#use wml::openssl-macros area=docs page=evp

<title>Documents, evp(3)</title>

<h1>evp(3)</h1>

#use wml::imp::generic

{:
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[[s|<P>\s+<P>|<P>|sg]]
[[s|<P>\s+</|</|sg]]
[[s|<DD>\s*<DT>|<DD>&nbsp;<DT>|sg]]
[[s|<DD>\s*</DL>|<DD>&nbsp;</DL>|sg]]
[[s|\[|&#91;|sg]]
[[s|\]|&#93;|sg]]

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<UL>

	<LI><A HREF="#NAME">NAME</A>
	<LI><A HREF="#SYNOPSIS">SYNOPSIS</A>
	<LI><A HREF="#DESCRIPTION">DESCRIPTION</A>
	<LI><A HREF="#SEE_ALSO">SEE ALSO</A>
</UL>
<!-- INDEX END -->

<HR>
<P>
<HR>
<H1><A NAME="NAME">NAME</A></H1>
<P>
evp - high-level cryptographic functions

</P>
<P>
<HR>
<H1><A NAME="SYNOPSIS">SYNOPSIS</A></H1>
<PRE> #include &lt;openssl/evp.h&gt;
</PRE>
<P>
<HR>
<H1><A NAME="DESCRIPTION">DESCRIPTION</A></H1>
<P>
The EVP library provides a high-level interface to cryptographic functions.

</P>
<P>
<STRONG>EVP_Seal</STRONG><EM>...</EM> and <STRONG>EVP_Open</STRONG><EM>...</EM> provide public key encryption and decryption to implement digital
``envelopes''.

</P>
<P>
The <STRONG>EVP_Sign</STRONG><EM>...</EM> and <STRONG>EVP_Verify</STRONG><EM>...</EM> functions implement digital signatures.

</P>
<P>
Symmetric encryption is available with the <STRONG>EVP_Encrypt</STRONG><EM>...</EM>
functions. The <STRONG>EVP_Digest</STRONG><EM>...</EM> functions provide message digests.

</P>
<P>
The <STRONG>EVP_PKEY</STRONG><EM>...</EM> functions provide a high level interface to asymmetric algorithms.

</P>
<P>
Algorithms are loaded with <CODE>OpenSSL_add_all_algorithms(3).</CODE>

</P>
<P>
All the symmetric algorithms (ciphers), digests and asymmetric algorithms
(public key algorithms) can be replaced by ENGINE modules providing
alternative implementations. If ENGINE implementations of ciphers or
digests are registered as defaults, then the various EVP functions will
automatically use those implementations automatically in preference to
built in software implementations. For more information, consult the
<CODE>engine(3)</CODE> man page.

</P>
<P>
Although low level algorithm specific functions exist for many algorithms
their use is discouraged. They cannot be used with an ENGINE and ENGINE
versions of new algorithms cannot be accessed using the low level
functions. Also makes code harder to adapt to new algorithms and some
options are not cleanly supported at the low level and some operations are
more efficient using the high level interface.

</P>
<P>
<HR>
<H1><A NAME="SEE_ALSO">SEE ALSO</A></H1>
<P>
<A HREF="../crypto/EVP_DigestInit.html#">EVP_DigestInit(3)</A>,
<A HREF="../crypto/EVP_EncryptInit.html#">EVP_EncryptInit(3)</A>,
<A HREF="../crypto/EVP_OpenInit.html#">EVP_OpenInit(3)</A>,
<A HREF="../crypto/EVP_SealInit.html#">EVP_SealInit(3)</A>,
<A HREF="../crypto/EVP_SignInit.html#">EVP_SignInit(3)</A>,
<A HREF="../crypto/EVP_VerifyInit.html#">EVP_VerifyInit(3)</A>,
<A HREF="../crypto/OpenSSL_add_all_algorithms.html#">OpenSSL_add_all_algorithms(3)</A>,
<A HREF="../crypto/engine.html#">engine(3)</A>



</P>
:}