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7<TITLE>SVC_HMACSHA1Init</TITLE>
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11<H1 align="left">SVC_HMACSHA1Init <IMG src="../image/BPT.gif" align="middle"><IMG src="../image/TWL.gif" align="middle"></H1>
12<H2>Syntax</H2>
13<DL>
14  <DD>
15  <PRE><CODE>#include &lt;twl/os/common/systemCall.h&gt;</CODE></PRE>
16  <PRE><CODE>void SVC_HMACSHA1Init( SVCHMACSHA1Context* context,
17             const void* key,
18             u32 keylen );</CODE></PRE>
19  <PRE><CODE>typedef struct SVCHMACSHA1Context
20{
21    <CODE><A href="SVC_SHA1Init.html">SVCSHA1Context</A></CODE>  sha1_ctx;
22    u8              key[SVC_SHA1_BLOCK_SIZE];
23    u32             keylen;
24}
25SVCHMACSHA1Context</CODE></PRE>
26</DL>
27<H2>Arguments</H2>
28<TABLE border="1">
29  <TBODY>
30    <TR>
31      <TD><B><I>context</I></B></TD>
32      <TD>Pointer to the context structure to initialize for HMAC-SHA1 generation.</TD>
33    </TR>
34    <TR>
35      <TD><B><I>key</I></B></TD>
36      <TD>Key string.</TD>
37    </TR>
38    <TR>
39      <TD><B><I>keylen</I></B></TD>
40      <TD>Length of key string.</TD>
41    </TR>
42  </TBODY>
43</TABLE>
44<H2>Return Values</H2>
45<P>None.</P>
46<H2>Description</H2>
47<P>Initializes the structure to use when calculating HMAC-SHA1. Make sure that this function is called before using the <CODE><A href="SVC_SHA1Update.html">SVC_HMACSHA1Update</A></CODE> or <CODE><A href="SVC_SHA1GetHash.html">SVC_HMACSHA1GetHash</A></CODE> functions.</P>
48<P><B><I>context</I></B> is the context structure to initialize for HMAC-SHA1 generation. You can reapply this function to a context structure that is already initialized. In this case, it will return the context structure to its initial state.</P>
49<P>In <B><I>key</I></B> and <B><I>keylen</I></B>, specify the key string to provide to HMAC-SHA1. Keys up to <CODE>SVC_SHA1_BLOCK_SIZE</CODE> (=64) bytes can be specified.</P>
50
51<H2>See Also</H2>
52<P><CODE><A href="SVC_SHA1Update.html">SVC_HMACSHA1Update</A></CODE>, <CODE><A href="SVC_SHA1GetHash.html">SVC_HMACSHA1GetHash</A></CODE>, <CODE><A href="SVC_SHA1Init.html">SVC_SHA1Init</A></CODE></P>
53<H2>Revision History</H2>
54<P>2007/10/24 Initial version.</P>
55<hr><p>CONFIDENTIAL</p></body>
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