.\"	$OpenBSD: crypto.3,v 1.23 2019/11/02 15:28:04 schwarze Exp $
.\"	OpenSSL a9c85cea Nov 11 09:33:55 2016 +0100
.\"
.\" This file was written by Ulf Moeller <ulf@openssl.org> and
.\" Dr. Stephen Henson <steve@openssl.org>.
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.Dd $Mdocdate: November 2 2019 $
.Dt CRYPTO 3
.Os
.Sh NAME
.Nm crypto
.Nd OpenSSL cryptographic library
.Sh DESCRIPTION
The OpenSSL crypto library implements a wide range of cryptographic
algorithms used in various Internet standards.
The services provided by this library are used by the OpenSSL
implementations of TLS and S/MIME, and they have also been used to
implement SSH, OpenPGP, and other cryptographic standards.
.Pp
.Sy Symmetric ciphers
including AES, Blowfish, CAST, Chacha20, IDEA, DES, RC2, and RC4
are provided by the generic interface
.Xr EVP_EncryptInit 3 .
Low-level stand-alone interfaces include
.Xr AES_encrypt 3 ,
.Xr BF_set_key 3 ,
.Xr DES_set_key 3 ,
and
.Xr RC4 3 .
.Pp
.Sy Public key cryptography and key agreement
are provided by
.Xr DH_new 3 ,
.Xr ECDH_compute_key 3 ,
.Xr X25519 3 ,
.Xr DSA_new 3 ,
.Xr ECDSA_SIG_new 3 ,
.Xr RSA_new 3 ,
and
.Xr EVP_PKEY_new 3 .
.Pp
.Sy Certificates
are handled by
.Xr X509_new 3
and
.Xr X509v3_add_ext 3 .
.Pp
.Sy Authentication codes and hash functions
offered include
.Xr EVP_DigestInit 3 ,
.Xr HMAC 3 ,
.Xr MD4 3 ,
.Xr MD5 3 ,
.Xr RIPEMD160 3 ,
.Xr SHA1 3 ,
and
.Xr SHA256 3 .
.Pp
.Sy Input, output, and data encoding
facilities include
.Xr ASN1_TYPE_get 3 ,
.Xr BIO_new 3 ,
.Xr CMS_ContentInfo_new 3 ,
.Xr evp 3 ,
.Xr EVP_EncodeInit 3 ,
.Xr PEM_read 3 ,
.Xr PKCS7_encrypt 3 ,
.Xr PKCS7_sign 3 ,
.Xr PKCS12_create 3 ,
and
.Xr SMIME_write_PKCS7 3 .
.Pp
.Sy Auxiliary features include:
.Bl -dash -compact
.It
configuration file handling: see
.Xr OPENSSL_config 3
.It
error reporting: see
.Xr ERR 3
.It
.Xr OCSP_REQUEST_new 3
.It
.Xr UI_new 3
.El
.Pp
.Sy Internal utilities
include
.Xr BIO_f_buffer 3 ,
.Xr BN_new 3 ,
.Xr EC_GROUP_new 3 ,
.Xr lh_new 3 ,
and
.Xr STACK_OF 3 .
.Pp
Some of the newer functions follow a naming convention using the numbers
.Sq 0
and
.Sq 1 .
For example consider the names of these functions:
.Pp
.Ft int
.Fo X509_CRL_add0_revoked
.Fa "X509_CRL *crl"
.Fa "X509_REVOKED *rev"
.Fc
.br
.Ft int
.Fo X509_add1_trust_object
.Fa "X509 *x"
.Fa "ASN1_OBJECT *obj"
.Fc
.Pp
The
.Sq 0
version uses the supplied structure pointer directly in the parent and
it will be freed up when the parent is freed.
In the above example
.Fa crl
would be freed but
.Fa rev
would not.
.Pp
The
.Sq 1
function uses a copy of the supplied structure pointer (or in some cases
increases its link count) in the parent and so both
.Pf ( Fa x
and
.Fa obj
above) should be freed up.
.Sh SEE ALSO
.Xr openssl 1 ,
.Xr ssl 3