From d27904098d1ca0b8df3f9793a17f0399635e8243 Mon Sep 17 00:00:00 2001
From: moneroexamples <moneroexamples@tuta.io>
Date: Wed, 17 Jan 2018 17:05:38 +0800
Subject: [PATCH] js decoding of ring ct amounts added

---
 src/templates/partials/tx_details.html | 100 ++++++++++++++-----------
 1 file changed, 57 insertions(+), 43 deletions(-)

diff --git a/src/templates/partials/tx_details.html b/src/templates/partials/tx_details.html
index 6665261..70ba3bf 100644
--- a/src/templates/partials/tx_details.html
+++ b/src/templates/partials/tx_details.html
@@ -165,10 +165,54 @@
         </div>
 
         <script>
+
             //  here we handle button presses from the above forms
             //  to decode and prove txs.
             $(document).ready(function() {
 
+                var H = "8b655970153799af2aeadc9ff1add0ea6c7251d54154cfa92c173a0dd39c1f94";
+
+                //decode amount and mask and check against commitment
+                // from https://xmr.llcoins.net/js/site.js
+                function decodeRct(rv, i, der){
+                    var key = derivation_to_scalar(der, i);
+                    var ecdh = decode_rct_ecdh(rv.ecdhInfo[i], key);
+                    console.log(ecdh);
+                    var Ctmp = commit(ecdh.amount, ecdh.mask);
+                    console.log(Ctmp);
+                    if (Ctmp !== rv.outPk[i]){
+                        throw "mismatched commitments!";
+                    }
+                    ecdh.amount = s2d(ecdh.amount);
+                    return ecdh;
+                }
+
+                //creates a Pedersen commitment from an amount (in scalar form) and a mask
+                //C = bG + aH where b = mask, a = amount
+                // from https://xmr.llcoins.net/js/site.js
+                function commit(amount, mask){
+                    if (!valid_hex(mask) || mask.length !== 64 || !valid_hex(amount) || amount.length !== 64){
+                        throw "invalid amount or mask!";
+                    }
+                    var C = ge_double_scalarmult_base_vartime(amount, H, mask);
+                    return C;
+                }
+
+                // // from https://xmr.llcoins.net/js/site.js
+                function s2d(scalar){
+                    return JSBigInt.parse(swapEndian(scalar), 16).toString();
+                }
+
+                //switch byte order for hex string
+                // from https://xmr.llcoins.net/js/site.js
+                function swapEndian(hex){
+                    if (hex.length % 2 !== 0){return "length must be a multiple of 2!";}
+                    var data = "";
+                    for (var i=1; i <= hex.length / 2; i++){
+                        data += hex.substr(0 - 2 * i, 2);
+                    }
+                    return data;
+                }
 
                 // we need output pubplic keys, their indexes and amounts.
                 // all this is already avaliable on the html, but we can use
@@ -176,7 +220,7 @@
 
                 var tx_json = {{#tx_json_raw}}{{/tx_json_raw}};
 
-                console.log(tx_json);
+                //console.log(tx_json);
 
                 var is_rct = ($("#is_ringct").val() === "yes");
                 var rct_type = parseInt($("#ringct_type").val());
@@ -217,7 +261,7 @@
 
                         var output_idx     = parseInt(output[0]);
                         var output_pub_key = output[1];
-                        var amount         = output[2];
+                        var amount         = parseInt(output[2]);
 
                         var pubkey_generated = derive_public_key(key_derivation, output_idx, address_decoded.spend);
 
@@ -226,7 +270,18 @@
                         var mine_output_str = "false";
 
                         if (mine_output) {
+
                             mine_output_str = '<span style="color: #008009;font-weight: bold">true</span>';
+
+                            if (is_rct) {
+                                try {
+                                    var ecdh = decodeRct(tx_json.rct_signatures, output_idx, key_derivation);
+                                    amount = ecdh.amount / 1e12;
+                                } catch (err) {
+                                    decoding_results_str += "<span class='validNo'>RingCT amount for output " + i + " with pubkey: " + output_pub_key + " decoded incorrectly! It will not be spendable." + "</span>" + "<br>"; //rct commitment != computed
+                                    //throw "invalid rct amount";
+                                }
+                            }
                         }
 
                         decoding_results_str += "<tr>"
@@ -259,47 +314,6 @@
                 });
 
 
-                //decode amount and mask and check against commitment
-                // from https://xmr.llcoins.net/js/site.js
-                function decodeRct(rv, i, der){
-                    var key = derivation_to_scalar(der, i);
-                    var ecdh = decode_rct_ecdh(rv.ecdhInfo[i], key);
-                    console.log(ecdh);
-                    var Ctmp = commit(ecdh.amount, ecdh.mask);
-                    console.log(Ctmp);
-                    if (Ctmp !== rv.outPk[i]){
-                        throw "mismatched commitments!";
-                    }
-                    ecdh.amount = s2d(ecdh.amount);
-                    return ecdh;
-                }
-
-                //creates a Pedersen commitment from an amount (in scalar form) and a mask
-                //C = bG + aH where b = mask, a = amount
-                // from https://xmr.llcoins.net/js/site.js
-                function commit(amount, mask){
-                    if (!valid_hex(mask) || mask.length !== 64 || !valid_hex(amount) || amount.length !== 64){
-                        throw "invalid amount or mask!";
-                    }
-                    var C = ge_double_scalarmult_base_vartime(amount, H, mask);
-                    return C;
-                }
-
-                // // from https://xmr.llcoins.net/js/site.js
-                function s2d(scalar){
-                    return JSBigInt.parse(swapEndian(scalar), 16).toString();
-                }
-
-                //switch byte order for hex string
-                // from https://xmr.llcoins.net/js/site.js
-                function swapEndian(hex){
-                    if (hex.length % 2 !== 0){return "length must be a multiple of 2!";}
-                    var data = "";
-                    for (var i=1; i <= hex.length / 2; i++){
-                        data += hex.substr(0 - 2 * i, 2);
-                    }
-                    return data;
-                }
 
             });