<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >mcrypt_get_iv_size</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REL="HOME" TITLE="Manual do PHP" HREF="index.html"><LINK REL="UP" TITLE="Mcrypt Encryption Functions" HREF="ref.mcrypt.html"><LINK REL="PREVIOUS" TITLE="mcrypt_get_cipher_name" HREF="function.mcrypt-get-cipher-name.html"><LINK REL="NEXT" TITLE="mcrypt_get_key_size" HREF="function.mcrypt-get-key-size.html"><META HTTP-EQUIV="Content-type" CONTENT="text/html; charset=UTF-8"></HEAD ><BODY CLASS="refentry" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >Manual do PHP</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="function.mcrypt-get-cipher-name.html" ACCESSKEY="P" >Anterior</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="function.mcrypt-get-key-size.html" ACCESSKEY="N" >Próxima</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="function.mcrypt-get-iv-size" ></A >mcrypt_get_iv_size</H1 ><DIV CLASS="refnamediv" ><A NAME="AEN112060" ></A ><P > (PHP 4 >= 4.0.2, PHP 5)</P >mcrypt_get_iv_size -- Returns the size of the IV belonging to a specific cipher/mode combination </DIV ><DIV CLASS="refsect1" ><A NAME="AEN112063" ></A ><H2 >Description</H2 >int <B CLASS="methodname" >mcrypt_get_iv_size</B > ( string cipher, string mode )<BR ></BR ><P > <B CLASS="function" >mcrypt_get_iv_size()</B > returns the size of the Initialisation Vector (IV) in bytes. On error the function returns <TT CLASS="constant" ><B >FALSE</B ></TT >. If the IV is ignored in the specified cipher/mode combination zero is returned. </P ><P > <CODE CLASS="parameter" >cipher</CODE > is one of the MCRYPT_ciphername constants of the name of the algorithm as string. </P ><P > <CODE CLASS="parameter" >mode</CODE > is one of the MCRYPT_MODE_modename constants or one of "ecb", "cbc", "cfb", "ofb", "nofb" or "stream". The IV is ignored in ECB mode as this mode does not require it. You will need to have the same IV (think: starting point) both at encryption and decryption stages, otherwise your encryption will fail. </P ><P > It is more useful to use the <A HREF="function.mcrypt-enc-get-iv-size.html" ><B CLASS="function" >mcrypt_enc_get_iv_size()</B ></A > function as this uses the resource returned by <A HREF="function.mcrypt-module-open.html" ><B CLASS="function" >mcrypt_module_open()</B ></A >. </P ><P > <TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" CLASS="EXAMPLE" ><TR ><TD ><DIV CLASS="example" ><A NAME="AEN112085" ></A ><P ><B >Exemplo 1. <B CLASS="function" >mcrypt_get_iv_size()</B > example</B ></P ><TABLE BORDER="0" BGCOLOR="#E0E0E0" CELLPADDING="5" ><TR ><TD ><code><font color="#000000"> <font color="#0000BB"><?php<br /> </font><font color="#007700">echo </font><font color="#0000BB">mcrypt_get_iv_size</font><font color="#007700">(</font><font color="#0000BB">MCRYPT_CAST_256</font><font color="#007700">, </font><font color="#0000BB">MCRYPT_MODE_CFB</font><font color="#007700">) . </font><font color="#DD0000">"\n"</font><font color="#007700">;<br /><br /> echo </font><font color="#0000BB">mcrypt_get_iv_size</font><font color="#007700">(</font><font color="#DD0000">'des'</font><font color="#007700">, </font><font color="#DD0000">'ecb'</font><font color="#007700">) . </font><font color="#DD0000">"\n"</font><font color="#007700">;<br /></font><font color="#0000BB">?></font> </font> </code></TD ></TR ></TABLE ></DIV ></TD ></TR ></TABLE > </P ><P > See also <A HREF="function.mcrypt-get-block-size.html" ><B CLASS="function" >mcrypt_get_block_size()</B ></A >, <A HREF="function.mcrypt-enc-get-iv-size.html" ><B CLASS="function" >mcrypt_enc_get_iv_size()</B ></A > and <A HREF="function.mcrypt-create-iv.html" ><B CLASS="function" >mcrypt_create_iv()</B ></A >. </P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="function.mcrypt-get-cipher-name.html" ACCESSKEY="P" >Anterior</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Principal</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="function.mcrypt-get-key-size.html" ACCESSKEY="N" >Próxima</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >mcrypt_get_cipher_name</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="ref.mcrypt.html" ACCESSKEY="U" >Acima</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >mcrypt_get_key_size</TD ></TR ></TABLE ></DIV ></BODY ></HTML >