In computing, a cryptographic accelerator is a co-processor designed specifically to perform computationally intensive cryptographic operations, doing so far more efficiently than the general-purpose CPU. Because many servers' system loads consist mostly of cryptographic operations, this can greatly increase performance.
Intel's AES-NI is by far the most common cryptographic accelerator in commodity hardware. VIA PadLock is another recent example.
Several operating systems provide some support for cryptographic hardware. The BSD family of systems has the OpenBSD Cryptographic Framework (OCF), Linux systems have the Crypto API, Solaris OS has the Solaris Cryptographic Framework (SCF) and Microsoft Windows has the Microsoft CryptoAPI.
Some cryptographic accelerators offer new machine instructions and can therefore be used directly by programs. Libraries such as OpenSSL and LibreSSL support some such cryptographic accelerators.
Almost all Unix-like operating systems use OpenSSL or the fork LibreSSL as their cryptography library. These libraries use cryptographic accelerators such as AES-NI if available.
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OpenSSL is a software library for applications that provide secure communications over computer networks against eavesdropping, and identify the party at the other end. It is widely used by Internet servers, including the majority of HTTPS websites.
In Unix-like operating systems, /dev/random and /dev/urandom are special files that serve as cryptographically secure pseudorandom number generators. They allow access to environmental noise collected from device drivers and other sources. /dev/random typically blocked if there was less entropy available than requested; more recently it usually blocks at startup until sufficient entropy has been gathered, then unblocks permanently. The /dev/urandom device typically was never a blocking device, even if the pseudorandom number generator seed was not fully initialized with entropy since boot. Not all operating systems implement the same methods for /dev/random and /dev/urandom.
GnuTLS is a free software implementation of the TLS, SSL and DTLS protocols. It offers an application programming interface (API) for applications to enable secure communication over the network transport layer, as well as interfaces to access X.509, PKCS #12, OpenPGP and other structures.
TLS acceleration is a method of offloading processor-intensive public-key encryption for Transport Layer Security (TLS) and its predecessor Secure Sockets Layer (SSL) to a hardware accelerator.
Crypto API is a cryptography framework in the Linux kernel, for various parts of the kernel that deal with cryptography, such as IPsec and dm-crypt. It was introduced in kernel version 2.5.45 and has since expanded to include essentially all popular block ciphers and hash functions.
Network Security Services (NSS) is a collection of cryptographic computer libraries designed to support cross-platform development of security-enabled client and server applications with optional support for hardware TLS/SSL acceleration on the server side and hardware smart cards on the client side. NSS provides a complete open-source implementation of cryptographic libraries supporting Transport Layer Security (TLS) / Secure Sockets Layer (SSL) and S/MIME. NSS releases prior to version 3.14 are tri-licensed under the Mozilla Public License 1.1, the GNU General Public License, and the GNU Lesser General Public License. Since release 3.14, NSS releases are licensed under GPL-compatible Mozilla Public License 2.0.
cryptlib is an open-source cross-platform software security toolkit library. It is distributed under the Sleepycat License, a free software license compatible with the GNU General Public License. Alternatively, cryptlib is available under a proprietary license for those preferring to use it under proprietary terms.
In computing, entropy is the randomness collected by an operating system or application for use in cryptography or other uses that require random data. This randomness is often collected from hardware sources, either pre-existing ones such as mouse movements or specially provided randomness generators. A lack of entropy can have a negative impact on performance and security.
OpenBSD is a security-focused, free and open-source, Unix-like operating system based on the Berkeley Software Distribution (BSD). Theo de Raadt created OpenBSD in 1995 by forking NetBSD 1.0. According to the website, the OpenBSD project emphasizes "portability, standardization, correctness, proactive security and integrated cryptography."
An Advanced Encryption Standard instruction set is now integrated into many processors. The purpose of the instruction set is to improve the speed and security of applications performing encryption and decryption using the Advanced Encryption Standard (AES).
There are various implementations of the Advanced Encryption Standard, also known as Rijndael.
Mbed TLS is an implementation of the TLS and SSL protocols and the respective cryptographic algorithms and support code required. It is distributed under the Apache License version 2.0. Stated on the website is that Mbed TLS aims to be "easy to understand, use, integrate and expand".
wolfSSL is a small, portable, embedded SSL/TLS library targeted for use by embedded systems developers. It is an open source implementation of TLS written in the C programming language. It includes SSL/TLS client libraries and an SSL/TLS server implementation as well as support for multiple APIs, including those defined by SSL and TLS. wolfSSL also includes an OpenSSL compatibility interface with the most commonly used OpenSSL functions.
Crypto++ is a free and open-source C++ class library of cryptographic algorithms and schemes written by Wei Dai. Crypto++ has been widely used in academia, student projects, open-source, and non-commercial projects, as well as businesses. Released in 1995, the library fully supports 32-bit and 64-bit architectures for many major operating systems and platforms, including Android, Apple, BSD, Cygwin, IBM AIX, Linux, MinGW, Solaris, Windows, Windows Phone and Windows RT. The project also supports compilation using C++03, C++11, C++14, and C++17 runtime libraries; and a variety of compilers and IDEs, including Borland Turbo C++, Borland C++ Builder, Clang, CodeWarrior Pro, GCC, Intel C++ Compiler (ICC), Microsoft Visual C/C++, and Sun Studio.
The Transport Layer Security (TLS) protocol provides the ability to secure communications across or inside networks. This comparison of TLS implementations compares several of the most notable libraries. There are several TLS implementations which are free software and open source.
The OpenBSD Cryptographic Framework (OCF) is a service virtualization layer for the uniform management of cryptographic hardware by an operating system. It is part of the OpenBSD Project, having been included in the operating system since OpenBSD 2.8. Like other OpenBSD projects such as OpenSSH, it has been ported to other systems based on Berkeley Unix such as FreeBSD and NetBSD, and to Solaris and Linux. One of the Linux ports is supported by Intel for use with its proprietary cryptographic software and hardware to provide hardware-accelerated SSL encryption for the open source Apache HTTP Server.
LibreSSL is an open-source implementation of the Transport Layer Security (TLS) protocol. The implementation is named after Secure Sockets Layer (SSL), the deprecated predecessor of TLS, for which support was removed in release 2.3.0. The OpenBSD project forked LibreSSL from OpenSSL 1.0.1g in April 2014 as a response to the Heartbleed security vulnerability, with the goals of modernizing the codebase, improving security, and applying development best practices.
The tables below compare cryptography libraries that deal with cryptography algorithms and have API function calls to each of the supported features.
Hardware-based encryption is the use of computer hardware to assist software, or sometimes replace software, in the process of data encryption. Typically, this is implemented as part of the processor's instruction set. For example, the AES encryption algorithm can be implemented using the AES instruction set on the ubiquitous x86 architecture. Such instructions also exist on the ARM architecture. However, more unusual systems exist where the cryptography module is separate from the central processor, instead being implemented as a coprocessor, in particular a secure cryptoprocessor or cryptographic accelerator, of which an example is the IBM 4758, or its successor, the IBM 4764. Hardware implementations can be faster and less prone to exploitation than traditional software implementations, and furthermore can be protected against tampering.