Cipher

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javacardx.crypto
Class Cipher

java.lang.Object
  extended by javacardx.crypto.Cipher
Direct Known Subclasses:
AssymetricCipherImpl, SymmetricCipherImpl
public abstract class Cipher
extends Object

The Cipher class is the abstract base class for Cipher algorithms. Implementations of Cipher algorithms must extend this class and implement all the abstract methods.

The term "pad" is used in the public key cipher algorithms below to refer to all the operations specified in the referenced scheme to transform the message block into the cipher block size.

The asymmetric key algorithms encrypt using either a public key (to cipher) or a private key (to sign). In addition they decrypt using the either a private key (to decipher) or a public key (to verify).

A tear or card reset event resets an initialized Cipher object to the state it was in when previously initialized via a call to init(). For algorithms which support keys with transient key data sets, such as DES, triple DES and AES, the Cipher object key becomes uninitialized on clear events associated with the Key object used to initialize the Cipher object.

Even if a transaction is in progress, update of intermediate result state in the implementation instance shall not participate in the transaction.

Note:

  • On a tear or card reset event, the AES, DES, and triple DES algorithms in CBC mode reset the initial vector(IV) to 0. The initial vector(IV) can be re-initialized using the init(Key, byte, byte[], short, short) method.

Field Summary
static byte ALG_AES_BLOCK_128_CBC_NOPAD
          Cipher algorithm ALG_AES_BLOCK_128_CBC_NOPAD provides a cipher using AES with block size 128 in CBC mode and does not pad input data.
static byte ALG_AES_BLOCK_128_ECB_NOPAD
          Cipher algorithm ALG_AES_BLOCK_128_ECB_NOPAD provides a cipher using AES with block size 128 in ECB mode and does not pad input data.
static byte ALG_DES_CBC_ISO9797_M1
          Cipher algorithm ALG_DES_CBC_ISO9797_M1 provides a cipher using DES in CBC mode or triple DES in outer CBC mode, and pads input data according to the ISO 9797 method 1 scheme.
static byte ALG_DES_CBC_ISO9797_M2
          Cipher algorithm ALG_DES_CBC_ISO9797_M2 provides a cipher using DES in CBC mode or triple DES in outer CBC mode, and pads input data according to the ISO 9797 method 2 (ISO 7816-4, EMV'96) scheme.
static byte ALG_DES_CBC_NOPAD
          Cipher algorithm ALG_DES_CBC_NOPAD provides a cipher using DES in CBC mode or triple DES in outer CBC mode, and does not pad input data.
static byte ALG_DES_CBC_PKCS5
          Cipher algorithm ALG_DES_CBC_PKCS5 provides a cipher using DES in CBC mode or triple DES in outer CBC mode, and pads input data according to the PKCS#5 scheme.
static byte ALG_DES_ECB_ISO9797_M1
          Cipher algorithm ALG_DES_ECB_ISO9797_M1 provides a cipher using DES in ECB mode, and pads input data according to the ISO 9797 method 1 scheme.
static byte ALG_DES_ECB_ISO9797_M2
          Cipher algorithm ALG_DES_ECB_ISO9797_M2 provides a cipher using DES in ECB mode, and pads input data according to the ISO 9797 method 2 (ISO 7816-4, EMV'96) scheme.
static byte ALG_DES_ECB_NOPAD
          Cipher algorithm ALG_DES_ECB_NOPAD provides a cipher using DES in ECB mode, and does not pad input data.
static byte ALG_DES_ECB_PKCS5
          Cipher algorithm ALG_DES_ECB_PKCS5 provides a cipher using DES in ECB mode, and pads input data according to the PKCS#5 scheme.
static byte ALG_RSA_ISO14888
          Cipher algorithm ALG_RSA_ISO14888 provides a cipher using RSA, and pads input data according to the ISO 14888 scheme.
static byte ALG_RSA_ISO9796
          This Cipher algorithm ALG_RSA_ISO9796 should not be used.
static byte ALG_RSA_NOPAD
          Cipher algorithm ALG_RSA_NOPAD provides a cipher using RSA and does not pad input data.
static byte ALG_RSA_PKCS1
          Cipher algorithm ALG_RSA_PKCS1 provides a cipher using RSA, and pads input data according to the PKCS#1 (v1.5) scheme.
static byte ALG_RSA_PKCS1_OAEP
          Cipher algorithm ALG_RSA_PKCS1_OAEP provides a cipher using RSA, and pads input data according to the PKCS#1-OAEP scheme (IEEE 1363-2000).
static byte MODE_DECRYPT
          Used in init() methods to indicate decryption mode.
static byte MODE_ENCRYPT
          Used in init() methods to indicate encryption mode.
 
