checksum.html

JAVA CARD 开发包规格说明,版本为2.2.2

 </ul>
 Algorithm specifics:<ul>
 <li>The input data is not reversed (reflected)
 <li>The ISO 3309 algorithm is used with the polynomial value <code>0x1021</code>
 <li>The resulting 16 bit FCS is not reversed (reflected)
 <li>The 16 bit FCS is xor'd with <code>OxFFFF</code>. This is the CRC16 result.</ul>
<P>
<DL>
<DT><B>See Also:</B><DD><A HREF="../../constant-values.html#javacard.security.Checksum.ALG_ISO3309_CRC16">Constant Field Values</A></DL>
</DL>
<HR>

<A NAME="ALG_ISO3309_CRC32"><!-- --></A><H3>
ALG_ISO3309_CRC32</H3>
<PRE>
public static final byte <B>ALG_ISO3309_CRC32</B></PRE>
<DL>
<DD>ISO/IEC 3309 compliant 32 bit CRC algorithm. This algorithm uses the generator
 polynomial : <code>X^32 +X^26 +X^23 +X^22 +X^16 +X^12 +X^11 +X^10 +X^8 +X^7 +X^5 +X^4 +X^2 +X +1</code>.
 The default initial checksum value used by this algorithm is 0.
 This algorithm is also compliant with the frame checking sequence as specified in 
 section 4.2.5.3 of the ISO/IEC 13239 specification.<p>
 To obtain the PKZIP (also JDK<sup>TM</sup> java.util.zip.CRC32 class) behavior: <ul>
 <li>Initialize with <code>0xFFFFFFFF</code> via the <code>init()</code> method 
 </ul>
 Algorithm specifics:<ul>
 <li>The input data is reversed (reflected)
 <li>The ISO 3309 algorithm is used with the polynomial value <code>0x04C11DB7</code>
 <li>The resulting 32 bit FCS is reversed (reflected)
 <li>The reversed 32 bit FCS is xor'd with OxFFFFFFFF. This is the CRC32 result.</ul>
<P>
<DL>
<DT><B>See Also:</B><DD><A HREF="../../constant-values.html#javacard.security.Checksum.ALG_ISO3309_CRC32">Constant Field Values</A></DL>
</DL>

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<A NAME="Checksum()"><!-- --></A><H3>
Checksum</H3>
<PRE>
protected <B>Checksum</B>()</PRE>
<DL>
<DD>Protected Constructor
<P>
</DL>

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<A NAME="getInstance(byte, boolean)"><!-- --></A><H3>
getInstance</H3>
<PRE>
public static final <A HREF="../../javacard/security/Checksum.html" title="class in javacard.security">Checksum</A> <B>getInstance</B>(byte&nbsp;algorithm,
                                         boolean&nbsp;externalAccess)
                                  throws <A HREF="../../javacard/security/CryptoException.html" title="class in javacard.security">CryptoException</A></PRE>
<DL>
<DD>Creates a <code>Checksum</code> object instance of the selected algorithm.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>algorithm</CODE> - the desired checksum algorithm.
 Valid codes listed in <code>ALG_*</code> constants above, for example, <A HREF="../../javacard/security/Checksum.html#ALG_ISO3309_CRC16"><CODE>ALG_ISO3309_CRC16</CODE></A>.<DD><CODE>externalAccess</CODE> - <code>true</code> indicates that the instance will be shared among
 multiple applet instances and that the <code>Checksum</code> instance will also be accessed (via a <code>Shareable</code>.
 interface) when the owner of the <code>Checksum</code> instance is not the currently selected applet.
 If <code>true</code> the implementation must not allocate CLEAR_ON_DESELECT transient space for internal data.
<DT><B>Returns:</B><DD>the <code>Checksum</code> object instance of the requested algorithm.
<DT><B>Throws:</B>
<DD><CODE><A HREF="../../javacard/security/CryptoException.html" title="class in javacard.security">CryptoException</A></CODE> - with the following reason codes:<ul>
 <li><code>CryptoException.NO_SUCH_ALGORITHM</code> if the requested algorithm
 or shared access mode is not supported.</ul></DL>
</DD>
</DL>
<HR>

