60 lines
2 KiB
Text
60 lines
2 KiB
Text
=pod
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=head1 NAME
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evp - high-level cryptographic functions
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=head1 SYNOPSIS
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#include <openssl/evp.h>
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=head1 DESCRIPTION
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The EVP library provides a high-level interface to cryptographic
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functions.
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B<EVP_Seal>I<...> and B<EVP_Open>I<...> provide public key encryption
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and decryption to implement digital "envelopes".
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The B<EVP_Sign>I<...> and B<EVP_Verify>I<...> functions implement
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digital signatures.
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Symmetric encryption is available with the B<EVP_Encrypt>I<...>
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functions. The B<EVP_Digest>I<...> functions provide message digests.
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The B<EVP_PKEY>I<...> functions provide a high level interface to
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asymmetric algorithms.
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The L<B<EVP_Encode>I<...>|EVP_EncodeInit(3)> and
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L<B<EVP_Decode>I<...>|EVP_EncodeInit(3)> functions implement base 64 encoding
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and decoding.
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Algorithms are loaded with OpenSSL_add_all_algorithms(3).
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All the symmetric algorithms (ciphers), digests and asymmetric algorithms
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(public key algorithms) can be replaced by ENGINE modules providing alternative
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implementations. If ENGINE implementations of ciphers or digests are registered
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as defaults, then the various EVP functions will automatically use those
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implementations automatically in preference to built in software
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implementations. For more information, consult the engine(3) man page.
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Although low level algorithm specific functions exist for many algorithms
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their use is discouraged. They cannot be used with an ENGINE and ENGINE
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versions of new algorithms cannot be accessed using the low level functions.
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Also makes code harder to adapt to new algorithms and some options are not
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cleanly supported at the low level and some operations are more efficient
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using the high level interface.
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=head1 SEE ALSO
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L<EVP_DigestInit(3)|EVP_DigestInit(3)>,
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L<EVP_EncryptInit(3)|EVP_EncryptInit(3)>,
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L<EVP_OpenInit(3)|EVP_OpenInit(3)>,
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L<EVP_SealInit(3)|EVP_SealInit(3)>,
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L<EVP_SignInit(3)|EVP_SignInit(3)>,
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L<EVP_VerifyInit(3)|EVP_VerifyInit(3)>,
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L<EVP_EncodeInit(3)>,
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L<OpenSSL_add_all_algorithms(3)|OpenSSL_add_all_algorithms(3)>,
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L<engine(3)|engine(3)>
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=cut
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