Constructor Summary
protected Cipher()
          Protected constructor.
 
Method Summary
abstract  short doFinal(byte[] inBuff, short inOffset, short inLength, byte[] outBuff, short outOffset)
          Generates encrypted/decrypted output from all/last input data.
abstract  byte getAlgorithm()
          Gets the Cipher algorithm.
static Cipher getInstance(byte algorithm, boolean externalAccess)
          Creates a Cipher object instance of the selected algorithm.
abstract  void init(Key theKey, byte theMode)
          Initializes the Cipher object with the appropriate Key.
abstract  void init(Key theKey, byte theMode, byte[] bArray, short bOff, short bLen)
          Initializes the Cipher object with the appropriate Key and algorithm specific parameters.
abstract  short update(byte[] inBuff, short inOffset, short inLength, byte[] outBuff, short outOffset)
          Generates encrypted/decrypted output from input data.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

ALG_DES_CBC_NOPAD

public static final byte ALG_DES_CBC_NOPAD
Cipher algorithm ALG_DES_CBC_NOPAD provides a cipher using DES in CBC mode or triple DES in outer CBC mode, and does not pad input data. If the input data is not (8-byte) block aligned it throws CryptoException with the reason code ILLEGAL_USE.

See Also:
Constant Field Values

ALG_DES_CBC_ISO9797_M1

public static final byte ALG_DES_CBC_ISO9797_M1
Cipher algorithm ALG_DES_CBC_ISO9797_M1 provides a cipher using DES in CBC mode or triple DES in outer CBC mode, and pads input data according to the ISO 9797 method 1 scheme.

See Also:
Constant Field Values

ALG_DES_CBC_ISO9797_M2

public static final byte ALG_DES_CBC_ISO9797_M2
Cipher algorithm ALG_DES_CBC_ISO9797_M2 provides a cipher using DES in CBC mode or triple DES in outer CBC mode, and pads input data according to the ISO 9797 method 2 (ISO 7816-4, EMV'96) scheme.

See Also:
Constant Field Values

ALG_DES_CBC_PKCS5

public static final byte ALG_DES_CBC_PKCS5
Cipher algorithm ALG_DES_CBC_PKCS5 provides a cipher using DES in CBC mode or triple DES in outer CBC mode, and pads input data according to the PKCS#5 scheme.

See Also:
Constant Field Values

ALG_DES_ECB_NOPAD

public static final byte ALG_DES_ECB_NOPAD
Cipher algorithm ALG_DES_ECB_NOPAD provides a cipher using DES in ECB mode, and does not pad input data. If the input data is not (8-byte) block aligned it throws CryptoException with the reason code ILLEGAL_USE.

See Also:
Constant Field Values

ALG_DES_ECB_ISO9797_M1

public static final byte ALG_DES_ECB_ISO9797_M1
Cipher algorithm ALG_DES_ECB_ISO9797_M1 provides a cipher using DES in ECB mode, and pads input data according to the ISO 9797 method 1 scheme.

See Also:
Constant Field Values

ALG_DES_ECB_ISO9797_M2

public static final byte ALG_DES_ECB_ISO9797_M2
Cipher algorithm ALG_DES_ECB_ISO9797_M2 provides a cipher using DES in ECB mode, and pads input data according to the ISO 9797 method 2 (ISO 7816-4, EMV'96) scheme.