<A NAME="init(byte[], short, short)"><!-- --></A><H3>
init</H3>
<PRE>
public abstract void <B>init</B>(byte[]&nbsp;bArray,
                          short&nbsp;bOff,
                          short&nbsp;bLen)
                   throws <A HREF="../../javacard/security/CryptoException.html" title="class in javacard.security">CryptoException</A></PRE>
<DL>
<DD>Resets and initializes the <code>Checksum</code> object with the algorithm specific
 parameters.
 <p>Note:<ul>
 <li><em>The ALG_ISO3309_CRC16 algorithm expects 2 bytes of parameter information in 
 </em><code>bArray</code><em> representing the initial checksum value.</em>
 <li><em>The ALG_ISO3309_CRC32 algorithm expects 4 bytes of parameter information in 
 </em><code>bArray</code><em> representing the initial checksum value.</em>
 </ul>
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>bArray</CODE> - byte array containing algorithm specific initialization information<DD><CODE>bOff</CODE> - offset within <code>bArray</code> where the algorithm specific data begins<DD><CODE>bLen</CODE> - byte length of algorithm specific parameter data
<DT><B>Throws:</B>
<DD><CODE><A HREF="../../javacard/security/CryptoException.html" title="class in javacard.security">CryptoException</A></CODE> - with the following reason codes:<ul>
 <li><code>CryptoException.ILLEGAL_VALUE</code> if a byte array parameter option is not supported by the algorithm or if
 the <code>bLen</code> is an incorrect byte length for the algorithm specific data.
 </ul></DL>
</DD>
</DL>
<HR>

<A NAME="getAlgorithm()"><!-- --></A><H3>
getAlgorithm</H3>
<PRE>
public abstract byte <B>getAlgorithm</B>()</PRE>
<DL>
<DD>Gets the Checksum algorithm. Valid codes listed in <code>ALG_*</code> constants above, for example, <A HREF="../../javacard/security/Checksum.html#ALG_ISO3309_CRC16"><CODE>ALG_ISO3309_CRC16</CODE></A>.
<P>
<DD><DL>

<DT><B>Returns:</B><DD>the algorithm code defined above</DL>
</DD>
</DL>
<HR>

<A NAME="doFinal(byte[], short, short, byte[], short)"><!-- --></A><H3>
doFinal</H3>
<PRE>
public abstract short <B>doFinal</B>(byte[]&nbsp;inBuff,
                              short&nbsp;inOffset,
                              short&nbsp;inLength,
                              byte[]&nbsp;outBuff,
                              short&nbsp;outOffset)</PRE>
<DL>
<DD>Generates a CRC checksum of all/last input data. The CRC engine processes input data
 starting with the byte at offset <CODE>inOffset</CODE> and continuing on until the
 byte at <CODE>(inOffset+inLength-1)</CODE> of the <CODE>inBuff</CODE> array. Within
 each byte the processing proceeds from the least significant bit to the most.
 <p>Completes and returns the checksum computation.
 The <code>Checksum</code> object is reset to the initial state(state upon construction)
 when this method completes.
 <p>Note:<ul>
 <li><em>The <CODE>ALG_ISO3309_CRC16</CODE> and <CODE>ALG_ISO3309_CRC32</CODE> algorithms reset the initial checksum
 value to 0. The initial checksum value can be re-initialized using the
 </em><A HREF="../../javacard/security/Checksum.html#init(byte[], short, short)"><CODE>init(byte[], short, short)</CODE></A> <em> method.</em>
 </ul>
 <p>The input and output buffer data may overlap.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>inBuff</CODE> - the input buffer of data to be checksummed<DD><CODE>inOffset</CODE> - the offset into the input buffer at which to begin checksum generation<DD><CODE>inLength</CODE> - the byte length to checksum<DD><CODE>outBuff</CODE> - the output buffer, may be the same as the input buffer<DD><CODE>outOffset</CODE> - the offset into the output buffer where the resulting checksum value begins
<DT><B>Returns:</B><DD>number of bytes of checksum output in <code>outBuff</code></DL>
</DD>
</DL>
<HR>

<A NAME="update(byte[], short, short)"><!-- --></A><H3>
update</H3>
<PRE>
public abstract void <B>update</B>(byte[]&nbsp;inBuff,
                            short&nbsp;inOffset,
                            short&nbsp;inLength)</PRE>
<DL>
<DD>Accumulates a partial checksum of the input data. The CRC engine processes input data
 starting with the byte at offset <CODE>inOffset</CODE> and continuing on until the
 byte at <CODE>(inOffset+inLength-1)</CODE> of the <CODE>inBuff</CODE> array. Within
 each byte the processing proceeds from the least significant bit to the most.
 <p>This method requires temporary storage of intermediate results. 
 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 checksum
 is not available in one byte array. The <A HREF="../../javacard/security/Checksum.html#doFinal(byte[], short, short, byte[], short)"><CODE>doFinal(byte[], short, short, byte[], short)</CODE></A>
 method is recommended whenever possible.
 <p>Note:<ul>
 <li><em>If <code>inLength</code> is 0 this method does nothing.</em>
 </ul>
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>inBuff</CODE> - the input buffer of data to be checksummed<DD><CODE>inOffset</CODE> - the offset into the input buffer at which to begin checksum generation<DD><CODE>inLength</CODE> - the byte length to checksum<DT><B>See Also:</B><DD><A HREF="../../javacard/security/Checksum.html#doFinal(byte[], short, short, byte[], short)"><CODE>doFinal</CODE></A></DL>
</DD>
</DL>
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