Abstract: Block chain mining methods and apparatus. A mid-state generator develops a plurality, n, of mid-states by selectively varying a portion of the block, and, in particular, the block header. A single message expander develops a message schedule by expanding a message in accordance with a predetermined expansion function; and the message schedule is shared with a plurality, n, of compressors, each developing a result as a function of the message schedule and a respective one of the n unique mid-states in accordance with a predetermined compression function. The compressors can be either rolled core or pipelined core.