A command line app that prompts the user to enter inputs from coin flips, or 4, 8, or 16-sided dice and turns them into a hexadecimal string. Prompted by my own desire to create a cryptographically secure Bitcoin private key offline using dice, and my unhappiness with relying on SHA-256 to produce truly random output, as "dice-wallet" does.

Build instructions:

gcc -o keygen keygen.c -lgmp -lm

Requires the GNU Multiple Precision Arithmetic Library.

If you are using this utility to create a Bitcoin private key, specify a bit length of at most 256 when prompted. Also, make sure that the generated hexadecimal string is not larger than FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141, which is the maximum value that can be turned into a Bitcoin private key, according to the wiki.

To go from the hexadecimal private key to a Bitcoin private key and public address with bash (preferably using a Linux live image on an offline, air-gapped computer), use Lucien Grondilu's bitcoin-bash-tools. Assuming you go this route and download bitcoin.sh from that project, use it like so:

source bitcoin.sh
newBitcoinKey <your hexadecimal key goes here>

I've also included a copy of Lucien's script in this repository in case the one hosted under his account ever goes offline or is compromised.