---
name: "crypto"
section: "3ssl"
platform: "linux"
package: "libssl-doc"
version: "1.0.1t-1+deb8u8"
release: "Debian 8 (Jessie)"
platforms: ["linux"]
url: "https://new.carta.tech/crypto/3ssl"
---

# crypto(3ssl)

OpenSSL cryptographic library

## NAME

crypto - OpenSSL cryptographic library

## SYNOPSIS

## 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.

## OVERVIEW

**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 and a cryptographic pseudo-random number generator.

- SYMMETRIC CIPHERS

  *blowfish*(3), *cast*(3), *des*(3), *idea*(3), *rc2*(3), *rc4*(3), *rc5*(3)

- PUBLIC KEY CRYPTOGRAPHY AND KEY AGREEMENT

  *dsa*(3), *dh*(3), *rsa*(3)

- CERTIFICATES

  *x509*(3), *x509v3*(3)

- AUTHENTICATION CODES, HASH FUNCTIONS

  *hmac*(3), [*md2*(3)](/md2/3.md), [*md4*(3)](/md4/3.md), [*md5*(3)](/md5/3.md), *mdc2*(3), [*ripemd*(3)](/ripemd/3.md), [*sha*(3)](/sha/3.md)

- AUXILIARY FUNCTIONS

  [*err*(3)](/err/3.md), [*threads*(3)](/threads/3.md), [*rand*(3)](/rand/3.md), *OPENSSL\_VERSION\_NUMBER*(3)

- INPUT/OUTPUT, DATA ENCODING

  [*asn1*(3)](/asn1/3.md), *bio*(3), *evp*(3), *pem*(3), *pkcs7*(3), *pkcs12*(3)

- INTERNAL FUNCTIONS

  *bn*(3), [*buffer*(3)](/buffer/3.md), *lhash*(3), [*objects*(3)](/objects/3.md), *stack*(3), *txt\_db*(3)

## NOTES

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, 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 ALSO

[*openssl*(1)](/openssl/1.md), [*ssl*(3)](/ssl/3.md)