Storing and loading the private key

[kroggen]

Hi!

Congrats for the great software! It is way faster than OpenSSL.

I was not able to find how to store and load the private key. Preferably in a small binary format.

[kroggen]

Analyzing the code I could notice that the private key is not stored on the context. I was used with mbed-crypto where it is the opposite.

So we are responsible for generating the private key with a strong RNG, checking if it is valid with the secp256k1_ec_seckey_verify function (or secp256k1_ec_privkey_verify when renamed), storing it and loading it.

A documentation on README would be helpful.

Cheers,

[real-or-random]

Have you seen the header file?
https://github.com/bitcoin-core/secp256k1/blob/master/include/secp256k1.h

It has a good documentation but I admit there's no general section on usage of the library.

Related to #184 .

[nickfarrow]

For anyone else interested in how to generate keys using this library, feel free to checkout my Bitcoin vanity address generator which I think provides a short and reasonably well commented example of how to generate private and public key pairs.