Big Endian: The Network Standard

While Bitcoin's internal data is Little Endian, the rest of the internet generally uses Big Endian. This is often referred to as Network Byte Order.

1. Why the Internet uses Big Endian

When you send an IP address (like 192.168.1.1) across a network, it is sent in Big Endian order.

• Byte 1: 192

• Byte 2: 168

• Byte 3: 1

• Byte 4: 1 This makes it easy for routers to read the "Most Significant" part of the address first and decide where to send the packet.

2. Bitcoin's Hybrid Packet

When a Bitcoin node talks to another node over the internet, it has to mix both standards:

• Packet Header: Often contains Big Endian network data.

• Packet Payload: Contains the raw transaction (Little Endian). This means a Bitcoin developer must constantly switch between "Network Order" and "Host Order."

3. Human-Readable Hashes

When you search for a transaction on a block explorer, you are using Big Endian.

• The Problem: SHA-256 (the math) produces a result. If you interpret that result as a number, it is naturally Big Endian.

• The Conflict: Because Satoshi wanted hashes to be Little Endian in the database, the txid you see on your screen is the Reverse of the txid stored in the raw block file.

4. Cryptographic Consistency

Most cryptographic standards (like ECDSA and SHA-256) were written by mathematicians who prefer Big Endian.

• Private Keys: Always Big Endian.

• Signatures: Always Big Endian.

• Public Keys: Always Big Endian. This creates a weird "Sandwich" in Bitcoin code: [LE Metadata] + [BE Cryptography] + [LE Metadata]

5. Summary of Conflict

Data	Standard	Endianness
IP Addresses	TCP/IP	Big Endian
Private Keys	SEC1 / OpenSSL	Big Endian
TXIDs	Bitcoin Protocol	Little Endian
Amounts	Bitcoin Protocol	Little Endian

In the next section, we will look at the Serialization Flip-Flop.