KeyStore (Java Platform SE 7 ) (original) (raw)

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 relying on the default type and providing a specific keystore type.

• 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 beloaded.

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

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

java.io.FileInputStream fis = null;
try {
    fis = new java.io.FileInputStream("keyStoreName");
    ks.load(fis, password);
} finally {
    if (fis != null) {
        fis.close();
    }
}

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.ProtectionParameter protParam =
    new KeyStore.PasswordProtection(password);

// 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
java.io.FileOutputStream fos = null;
try {
    fos = new java.io.FileOutputStream("newKeyStoreName");
    ks.store(fos, password);
} finally {
    if (fos != null) {
        fos.close();
    }
}

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 Cryptography Architecture Standard Algorithm Name Documentation. Consult the release documentation for your implementation to see if any other types are supported.