificate`

public abstract class Certificate extends Object implements Serializable

Abstract class for managing a variety of identity certificates. An identity certificate is a binding of a principal to a public key which is vouched for by another principal. (A principal represents an entity such as an individual user, a group, or a corporation.)

This class is an abstraction for certificates that have different formats but important common uses. For example, different types of certificates, such as X.509 and PGP, share general certificate functionality (like encoding and verifying) and some types of information (like a public key).

X.509, PGP, and SDSI certificates can all be implemented by subclassing the Certificate class, even though they contain different sets of information, and they store and retrieve the information in different ways.

Since:
  1.2
See Also:
  - `X509Certificate`
  - `CertificateFactory`
  - Serialized Form

## Nested Class Summary

Nested Classes
Modifier and Type
Class
Description
`protected static class`
`Certificate.CertificateRep`
Alternate Certificate class for serialization.

## Constructor Summary

Constructors
Modifier
Constructor
Description
`protected`
`Certificate(String type)`
Creates a certificate of the specified type.

## Method Summary

Modifier and Type
Method
Description
`boolean`
`equals(Object other)`
Compares this certificate for equality with the specified object.
`abstract byte[]`
`getEncoded()`
Returns the encoded form of this certificate.
`abstract PublicKey`
`getPublicKey()`
Gets the public key from this certificate.
`final String`
`getType()`
Returns the type of this certificate.
`int`
`hashCode()`
Returns a hashcode value for this certificate from its encoded form.
`abstract String`
`toString()`
Returns a string representation of this certificate.
`abstract void`
`verify(PublicKey key)`
Verifies that this certificate was signed using the private key that corresponds to the specified public key.
`abstract void`
`verify(PublicKey key, String sigProvider)`
Verifies that this certificate was signed using the private key that corresponds to the specified public key.
`void`
`verify(PublicKey key, Provider sigProvider)`
Verifies that this certificate was signed using the private key that corresponds to the specified public key.
`protected Object`
`writeReplace()`
Replace the Certificate to be serialized.

### Methods declared in class java.lang.Object

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

## Constructor Details

### Certificate

protected Certificate(String type)
Creates a certificate of the specified type.

Parameters:
  `type` - the standard name of the certificate type. See the CertificateFactory section in the Java Security Standard Algorithm Names Specification for information about standard certificate types.

## Method Details

### getType

public final String getType()
Returns the type of this certificate.

Returns:
  the type of this certificate.

### equals

public boolean equals(Object other)
Compares this certificate for equality with the specified object. If the `other` object is an `instanceof` `Certificate`, then its encoded form is retrieved and compared with the encoded form of this certificate.

Overrides:
  `equals` in class `Object`
Parameters:
  `other` - the object to test for equality with this certificate.
Returns:
  true iff the encoded forms of the two certificates match, false otherwise.
See Also:
  - `Object.hashCode()`
  - `HashMap`

### hashCode

public int hashCode()
Returns a hashcode value for this certificate from its encoded form.

Overrides:
  `hashCode` in class `Object`
Returns:
  the hashcode value.
See Also:
  - `Object.equals(java.lang.Object)`
  - `System.identityHashCode(java.lang.Object)`

### getEncoded

public abstract byte[] getEncoded() throws CertificateEncodingException
Returns the encoded form of this certificate. It is assumed that each certificate type would have only a single form of encoding; for example, X.509 certificates would be encoded as ASN.1 DER.

Returns:
  the encoded form of this certificate
Throws:
  `CertificateEncodingException` - if an encoding error occurs.

### verify

public abstract 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 abstract 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.

### verify

public void verify(PublicKey key, Provider sigProvider) throws CertificateException, NoSuchAlgorithmException, InvalidKeyException, 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. Note that the specified Provider object does not have to be registered in the provider list.

This method was added to version 1.8 of the Java Platform Standard Edition. In order to maintain backwards compatibility with existing service providers, this method cannot be `abstract` and by default throws an `UnsupportedOperationException`.

Parameters:
  `key` - the PublicKey used to carry out the verification.
  `sigProvider` - the signature provider.
Throws:
  `NoSuchAlgorithmException` - on unsupported signature algorithms.
  `InvalidKeyException` - on incorrect key.
  `SignatureException` - on signature errors.
  `CertificateException` - on encoding errors.
  `UnsupportedOperationException` - if the method is not supported
Since:
  1.8

### toString

public abstract String toString()
Returns a string representation of this certificate.

Overrides:
  `toString` in class `Object`
Returns:
  a string representation of this certificate.

### getPublicKey

public abstract PublicKey getPublicKey()
Gets the public key from this certificate.

Returns:
  the public key.

### writeReplace

protected Object writeReplace() throws ObjectStreamException
Replace the Certificate to be serialized.

Returns:
  the alternate Certificate object to be serialized
Throws:
  `ObjectStreamException` - if a new object representing this Certificate could not be created
Since:
  1.3