evp

- NAME
- SYNOPSIS
- DESCRIPTION
- SEE ALSO
- COPYRIGHT

# NAME

evp - high-level cryptographic functions

# SYNOPSIS

     #include <openssl/evp.h>

# DESCRIPTION

The EVP library provides a high-level interface to cryptographic functions.

EVP_Open... provide public key encryption and decryption to implement digital "envelopes".

The EVP_DigestVerify... functions implement digital signatures and Message Authentication Codes (MACs). Also see the older EVP_Verify... functions.

Symmetric encryption is available with 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_set1_RSA(3) page, or new keys can be generated using EVP_PKEY_cmp(3), or printed using For key agreement see For signing and verifying see EVP_PKEY_verify(3) and EVP_DigestSignInit(3) functions for this purpose.

For encryption and decryption see 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_OpenInit(3) functions.

The EVP_Encode... and engine(3) 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_EncryptInit(3), EVP_SealInit(3), EVP_SignInit(3), EVP_EncodeInit(3), EVP_PKEY_set1_RSA(3), EVP_PKEY_print_private(3), EVP_PKEY_encrypt(3), EVP_PKEY_verify(3), EVP_PKEY_derive(3), engine(3)

# COPYRIGHT

Copyright 2000-2016 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 https://www.openssl.org/source/license.html.