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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Frameset//EN""http://www.w3.org/TR/REC-html40/frameset.dtd"><!--NewPage--><HTML><HEAD><!-- Generated by javadoc on Thu Apr 27 23:36:01 PDT 2000 --><TITLE>Java 2 Platform SE v1.3: Class MessageDigestSpi</TITLE><LINK REL ="stylesheet" TYPE="text/css" HREF="../../stylesheet.css" TITLE="Style"></HEAD><BODY BGCOLOR="white"><!-- ========== START OF NAVBAR ========== --><A NAME="navbar_top"><!-- --></A><TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0"><TR><TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"><A NAME="navbar_top_firstrow"><!-- --></A><TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3"> <TR ALIGN="center" VALIGN="top"> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>Overview</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A> </TD> <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> <FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="class-use/MessageDigestSpi.html"><FONT CLASS="NavBarFont1"><B>Use</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../index-files/index-1.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A> </TD> </TR></TABLE></TD><TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM><b>Java<sup><font size=-2>TM</font></sup> 2 Platform<br>Std. Ed. v1.3</b></EM></TD></TR><TR><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../java/security/MessageDigest.html"><B>PREV CLASS</B></A> <A HREF="../../java/security/Permission.html"><B>NEXT CLASS</B></A></FONT></TD><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../index.html" TARGET="_top"><B>FRAMES</B></A> <A HREF="MessageDigestSpi.html" TARGET="_top"><B>NO FRAMES</B></A></FONT></TD></TR><TR><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> SUMMARY: INNER | FIELD | <A HREF="#constructor_summary">CONSTR</A> | <A HREF="#method_summary">METHOD</A></FONT></TD><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">DETAIL: FIELD | <A HREF="#constructor_detail">CONSTR</A> | <A HREF="#method_detail">METHOD</A></FONT></TD></TR></TABLE><!-- =========== END OF NAVBAR =========== --><HR><!-- ======== START OF CLASS DATA ======== --><H2><FONT SIZE="-1">java.security</FONT><BR>Class MessageDigestSpi</H2><PRE><A HREF="../../java/lang/Object.html">java.lang.Object</A> | +--<B>java.security.MessageDigestSpi</B></PRE><DL><DT><B>Direct Known Subclasses:</B> <DD><A HREF="../../java/security/MessageDigest.html">MessageDigest</A></DD></DL><HR><DL><DT>public abstract class <B>MessageDigestSpi</B><DT>extends <A HREF="../../java/lang/Object.html">Object</A></DL><P>This class defines the <i>Service Provider Interface</i> (<b>SPI</b>) for the <code>MessageDigest</code> class, which provides the functionality of a message digest algorithm, such as MD5 or SHA. Message digests are secure one-way hash functions that take arbitrary-sized data and output a fixed-length hash value. <p> All the abstract methods in this class must be implemented by a cryptographic service provider who wishes to supply the implementation of a particular message digest algorithm. <p> Implementations are free to implement the Cloneable interface.<P><DL><DT><B>See Also: </B><DD><A HREF="../../java/security/MessageDigest.html"><CODE>MessageDigest</CODE></A></DL><HR><P><!-- ======== INNER CLASS SUMMARY ======== --><!-- =========== FIELD SUMMARY =========== --><!-- ======== CONSTRUCTOR SUMMARY ======== --><A NAME="constructor_summary"><!-- --></A><TABLE BORDER="1" CELLPADDING="3" CELLSPACING="0" WIDTH="100%"><TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"><TD COLSPAN=2><FONT SIZE="+2"><B>Constructor Summary</B></FONT></TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD><CODE><B><A HREF="../../java/security/MessageDigestSpi.html#MessageDigestSpi()">MessageDigestSpi</A></B>()</CODE><BR> </TD></TR></TABLE> <!-- ========== METHOD SUMMARY =========== --><A NAME="method_summary"><!-- --></A><TABLE BORDER="1" CELLPADDING="3" CELLSPACING="0" WIDTH="100%"><TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"><TD COLSPAN=2><FONT SIZE="+2"><B>Method Summary</B></FONT></TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../java/lang/Object.html">Object</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../java/security/MessageDigestSpi.html#clone()">clone</A></B>()</CODE><BR> Returns a clone if the implementation is cloneable.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected abstract byte[]</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/security/MessageDigestSpi.html#engineDigest()">engineDigest</A></B>()</CODE><BR> Completes the hash computation by performing final operations such as padding.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/security/MessageDigestSpi.html#engineDigest(byte[], int, int)">engineDigest</A></B>(byte[] buf, int offset, int len)</CODE><BR> Completes the hash computation by performing final operations such as padding.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/security/MessageDigestSpi.html#engineGetDigestLength()">engineGetDigestLength</A></B>()</CODE><BR> Returns the digest length in bytes.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected abstract void</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/security/MessageDigestSpi.html#engineReset()">engineReset</A></B>()</CODE><BR> Resets the digest for further use.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected abstract void</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/security/MessageDigestSpi.html#engineUpdate(byte)">engineUpdate</A></B>(byte input)</CODE><BR> Updates the digest using the specified byte.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected abstract void</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/security/MessageDigestSpi.html#engineUpdate(byte[], int, int)">engineUpdate</A></B>(byte[] input, int offset, int len)</CODE><BR> Updates the digest using the specified array of bytes, starting at the specified offset.</TD></TR></TABLE> <A NAME="methods_inherited_from_class_java.lang.Object"><!-- --></A><TABLE BORDER="1" CELLPADDING="3" CELLSPACING="0" WIDTH="100%"><TR BGCOLOR="#EEEEFF" CLASS="TableSubHeadingColor"><TD><B>Methods inherited from class java.lang.<A HREF="../../java/lang/Object.html">Object</A></B></TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD><CODE><A HREF="../../java/lang/Object.html#equals(java.lang.Object)">equals</A>, <A HREF="../../java/lang/Object.html#finalize()">finalize</A>, <A HREF="../../java/lang/Object.html#getClass()">getClass</A>, <A HREF="../../java/lang/Object.html#hashCode()">hashCode</A>, <A HREF="../../java/lang/Object.html#notify()">notify</A>, <A HREF="../../java/lang/Object.html#notifyAll()">notifyAll</A>, <A HREF="../../java/lang/Object.html#toString()">toString</A>, <A HREF="../../java/lang/Object.html#wait()">wait</A>, <A HREF="../../java/lang/Object.html#wait(long)">wait</A>, <A HREF="../../java/lang/Object.html#wait(long, int)">wait</A></CODE></TD></TR></TABLE> <P>⌨️ 快捷键说明
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