Added in API level 1

Key

interface Key : Serializable

java.security.Key

Known Direct Subclasses

PrivateKey, PublicKey, SecretKey

PrivateKey	A private key.
PublicKey	A public key.
SecretKey	A secret (symmetric) key.

Known Indirect Subclasses

DHPrivateKey, DHPublicKey, DSAPrivateKey, DSAPublicKey, ECPrivateKey, ECPublicKey, EdECPrivateKey, EdECPublicKey, PBEKey, RSAMultiPrimePrivateCrtKey, RSAPrivateCrtKey, RSAPrivateKey, and 4 others.

DHPrivateKey	The interface to a Diffie-Hellman private key.
DHPublicKey	The interface to a Diffie-Hellman public key.
DSAPrivateKey	The standard interface to a DSA private key.
DSAPublicKey	The interface to a DSA public key.
ECPrivateKey	The interface to an elliptic curve (EC) private key.
ECPublicKey	The interface to an elliptic curve (EC) public key.
EdECPrivateKey	An interface for an elliptic curve private key as defined by RFC 8032: Edwards-Curve Digital Signature Algorithm (EdDSA).
EdECPublicKey	An interface for an elliptic curve public key as defined by RFC 8032: Edwards-Curve Digital Signature Algorithm (EdDSA).
PBEKey	The interface to a PBE key.
RSAMultiPrimePrivateCrtKey	The interface to an RSA multi-prime private key, as defined in the PKCS#1 v2.2 standard, using the Chinese Remainder Theorem (CRT) information values.
RSAPrivateCrtKey	The interface to an RSA private key, as defined in the PKCS#1 v2.2 standard, using the Chinese Remainder Theorem (CRT) information values.
RSAPrivateKey	The interface to an RSA private key.
RSAPublicKey	The interface to an RSA public key.
SecretKeySpec	This class specifies a secret key in a provider-independent fashion.
XECPrivateKey	An interface for an elliptic curve private key as defined by RFC 7748.
XECPublicKey	An interface for an elliptic curve public key as defined by RFC 7748.

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 Serialization Specification for more information.

Summary

Constants
static Long	`serialVersionUID` The class fingerprint that is set to indicate serialization compatibility with a previous version of the class.

Public methods
abstract String!	`getAlgorithm()` Returns the standard algorithm name for this key.
abstract ByteArray!	`getEncoded()` Returns the key in its primary encoding format, or null if this key does not support encoding.
abstract String!	`getFormat()` Returns the name of the primary encoding format of this key, or null if this key does not support encoding.

Constants

serialVersionUID

Added in API level 1
Deprecated in API level 34

static val serialVersionUID: Long

Deprecated: A serialVersionUID field in an interface is ineffectual. Do not use; no replacement.

The class fingerprint that is set to indicate serialization compatibility with a previous version of the class.

Value: 6603384152749567654L

Public methods

getAlgorithm

Added in API level 1

abstract fun getAlgorithm(): String!

Returns the standard algorithm name for this key. For example, "DSA" would indicate that this key is a DSA key. See the key related sections (KeyFactory, KeyGenerator, KeyPairGenerator, and SecretKeyFactory) in the Java Security Standard Algorithm Names Specification for information about standard key algorithm names.

Return
`String!`	the name of the algorithm associated with this key.

getEncoded

Added in API level 1

abstract fun getEncoded(): ByteArray!

Returns the key in its primary encoding format, or null if this key does not support encoding.

Return
`ByteArray!`	the encoded key, or null if the key does not support encoding.

getFormat

Added in API level 1

abstract fun getFormat(): String!

Returns the name of the primary encoding format of this key, or null if this key does not support encoding. The primary encoding format is named in terms of the appropriate ASN.1 data format, if an ASN.1 specification for this key exists. For example, the name of the ASN.1 data format for public keys is SubjectPublicKeyInfo, as defined by the X.509 standard; in this case, the returned format is "X.509". Similarly, the name of the ASN.1 data format for private keys is PrivateKeyInfo, as defined by the PKCS #8 standard; in this case, the returned format is "PKCS#8".

Return
`String!`	the primary encoding format of the key.