java.security.interfaces
Interface RSAPublicKey

All Known Implementing Classes:

RSAPublicKey

public interface RSAPublicKey

extends PublicKey

Interface to be implemented for supporting RSA public keys.

Attention: This is not a SUN implementation!

This class has been developed by IAIK according to the documentation publically available.
For SUNīs documentation of this class see http://java.sun.com/security/JCE1.2/earlyaccess/javax.crypto.interfaces.RSAPublicKey.html

PKCS#1 describes a X.509/PEM compatible syntax for RSA public keys to be used in certificates. The corresponding ASN.1 type RSAPublicKey is defined as ASN.1 SEQUENCE:

 RSAPublicKey ::= SEQUENCE {
   modulus INTEGER, -- n
   publicExponent INTEGER -- e }
 

An application wishing to create a RSAPublicKey to be used for, e.g. data encryption or signature verifying with the RSA algorithm, uses a proper getInstance method of the java.security.KeyPairGenerator class, which subsequently maybe casted to RSAKeyPairGenerator for performing an algorithm-specific initialization with proper RSA parameters. If an algorithm-specific initialization is not required, the cast to RSAKeyPairGenerator can be omitted.

Generally four steps have to be performed for creating a RSAPublicKey by using a proper KeyPairGenerator:

• First the KeyPairGenerator has to be instantiated thereby specifying the applicationīs intention to create keys for use within the RSA algorithm:

   KeyPairGenerator key_gen = KeyPairGenerator.getInstance("RSA");
   

• Second, the KeyPairGenerator just created may be initialized using a proper initialize method. For initializing the generator to create keys with a modulus length of, e.g., 512 bits, this can be explicitly specified (when not initializing the generator explicitly, per default the modulus length is set to 1024 bits):

   key_gen.initialize(512);
   

• Third the key pair is created by calling generateKeyPair():

   KeyPair key_pair = key_gen.generateKeyPair();
   

• And finally, if there is need for the RSA public key, it has to be obtained from the key pair just created:

   RSAPublicKey rsa_pub_key = (RSAPublicKey)key_pair.getPublic();
   

For performing an algorithm-specific initialization with particular RSA parameters (e.g. using a particular public exponent e), an explicit cast of the KeyPairGenerator will be necessary for obtaining a specific RSAKeyPairGenerator to be initialized with the desired RSA parameters:

 RSAKeyPairGenerator rsa_key_gen = (RSAKeyPairGenerator)key_gen;
 rsa_key_gen.initialize(512, pub_exponent, sec_random);
 

(where sec_random denotes some random seed)

Guidelines on how to create some key using a KeyPairGenerator can be found in http://java.sun.com/products/JDK/1.1/docs/guide/security/CryptoSpec.html.

Fields inherited from interface java.security.PublicKey

serialVersionUID

Fields inherited from interface java.security.Key

serialVersionUID

Method Summary

java.math.BigInteger	getModulus() Returns the modulus n.
java.math.BigInteger	getPublicExponent() Returns the public exponent e.

Methods inherited from interface java.security.Key

getAlgorithm, getEncoded, getFormat

Method Detail

getModulus

public java.math.BigInteger getModulus()

Returns the modulus n.

Returns:

the modulus

getPublicExponent

public java.math.BigInteger getPublicExponent()

Returns the public exponent e.