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_Sign... and
EVP_Verify... functions
implement digital signatures.
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.
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.
SEE ALSO¶
EVP_DigestInit(3),
EVP_EncryptInit(3),
EVP_OpenInit(3),
EVP_SealInit(3),
EVP_SignInit(3),
EVP_VerifyInit(3),
OpenSSL_add_all_algorithms(3),
engine(3)