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.IX Title &quot;EVP 7&quot;
.TH EVP 7 &quot;2023-09-11&quot; &quot;1.1.1w&quot; &quot;OpenSSL&quot;
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.SH &quot;NAME&quot;
evp \- high\-level cryptographic functions
.SH &quot;SYNOPSIS&quot;
.IX Header &quot;SYNOPSIS&quot;
.Vb 1
\&amp; #include &lt;openssl/evp.h&gt;
.Ve
.SH &quot;DESCRIPTION&quot;
.IX Header &quot;DESCRIPTION&quot;
The \s-1EVP\s0 library provides a high-level interface to cryptographic
functions.
.PP
The \fBEVP_Seal\fR\fI\s-1XXX\s0\fR and \fBEVP_Open\fR\fI\s-1XXX\s0\fR
functions provide public key encryption and decryption to implement digital \*(L&quot;envelopes\*(R&quot;.
.PP
The \fBEVP_DigestSign\fR\fI\s-1XXX\s0\fR and
\&amp;\fBEVP_DigestVerify\fR\fI\s-1XXX\s0\fR functions implement
digital signatures and Message Authentication Codes (MACs). Also see the older
\&amp;\fBEVP_Sign\fR\fI\s-1XXX\s0\fR and \fBEVP_Verify\fR\fI\s-1XXX\s0\fR
functions.
.PP
Symmetric encryption is available with the \fBEVP_Encrypt\fR\fI\s-1XXX\s0\fR
functions.  The \fBEVP_Digest\fR\fI\s-1XXX\s0\fR functions provide message digests.
.PP
The \fB\s-1EVP_PKEY\s0\fR\fI\s-1XXX\s0\fR functions provide a high-level interface to
asymmetric algorithms. To create a new \s-1EVP_PKEY\s0 see
\&amp;\fBEVP_PKEY_new\fR\|(3). EVP_PKEYs can be associated
with a private key of a particular algorithm by using the functions
described on the \fBEVP_PKEY_set1_RSA\fR\|(3) page, or
new keys can be generated using \fBEVP_PKEY_keygen\fR\|(3).
EVP_PKEYs can be compared using \fBEVP_PKEY_cmp\fR\|(3), or printed using
\&amp;\fBEVP_PKEY_print_private\fR\|(3).
.PP
The \s-1EVP_PKEY\s0 functions support the full range of asymmetric algorithm operations:
.IP &quot;For key agreement see \fBEVP_PKEY_derive\fR\|(3)&quot; 4
.IX Item &quot;For key agreement see EVP_PKEY_derive&quot;
.PD 0
.IP &quot;For signing and verifying see \fBEVP_PKEY_sign\fR\|(3), \fBEVP_PKEY_verify\fR\|(3) and \fBEVP_PKEY_verify_recover\fR\|(3). However, note that these functions do not perform a digest of the data to be signed. Therefore, normally you would use the \fBEVP_DigestSignInit\fR\|(3) functions for this purpose.&quot; 4
.IX Item &quot;For signing and verifying see EVP_PKEY_sign, EVP_PKEY_verify and EVP_PKEY_verify_recover. However, note that these functions do not perform a digest of the data to be signed. Therefore, normally you would use the EVP_DigestSignInit functions for this purpose.&quot;
.ie n .IP &quot;For encryption and decryption see \fBEVP_PKEY_encrypt\fR\|(3) and \fBEVP_PKEY_decrypt\fR\|(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 &quot;&quot;digital envelope&quot;&quot; using the \fBEVP_SealInit\fR\|(3) and \fBEVP_OpenInit\fR\|(3) functions.&quot; 4
.el .IP &quot;For encryption and decryption see \fBEVP_PKEY_encrypt\fR\|(3) and \fBEVP_PKEY_decrypt\fR\|(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 \fBEVP_SealInit\fR\|(3) and \fBEVP_OpenInit\fR\|(3) functions.&quot; 4
.IX Item &quot;For encryption and decryption see EVP_PKEY_encrypt and EVP_PKEY_decrypt 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 EVP_SealInit and EVP_OpenInit functions.&quot;
.PD
.PP
The \fBEVP_BytesToKey\fR\|(3) function provides some limited support for password
based encryption. Careful selection of the parameters will provide a PKCS#5 \s-1PBKDF1\s0 compatible
implementation. However, new applications should not typically use this (preferring, for example,
\&amp;\s-1PBKDF2\s0 from PCKS#5).
.PP
The \fBEVP_Encode\fR\fI\s-1XXX\s0\fR and
\&amp;\fBEVP_Decode\fR\fI\s-1XXX\s0\fR functions implement base 64 encoding
and decoding.
.PP
All the symmetric algorithms (ciphers), digests and asymmetric algorithms
(public key algorithms) can be replaced by \s-1ENGINE\s0 modules providing alternative
implementations. If \s-1ENGINE\s0 implementations of ciphers or digests are registered
as defaults, then the various \s-1EVP\s0 functions will automatically use those
implementations automatically in preference to built in software
implementations. For more information, consult the \fBengine\fR\|(3) man page.
.PP
Although low-level algorithm specific functions exist for many algorithms
their use is discouraged. They cannot be used with an \s-1ENGINE\s0 and \s-1ENGINE\s0
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.
.SH &quot;SEE ALSO&quot;
.IX Header &quot;SEE ALSO&quot;
\&amp;\fBEVP_DigestInit\fR\|(3),
\&amp;\fBEVP_EncryptInit\fR\|(3),
\&amp;\fBEVP_OpenInit\fR\|(3),
\&amp;\fBEVP_SealInit\fR\|(3),
\&amp;\fBEVP_DigestSignInit\fR\|(3),
\&amp;\fBEVP_SignInit\fR\|(3),
\&amp;\fBEVP_VerifyInit\fR\|(3),
\&amp;\fBEVP_EncodeInit\fR\|(3),
\&amp;\fBEVP_PKEY_new\fR\|(3),
\&amp;\fBEVP_PKEY_set1_RSA\fR\|(3),
\&amp;\fBEVP_PKEY_keygen\fR\|(3),
\&amp;\fBEVP_PKEY_print_private\fR\|(3),
\&amp;\fBEVP_PKEY_decrypt\fR\|(3),
\&amp;\fBEVP_PKEY_encrypt\fR\|(3),
\&amp;\fBEVP_PKEY_sign\fR\|(3),
\&amp;\fBEVP_PKEY_verify\fR\|(3),
\&amp;\fBEVP_PKEY_verify_recover\fR\|(3),
\&amp;\fBEVP_PKEY_derive\fR\|(3),
\&amp;\fBEVP_BytesToKey\fR\|(3),
\&amp;\fBENGINE_by_id\fR\|(3)
.SH &quot;COPYRIGHT&quot;
.IX Header &quot;COPYRIGHT&quot;
Copyright 2000\-2020 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the OpenSSL license (the \*(L&quot;License\*(R&quot;).  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
&lt;https://www.openssl.org/source/license.html&gt;.
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