Are privatekeys Case-sensitive? I want to print privatekey into block of steel, but I have only uppercase letters, so I wonder if privatekey is case sensitive?
A private key is a 256-bit number. You can represent it using only digits (so there is no need for lowercase letters). However, if you want to use the Wallet import format to represent the key, then you will need both upper and lower case letters (keys are encoded in Base58).