user37419: I am working on a tiny C++ bitcoin application for a university project. I'm using Blockcypher API to create transactions, but I faced a problem with signing transaction's hash that returns one of the methods. Are there any simple C++ libraries that will allow me to sign this hash with secp256k1 ECDSA? Also, library must work for Android NDK development.
Maybe I have found one, but I have a problem with installation, and I don't exactly know if I can use it with Android NDK. 
Thanks for all answers! 

user5292: Maybe libsecp256k1, which is what Bitcoin Core itself uses. Not sure about Android usability, but it compiles on many architectures.

37419: <p>I am working on a tiny C++ bitcoin application for a university project. I'm using <a href="http://www.blockcypher.com/" rel="nofollow">Blockcypher API</a> to create transactions, but I faced a problem with signing transaction's hash that returns one of the methods. Are there any simple C++ libraries that will allow me to sign this hash with secp256k1 ECDSA? Also, library must work for Android NDK development.</p>

<p>Maybe I have found <a href="https://github.com/libbitcoin/secp256k1" rel="nofollow">one</a>, but I have a problem with installation, and I don't exactly know if I can use it with Android NDK. </p>

<p>Thanks for all answers! </p>
 5292: <p>Maybe <a href="https://github.com/bitcoin-core/secp256k1" rel="nofollow">libsecp256k1</a>, which is what Bitcoin Core itself uses. Not sure about Android usability, but it compiles on many architectures.</p>
