Save signed PDFs (close #2)

index.html

@@ -99,10 +99,6 @@ file, You can obtain one at http://mozilla.org/MPL/2.0/.
     </div>
 </div>
 
-<form style="display: none; height: 0; width: 0; margin: 0; padding: 0;">
-    <input type="file" id="open-file-input" accept=".pdf"/>
-</form>
-
 <div id="svgtrimbox"></div>
 
 
@@ -111,10 +107,13 @@ file, You can obtain one at http://mozilla.org/MPL/2.0/.
 <script src="node_modules/pdfjs-dist/build/pdf.min.js"></script>
 <script src="node_modules/jspdf/dist/jspdf.umd.min.js"></script>
 <script src="node_modules/signature_pad/dist/signature_pad.umd.min.js"></script>
+<script src="node_modules/jshashes/hashes.min.js"></script>
+<script src="js/kbpgp-2.1.15.js"></script>
 <script src="js/svg-to-image.js"></script>
 <script src="js/util.js"></script>
 <script src="js/storage.js"></script>
 <script src="js/filesystem.js"></script>
+<script src="js/crypto.js"></script>
 <script src="js/drawtools.js"></script>
 <script src="js/pdf.js"></script>
 <script src="js/main.js"></script>

js/crypto.js

@@ -0,0 +1,124 @@
+/*
+ * Copyright 2021 Netsyms Technologies.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+var keymgr;
+
+/**
+ * Load and unlock the private key in localstorage, prompting user as needed. If there is no key, generates, saves, and loads a new one.
+ * @param {function} callback Passed two arguments: message for user, and boolean true if OK false if error.
+ * @returns {undefined}
+ */
+function loadKeyFromLocalStorage(callback) {
+    if (!inStorage("signingkey") || getStorage("signingkey") == "undefined") {
+        var pass = prompt("Generating a new signing key. Enter a password to protect it. You'll need to save this password somewhere safe; it cannot be recovered.");
+        generatePrivateKey(getStorage("notary_name") + " <null@null.com>", pass, function (key) {
+            if (typeof key == "undefined") {
+                callback("Could not generate key.", false);
+                return;
+            }
+            keymgr = key;
+            setStorage("signingkey", keymgr.armored_pgp_private);
+            callback("Signing key generated.", true);
+        });
+    } else {
+        var pass = prompt("Enter password to unlock signing key.");
+        loadPrivateKey(getStorage("signingkey"), pass, function (key) {
+            if (typeof key == "undefined") {
+                callback("Could not unlock key. Password is probably incorrect.", false);
+                return;
+            }
+            keymgr = key;
+            callback("Signing key unlocked.", true);
+        });
+    }
+}
+
+/**
+ * Load a private key.
+ * @param {string} armoredkey PGP private key
+ * @param {string} pass key password
+ * @param {function} callback Passed a new keymanager for the key.
+ * @returns {undefined}
+ */
+function loadPrivateKey(armoredkey, pass, callback) {
+    kbpgp.KeyManager.import_from_armored_pgp({
+        armored: armoredkey
+    }, function (err, key) {
+        if (!err) {
+            if (key.is_pgp_locked()) {
+                key.unlock_pgp({
+                    passphrase: pass
+                }, function (err) {
+                    if (!err) {
+                        console.log("Loaded private key with passphrase");
+                        callback(key);
+                    } else {
+                        console.error(err);
+                        callback(undefined);
+                    }
+                });
+            } else {
+                console.log("Loaded private key w/o passphrase");
+                callback(key);
+            }
+        } else {
+            console.error(err);
+            callback(undefined);
+        }
+    });
+}
+
+/**
+ * Sign a message with a key and return the signed message in the callback.
+ * @param {type} text
+ * @param {type} key
+ * @param {type} callback
+ * @returns {undefined}
+ */
+function signMessage(text, key, callback) {
+    var params = {
+        msg: text,
+        sign_with: key
+    };
+    kbpgp.box(params, function (err, result_string, result_buffer) {
+        //console.log(err, result_string, result_buffer);
+        callback(result_string);
+    });
+}
+
+/**
+ * Generate a new private key.
+ * @param {string} userid Something like "Test User <test@netsyms.com>"
+ * @param {string} passphrase protects the key
+ * @param {function} callback Passed the keymanager for the new key
+ * @returns {undefined}
+ */
+function generatePrivateKey(userid, passphrase, callback) {
+    var F = kbpgp["const"].openpgp;
+
+    var opts = {
+        userid: userid,
+        primary: {
+            nbits: 2048,
+            flags: F.certify_keys | F.sign_data | F.auth | F.encrypt_comm | F.encrypt_storage,
+            expire_in: 0  // never expire
+        },
+        subkeys: []
+    };
+
+    kbpgp.KeyManager.generate(opts, function (err, alice) {
+        if (!err) {
+            alice.sign({}, function (err) {
+                alice.export_pgp_private({
+                    passphrase: passphrase
+                }, function (err, pgp_private) {
+                    callback(alice);
+                });
+            });
+        }
+    });
+}

