crypto
Class PublicEncryptor

java.lang.Object
  crypto.PublicEncryptor

public class PublicEncryptor
extends java.lang.Object

Implements public part of the asymmetric cipher (with public key) used to send encrypted local secret key (used for symmetric ciphering of peer-to-peer datagram packets) to remote peer. The class holds also list of authorized public keys, which is used to verify signed objects received from peers.

Author:

Mikica B Kocic

Field Summary

private static java.util.ArrayList<NamedPublicKey>	authorizedKeys Authorized public keys (loaded from file)
private static java.lang.String	authorizedKeysFile The name of the file holding authorized public keys of remote peers
private javax.crypto.Cipher	cipher Instance of the encrypting engine based on remote public key
private static java.lang.String	digest Message digest used for creating/validating signatures
private static java.lang.String	padding Padding to be used when ciphering/deciphering JCE does not support RSA/CBC so the CBC mode is built on the top of ECB in PublicEncryptor.encrypt().
private java.security.PublicKey	publicKey Public key
private java.lang.String	serializedPublicKey Remote public key: serialized and encoded as Base64 string.
private java.lang.String	verificator Contains name of the verificator (i.e the name associated with authorized public key that has verified this public key).

Constructor Summary

PublicEncryptor(java.lang.String serializedPublicKey, java.lang.String remoteUserId)
Deserializes public key from the Base64 string and instantiates PublicEncryptor.

Method Summary

private static void	createEmptyAuthorizedPublicKeys(java.lang.String filename) Create empty authorized keys file if it does not exist and adjust permissions.
byte[]	encrypt(byte[] plainText) Encrypts plain text using public key.
java.lang.String	encryptAndSerialize(java.io.Serializable object) Returns Base64 of encrypted (using our public key) object.
java.lang.String	getVerificatorName() Returns if name of the verificator from authorized keys that verified this public key
boolean	isActive() Returns if cipher is properly initialized
boolean	isVerified() Returns if public key was verified
static void	loadAuthorizedPublicKeys() Loads authorized keys
static java.lang.String	verifyObject(java.security.SignedObject object) Verifies signed object with a public key from the authorized public keys

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

padding

private static final java.lang.String padding

Padding to be used when ciphering/deciphering JCE does not support RSA/CBC so the CBC mode is built on the top of ECB in PublicEncryptor.encrypt().

See Also:

Constant Field Values

digest

private static final java.lang.String digest

Message digest used for creating/validating signatures

See Also:

Constant Field Values

authorizedKeysFile

private static final java.lang.String authorizedKeysFile

The name of the file holding authorized public keys of remote peers

See Also:

Constant Field Values

authorizedKeys

private static java.util.ArrayList<NamedPublicKey> authorizedKeys

Authorized public keys (loaded from file)

publicKey

private java.security.PublicKey publicKey

Public key

cipher

private javax.crypto.Cipher cipher

Instance of the encrypting engine based on remote public key

serializedPublicKey

private java.lang.String serializedPublicKey

Remote public key: serialized and encoded as Base64 string.

verificator

private java.lang.String verificator

Contains name of the verificator (i.e the name associated with authorized public key that has verified this public key). Not null indicates that the public key was successfully verified.

Constructor Detail

PublicEncryptor

public PublicEncryptor(java.lang.String serializedPublicKey,
                       java.lang.String remoteUserId)

Deserializes public key from the Base64 string and instantiates PublicEncryptor. Verifies public key with the public key retrieved from the authorized keys.

Method Detail

createEmptyAuthorizedPublicKeys

private static void createEmptyAuthorizedPublicKeys(java.lang.String filename)

Create empty authorized keys file if it does not exist and adjust permissions.

loadAuthorizedPublicKeys

public static void loadAuthorizedPublicKeys()

Loads authorized keys

verifyObject

public static java.lang.String verifyObject(java.security.SignedObject object)

Verifies signed object with a public key from the authorized public keys

Returns:

not null if verified with the name associated to authorized public key

isActive

public boolean isActive()

Returns if cipher is properly initialized

isVerified

public boolean isVerified()

Returns if public key was verified

getVerificatorName

public java.lang.String getVerificatorName()

Returns if name of the verificator from authorized keys that verified this public key

Returns:

name of the verificator; May be null indicating not verified public key

encrypt

public byte[] encrypt(byte[] plainText)

Encrypts plain text using public key. Emulates CBC (cipher-block chaining) using plain ECB. Why? -- Because JCE does not support RSA/CBC cipher (only RSA/ECB). See Cipher-block chaining (CBC) \image html cbc_encryption.png

See Also:

AsymmetricCipher.decrypt(byte[])

encryptAndSerialize

public java.lang.String encryptAndSerialize(java.io.Serializable object)

Returns Base64 of encrypted (using our public key) object.