OpenCard  
 
OCF, the OpenCard Framework is a standard Java framework for working with Smart Cards.  
 

com.ibm.opencard.access
Class DESSecureCredential

java.lang.Object
  |
  +--com.ibm.opencard.access.DESSignCredential
        |
        +--com.ibm.opencard.access.DESSecureCredential
public final class DESSecureCredential
extends DESSignCredential
implements SecureCredential

A DES credential to be provided by applications for MFC smartcards. A DES credential can be thought of as a DES algorithm with a fixed key.

Version:
$Id: DESSecureCredential.java,v 1.1 1999/12/02 16:05:59 damke Exp $

Fields inherited from class com.ibm.opencard.access.DESSignCredential
des_algorithm, des_key
 
Constructor Summary
DESSecureCredential(DESKey key)
          Creates a new DES credential from a key.
DESSecureCredential(java.lang.String key)
          Creates a new DES credential from a hex dump of the key.
 
Method Summary
 void decryptChained(byte[] data, int offset, int length)
          Decrypts a series of data blocks in CBC mode.
 void encryptChained(byte[] data, int offset, int length)
          Encrypts a series of data blocks in CBC mode.
 byte[] finishMAC(byte[] data)
          Finishes a MAC computation and returns the message authentication code.
 byte[] getStrongRandom()
          Returns a random number.
static byte[] parseDESKey(java.lang.String data)
          Converts a string encoded DES key into a byte array.
 void setICV(byte[] icv)
          Sets an initial chaining value (ICV).
 void setRNG(java.util.Random rng)
          Specifies the random number generator (RNG) to be used.
static java.lang.String toHexDump(byte[] data)
          Returns a hex dump of a byte array.
 java.lang.String toString()
          Returns a human-readable string representation of this credential.
 void updateMAC(byte[] data)
          Passes one data block of a multi-block message to compute a MAC for.
 
Methods inherited from class com.ibm.opencard.access.DESSignCredential
getInputLength, sign
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

DESSecureCredential

public DESSecureCredential(DESKey key)
Creates a new DES credential from a key.
Parameters:
key - the DES key to encapsulate
Throws:
java.lang.NumberFormatException - if the argument could not be parsed as a DES key

DESSecureCredential

public DESSecureCredential(java.lang.String key)
                    throws java.lang.NumberFormatException
Creates a new DES credential from a hex dump of the key.
Parameters:
key - the DES key as a hex dump
Throws:
java.lang.NumberFormatException - if the argument could not be parsed as a DES key
Method Detail

setRNG

public final void setRNG(java.util.Random rng)
Specifies the random number generator (RNG) to be used. The RNG is required by getStrongRandom, in cases where the application needs to provide a random challenge to the smartcard.
By default, java.security.SecureRandom will be instantiated on first use. Since it takes about 10 seconds to create the first instance of that class, this method can be used to provide another RNG.
Note: The generation of random challenges is important for security. The random number generator should therefore generate cryptographically strong random numbers.
Parameters:
rng - a cryptographically strong random number generator

getStrongRandom

public byte[] getStrongRandom()
Returns a random number. See setRandomGenerator for information on the random number generator. If none has been provided, an instance of java.security.SecureRandom will be used to generate cryptographically strong random numbers.
Specified by:
getStrongRandom in interface SecureCredential
Returns:
an 8 byte random number

setICV

public void setICV(byte[] icv)
Sets an initial chaining value (ICV). Chaining values are needed for DES CBC encryption and decryption as well as for MAC computation. Only one chaining value is stored in a credential, so only one of these operations can be performed at any time. Each operation starts with an invocation of this method.
Specified by:
setICV in interface SecureCredential
Parameters:
icv - the initial chaining value to use for subsequent computations
See Also:
encryptChained(byte[], int, int), decryptChained(byte[], int, int), updateMAC(byte[]), finishMAC(byte[])

encryptChained

public void encryptChained(byte[] data,
                           int offset,
                           int length)
Encrypts a series of data blocks in CBC mode. The initial chaining value must have been set before invoking this method.
Specified by:
encryptChained in interface SecureCredential
Parameters:
data - the array holding the data to encrypt
offset - the index of the first byte to encrypt
length - the number of bytes to encrypt
See Also:
setICV

decryptChained

public void decryptChained(byte[] data,
                           int offset,
                           int length)
Decrypts a series of data blocks in CBC mode. The initial chaining value must have been set before invoking this method.
Specified by:
decryptChained in interface SecureCredential
Parameters:
data - the array holding the data to decrypt
offset - the index of the first byte to decrypt
length - the number of bytes to decrypt
See Also:
setICV(byte[]), encryptChained(byte[], int, int)

updateMAC

public final void updateMAC(byte[] data)
Passes one data block of a multi-block message to compute a MAC for.
Specified by:
updateMAC in interface SecureCredential
Parameters:
data - the next data block in the message to compute a MAC for
See Also:
finishMAC(byte[]), setICV(byte[])

finishMAC

public final byte[] finishMAC(byte[] data)
Finishes a MAC computation and returns the message authentication code.
Specified by:
finishMAC in interface SecureCredential
Parameters:
data - the last block of the message to compute the MAC for
Returns:
the MAC for the complete message
See Also:
updateMAC(byte[]), setICV(byte[])

toString

public java.lang.String toString()
Returns a human-readable string representation of this credential.
Returns:
a string describing this credential
Overrides:
toString in class java.lang.Object

parseDESKey

public static byte[] parseDESKey(java.lang.String data)
                          throws java.lang.NumberFormatException
Converts a string encoded DES key into a byte array. The string holds the key data as a sequence of 16 hex digits for DES, or 32 hex digits for triple DES, optionally prefixed by 0x or 0X. In the case of a triple DES key, the first 16 digits specify the key for the encryptions in phase 1 and 3, while the remaining 16 digits specify the key for the decryption in phase 2.
Parameters:
data - the key data in a string encoding
Returns:
the key data in a byte array, or null if parsing failed

toHexDump

public static java.lang.String toHexDump(byte[] data)
Returns a hex dump of a byte array.
Parameters:
data - the byte array to hexdump
Returns:
a string holding the hexdump