js/filesystem.js

@@ -3,16 +3,64 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
+//
+//function openFileDialog(callback) {
+//    $("#open-file-input").off("change");
+//    if (typeof callback != "undefined") {
+//        $("#open-file-input").on("change", function () {
+//            callback($("#open-file-input").val());
+//        });
+//    }
+//    $("#open-file-input").click();
+//}
 
-function openFileDialog(callback) {
+/**
-    $("#open-file-input").off("change");
+ * Open a save file dialog and passes the file path back.
-    if (typeof callback != "undefined") {
+ * @param {function} callback
-        $("#open-file-input").on("change", function () {
+ * @param {string} accept HTML5 accept="thisvar" (optional)
-            callback($("#open-file-input").val());
+ * @returns {undefined}
-        });
+ */
+function openFileDialog(callback, accept) {
+    var dialog = document.createElement("input");
+    dialog.setAttribute("type", "file");
+    if (typeof accept != "undefined") {
+        dialog.setAttribute("accept", accept);
+    }
+    dialog.onchange = function () {
+        callback(dialog.value);
+    }
+    dialog.dispatchEvent(new MouseEvent("click", {
+        "view": window,
+        "bubbles": false,
+        "cancelable": false
+    }));
 }
-    $("#open-file-input").click();
 
+/**
+ * Open a save file dialog and passes the file path back.
+ * @param {function} callback
+ * @param {string} defaultfilename something like file.pdf (optional)
+ * @param {string} accept HTML5 accept="thisvar" (optional)
+ * @returns {undefined}
+ */
+function openSaveFileDialog(callback, defaultfilename, accept) {
+    var dialog = document.createElement("input");
+    dialog.setAttribute("type", "file");
+    if (typeof defaultfilename == "undefined") {
+        defaultfilename = "";
+    }
+    dialog.setAttribute("nwsaveas", defaultfilename);
+    if (typeof accept != "undefined") {
+        dialog.setAttribute("accept", accept);
+    }
+    dialog.onchange = function () {
+        callback(dialog.value);
+    }
+    dialog.dispatchEvent(new MouseEvent("click", {
+        "view": window,
+        "bubbles": false,
+        "cancelable": false
+    }));
 }
 
 function getFileAsString(path) {
@@ -25,21 +73,26 @@ function getFileAsUint8Array(path) {
     return fs.readFileSync(path, null);
 }
 
-function writeStringToFile(path, text) {
+function writeToFile(path, data) {
-    const fs = require("fs");
-    fs.writeFileSync(path, text);
-}
-
-function writeDataToFile(path, data) {
     const fs = require("fs");
     fs.writeFileSync(path, data);
 }
 
+function appendToFile(path, data) {
+    const fs = require("fs");
+    fs.appendFileSync(path, data);
+}
+
 function copyFile(source, dest) {
     const fs = require("fs");
     fs.copyFileSync(source, dest);
 }
 
+function deleteFile(path) {
+    const fs = require('fs');
+    fs.unlinkSync(path);
+}
+
 function getBasename(fullpath) {
     var path = require("path");
     return path.basename(fullpath);

js/pdf.js

@@ -7,7 +7,7 @@
 
 const {jsPDF} = window.jspdf;
 
-var pdfPageScale = 4;
+var pdfPageScale = 3;
 var pdfAssumedDPI = 72;
 var pdfDoc = null;
 var pageNumber = 0;
@@ -27,10 +27,10 @@ function addPDF() {
             // Initial/first page rendering
             //renderPage(pageNum);
         });
-    });
+    }, ".pdf");
 }
 
