USE IN DEBIAN wolfSSL is solely provided as an alternative to OpenSSL for packages whose licenses are incompatible with Apache 2.0. For details, please see Bug#1023697. OPENSSL COMPATIBILITY LAYER To use the OpenSSL compatibility layer in an application, please take the following steps: 1. Convert every #include directive for in your source code to . 2. As the first such file included, add . You may not have to do (1) if you tweak your application's build system to use -I/usr/include/wolfssl. Please remember, however, to remove libssl-dev from your system before building. If you do not do (2), you will probably see warnings like n file included from /usr/include/wolfssl/openssl/bn.h:33, from /usr/include/wolfssl/openssl/rsa.h:28, from core/utils.cpp:28: /usr/include/wolfssl/wolfcrypt/settings.h:2060:14: warning: #warning "For timing resistance / side-channel attack prevention consider using harden options" [-Wcpp] 2060 | #warning "For timing resistance / side-channel attack prevention consider using harden options" | ^~~~~~~ For details, please have a look at Bug#964215. The same steps are also mentioned in the documentation [1], but that part of it may not be phrased clearly. (The API documentation is great.) The instructions in this file were relayed verbally by wolfSSl staff in 2014. They worked in multiple cases. [1] https://www.wolfssl.com/docs/wolfssl-manual/ch13/ Please note that implementation of the OpenSSL compatibility layer is not complete. Some functionality, such as access to cryptographic primitives via OpenSSL's EVP feature was not implemented at the time of writing. You may have to use the native interface for some parts. ADDITIONAL LICENSING OPTIONS For a FIPS Ready module, please contact the wolfSSL company. The wolfSSL library is commercial product that is popular in the embedded space. It has an extremely small footprint. It is available under two licenses. For details, please check their website. Many open source products work with it, such as cURL, stunnel and lighttpd. [2] [2] https://www.wolfssl.com/community/ For help with porting an application, please contact the maintainer of this package.