See Also:
Constant Field Values

ALG_DES_ECB_PKCS5

public static final byte ALG_DES_ECB_PKCS5
Cipher algorithm ALG_DES_ECB_PKCS5 provides a cipher using DES in ECB mode, and pads input data according to the PKCS#5 scheme.

See Also:
Constant Field Values

ALG_RSA_ISO14888

public static final byte ALG_RSA_ISO14888
Cipher algorithm ALG_RSA_ISO14888 provides a cipher using RSA, and pads input data according to the ISO 14888 scheme.

See Also:
Constant Field Values

ALG_RSA_PKCS1

public static final byte ALG_RSA_PKCS1
Cipher algorithm ALG_RSA_PKCS1 provides a cipher using RSA, and pads input data according to the PKCS#1 (v1.5) scheme.

Note:

  • This algorithm is only suitable for messages of limited length. The total number of input bytes processed may not be more than k-11, where k is the RSA key's modulus size in bytes.
  • The encryption block(EB) during encryption with a Public key is built as follows:
      EB = 00 || 02 || PS || 00 || M
          :: M (input bytes) is the plaintext message
          :: PS is an octet string of length k-3-||M|| of pseudo random nonzero octets. The length of PS must be at least 8 octets.
          :: k is the RSA modulus size.
  • The encryption block(EB) during encryption with a Private key (used to compute signatures when the message digest is computed off-card) is built as follows:
      EB = 00 || 01 || PS || 00 || D
          :: D (input bytes) is the DER encoding of the hash computed elsewhere with an algorithm ID prepended if appropriate
          :: PS is an octet string of length k-3-||D|| with value FF. The length of PS must be at least 8 octets.
          :: k is the RSA modulus size.

See Also:
Constant Field Values

ALG_RSA_ISO9796

public static final byte ALG_RSA_ISO9796
This Cipher algorithm ALG_RSA_ISO9796 should not be used. The ISO 9796-1 algorithm was withdrawn by ISO in July 2000.

See Also:
Constant Field Values

ALG_RSA_NOPAD

public static final byte ALG_RSA_NOPAD
Cipher algorithm ALG_RSA_NOPAD provides a cipher using RSA and does not pad input data. If the input data is bounded by incorrect padding bytes while using RSAPrivateCrtKey, incorrect output may result. If the input data is not block aligned it throws CryptoException with the reason code ILLEGAL_USE.

See Also:
Constant Field Values

ALG_AES_BLOCK_128_CBC_NOPAD

public static final byte ALG_AES_BLOCK_128_CBC_NOPAD
Cipher algorithm ALG_AES_BLOCK_128_CBC_NOPAD provides a cipher using AES with block size 128 in CBC mode and does not pad input data. If the input data is not block aligned it throws CryptoException with the reason code ILLEGAL_USE.

See Also:
Constant Field Values

ALG_AES_BLOCK_128_ECB_NOPAD

public static final byte ALG_AES_BLOCK_128_ECB_NOPAD
Cipher algorithm ALG_AES_BLOCK_128_ECB_NOPAD provides a cipher using AES with block size 128 in ECB mode and does not pad input data. If the input data is not block aligned it throws CryptoException with the reason code ILLEGAL_USE.

See Also:
Constant Field Values

ALG_RSA_PKCS1_OAEP

public static final byte ALG_RSA_PKCS1_OAEP
Cipher algorithm ALG_RSA_PKCS1_OAEP provides a cipher using RSA, and pads input data according to the PKCS#1-OAEP scheme (IEEE 1363-2000).

See Also:
Constant Field Values

MODE_DECRYPT

public static final byte MODE_DECRYPT
Used in init() methods to indicate decryption mode.

See Also:
Constant Field Values

MODE_ENCRYPT

public static final byte MODE_ENCRYPT
Used in init() methods to indicate encryption mode.

See Also:
Constant Field Values
Constructor Detail

Cipher

protected Cipher()
Protected constructor.