-function savePDF() {
+function generatePDF() {
     var canvases = $("#page-canvas-container .page-canvas");
     const pdf = new jsPDF({
         unit: "in",
@@ -51,7 +51,49 @@ function savePDF() {
         pdf.addPage(pageFormat, pageOrientation);
         pdf.addImage($("#page-canvas-container .page-canvas")[i].toDataURL(), 0, 0, pageWidthInches, pageHeightInches);
     }
-    pdf.save("signed.pdf");
+    return pdf;
+}
+
+function getPDFAsByteArray(pdf) {
+    return pdf.output("arraybuffer");
+}
+
+function makeAndSaveSignedPDF(pdf, savepath, callback) {
+    const hasha = require('hasha');
+
+    var pdfbuffer = pdf.output("arraybuffer");
+    var hashstr = hasha(Buffer.from(pdfbuffer), {algorithm: 'sha256'});
+
+    var message = "HASH:" + hashstr
+            + "\nNOTARY:" + getStorage("notary_name")
+            + "\nSTATE:" + getStorage("notary_state")
+            + "\n";
+    signMessage(message, keymgr, function (sig) {
+        writeToFile(savepath, Buffer.from(pdfbuffer));
+        appendToFile(savepath, sig);
+
+        //writeToFile(savepath + ".notsigned.pdf", Buffer.from(pdfbuffer));
+        writeToFile(savepath + ".sig", sig);
+        callback({
+            signature: sig,
+            hash: hashstr
+        });
+    });
+}
+
+function savePDF() {
+    loadKeyFromLocalStorage(function (message, ok) {
+        if (ok) {
+            openSaveFileDialog(function (path) {
+                var pdf = generatePDF();
+                makeAndSaveSignedPDF(pdf, path, function (result) {
+                    alert("File signed and saved.\n SHA256 of file (without signature): " + result.hash);
+                });
+            }, "signed.pdf", ".pdf");
+        } else {
+            alert("Error: " + message);
+        }
+    });
 }
 
 function pdfZoom(str) {

package-lock.json

@@ -108,6 +108,15 @@
             "resolved": "https://registry.npmjs.org/fflate/-/fflate-0.4.8.tgz",
             "integrity": "sha512-FJqqoDBR00Mdj9ppamLa/Y7vxm+PRmNWA67N846RvsoYVMKB4q3y/de5PA7gUmRMYK/8CMz2GDZQmCRN1wBcWA=="
         },
+        "hasha": {
+            "version": "5.2.2",
+            "resolved": "https://registry.npmjs.org/hasha/-/hasha-5.2.2.tgz",
+            "integrity": "sha512-Hrp5vIK/xr5SkeN2onO32H0MgNZ0f17HRNH39WfL0SYUNOTZ5Lz1TJ8Pajo/87dYGEFlLMm7mIc/k/s6Bvz9HQ==",
+            "requires": {
+                "is-stream": "^2.0.0",
+                "type-fest": "^0.8.0"
+            }
+        },
         "html2canvas": {
             "version": "1.0.0-rc.7",
             "resolved": "https://registry.npmjs.org/html2canvas/-/html2canvas-1.0.0-rc.7.tgz",
@@ -117,6 +126,11 @@
                 "css-line-break": "1.1.1"
             }
         },
+        "is-stream": {
+            "version": "2.0.0",
+            "resolved": "https://registry.npmjs.org/is-stream/-/is-stream-2.0.0.tgz",
+            "integrity": "sha512-XCoy+WlUr7d1+Z8GgSuXmpuUFC9fOhRXglJMx+dwLKTkL44Cjd4W1Z5P+BQZpr+cR93aGP4S/s7Ftw6Nd/kiEw=="
+        },
         "jquery": {
             "version": "3.6.0",
             "resolved": "https://registry.npmjs.org/jquery/-/jquery-3.6.0.tgz",
@@ -205,6 +219,11 @@
             "version": "1.14.1",
             "resolved": "https://registry.npmjs.org/tslib/-/tslib-1.14.1.tgz",
             "integrity": "sha512-Xni35NKzjgMrwevysHTCArtLDpPvye8zV/0E4EyYn43P7/7qvQwPh9BGkHewbMulVntbigmcT7rdX3BNo9wRJg=="
+        },
+        "type-fest": {
+            "version": "0.8.1",
+            "resolved": "https://registry.npmjs.org/type-fest/-/type-fest-0.8.1.tgz",
+            "integrity": "sha512-4dbzIzqvjtgiM5rw1k5rEHtBANKmdudhGyBEajN01fEyhaAIhsoKNy6y7+IN93IfpFtwY9iqi7kD+xwKhQsNJA=="
         }
     }
 }

package.json

@@ -14,6 +14,7 @@
     "dependencies": {
         "@fortawesome/fontawesome-free": "^5.15.3",
         "bootstrap": "^5.0.2",
+        "hasha": "^5.2.2",
         "jquery": "^3.6.0",
         "jspdf": "^2.3.1",
         "pdf-lib": "^1.16.0",