I'm still really struggling with this. I've tried to back the calculation up a few steps in the JS code, but that's leading to a ton of other problems for me, so I'm not sure that's going to work too well. I keep coming back to attempting to do this in Perl instead. I've boiled this down to a simple example: 
#!/usr/bin/perl -w

use strict;
use CGI;
use URI::Escape;
use JSON;
use Digest::SHA qw(hmac_sha512_hex);

my $query         = CGI->new;
my $raw_data     = $query->param('data');
my $data             = decode_json($raw_data);
my $actual_data = '{"request":{"service":"test"},"data":{"test_input":
+"%2B2"}}';

print "raw_data: ".$raw_data."\n";
print "no escaping: ".$data->{data}->{test_input}." vs escaping: ";
print uri_escape($data->{data}->{test_input})."\n";

print hmac_sha512_hex($raw_data,"ABCD1234")."\n";
print hmac_sha512_hex($actual_data,"ABCD1234")."\n";

[download]
If you run that on the command line like this: ./script.pl 'data={"request":{"service":"test"},"data":{"test_input":"%2B2"}}' You'll get this: 
raw_data: {"request":{"service":"test"},"data":{"test_input":"+2"}}
no escaping: +2 vs escaping: %2B2
3c6de296682e7f3896073fe41af9732a294ef723bb1e5c75aa1eba1af981f04f0a0963
+d03604119ea92b719a2912ef0c957c03a7268b51e2170f8fed7c875465
32595bf215b309a73c8dd4d09600430378f455c7cb44d31573b08566ddff0a7bd3c536
+8d70696b57a2c1c95e862ed7b062501e39820bf973c9309812250df460

[download]
I need the 32595... calculation to compare to the input (which I removed from the Perl example to make it shorter). I can't just unescape the whole string, because then it'll attempt to escape the part that makes it a JSON input ({, :, etc). It's as if the CGI input unescapes automatically and I can't figure out how to make it not unescape (or "re-escape"). Any ideas on how to do that before I write something myself to deal with escaped characters in a hmac sha? Thanks!

In reply to Re^2: CGI Input with Escaped Characters by hoyt
in thread CGI Input with Escaped Characters by hoyt

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