diff --git a/scripts/btcMortgage.js b/scripts/btcMortgage.js
new file mode 100644
index 0000000..aaf6556
--- /dev/null
+++ b/scripts/btcMortgage.js
@@ -0,0 +1,114 @@
+(function (EXPORTS) {
+    const btcMortgage = EXPORTS;
+
+    //USERS: B: Borrower, L: Lender, C: Collateral provider, T: Trusted banker (us)
+
+    var BankerPubKey = "0257a9c47462fe89b159daa204ddb964c9b098a020641cc8090a9cad4f6dd2172a";
+
+    const CURRENCY = "USD";
+
+    const PERIOD_REGEX = /^\d{1,5}(Y|M|D)$/,
+        TXID_REGEX = /^[0-9a-f]{64}$/i,
+        VALUE_REGEX = /^\d+(.\d{1,8})?$/;
+
+    const POLICIES = {}
+
+    const toFixedDecimal = value => parseFloat((value).toFixed(8));
+
+    function encodePeriod(str) {
+
+        if (typeof str != 'string')
+            throw "passed value must be string";
+
+        if (PERIOD_REGEX.test(str)) //already in format
+            return str;
+
+        let P = '', n = 0;
+        str.toLowerCase().replace(/,/g, '').split(" ").forEach(s => {
+            if (!isNaN(s))
+                n = parseInt(s);
+            else switch (s) {
+                case "year(s)": case "year": case "years": P += (n + 'Y'); n = 0; break;
+                case "month(s)": case "month": case "months": P += (n + 'M'); n = 0; break;
+                case "day(s)": case "day": case "days": P += (n + 'D'); n = 0; break;
+            }
+        });
+
+        if (!PERIOD_REGEX.test(P)) {//not in format: something wrong
+            console.error(`encodePeriod('${str}') failed`, P)
+            throw "Invalid period";
+        }
+
+        return P;
+    }
+
+    function decodePeriod(str) {
+        if (typeof str != 'string')
+            throw "passed value must be string";
+
+        else if (!PERIOD_REGEX.test(str)) //not in format
+            throw "Invalid period";
+
+        let n = parseInt(str);
+        let v = str[str.length - 1];
+
+        switch (v) {
+            case 'Y': return n + (n == 1 ? "year" : "years");
+            case 'M': return n + (n == 1 ? "month" : "months");
+            case "D": return n + (n == 1 ? "day" : "days");
+        }
+
+    }
+
+    const dateFormat = (date = null) => {
+        let d = (date ? new Date(date) : new Date()).toDateString();
+        return [d.substring(8, 10), d.substring(4, 7), d.substring(11, 15)].join(" ");
+    }
+    const yearDiff = (d1 = null, d2 = null) => {
+        d1 = d1 ? new Date(d1) : new Date();
+        d2 = d2 ? new Date(d2) : new Date();
+        let y = d1.getYear() - d2.getYear(),
+            m = d1.getMonth() - d2.getMonth(),
+            d = d1.getDate() - d2.getDate()
+        return y + m / 12 + d / 365;
+    }
+
+    const dateAdder = function (start_date, duration) {
+        let date = new Date(start_date);
+        let y = parseInt(duration.match(/\d+Y/)),
+            m = parseInt(duration.match(/\d+M/)),
+            d = parseInt(duration.match(/\d+D/));
+        if (!isNaN(y))
+            date.setFullYear(date.getFullYear() + y);
+        if (!isNaN(m))
+            date.setMonth(date.getMonth() + m);
+        if (!isNaN(d))
+            date.setDate(date.getDate() + d);
+        return date;
+    }
+
+    function calcAllowedLoan(collateralQuantity, security_percent) {
+        return collateralQuantity * security_percent;
+    }
+
+    function calcRequiredCollateral(loanEquivalent, security_percent) {
+        let inverse_security_percent = 1 / security_percent;
+        return loanEquivalent * inverse_security_percent;
+    }
+
+    function findLocker(coborrower_pubKey, lender_pubKey) {
+        return btcOperator.multiSigAddress([coborrower_pubKey, lender_pubKey, BankerPubKey], 2);
+    }
+
+    function extractPubKeyFromSign(sign) {
+        return sign.split('.')[0];
+    }
+
+    btcMortgage.util = {
+        toFixedDecimal,
+        encodePeriod, decodePeriod,
+        calcAllowedLoan, calcRequiredCollateral,
+        findLocker, extractPubKeyFromSign
+    }
+
+})(window.btcMortgage = {})
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