This class represents a storage facility for cryptographic keys and certificates.

A KeyStore manages different types of entries. Each type of entry implements the KeyStore.Entry interface. Three basic KeyStore.Entry implementations are provided:

• KeyStore.PrivateKeyEntry

  This type of entry holds a cryptographic PrivateKey, which is optionally stored in a protected format to prevent unauthorized access. It is also accompanied by a certificate chain for the corresponding public key.

  Private keys and certificate chains are used by a given entity for self-authentication. Applications for this authentication include software distribution organizations which sign JAR files as part of releasing and/or licensing software.

• KeyStore.SecretKeyEntry

  This type of entry holds a cryptographic SecretKey, which is optionally stored in a protected format to prevent unauthorized access.

• KeyStore.TrustedCertificateEntry

  This type of entry contains a single public key Certificate belonging to another party. It is called a trusted certificate because the keystore owner trusts that the public key in the certificate indeed belongs to the identity identified by the subject (owner) of the certificate.

  This type of entry can be used to authenticate other parties.

Each entry in a keystore is identified by an "alias" string. In the case of private keys and their associated certificate chains, these strings distinguish among the different ways in which the entity may authenticate itself. For example, the entity may authenticate itself using different certificate authorities, or using different public key algorithms.

Whether aliases are case-sensitive is implementation dependent. In order to avoid problems, it is recommended not to use aliases in a KeyStore that only differ in case.

Whether keystores are persistent, and the mechanisms used by the keystore if it is persistent, are not specified here. This allows use of a variety of techniques for protecting sensitive (e.g., private or secret) keys. Smart cards or other integrated cryptographic engines (SafeKeyper) are one option, and simpler mechanisms such as files may also be used (in a variety of formats).

Typical ways to request a KeyStore object include specifying an existing keystore file, relying on the default type and providing a specific keystore type.

• To specify an existing keystore file:

      // get keystore password
      char[] password = getPassword();
  
      // probe the keystore file and load the keystore entries
      KeyStore ks = KeyStore.getInstance(new File("keyStoreName"), password);
  

  The system will probe the specified file to determine its keystore type and return a keystore implementation with its entries already loaded. When this approach is used there is no need to call the keystore's load method.
• To rely on the default type:

      KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());
   

  The system will return a keystore implementation for the default type.
• To provide a specific keystore type:

        KeyStore ks = KeyStore.getInstance("JKS");
   

  The system will return the most preferred implementation of the specified keystore type available in the environment.

Before a keystore can be accessed, it must be loaded (unless it was already loaded during instantiation).

    KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());

    // get user password and file input stream
    char[] password = getPassword();

    try (FileInputStream fis = new FileInputStream("keyStoreName")) {
        ks.load(fis, password);
    }
 

To create an empty keystore using the above load method, pass null as the InputStream argument.

Once the keystore has been loaded, it is possible to read existing entries from the keystore, or to write new entries into the keystore:

    KeyStore.PasswordProtection protParam =
        new KeyStore.PasswordProtection(password);
    try (FileOutputStream fos = new FileOutputStream("newKeyStoreName")) {
        // get my private key
        KeyStore.PrivateKeyEntry pkEntry = (KeyStore.PrivateKeyEntry)
            ks.getEntry("privateKeyAlias", protParam);
        PrivateKey myPrivateKey = pkEntry.getPrivateKey();

        // save my secret key
        javax.crypto.SecretKey mySecretKey;
        KeyStore.SecretKeyEntry skEntry =
            new KeyStore.SecretKeyEntry(mySecretKey);
        ks.setEntry("secretKeyAlias", skEntry, protParam);

        // store away the keystore
        ks.store(fos, password);
    } finally {
        protParam.destroy();
    }
 

Note that although the same password may be used to load the keystore, to protect the private key entry, to protect the secret key entry, and to store the keystore (as is shown in the sample code above), different passwords or other protection parameters may also be used.

Every implementation of the Java platform is required to support the following standard KeyStore type:

• PKCS12

This type is described in the KeyStore section of the Java Security Standard Algorithm Names Specification. Consult the release documentation for your implementation to see if any other types are supported.