If you have disabled javascript, you will be presented with a perl script to run. Here is a short explanation of what it does. A sample script looks like this:

perl -MDigest::SHA=sha256_hex -e '$n="58c80c8c2271cb295b47cc553736efea3633c5653365947c12cdcafd67085c585613208637ea9c680a121d2d1fda260c42ba620c47a6ddae406233b827986b5e689796e82f559de773fba4b257faffd5574a8aab0357831c32e8f62d6e72a9296add515f70c05b370c0092c941492ebc277449c1388b42c32153430c4cfa9525";$d=4;for($i=0;;$i++){$h=sha256_hex($n.$i);if(substr($h,0,$d) eq "0"x$d){print "$i\n";last }}'

Let's break it down a bit:

perl
-MDigest::SHA=sha256_hex
-e

'
$n="58c80c8c2271cb295b47cc553736efea3633c5653365947c12cdcafd67085c585613208637ea9c680a121d2d1fda260c42ba620c47a6ddae406233b827986b5e689796e82f559de773fba4b257faffd5574a8aab0357831c32e8f62d6e72a9296add515f70c05b370c0092c941492ebc277449c1388b42c32153430c4cfa9525";
$d=4;
for($i=0;;$i++){
$h=sha256_hex($n.$i);
if(substr($h,0,$d) eq "0"x$d){
print "$i\n";last
}
}
'

Line by line:

• perl runs perl
• -e means evaluate a string of code
• $n="58c80c8c2..."; sets a string of text to the variable n
• $d=4; sets the number 4 to the variable n
• for($i=0;;$i++) runs a loop from zero upwards where the current iteration is stored in the variable i
• $h=sha256_hex($n.$i) calculates a sha256 hash of a string which is made by concatenating variables n and i
• if(substr($h,0,$d) eq "0"x$d) checks if the first d (in this case, 4) characters of the sha256 hash are zeroes. If so:
• print "$i\n";last prints the iteration and exits the loop.

Please note that if ANYTHING but the string in $n and number in $d are different, the script is forged and not genuine!