Ethereum Cookbook

How to do it...

1. To calculate the SHA-3 (keccak-256) hash of something, use the keccak256/sha3 function:

keccak256(...)// ORsha3(...) // alias to keccak256

2. The function returns the hash in bytes32 format:

keccak256(...) returns (bytes32);

3. Since the arguments to this functions are concatenated without padding, use any of the following input formats to yield the same value:

keccak256("hello", "world")keccak256("helloworld")keccak256(0x68656c6c6f776f726c64)keccak256(68656c6c6f776f726c64)

4. Use solidity's sha3 function to calculate the SHA-256 hash of the input. It works just like the keccak256 function:

sha256(...) returns (bytes32);

5. Use the ecrecover function to verify the address associated with a public key. The function accepts a signed ...