Solidity provides a number of global variables that are always available in the global namespace. These variables provide information about blocks and transactions. Additionally, cryptographic functions and address-related variables are available as well.
A subset of available functions and variables is shown as follows:
keccak256(...) returns (bytes32)
This function is used to compute the Keccak-256 hash of the argument provided to the function:
ecrecover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) returns (address)
This function returns the associated address of the public key from the elliptic curve signature:
block.number
This returns the current block number.
