Botan (Japanese for peony) is a cryptography library written in C++11 and released under the permissive Simplified BSD license.

Botan's goal is to be the best option for cryptography in new C++ code by offering the tools necessary to implement a range of practical systems, such as TLS/DTLS, PKIX certificate handling, PKCS#11 and TPM hardware support, password hashing, and post quantum crypto schemes. Find the full feature list below.

Development is coordinated on GitHub and contributions are welcome (read doc/contributing.rst for more info).

If you need help, open a GitHub issue, email the mailing list, or try the botan gitter.im channel.

If you think you've found a security bug, read the security page for contact information and procedures.

For all the details on building the library, read the users manual, but basically:

$ ./configure.py --help
$ ./configure.py [probably some options]
$ make
$ ./botan-test
# lots of output...
Tests all ok
$ ./botan
# shows available commands
$ make install

The library can also be built into a single-file amalgamation for easy inclusion into external build systems.

In addition to C++, botan has a C89 API specifically designed to be easy to call from other languages. A Python binding using ctypes is included.

See the change notes and security page

All releases are signed with a PGP key:

pub   2048R/EFBADFBC 2004-10-30
      Key fingerprint = 621D AF64 11E1 851C 4CF9  A2E1 6211 EBF1 EFBA DFBC
uid                  Botan Distribution Key

Some distributions such as Arch, Fedora and Debian include packages for Botan. However these are often out of date; using the latest source release is recommended.

The 1.11 branch is highly recommended, especially for new projects. While still technically API unstable, the 1.11 branch is very close to an API freeze for a new stable release branch.

Versions 1.11 and later require a working C++11 compiler; GCC 4.8 and later, Clang 3.5 and later, and MSVC 2015 are regularly tested.

The latest 1.11 release is 1.11.34 (sig) released on 2016-11-28

The 1.10 branch is the last version of the library written in C++98 and is still the most commonly packaged version. It is no longer supported except for critical security updates (with all support ending on 2018-1-1), and the developers do not recommend its use anymore.

The latest 1.10 release is 1.10.14 (sig) released on 2016-11-28

You should have some knowledge of cryptography before trying to use the library. This is an area where it is very easy to make mistakes, and where things are often subtle and/or counterintuitive. Obviously the library tries to provide things at a high level precisely to minimize the number of ways things can go wrong, but naive use will almost certainly not result in a secure system.

Especially recommended are:

• Cryptography Engineering by Niels Ferguson, Bruce Schneier, and Tadayoshi Kohno
• Security Engineering -- A Guide to Building Dependable Distributed Systems by Ross Anderson (available online)
• Handbook of Applied Cryptography by Alfred J. Menezes, Paul C. Van Oorschot, and Scott A. Vanstone (available online)

If you're doing something non-trivial or unique, you might want to at the very least ask for review/input on a mailing list such as the metzdowd or randombit crypto lists. And (if possible) pay a professional cryptographer or security company to review your design and code.

• TLS and DTLS (v1.0 to v1.2), including using preshared keys (TLS-PSK) and passwords (TLS-SRP) and most important extensions, such as session tickets, SNI, and ALPN.
• X.509v3 certificates and CRLs
• PKIX certificate path validation
• OCSP requests
• PKCS #10 certificate requests

• RSA signatures and encryption
• DH and ECDH key agreement
• Signature schemes DSA, ECDSA, ECGDSA, ECKCDSA, GOST 34.10-2001
• Post-quantum XMSS (hash based) signature scheme
• Post-quantum KEM schemes McEliece (code based) and NewHope (Ring-LWE)
• ElGamal encryption
• Padding schemes OAEP, PSS, PKCS #1 v1.5, X9.31

• Authenticated cipher modes EAX, OCB, GCM, SIV, CCM, and ChaCha20Poly1305
• Unauthenticated cipher modes CTR, CBC, XTS, CFB, OFB, and ECB
• AES (including constant time SSSE3 and AES-NI versions)
• AES candidates Serpent, Twofish, CAST-256
• Stream ciphers Salsa20/XSalsa20, ChaCha20, SHAKE-128, and RC4
• DES, 3DES and DESX
• Threefish-512, Noekeon, Blowfish, CAST-128, IDEA, XTEA
• National/telecom block ciphers SEED, KASUMI, MISTY1, GOST 28147
• Large block cipher construction Lion

• SHA-1, SHA-224, SHA-256, SHA-384, and SHA-512
• SHA-3 (and Keccak-1600)
• Skein-512, BLAKE2b
• RIPEMD-160, Tiger, Whirlpool, GOST 34.11
• Authentication codes CMAC, GMAC, HMAC, Poly1305, SipHash
• Hash function combiners (Parallel and Comb4P)
• Non-cryptographic checksums Adler32, CRC24, CRC32
• Obsolete algorithms MD5, MD4, CBC-MAC, X9.19 DES-MAC

• Interfaces for accessing PKCS #11 and TPM hardware
• Key derivation functions for passwords, including PBKDF2
• Password hashing functions, including bcrypt and a PBKDF based scheme
• General key derivation functions KDF1 and KDF2 from IEEE 1363
• Format preserving encryption scheme FE1
• Threshold secret sharing
• RFC 3394 keywrapping
• Rivest's all or nothing transform

• For encryption of network traffic use TLS v1.2
• Packet encryption: AES-256/GCM, AES-256/OCB, Serpent/OCB, or ChaCha20Poly1305
• General hash functions: SHA-256 or SHA-384
• Message authentication: HMAC with SHA-256
• Public Key Encryption: RSA, 2048+ bit keys, with OAEP and SHA-256
• Public Key Signatures: RSA, 2048+ bit keys with PSS and SHA-512, or ECDSA with P-256/SHA-256 or P-384/SHA-384
• Key Agreement: ECDH P-256 or Curve25519, with KDF2(SHA-256) If you are concerned about quantum computers, combine ECC with NewHope