The Key interface is the top-level interface for all keys. It defines the functionality shared by all Key objects. All keys have three characteristics:

• An Algorithm

  This is the key algorithm for that key. The key algorithm is usually an encryption or asymmetric operation algorithm (such as DSA or RSA), which will work with those algorithms and with related algorithms (such as MD5 with RSA, SHA-1 with RSA, Raw DSA, etc.) The name of the algorithm of a key is obtained using the getAlgorithm method.

• An Encoded Form

  This is an external encoded form for the key used when a standard representation of the key is needed outside the Java Virtual Machine, as when transmitting the key to some other party. The key is encoded according to a standard format (such as X.509 SubjectPublicKeyInfo or PKCS#8), and is returned using the getEncoded method.

  Note

  The syntax of the ASN.1 type SubjectPublicKeyInfo is defined as follows:

  SubjectPublicKeyInfo ::= SEQUENCE {
    algorithm AlgorithmIdentifier,
    subjectPublicKey BIT STRING }
  
  AlgorithmIdentifier ::= SEQUENCE {
    algorithm OBJECT IDENTIFIER,
    parameters ANY DEFINED BY algorithm OPTIONAL }
  

  For more information, see RFC 5280: Internet X.509 Public Key Infrastructure Certificate and CRL Profile.
• A Format

  This is the name of the format of the encoded key. It is returned by the getFormat method.

Keys are generally obtained through key generators, certificates, key stores or other classes used to manage keys. Keys may also be obtained from key specifications (transparent representations of the underlying key material) through the use of a key factory (see KeyFactory).

A Key should use KeyRep as its serialized representation. Note that a serialized Key may contain sensitive information which should not be exposed in untrusted environments. See the Security Appendix of the Java Object Serialization Specification for more information.