.Dd $Mdocdate: November 12 2015 $
.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 SSL, TLS and S/MIME, and they have also been used to
implement SSH, OpenPGP, and other cryptographic standards.
.Sh OVERVIEW
.Sy libcrypto
consists of a number of sub-libraries that implement the individual
algorithms.
.Pp
The functionality includes symmetric encryption, public key cryptography
and key agreement, certificate handling, cryptographic hash functions
and a cryptographic pseudo-random number generator.
.Bl -tag -width Ds
.It SYMMETRIC CIPHERS
.Xr blowfish 3 ,
cast,
.Xr des 3 ,
idea,
rc2,
.Xr rc4 3 ,
rc5
.It PUBLIC KEY CRYPTOGRAPHY AND KEY AGREEMENT
.Xr dsa 3 ,
.Xr dh 3 ,
.Xr rsa 3
.It CERTIFICATES
.Xr x509 3 ,
x509v3
.It AUTHENTICATION CODES, HASH FUNCTIONS
.Xr hmac 3 ,
.Xr MD2 3 ,
.Xr MD4 3 ,
.Xr MD5 3 ,
.Xr ripemd 3 ,
.Xr sha 3
.It AUXILIARY FUNCTIONS
.Xr ERR 3 ,
.Xr threads 3 ,
.Xr rand 3 ,
.Xr OPENSSL_VERSION_NUMBER 3
.It INPUT/OUTPUT, DATA ENCODING
asn1,
.Xr bio 3 ,
.Xr evp 3 ,
.Xr pem 3 ,
pkcs7,
pkcs12
.It INTERNAL FUNCTIONS
.Xr bn 3 ,
.Xr buffer 3 ,
.Xr ec 3 ,
.Xr lh_new 3 ,
objects,
stack,
txt_db
.El
.Sh NOTES
Some of the newer functions follow a naming convention using the numbers
.Sq 0
and
.Sq 1 .
For example the 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