Method Detail

getInstance

public static final Cipher getInstance(byte algorithm,
                                       boolean externalAccess)
                                throws CryptoException
Creates a Cipher object instance of the selected algorithm.

Parameters:
algorithm - the desired Cipher algorithm. Valid codes listed in ALG_ .. constants above, for example, ALG_DES_CBC_NOPAD
externalAccess - indicates that the instance will be shared among multiple applet instances and that the Cipher instance will also be accessed (via a Shareable interface) when the owner of the Cipher instance is not the currently selected applet. If true the implementation must not allocate CLEAR_ON_DESELECT transient space for internal data.
Returns:
the Cipher object instance of the requested algorithm
Throws:
CryptoException - with the following reason codes:
  • CryptoException.NO_SUCH_ALGORITHM if the requested algorithm is not supported or shared access mode is not supported.

init

public abstract void init(Key theKey,
                          byte theMode)
                   throws CryptoException
Initializes the Cipher object with the appropriate Key. This method should be used for algorithms which do not need initialization parameters or use default parameter values.

init() must be used to update the Cipher object with a new key. If the Key object is modified after invoking the init() method, the behavior of the update() and doFinal() methods is unspecified.

Note:

  • AES, DES, and triple DES algorithms in CBC mode will use 0 for initial vector(IV) if this method is used.

Parameters:
theKey - the key object to use for encrypting or decrypting
theMode - one of MODE_DECRYPT or MODE_ENCRYPT
Throws:
CryptoException - with the following reason codes:
  • CryptoException.ILLEGAL_VALUE if theMode option is an undefined value or if the Key is inconsistent with the Cipher implementation.
  • CryptoException.UNINITIALIZED_KEY if theKey instance is uninitialized.

init

public abstract void init(Key theKey,
                          byte theMode,
                          byte[] bArray,
                          short bOff,
                          short bLen)
                   throws CryptoException
Initializes the Cipher object with the appropriate Key and algorithm specific parameters.

init() must be used to update the Cipher object with a new key. If the Key object is modified after invoking the init() method, the behavior of the update() and doFinal() methods is unspecified.

Note:

  • DES and triple DES algorithms in CBC mode expect an 8-byte parameter value for the initial vector(IV) in bArray.
  • AES algorithms in CBC mode expect a 16-byte parameter value for the initial vector(IV) in bArray.
  • AES algorithms in ECB mode, DES algorithms in ECB mode, RSA and DSA algorithms throw CryptoException.ILLEGAL_VALUE.

Parameters:
theKey - the key object to use for encrypting or decrypting.
theMode - one of MODE_DECRYPT or MODE_ENCRYPT
bArray - byte array containing algorithm specific initialization info
bOff - offset within bArray where the algorithm specific data begins
bLen - byte length of algorithm specific parameter data
Throws:
CryptoException - with the following reason codes:
  • CryptoException.ILLEGAL_VALUE if theMode option is an undefined value or if a byte array parameter option is not supported by the algorithm or if the bLen is an incorrect byte length for the algorithm specific data or if the Key is inconsistent with the Cipher implementation.
  • CryptoException.UNINITIALIZED_KEY if theKey instance is uninitialized.

getAlgorithm

public abstract byte getAlgorithm()
Gets the Cipher algorithm.

Returns:
the algorithm code defined above

doFinal

public abstract short doFinal(byte[] inBuff,
                              short inOffset,
                              short inLength,
                              byte[] outBuff,
                              short outOffset)
                       throws CryptoException
Generates encrypted/decrypted output from all/last input data. This method must be invoked to complete a cipher operation. This method processes any remaining input data buffered by one or more calls to the update() method as well as input data supplied in the inBuff parameter.

A call to this method also resets this Cipher object to the state it was in when previously initialized via a call to init(). That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to init()) more data. In addition, note that the initial vector(IV) used in AES and DES algorithms will be reset to 0.

