javacard.security
Class MessageDigest

java.lang.Object
  javacard.security.MessageDigest

Direct Known Subclasses:

InitializedMessageDigest

public abstract class MessageDigest
extends Object

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

A tear or card reset event resets a MessageDigest object to the initial state (state upon construction).

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

Field Summary

static byte	ALG_MD5 Message Digest algorithm MD5.
static byte	ALG_RIPEMD160 Message Digest algorithm RIPE MD-160.
static byte	ALG_SHA Message Digest algorithm SHA.
static byte	ALG_SHA_256 Message Digest algorithm SHA-256.
static byte	ALG_SHA_384 Message Digest algorithm SHA-384.
static byte	ALG_SHA_512 Message Digest algorithm SHA-512.
static byte	LENGTH_MD5 Length of digest in bytes for SHA
static byte	LENGTH_RIPEMD160 Length of digest in bytes for RIPE MD-160
static byte	LENGTH_SHA Length of digest in bytes for SHA-256
static byte	LENGTH_SHA_256 Length of digest in bytes for MD5
static byte	LENGTH_SHA_384 Length of digest in bytes for SHA-384
static byte	LENGTH_SHA_512 Length of digest in bytes for SHA-512

Constructor Summary

protected

MessageDigest() Protected Constructor

Method Summary

abstract short	doFinal(byte[] inBuff, short inOffset, short inLength, byte[] outBuff, short outOffset) Generates a hash of all/last input data.
abstract byte	getAlgorithm() Gets the Message digest algorithm.
static InitializedMessageDigest	getInitializedMessageDigestInstance(byte algorithm, boolean externalAccess) Creates a InitializedMessageDigest object instance of the selected algorithm.
static MessageDigest	getInstance(byte algorithm, boolean externalAccess) Creates a MessageDigest object instance of the selected algorithm.
abstract byte	getLength() Returns the byte length of the hash.
abstract void	reset() Resets the MessageDigest object to the initial state for further use.
abstract void	update(byte[] inBuff, short inOffset, short inLength) Accumulates a hash of the input data.

Methods inherited from class java.lang.Object

equals

Field Detail

ALG_SHA

public static final byte ALG_SHA

Message Digest algorithm SHA. The block size used by this algorithm is 64 bytes.

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Constant Field Values

ALG_MD5

public static final byte ALG_MD5

Message Digest algorithm MD5. The block size used by this algorithm is 64 bytes.

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Constant Field Values

ALG_RIPEMD160

public static final byte ALG_RIPEMD160

Message Digest algorithm RIPE MD-160. The block size used by this algorithm is 64 bytes.

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Constant Field Values

ALG_SHA_256

public static final byte ALG_SHA_256

Message Digest algorithm SHA-256. The block size used by this algorithm is 64 bytes.

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Constant Field Values

ALG_SHA_384

public static final byte ALG_SHA_384

Message Digest algorithm SHA-384. The block size used by this algorithm is 128 bytes.

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Constant Field Values

ALG_SHA_512

public static final byte ALG_SHA_512

Message Digest algorithm SHA-512. The block size used by this algorithm is 128 bytes.

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Constant Field Values

LENGTH_MD5

public static final byte LENGTH_MD5

Length of digest in bytes for SHA

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Constant Field Values

LENGTH_RIPEMD160

public static final byte LENGTH_RIPEMD160

Length of digest in bytes for RIPE MD-160

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Constant Field Values

LENGTH_SHA

public static final byte LENGTH_SHA

Length of digest in bytes for SHA-256

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Constant Field Values

LENGTH_SHA_256

public static final byte LENGTH_SHA_256

Length of digest in bytes for MD5

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Constant Field Values

LENGTH_SHA_384

public static final byte LENGTH_SHA_384

Length of digest in bytes for SHA-384

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Constant Field Values

LENGTH_SHA_512

public static final byte LENGTH_SHA_512

Length of digest in bytes for SHA-512

See Also:

Constant Field Values

Constructor Detail

MessageDigest

protected MessageDigest()

Protected Constructor

Method Detail

getInstance

public static final MessageDigest getInstance(byte algorithm,
                                              boolean externalAccess)
                                       throws CryptoException

Creates a MessageDigest object instance of the selected algorithm.

Parameters:

algorithm - the desired message digest algorithm. Valid codes listed in ALG_* constants above, for example, ALG_SHA.

externalAccess - true indicates that the instance will be shared among multiple applet instances and that the MessageDigest instance will also be accessed (via a Shareable. interface) when the owner of the MessageDigest instance is not the currently selected applet. If true the implementation must not allocate CLEAR_ON_DESELECT transient space for internal data.

Returns:

the MessageDigest object instance of the requested algorithm

Throws:

CryptoException - with the following reason codes:

• CryptoException.NO_SUCH_ALGORITHM if the requested algorithm or shared access mode is not supported.

getInitializedMessageDigestInstance

public static final InitializedMessageDigest getInitializedMessageDigestInstance(byte algorithm,
                                                                                 boolean externalAccess)
                                                                          throws CryptoException

Creates a InitializedMessageDigest object instance of the selected algorithm.

Parameters:

algorithm - the desired message digest algorithm. Valid codes listed in ALG_* constants above, for example, ALG_SHA.

externalAccess - true indicates that the instance will be shared among multiple applet instances and that the InitializedMessageDigest instance will also be accessed (via a Shareable. interface) when the owner of the InitializedMessageDigest instance is not the currently selected applet. If true the implementation must not allocate CLEAR_ON_DESELECT transient space for internal data.

Returns:

the InitializedMessageDigest object instance of the requested algorithm

Throws:

CryptoException - with the following reason codes:

• CryptoException.NO_SUCH_ALGORITHM if the requested algorithm or shared access mode is not supported.

Since:

2.2.2

getAlgorithm

public abstract byte getAlgorithm()

Gets the Message digest algorithm.

Returns:

the algorithm code defined above

getLength

public abstract byte getLength()

Returns the byte length of the hash.

Returns:

hash length

doFinal

public abstract short doFinal(byte[] inBuff,
                              short inOffset,
                              short inLength,
                              byte[] outBuff,
                              short outOffset)
                       throws CryptoException

Generates a hash of all/last input data. Completes and returns the hash computation after performing final operations such as padding. The MessageDigest object is reset to the initial state after this call is made.

The input and output buffer data may overlap.

Parameters:

inBuff - the input buffer of data to be hashed

inOffset - the offset into the input buffer at which to begin hash generation

inLength - the byte length to hash

outBuff - the output buffer, may be the same as the input buffer

outOffset - the offset into the output buffer where the resulting hash value begins

Returns:

number of bytes of hash output in outBuff

Throws:

CryptoException - with the following reason codes:

• CryptoException.ILLEGAL_USE if the accumulated message length is greater than the maximum length supported by the algorithm.

update

public abstract void update(byte[] inBuff,
                            short inOffset,
                            short inLength)
                     throws CryptoException

Accumulates a hash of the input data. 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 hash is not available in one byte array. If all of the input data required for the hash is located in a single byte array, use of the doFinal() method is recommended. The doFinal() method must be called to complete processing of input data accumulated by one or more calls to the update() method.

Note:

• If inLength is 0 this method does nothing.

Parameters:

inBuff - the input buffer of data to be hashed

inOffset - the offset into the input buffer at which to begin hash generation

inLength - the byte length to hash

Throws:

CryptoException - with the following reason codes:

• CryptoException.ILLEGAL_USE if the accumulated message length is greater than the maximum length supported by the algorithm.

See Also:

doFinal

reset

public abstract void reset()

Resets the MessageDigest object to the initial state for further use.