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How Polykey Handles Node IDs

The Basics​

Polykey generates and encodes Node IDs using Multihash and Multibase to make them flexible, self-describing, and interoperable.

  • Multihash: A format that encodes the hashing algorithm alongside the hash itself. This ensures that the Node ID always carries metadata about how it was generated.
  • Multibase: A format that specifies how the hash is encoded, like Base32 Hex. The 'v' prefix is used to indicate Base32 Hex encoding in Polykey.

How Node IDs Are Generated​

Step 1: Public Key to Multihash​

  • The Ed25519 Public Key is first hashed using a cryptographic hash function.
  • This produces a Multihash output, which includes both the hash algorithm and the digest.

Step 2: Multihash to Multibase​

  • The Multihash result is then encoded using Multibase.
  • In Polykey, we use Base32 Hex encoding with a 'v' prefix to keep it easy to read and portable.

Why Multihash and Multibase?​

  • Future-Proofing: Since Multihash includes the hash algorithm, we can change the algorithm later without breaking compatibility.
  • Interoperability: Other cryptographic systems that use Multihash and Multibase can parse Polykey Node IDs without any issues.
  • Flexible Rendering: A single Node ID can be represented differently if a different encoding or hash function is chosen.

Default Representation in Polykey​

Polykey defaults to rendering Node IDs as Base32 Hex, which has some major advantages:

  • A 32-byte hash always results in a 52-character string.
  • The alphabet is simple and does not use special characters, making it easy to copy, paste, and use anywhere.
  • The lexicographic sort order of the raw 32-byte Node ID matches its encoded form. This keeps things consistent whether Node IDs are stored in memory or displayed in a human-readable format.

How This Works in Practice​

  • Node IDs always go through Multihash first, then Multibase.
  • Base32 Hex is the default format, but the same Node ID can be rendered in other ways.
  • If a different base or hash is chosen, the Node ID will look different but still represent the same key.

Key Takeaways​

  • Node IDs are hashed first (Multihash) and then encoded (Multibase).
  • The default encoding is Base32 Hex, but other formats are possible.
  • Base32 Hex ensures sort order consistency, easy readability, and portability.
  • The Polykey codebase and the js-id repo have more details if needed.