bitcoin/bitcoin_proof_of_work.rb/target.rb at master · openblockchains/bitcoin · GitHub

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###
#   type to run:
#     $ ruby ./target.rb

require 'digest'

def sha256( msg )
  Digest::SHA256.hexdigest( msg )
end


p hash = sha256( "Hello, world!0" )
#=> "1312af178c253f84028d480a6adc1e25e81caa44c749ec81976192e2ec934c64"

p num = hash.to_i( 16 )  ## convert hex(adecimal) hash to (integer) number
#=> 8626955810696577806643191367156697543225924734479747394789354329720975740004

p log2 = Math.log2( num )
#=> 252.2534586827243


#########
# Let's try the winning lucky number example:
#  "Hello, world!4250" => 0000c3af42fc31103f1fdc0151fa747ff87349a4714df7cc52ea464e12dcd4e9 = 2^239.61238653


p hash = sha256( "Hello, world!4250" )
#=> "0000c3af42fc31103f1fdc0151fa747ff87349a4714df7cc52ea464e12dcd4e9"

p num = hash.to_i( 16 )
#=> 1350565582647790482127632554504241516291697500941742491868079705537959145

p log2 = Math.log2( num )
#=> 239.61238652983653


puts "%0256b" % num
#=> 0000000000000000110000111010111101000010111111000011000100010000
#   0011111100011111110111000000000101010001111110100111010001111111
#   1111100001110011010010011010010001110001010011011111011111001100
#   0101001011101010010001100100111000010010110111001101010011101001


####################
# The maximum for a 256-bit number is - surprise, surprise - 256


p max = "f"*64
#=> "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"

p num = max.to_i( 16 )
#=> 115792089237316195423570985008687907853269984665640564039457584007913129639935

p log2 = Math.log2( num )
#=> 256.0