Edit File: evp.7
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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" evp \- high\-level cryptographic functions .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& #include <openssl/evp.h> .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" The \s-1EVP\s0 library provides a high-level interface to cryptographic functions. .PP The \fBEVP_Seal\fR\fI\s-1XXX\s0\fR and \fBEVP_Open\fR\fI\s-1XXX\s0\fR functions provide public key encryption and decryption to implement digital \*(L"envelopes\*(R". .PP The \fBEVP_DigestSign\fR\fI\s-1XXX\s0\fR and \&\fBEVP_DigestVerify\fR\fI\s-1XXX\s0\fR functions implement digital signatures and Message Authentication Codes (MACs). Also see the older \&\fBEVP_Sign\fR\fI\s-1XXX\s0\fR and \fBEVP_Verify\fR\fI\s-1XXX\s0\fR functions. .PP Symmetric encryption is available with the \fBEVP_Encrypt\fR\fI\s-1XXX\s0\fR functions. The \fBEVP_Digest\fR\fI\s-1XXX\s0\fR functions provide message digests. .PP The \fB\s-1EVP_PKEY\s0\fR\fI\s-1XXX\s0\fR functions provide a high-level interface to asymmetric algorithms. To create a new \s-1EVP_PKEY\s0 see \&\fBEVP_PKEY_new\fR\|(3). EVP_PKEYs can be associated with a private key of a particular algorithm by using the functions described on the \fBEVP_PKEY_set1_RSA\fR\|(3) page, or new keys can be generated using \fBEVP_PKEY_keygen\fR\|(3). EVP_PKEYs can be compared using \fBEVP_PKEY_cmp\fR\|(3), or printed using \&\fBEVP_PKEY_print_private\fR\|(3). .PP The \s-1EVP_PKEY\s0 functions support the full range of asymmetric algorithm operations: .IP "For key agreement see \fBEVP_PKEY_derive\fR\|(3)" 4 .IX Item "For key agreement see EVP_PKEY_derive" .PD 0 .IP "For signing and verifying see \fBEVP_PKEY_sign\fR\|(3), \fBEVP_PKEY_verify\fR\|(3) and \fBEVP_PKEY_verify_recover\fR\|(3). However, note that these functions do not perform a digest of the data to be signed. Therefore, normally you would use the \fBEVP_DigestSignInit\fR\|(3) functions for this purpose." 4 .IX Item "For signing and verifying see EVP_PKEY_sign, EVP_PKEY_verify and EVP_PKEY_verify_recover. However, note that these functions do not perform a digest of the data to be signed. Therefore, normally you would use the EVP_DigestSignInit functions for this purpose." .ie n .IP "For encryption and decryption see \fBEVP_PKEY_encrypt\fR\|(3) and \fBEVP_PKEY_decrypt\fR\|(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 \fBEVP_SealInit\fR\|(3) and \fBEVP_OpenInit\fR\|(3) functions." 4 .el .IP "For encryption and decryption see \fBEVP_PKEY_encrypt\fR\|(3) and \fBEVP_PKEY_decrypt\fR\|(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 \fBEVP_SealInit\fR\|(3) and \fBEVP_OpenInit\fR\|(3) functions." 4 .IX Item "For encryption and decryption see EVP_PKEY_encrypt and EVP_PKEY_decrypt 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 and EVP_OpenInit functions." .PD .PP The \fBEVP_BytesToKey\fR\|(3) function provides some limited support for password based encryption. Careful selection of the parameters will provide a PKCS#5 \s-1PBKDF1\s0 compatible implementation. However, new applications should not typically use this (preferring, for example, \&\s-1PBKDF2\s0 from PCKS#5). .PP The \fBEVP_Encode\fR\fI\s-1XXX\s0\fR and \&\fBEVP_Decode\fR\fI\s-1XXX\s0\fR functions implement base 64 encoding and decoding. .PP All the symmetric algorithms (ciphers), digests and asymmetric algorithms (public key algorithms) can be replaced by \s-1ENGINE\s0 modules providing alternative implementations. If \s-1ENGINE\s0 implementations of ciphers or digests are registered as defaults, then the various \s-1EVP\s0 functions will automatically use those implementations automatically in preference to built in software implementations. For more information, consult the \fBengine\fR\|(3) man page. .PP Although low-level algorithm specific functions exist for many algorithms their use is discouraged. They cannot be used with an \s-1ENGINE\s0 and \s-1ENGINE\s0 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. .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBEVP_DigestInit\fR\|(3), \&\fBEVP_EncryptInit\fR\|(3), \&\fBEVP_OpenInit\fR\|(3), \&\fBEVP_SealInit\fR\|(3), \&\fBEVP_DigestSignInit\fR\|(3), \&\fBEVP_SignInit\fR\|(3), \&\fBEVP_VerifyInit\fR\|(3), \&\fBEVP_EncodeInit\fR\|(3), \&\fBEVP_PKEY_new\fR\|(3), \&\fBEVP_PKEY_set1_RSA\fR\|(3), \&\fBEVP_PKEY_keygen\fR\|(3), \&\fBEVP_PKEY_print_private\fR\|(3), \&\fBEVP_PKEY_decrypt\fR\|(3), \&\fBEVP_PKEY_encrypt\fR\|(3), \&\fBEVP_PKEY_sign\fR\|(3), \&\fBEVP_PKEY_verify\fR\|(3), \&\fBEVP_PKEY_verify_recover\fR\|(3), \&\fBEVP_PKEY_derive\fR\|(3), \&\fBEVP_BytesToKey\fR\|(3), \&\fBENGINE_by_id\fR\|(3) .SH "COPYRIGHT" .IX Header "COPYRIGHT" Copyright 2000\-2020 The OpenSSL Project Authors. All Rights Reserved. .PP Licensed under the OpenSSL license (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.