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EVP(7)				    OpenSSL				EVP(7)

       evp - high-level	cryptographic functions

	#include <openssl/evp.h>

       The EVP library provides	a high-level interface to cryptographic

       The EVP_SealXXX and EVP_OpenXXX functions provide public	key encryption
       and decryption to implement digital "envelopes".

       The EVP_DigestSignXXX and EVP_DigestVerifyXXX functions implement
       digital signatures and Message Authentication Codes (MACs). Also	see
       the older EVP_SignXXX and EVP_VerifyXXX functions.

       Symmetric encryption is available with the EVP_EncryptXXX functions.
       The EVP_DigestXXX functions provide message digests.

       The EVP_PKEYXXX 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

       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_DigestSignInit(3) 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_SealInit(3) and	EVP_OpenInit(3)

       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_EncodeXXX and EVP_DecodeXXX functions implement base 64
       encoding	and decoding.

       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.

       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), ENGINE_by_id(3)

       Copyright 2000-2020 The OpenSSL Project Authors.	All Rights Reserved.

       Licensed	under the OpenSSL license (the "License").  You	may not	use
       this file except	in compliance with the License.	 You can obtain	a copy
       in the file LICENSE in the source distribution or at

1.1.1k				  2021-03-25				EVP(7)


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