Simple usage example

[josephernest]

It would be interesting to provide a simple usage example in C / C++, i.e. how to use the library on an input private key to produce an output public key, ready to be SHA256d and RIPEMD160d.

Example:

// private key: abcd1234abcd1234abcd1234abcd1234abcd1234abcd1234abcd1234abcd1234
unsigned char private[32] = { 0xAB, 0xCD, 0x12, 0x34, 0xAB, 0xCD, 0x12, 0x34, 0xAB, 0xCD, 0x12, 0x34, 0xAB, 0xCD, 0x12, 0x34, 0xAB, 0xCD, 0x12, 0x34, 0xAB, 0xCD, 0x12, 0x34, 0xAB, 0xCD, 0x12, 0x34, 0xAB, 0xCD, 0x12, 0x34 };

unsigned char pub[65] = ?secp256k1_pub_from_pvt?(private);   // which function to use here?
unsigned char pub_compr[33] = ?secp256k1_pub_compr_from_pvt?(private);
unsigned char hash160[20] = ripemd160(sha256(...));         // what is the common implementation used here?

[elichai]

👍

[afk11]

The best place to start is the header file:

Creating a context: https://github.com/bitcoin-core/secp256k1/blob/master/include/secp256k1.h#L182
Creating a public key: https://github.com/bitcoin-core/secp256k1/blob/master/include/secp256k1.h#L518
Serialize a public key (for hashing): https://github.com/bitcoin-core/secp256k1/blob/master/include/secp256k1.h#L317

For example usage, see the tests.

[jenokizm]

Hi! secret key this is the private key? If so, how to generate it?
and how to get key as string or char array for printf or cout to console?

[sipa]

EC private keys are just random bytes.

[gmaxwell]

Dupe of #184