[][src]Crate openssl

Bindings to OpenSSL

This crate provides a safe interface to the popular OpenSSL cryptography library. OpenSSL versions 1.0.1 through 1.1.1 and LibreSSL versions 2.5 through 2.8 are supported.

Building

Both OpenSSL libraries and headers are required to build this crate. There are multiple options available to locate OpenSSL.

Vendored

If the vendored Cargo feature is enabled, the openssl-src crate will be used to compile and statically link to a copy of OpenSSL. The build process requires a C compiler, perl, and make. The OpenSSL version will generally track the newest OpenSSL release, and changes to the version are not considered breaking changes.

[dependencies]
openssl = { version = "0.10", features = ["vendored"] }

The vendored copy will not be configured to automatically find the system's root certificates, but the openssl-probe crate can be used to do that instead.

Automatic

The openssl-sys crate will automatically detect OpenSSL installations via Homebrew on macOS and vcpkg on Windows. Additionally, it will use pkg-config on Unix-like systems to find the system installation.

# macOS
$ brew install openssl@1.1

# Arch Linux
$ sudo pacman -S pkg-config openssl

# Debian and Ubuntu
$ sudo apt-get install pkg-config libssl-dev

# Fedora
$ sudo dnf install pkg-config openssl-devel

Manual

A set of environment variables can be used to point openssl-sys towards an OpenSSL installation. They will override the automatic detection logic.

Additionally, these variables can be prefixed with the upper-cased target architecture (e.g. X86_64_UNKNOWN_LINUX_GNU_OPENSSL_DIR), which can be useful when cross compiling.

Feature Detection

APIs have been added to and removed from the various supported OpenSSL versions, and this library exposes the functionality available in the version being linked against. This means that methods, constants, and even modules will be present when building against one version of OpenSSL but not when building against another! APIs will document any version-specific availability restrictions.

A build script can be used to detect the OpenSSL or LibreSSL version at compile time if needed. The openssl-sys crate propagates the version via the DEP_OPENSSL_VERSION_NUMBER and DEP_OPENSSL_LIBRESSL_VERSION_NUMBER environment variables to build scripts. The version format is a hex-encoding of the OpenSSL release version: 0xMNNFFPPS. For example, version 1.0.2g's encoding is 0x1_00_02_07_0.

For example, let's say we want to adjust the TLSv1.3 cipher suites used by a client, but also want to compile against OpenSSL versions that don't support TLSv1.3:

Cargo.toml:

[dependencies]
openssl-sys = "0.9"
openssl = "0.10"

build.rs:

use std::env;

fn main() {
    if let Ok(v) = env::var("DEP_OPENSSL_VERSION_NUMBER") {
        let version = u64::from_str_radix(&v, 16).unwrap();

        if version >= 0x1_01_01_00_0 {
            println!("cargo:rustc-cfg=openssl111");
        }
    }
}

lib.rs:

use openssl::ssl::{SslConnector, SslMethod};

let mut ctx = SslConnector::builder(SslMethod::tls()).unwrap();

// set_ciphersuites was added in OpenSSL 1.1.1, so we can only call it when linking against that version
#[cfg(openssl111)]
ctx.set_ciphersuites("TLS_AES_256_GCM_SHA384:TLS_AES_128_GCM_SHA256").unwrap();

Modules

aes

Low level AES IGE and key wrapping functionality

asn1

Defines the format of certificiates

base64

Base64 encoding support.

bn

BigNum implementation

cms

SMIME implementation using CMS

conf

Interface for processing OpenSSL configuration files.

derive

Shared secret derivation.

dh
dsa

Digital Signatures

ec

Elliptic Curve

ecdsa

Low level Elliptic Curve Digital Signature Algorithm (ECDSA) functions.

envelope

Envelope encryption.

error

Errors returned by OpenSSL library.

ex_data
fips

FIPS 140-2 support.

hash
memcmp

Utilities to safely compare cryptographic values.

nid

A collection of numerical identifiers for OpenSSL objects.

ocsp
pkcs5
pkcs7
pkcs12

PKCS #12 archives.

pkey

Public/private key processing.

rand

Utilities for secure random number generation.

rsa

Rivest–Shamir–Adleman cryptosystem

sha

The SHA family of hashes.

sign

Message signatures.

srtp
ssl

SSL/TLS support.

stack
string
symm

High level interface to certain symmetric ciphers.

version
x509

The standard defining the format of public key certificates.

Functions

init