163 lines
7.8 KiB
HTML
163 lines
7.8 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of EVP</TITLE>
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</HEAD><BODY>
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<H1>EVP</H1>
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Section: OpenSSL (7SSL)<BR>Updated: 2021-03-22<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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evp - high-level cryptographic functions
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<PRE>
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#include <<A HREF="file:///usr/include/openssl/evp.h">openssl/evp.h</A>>
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</PRE>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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The <FONT SIZE="-1">EVP</FONT> library provides a high-level interface to cryptographic
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functions.
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<P>
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The <B>EVP_Seal</B><I></I><FONT SIZE="-1"><I>XXX</I></FONT><I></I> and <B>EVP_Open</B><I></I><FONT SIZE="-1"><I>XXX</I></FONT><I></I>
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functions provide public key encryption and decryption to implement digital ``envelopes''.
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<P>
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The <B>EVP_DigestSign</B><I></I><FONT SIZE="-1"><I>XXX</I></FONT><I></I> and
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<B>EVP_DigestVerify</B><I></I><FONT SIZE="-1"><I>XXX</I></FONT><I></I> functions implement
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digital signatures and Message Authentication Codes (MACs). Also see the older
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<B>EVP_Sign</B><I></I><FONT SIZE="-1"><I>XXX</I></FONT><I></I> and <B>EVP_Verify</B><I></I><FONT SIZE="-1"><I>XXX</I></FONT><I></I>
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functions.
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<P>
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Symmetric encryption is available with the <B>EVP_Encrypt</B><I></I><FONT SIZE="-1"><I>XXX</I></FONT><I></I>
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functions. The <B>EVP_Digest</B><I></I><FONT SIZE="-1"><I>XXX</I></FONT><I></I> functions provide message digests.
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<P>
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The <B></B><FONT SIZE="-1"><B>EVP_PKEY</B></FONT><B></B><I></I><FONT SIZE="-1"><I>XXX</I></FONT><I></I> functions provide a high level interface to
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asymmetric algorithms. To create a new <FONT SIZE="-1">EVP_PKEY</FONT> see
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_new">EVP_PKEY_new</A></B>(3). EVP_PKEYs can be associated
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with a private key of a particular algorithm by using the functions
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described on the <B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_set1_RSA">EVP_PKEY_set1_RSA</A></B>(3) page, or
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new keys can be generated using <B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_keygen">EVP_PKEY_keygen</A></B>(3).
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EVP_PKEYs can be compared using <B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_cmp">EVP_PKEY_cmp</A></B>(3), or printed using
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_print_private">EVP_PKEY_print_private</A></B>(3).
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<P>
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The <FONT SIZE="-1">EVP_PKEY</FONT> functions support the full range of asymmetric algorithm operations:
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<DL COMPACT>
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<DT id="1">For key agreement see <B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_derive">EVP_PKEY_derive</A></B>(3)<DD>
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<DT id="2">For signing and verifying see <B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_sign">EVP_PKEY_sign</A></B>(3), <B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_verify">EVP_PKEY_verify</A></B>(3) and <B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_verify_recover">EVP_PKEY_verify_recover</A></B>(3). However, note that these functions do not perform a digest of the data to be signed. Therefore normally you would use the <B><A HREF="/cgi-bin/man/man2html?3+EVP_DigestSignInit">EVP_DigestSignInit</A></B>(3) functions for this purpose.<DD>
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<DT id="3">For encryption and decryption see <B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_encrypt">EVP_PKEY_encrypt</A></B>(3) and <B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_decrypt">EVP_PKEY_decrypt</A></B>(3) respectively. However, note that these functions perform encryption and decryption only. As public key encryption is an expensive operation, normally you would wrap an encrypted message in a "digital envelope" using the <B><A HREF="/cgi-bin/man/man2html?3+EVP_SealInit">EVP_SealInit</A></B>(3) and <B><A HREF="/cgi-bin/man/man2html?3+EVP_OpenInit">EVP_OpenInit</A></B>(3) functions.<DD>
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</DL>
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<P>
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The <B><A HREF="/cgi-bin/man/man2html?3+EVP_BytesToKey">EVP_BytesToKey</A></B>(3) function provides some limited support for password
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based encryption. Careful selection of the parameters will provide a PKCS#5 <FONT SIZE="-1">PBKDF1</FONT> compatible
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implementation. However, new applications should not typically use this (preferring, for example,
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<FONT SIZE="-1">PBKDF2</FONT> from PCKS#5).
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<P>
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The <B>EVP_Encode</B><I></I><FONT SIZE="-1"><I>XXX</I></FONT><I></I> and
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<B>EVP_Decode</B><I></I><FONT SIZE="-1"><I>XXX</I></FONT><I></I> functions implement base 64 encoding
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and decoding.
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<P>
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All the symmetric algorithms (ciphers), digests and asymmetric algorithms
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(public key algorithms) can be replaced by <FONT SIZE="-1">ENGINE</FONT> modules providing alternative
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implementations. If <FONT SIZE="-1">ENGINE</FONT> implementations of ciphers or digests are registered
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as defaults, then the various <FONT SIZE="-1">EVP</FONT> functions will automatically use those
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implementations automatically in preference to built in software
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implementations. For more information, consult the <B><A HREF="/cgi-bin/man/man2html?3+engine">engine</A></B>(3) man page.
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<P>
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Although low level algorithm specific functions exist for many algorithms
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their use is discouraged. They cannot be used with an <FONT SIZE="-1">ENGINE</FONT> and <FONT SIZE="-1">ENGINE</FONT>
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versions of new algorithms cannot be accessed using the low level functions.
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Also makes code harder to adapt to new algorithms and some options are not
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cleanly supported at the low level and some operations are more efficient
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using the high level interface.
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<A NAME="lbAE"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_DigestInit">EVP_DigestInit</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_EncryptInit">EVP_EncryptInit</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_OpenInit">EVP_OpenInit</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_SealInit">EVP_SealInit</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_DigestSignInit">EVP_DigestSignInit</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_SignInit">EVP_SignInit</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_VerifyInit">EVP_VerifyInit</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_EncodeInit">EVP_EncodeInit</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_new">EVP_PKEY_new</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_set1_RSA">EVP_PKEY_set1_RSA</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_keygen">EVP_PKEY_keygen</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_print_private">EVP_PKEY_print_private</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_decrypt">EVP_PKEY_decrypt</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_encrypt">EVP_PKEY_encrypt</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_sign">EVP_PKEY_sign</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_verify">EVP_PKEY_verify</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_verify_recover">EVP_PKEY_verify_recover</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_PKEY_derive">EVP_PKEY_derive</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+EVP_BytesToKey">EVP_BytesToKey</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+ENGINE_by_id">ENGINE_by_id</A></B>(3)
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<A NAME="lbAF"> </A>
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<H2>COPYRIGHT</H2>
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Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
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<P>
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Licensed under the OpenSSL license (the ``License''). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file <FONT SIZE="-1">LICENSE</FONT> in the source distribution or at
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<<A HREF="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</A>>.
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="4"><A HREF="#lbAB">NAME</A><DD>
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<DT id="5"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="6"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="7"><A HREF="#lbAE">SEE ALSO</A><DD>
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<DT id="8"><A HREF="#lbAF">COPYRIGHT</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:06:08 GMT, March 31, 2021
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</BODY>
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</HTML>
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