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).

       The EVP_Encode... and EVP_Decode... 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.

SEE ALSO

       EVP_DigestInit(3), EVP_EncryptInit(3), EVP_OpenInit(3), EVP_SealInit(3), EVP_SignInit(3),
       EVP_EncodeInit(3), EVP_VerifyInit(3), OpenSSL_add_all_algorithms(3), engine(3)