Cryptography and SSL/TLS Toolkit



crypto - OpenSSL cryptographic library


See the individual manual pages for details.


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.

libcrypto consists of a number of sub-libraries that implement the individual algorithms.

The functionality includes symmetric encryption, public key cryptography and key agreement, certificate handling, cryptographic hash functions, cryptographic pseudo-random number generator, and various utilities.


Some of the newer functions follow a naming convention using the numbers 0 and 1. For example the functions:

 int X509_CRL_add0_revoked(X509_CRL *crl, X509_REVOKED *rev);
 int X509_add1_trust_object(X509 *x, const ASN1_OBJECT *obj);

The 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 crl would be freed but rev would not.

The 1 function uses a copy of the supplied structure pointer (or in some cases increases its link count) in the parent and so both (x and obj above) should be freed up.


See the individual manual pages for details.


openssl, ssl

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