Certificate (Java Platform SE 8 )
Keywords: java.security.cert.Certificate class
Date: 2020-03-26

compact1, compact2, compact3
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.

  See Also:
    `X509Certificate`, `CertificateFactory`, Serialized Form

- - ### Nested Class Summary

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

  - ### Constructor Summary

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

  - ### Method Summary

    All Methods Instance Methods Abstract Methods Concrete Methods
    Modifier and Type | Method and 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.
    `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.
    `void` | `verify(PublicKey key, Provider sigProvider)` 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.
    `protected Object` | `writeReplace()` Replace the Certificate to be serialized.

    - ### Methods inherited from class java.lang.Object

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

- - ### Constructor Detail

    - #### 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 Cryptography Architecture Standard Algorithm Name Documentation for information about standard certificate types.

  - ### Method Detail

    - #### 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

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