API java : SecretKeySpec

javax.crypto.spec
Class SecretKeySpec

java.lang.Object
  javax.crypto.spec.SecretKeySpec

All Implemented Interfaces:

Serializable, Key, KeySpec, SecretKey

public class SecretKeySpec
extends Object
implements KeySpec, SecretKey

This class specifies a secret key in a provider-independent fashion.

It can be used to construct a SecretKey from a byte array, without having to go through a (provider-based) SecretKeyFactory.

This class is only useful for raw secret keys that can be represented as a byte array and have no key parameters associated with them, e.g., DES or Triple DES keys.

Since:

1.4

See Also:

SecretKey, SecretKeyFactory, Serialized Form

Field Summary

 

Fields inherited from interface javax.crypto.SecretKey
serialVersionUID

 

Constructor Summary
SecretKeySpec(byte[] key, int offset, int len, String algorithm)           Constructs a secret key from the given byte array, using the first len bytes of key, starting at offset inclusive.
SecretKeySpec(byte[] key, String algorithm)           Constructs a secret key from the given byte array.

 

Method Summary
boolean	equals(Object obj)           Tests for equality between the specified object and this object.
String	getAlgorithm()           Returns the name of the algorithm associated with this secret key.
byte[]	getEncoded()           Returns the key material of this secret key.
String	getFormat()           Returns the name of the encoding format for this secret key.
int	hashCode()           Calculates a hash code value for the object.

 

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

 

Constructor Detail

SecretKeySpec

public SecretKeySpec(byte[] key,
                    
                    
                    
                    
                    
                     String algorithm)

Constructs a secret key from the given byte array.

This constructor does not check if the given bytes indeed specify a secret key of the specified algorithm. For example, if the algorithm is DES, this constructor does not check if key is 8 bytes long, and also does not check for weak or semi-weak keys. In order for those checks to be performed, an algorithm-specific key specification class (in this case: DESKeySpec) should be used.

Parameters:

key - the key material of the secret key. The contents of the array are copied to protect against subsequent modification.

algorithm - the name of the secret-key algorithm to be associated with the given key material. See Appendix A in the Java Cryptography Extension Reference Guide for information about standard algorithm names.

Throws:

IllegalArgumentException - if algorithm is null or key is null or empty.

SecretKeySpec

public SecretKeySpec(byte[] key,
                     int offset,
                     int len,
                    
                    
                    
                    
                    
                     String algorithm)

Constructs a secret key from the given byte array, using the first len bytes of key, starting at offset inclusive.

The bytes that constitute the secret key are those between key[offset] and key[offset+len-1] inclusive.

This constructor does not check if the given bytes indeed specify a secret key of the specified algorithm. For example, if the algorithm is DES, this constructor does not check if key is 8 bytes long, and also does not check for weak or semi-weak keys. In order for those checks to be performed, an algorithm-specific key specification class (in this case: DESKeySpec) must be used.

Parameters:

key - the key material of the secret key. The first len bytes of the array beginning at offset inclusive are copied to protect against subsequent modification.

offset - the offset in key where the key material starts.

len - the length of the key material.

algorithm - the name of the secret-key algorithm to be associated with the given key material. See Appendix A in the Java Cryptography Extension Reference Guide for information about standard algorithm names.

Throws:

IllegalArgumentException - if algorithm is null or key is null, empty, or too short, i.e. key.length-offset < len.

ArrayIndexOutOfBoundsException - is thrown if offset or len index bytes outside the key.

getAlgorithm

public String getAlgorithm()

Returns the name of the algorithm associated with this secret key.

Specified by:

getAlgorithm in interface Key

Returns:

the secret key algorithm.

getFormat

public String getFormat()

Returns the name of the encoding format for this secret key.

Specified by:

getFormat in interface Key

Returns:

the string "RAW".

getEncoded

public byte[] getEncoded()

Returns the key material of this secret key.

Specified by:

getEncoded in interface Key

Returns:

the key material. Returns a new array each time this method is called.

hashCode

public int hashCode()

Calculates a hash code value for the object. Objects that are equal will also have the same hashcode.

Overrides:

hashCode in class Object

Returns:

a hash code value for this object.

See Also:

Object.equals(java.lang.Object), Hashtable

equals

public boolean equals(Object obj)

Tests for equality between the specified object and this object. Two SecretKeySpec objects are considered equal if they are both SecretKey instances which have the same case-insensitive algorithm name and key encoding.

Overrides:

equals in class Object

Parameters:

obj - the object to test for equality with this object.

Returns:

true if the objects are considered equal, false if obj is null or otherwise.

See Also:

Object.hashCode(), Hashtable