evp - level cryptographic functions
#include <openssl/evp.h>
evp(3openssl) OpenSSL evp(3openssl)
NAME
evp - high-level cryptographic functions
SYNOPSIS
#include <openssl/evp.h>
DESCRIPTION
The EVP library provides a high-level interface to cryptographic
functions.
EVP_Seal... and EVP_Open... provide public key encryption and
decryption to implement digital "envelopes".
The EVP_DigestSign... and EVP_DigestVerify... functions implement
digital signatures and Message Authentication Codes (MACs). Also see
the older EVP_Sign... and EVP_Verify... functions.
Symmetric encryption is available with the EVP_Encrypt... functions.
The EVP_Digest... functions provide message digests.
The EVP_PKEY... functions provide a high level interface to asymmetric
algorithms. To create a new EVP_PKEY see EVP_PKEY_new(3). EVP_PKEYs can
be associated with a private key of a particular algorithm by using the
functions described on the EVP_PKEY_set1_RSA(3) page, or new keys can
be generated using EVP_PKEY_keygen(3). EVP_PKEYs can be compared using
EVP_PKEY_cmp(3), or printed using EVP_PKEY_print_private(3).
The EVP_PKEY functions support the full range of asymmetric algorithm
operations:
For key agreement see EVP_PKEY_derive(3)
For signing and verifying see EVP_PKEY_sign(3), EVP_PKEY_verify(3) and
EVP_PKEY_verify_recover(3). However, note that these functions do not
perform a digest of the data to be signed. Therefore normally you would
use the EVP_DigestSign... functions for this purpose.
For encryption and decryption see EVP_PKEY_encrypt(3) and
EVP_PKEY_decrypt(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 EVP_Seal... and EVP_Open... functions.
The EVP_BytesToKey(3) function provides some limited support for
password based encryption. Careful selection of the parameters will
provide a PKCS#5 PBKDF1 compatible implementation. However, new
applications should not typically use this (preferring, for example,
PBKDF2 from PCKS#5).
The EVP_Encode... and EVP_Decode... functions implement base 64
encoding and decoding.
Algorithms are loaded with OpenSSL_add_all_algorithms(3).
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 engine(3) man page.
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.
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
+---------------+--------------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+--------------------------+
|Availability | library/security/openssl |
+---------------+--------------------------+
|Stability | Pass-through uncommitted |
+---------------+--------------------------+
SEE ALSO
EVP_DigestInit(3), EVP_EncryptInit(3), EVP_OpenInit(3),
EVP_SealInit(3), EVP_DigestSignInit(3), EVP_SignInit(3),
EVP_VerifyInit(3), EVP_EncodeInit(3), EVP_PKEY_new(3),
EVP_PKEY_set1_RSA(3), EVP_PKEY_keygen(3), EVP_PKEY_print_private(3),
EVP_PKEY_decrypt(3), EVP_PKEY_encrypt(3), EVP_PKEY_sign(3),
EVP_PKEY_verify(3), EVP_PKEY_verify_recover(3), EVP_PKEY_derive(3),
EVP_BytesToKey(3), OpenSSL_add_all_algorithms(3), engine(3)
NOTES
Source code for open source software components in Oracle Solaris can
be found at https://www.oracle.com/downloads/opensource/solaris-source-
code-downloads.html.
This software was built from source available at
https://github.com/oracle/solaris-userland. The original community
source was downloaded from
https://www.openssl.org/source/openssl-1.0.2ze.tar.gz.
Further information about this software can be found on the open source
community website at https://www.openssl.org/.
1.0.2ze 2022-05-03 evp(3openssl)