diff --git a/lib/bcoin/utils.js b/lib/bcoin/utils.js
index 40571777..9ce5b2be 100644
--- a/lib/bcoin/utils.js
+++ b/lib/bcoin/utils.js
@@ -1241,6 +1241,120 @@ utils.writeU64BE = function writeU64BE(dst, num, off) {
   return 8;
 };
 
+utils.writeU64N = function writeU64N(dst, num, off) {
+  return utils.write64N(dst, num, off);
+};
+
+utils.writeU64NBE = function writeU64NBE(dst, num, off) {
+  return utils.write64NBE(dst, num, off);
+};
+
+utils.write64N = function write64N(dst, num, off) {
+  var neg, hi, lo, one, i, b;
+
+  off = off >>> 0;
+
+  if (num < 0)
+    neg = true;
+
+  num = num < 0 ? -num : num;
+
+  hi = num / 0x100000000 | 0;
+  lo = num % 0x100000000;
+
+  dst[off + 0] = (lo >>> 0) & 0xff;
+  dst[off + 1] = (lo >>> 8) & 0xff;
+  dst[off + 2] = (lo >>> 16) & 0xff;
+  dst[off + 3] = (lo >>> 24) & 0xff;
+  dst[off + 4] = (hi >>> 0) & 0xff;
+  dst[off + 5] = (hi >>> 8) & 0xff;
+  dst[off + 6] = (hi >>> 16) & 0xff;
+  dst[off + 7] = (hi >>> 24) & 0xff;
+
+  if (neg) {
+    one = 1;
+    for (i = off; i < off + 8; i++) {
+      b = (dst[i] ^ 0xff) + one;
+      dst[i] = b & 0xff;
+      one = b >>> 8;
+    }
+  }
+
+  return 8;
+};
+
+utils.write64NBE = function write64NBE(dst, num, off) {
+  var neg, hi, lo, one, i, b;
+
+  off = off >>> 0;
+
+  if (num < 0)
+    neg = true;
+
+  num = num < 0 ? -num : num;
+
+  hi = num / 0x100000000 | 0;
+  lo = num % 0x100000000;
+
+  dst[off + 7] = (lo >>> 0) & 0xff;
+  dst[off + 6] = (lo >>> 8) & 0xff;
+  dst[off + 5] = (lo >>> 16) & 0xff;
+  dst[off + 4] = (lo >>> 24) & 0xff;
+  dst[off + 3] = (hi >>> 0) & 0xff;
+  dst[off + 2] = (hi >>> 8) & 0xff;
+  dst[off + 1] = (hi >>> 16) & 0xff;
+  dst[off + 0] = (hi >>> 24) & 0xff;
+
+  if (neg) {
+    one = 1;
+    for (i = off + 7; i >= off; i--) {
+      b = (dst[i] ^ 0xff) + one;
+      dst[i] = b & 0xff;
+      one = b >>> 8;
+    }
+  }
+
+  return 8;
+};
+
+utils.readU64N = function readU64N(dst, off) {
+  off = off >>> 0;
+  var hi = utils.readU32(dst, off + 4);
+  var lo = utils.readU32(dst, off);
+  return (hi * 0x100000000) + lo;
+};
+
+utils.readU64NBE = function readU64NBE(dst, off) {
+  off = off >>> 0;
+  var hi = utils.readU32BE(dst, off);
+  var lo = utils.readU32BE(dst, off + 4);
+  return (hi * 0x100000000) + lo;
+};
+
+utils.read64N = function read64N(dst, off) {
+  off = off >>> 0;
+  var hi = utils.readU32(dst, off + 4);
+  var lo = utils.readU32(dst, off);
+  if (hi & 0x80000000) {
+    hi = ~hi + 1;
+    lo = ~lo + 1;
+    return -(hi * 0x100000000 + lo);
+  }
+  return (hi * 0x100000000) + lo;
+};
+
+utils.read64NBE = function read64NBE(dst, off) {
+  off = off >>> 0;
+  var hi = utils.readU32BE(dst, off);
+  var lo = utils.readU32BE(dst, off + 4);
+  if (hi & 0x80000000) {
+    hi = ~hi + 1;
+    lo = ~lo + 1;
+    return -(hi * 0x100000000 + lo);
+  }
+  return (hi * 0x100000000) + lo;
+};
+
 utils.writeU256 = function writeU256(dst, num, off) {
   var i;