Notes:

  • When using block-aligned data (multiple of block size), if the input buffer, inBuff and the output buffer, outBuff are the same array, then the output data area must not partially overlap the input data area such that the input data is modified before it is used; if inBuff==outBuff and
    inOffset < outOffset < inOffset+inLength, incorrect output may result.
  • When non-block aligned data is presented as input data, no amount of input and output buffer data overlap is allowed; if inBuff==outBuff and
    outOffset < inOffset+inLength, incorrect output may result.
  • AES, DES, and triple DES algorithms in CBC mode reset the initial vector(IV) to 0. The initial vector(IV) can be re-initialized using the init(Key, byte, byte[], short, short) method.
  • On decryption operations (except when ISO 9797 method 1 padding is used), the padding bytes are not written to outBuff.
  • On encryption and decryption operations, the number of bytes output into outBuff may be larger or smaller than inLength or even 0.
  • On decryption operations resulting in an ArrayIndexOutOfBoundException, outBuff may be partially modified.

Parameters:
inBuff - the input buffer of data to be encrypted/decrypted
inOffset - the offset into the input buffer at which to begin encryption/decryption
inLength - the byte length to be encrypted/decrypted
outBuff - the output buffer, may be the same as the input buffer
outOffset - the offset into the output buffer where the resulting output data begins
Returns:
number of bytes output in outBuff
Throws:
CryptoException - with the following reason codes:
  • CryptoException.UNINITIALIZED_KEY if key not initialized.
  • CryptoException.INVALID_INIT if this Cipher object is not initialized.
  • CryptoException.ILLEGAL_USE if one of the following conditions is met:
    • This Cipher algorithm does not pad the message and the message is not block aligned.
    • This Cipher algorithm does not pad the message and no input data has been provided in inBuff or via the update() method.
    • The input message length is not supported.
    • The decrypted data is not bounded by appropriate padding bytes.

update

public abstract short update(byte[] inBuff,
                             short inOffset,
                             short inLength,
                             byte[] outBuff,
                             short outOffset)
                      throws CryptoException
Generates encrypted/decrypted output from input data. This method is intended for multiple-part encryption/decryption operations.

This method requires temporary storage of intermediate results. In addition, if the input data length is not block aligned (multiple of block size) then additional internal storage may be allocated at this time to store a partial input data block. This may result in additional resource consumption and/or slow performance.

This method should only be used if all the input data required for the cipher is not available in one byte array. If all the input data required for the cipher is located in a single byte array, use of the doFinal() method to process all of the input data is recommended. The doFinal() method must be invoked to complete processing of any remaining input data buffered by one or more calls to the update() method.

Notes:

  • When using block-aligned data (multiple of block size), if the input buffer, inBuff and the output buffer, outBuff are the same array, then the output data area must not partially overlap the input data area such that the input data is modified before it is used; if inBuff==outBuff and
    inOffset < outOffset < inOffset+inLength, incorrect output may result.
  • When non-block aligned data is presented as input data, no amount of input and output buffer data overlap is allowed; if inBuff==outBuff and
    outOffset < inOffset+inLength, incorrect output may result.
  • On decryption operations(except when ISO 9797 method 1 padding is used), the padding bytes are not written to outBuff.
  • On encryption and decryption operations, block alignment considerations may require that the number of bytes output into outBuff be larger or smaller than inLength or even 0.
  • If inLength is 0 this method does nothing.

Parameters:
inBuff - the input buffer of data to be encrypted/decrypted
inOffset - the offset into the input buffer at which to begin encryption/decryption
inLength - the byte length to be encrypted/decryptedv
outBuff - the output buffer, may be the same as the input buffer
outOffset - the offset into the output buffer where the resulting ciphertext/plaintext begins
Returns:
number of bytes output in outBuff
Throws:
CryptoException - with the following reason codes:
  • CryptoException.UNINITIALIZED_KEY if key not initialized.
  • CryptoException.INVALID_INIT if this Cipher object is not initialized.
  • CryptoException.ILLEGAL_USE if the input message length is not supported.
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