public abstract class InitializedMessageDigest extends MessageDigest
InitializedMessageDigest
class is a subclass of the base
class MessageDigest
. This class is used to generate a hash
representing a specified message but with the additional capability to
initialize the starting hash value corresponding to a previously hashed part
of the message. Implementations of InitializedMessageDigest
algorithms must extend this class and implement all the abstract methods.
A tear or card reset event resets a InitializedMessageDigest
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.
Modifier and Type | Class and Description |
---|---|
static class |
InitializedMessageDigest.OneShot
The
OneShot class is a specialization of the
InitializedMessageDigest class intended to support efficient one-shot
hash operations that may avoid persistent memory writes entirely. |
ALG_MD5, ALG_NULL, ALG_RIPEMD160, ALG_SHA, ALG_SHA_224, ALG_SHA_256, ALG_SHA_384, ALG_SHA_512, ALG_SHA3_224, ALG_SHA3_256, ALG_SHA3_384, ALG_SHA3_512, LENGTH_MD5, LENGTH_RIPEMD160, LENGTH_SHA, LENGTH_SHA_224, LENGTH_SHA_256, LENGTH_SHA_384, LENGTH_SHA_512, LENGTH_SHA3_224, LENGTH_SHA3_256, LENGTH_SHA3_384, LENGTH_SHA3_512
Modifier | Constructor and Description |
---|---|
protected |
InitializedMessageDigest()
protected constructor
|
Modifier and Type | Method and Description |
---|---|
abstract void |
setInitialDigest(byte[] initialDigestBuf,
short initialDigestOffset,
short initialDigestLength,
byte[] digestedMsgLenBuf,
short digestedMsgLenOffset,
short digestedMsgLenLength)
This method initializes the starting hash value in place of the default
value used by the
MessageDigest superclass. |
doFinal, getAlgorithm, getInitializedMessageDigestInstance, getInstance, getLength, reset, update
protected InitializedMessageDigest()
public abstract void setInitialDigest(byte[] initialDigestBuf, short initialDigestOffset, short initialDigestLength, byte[] digestedMsgLenBuf, short digestedMsgLenOffset, short digestedMsgLenLength) throws CryptoException
MessageDigest
superclass. The starting
hash value represents the previously computed hash (using the same
algorithm) of the first part of the message. The remaining bytes of the
message must be presented to this InitializedMessageDigest
object via the update
and doFinal
methods
to generate the final message digest.
Note:
initialDigestBuf
- input buffer containing the starting hash value representing
the previously computed hash (using the same algorithm) of
first part of the messageinitialDigestOffset
- offset into initialDigestBuf
array where the
starting digest value data beginsinitialDigestLength
- the length of data in initialDigestBuf
array.digestedMsgLenBuf
- the byte array containing the number of bytes in the first
part of the message that has previously been hashed to obtain
the specified starting digest valuedigestedMsgLenOffset
- the offset within digestedMsgLenBuf
where the
digested length begins(the bytes starting at this offset for
digestedMsgLenLength
bytes are concatenated to
form the actual digested message length value)digestedMsgLenLength
- byte length of the digested lengthCryptoException
- with the following reason codes:
CryptoException.ILLEGAL_VALUE
if the
parameter initialDigestLength
is not equal
to the intermediate hash value size of the algorithm
or if the number of bytes
in the first part of the message that has previously been
hashed is 0 or not a multiple of the algorithm's block
size or greater than the maximum length supported by the
algorithm (see ALG_*
algorithm descriptions
ALG_SHA
).
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