1=pod 2 3=head1 NAME 4 5evp - high-level cryptographic functions 6 7=head1 SYNOPSIS 8 9 #include <openssl/evp.h> 10 11=head1 DESCRIPTION 12 13The EVP library provides a high-level interface to cryptographic 14functions. 15 16B<EVP_Seal>I<...> and B<EVP_Open>I<...> provide public key encryption 17and decryption to implement digital "envelopes". 18 19The B<EVP_Sign>I<...> and B<EVP_Verify>I<...> functions implement 20digital signatures. 21 22Symmetric encryption is available with the B<EVP_Encrypt>I<...> 23functions. The B<EVP_Digest>I<...> functions provide message digests. 24 25The B<EVP_PKEY>I<...> functions provide a high level interface to 26asymmetric algorithms. 27 28Algorithms are loaded with OpenSSL_add_all_algorithms(3). 29 30All the symmetric algorithms (ciphers), digests and asymmetric algorithms 31(public key algorithms) can be replaced by ENGINE modules providing alternative 32implementations. If ENGINE implementations of ciphers or digests are registered 33as defaults, then the various EVP functions will automatically use those 34implementations automatically in preference to built in software 35implementations. For more information, consult the engine(3) man page. 36 37Although low level algorithm specific functions exist for many algorithms 38their use is discouraged. They cannot be used with an ENGINE and ENGINE 39versions of new algorithms cannot be accessed using the low level functions. 40Also makes code harder to adapt to new algorithms and some options are not 41cleanly supported at the low level and some operations are more efficient 42using the high level interface. 43 44=head1 SEE ALSO 45 46L<EVP_DigestInit(3)|EVP_DigestInit(3)>, 47L<EVP_EncryptInit(3)|EVP_EncryptInit(3)>, 48L<EVP_OpenInit(3)|EVP_OpenInit(3)>, 49L<EVP_SealInit(3)|EVP_SealInit(3)>, 50L<EVP_SignInit(3)|EVP_SignInit(3)>, 51L<EVP_VerifyInit(3)|EVP_VerifyInit(3)>, 52L<OpenSSL_add_all_algorithms(3)|OpenSSL_add_all_algorithms(3)>, 53L<engine(3)|engine(3)> 54 55=cut 56