=pod=head1 NAMEcrypto - OpenSSL cryptographic library=head1 SYNOPSIS=head1 DESCRIPTIONThe OpenSSL B<crypto> library implements a wide range of cryptographicalgorithms used in various Internet standards. The services providedby this library are used by the OpenSSL implementations of SSL, TLSand S/MIME, and they have also been used to implement SSH, OpenPGP, andother cryptographic standards.=head1 OVERVIEWB<libcrypto> consists of a number of sub-libraries that implement theindividual algorithms.The functionality includes symmetric encryption, public keycryptography and key agreement, certificate handling, cryptographichash functions and a cryptographic pseudo-random number generator.=over 4=item SYMMETRIC CIPHERSL<blowfish(3)|blowfish(3)>, L<cast(3)|cast(3)>, L<des(3)|des(3)>,L<idea(3)|idea(3)>, L<rc2(3)|rc2(3)>, L<rc4(3)|rc4(3)>, L<rc5(3)|rc5(3)> =item PUBLIC KEY CRYPTOGRAPHY AND KEY AGREEMENTL<dsa(3)|dsa(3)>, L<dh(3)|dh(3)>, L<rsa(3)|rsa(3)>=item CERTIFICATESL<x509(3)|x509(3)>, L<x509v3(3)|x509v3(3)>=item AUTHENTICATION CODES, HASH FUNCTIONSL<hmac(3)|hmac(3)>, L<md2(3)|md2(3)>, L<md4(3)|md4(3)>,L<md5(3)|md5(3)>, L<mdc2(3)|mdc2(3)>, L<ripemd(3)|ripemd(3)>,L<sha(3)|sha(3)>=item AUXILIARY FUNCTIONSL<err(3)|err(3)>, L<threads(3)|threads(3)>, L<rand(3)|rand(3)>,L<OPENSSL_VERSION_NUMBER(3)|OPENSSL_VERSION_NUMBER(3)>=item INPUT/OUTPUT, DATA ENCODINGL<asn1(3)|asn1(3)>, L<bio(3)|bio(3)>, L<evp(3)|evp(3)>, L<pem(3)|pem(3)>,L<pkcs7(3)|pkcs7(3)>, L<pkcs12(3)|pkcs12(3)> =item INTERNAL FUNCTIONSL<bn(3)|bn(3)>, L<buffer(3)|buffer(3)>, L<lhash(3)|lhash(3)>,L<objects(3)|objects(3)>, L<stack(3)|stack(3)>,L<txt_db(3)|txt_db(3)> =back=head1 NOTESSome of the newer functions follow a naming convention using the numbersB<0> and B<1>. For example the functions: int X509_CRL_add0_revoked(X509_CRL *crl, X509_REVOKED *rev); int X509_add1_trust_object(X509 *x, ASN1_OBJECT *obj);The B<0> version uses the supplied structure pointer directlyin the parent and it will be freed up when the parent is freed.In the above example B<crl> would be freed but B<rev> would not.The B<1> function uses a copy of the supplied structure pointer(or in some cases increases its link count) in the parent andso both (B<x> and B<obj> above) should be freed up.=head1 SEE ALSOL<openssl(1)|openssl(1)>, L<ssl(3)|ssl(3)>=cut