What is the use of this prefix https://github.com/paritytech/ss58-registry/blob/main/ss58-registry.json

Question

I was going through ss58 documentation and trying to find out the relationship between ss58 and public key.

I want to know what is the use of this prefix https://github.com/paritytech/ss58-registry/blob/main/ss58-registry.json?

Answer 1

First thing to keep in mind is that an SS58 address is just a sequence of bytes encoded in base 58. This sequence can be dissected in three components:

1. Network-Id
2. Public Key (verbatim in case of sr25519/ed25519 or hashed in case of secp255k1 key)
3. Checksum

The Network-Id is what is referred as the "prefix" in the ss58 registry you shared. For example a generic Substrate address has a prefix set to 42 (here).

The same public key can be used to generate different addresses by changing the prefix (the checksum changes as a consequence).

---

An example may help.

Generate a sr25519 keypair via subkey tool:

❯ subkey generate --scheme sr25519
Secret phrase `trip embody match refuse exchange cabin brand try write eight lamp endorse` is account:
  Secret seed:      0xa444d232c8a70098d94add70f9ceb4702c58aca4558966e2ce7d59c153306389
  Public key (hex): 0x6a5bfc392d5479b306d85c1e03766207b5443466f8e4668eedb97c26918e2e79
  Account ID:       0x6a5bfc392d5479b306d85c1e03766207b5443466f8e4668eedb97c26918e2e79
  SS58 Address:     5EUAFw4JM21WgrjqEqBPXGSZ2zUCkxdCiaNTeuzC7t8twpiD

Convert the SS58 address from base 58 to hex to inspect the content (for example using this website).

B58: 5EUAFw4JM21WgrjqEqBPXGSZ2zUCkxdCiaNTeuzC7t8twpiD
Hex: 2a6a5bfc392d5479b306d85c1e03766207b5443466f8e4668eedb97c26918e2e7973b2

The hex version can be decomposed as follows:

• 2a = Network id (42 in decimal == generic Substrate network)
• 6a5bfc392d5479b306d85c1e03766207b5443466f8e4668eedb97c26918e2e79 = sr25519 Public Key
• 73b2 = checksum

The very same public key can be part of an address used in a different network. For example, for Polkadot:

❯ subkey inspect --network polkadot --scheme sr25519 "trip embody match refuse exchange cabin brand try write eight lamp endorse"
Secret phrase `trip embody match refuse exchange cabin brand try write eight lamp endorse` is account:
  Secret seed:      0xa444d232c8a70098d94add70f9ceb4702c58aca4558966e2ce7d59c153306389
  Public key (hex): 0x6a5bfc392d5479b306d85c1e03766207b5443466f8e4668eedb97c26918e2e79
  Account ID:       0x6a5bfc392d5479b306d85c1e03766207b5443466f8e4668eedb97c26918e2e79
  SS58 Address:     13QTQGKNCoGz8PkMCUEPfRGhtcTrTGBLo56wpCyYfyAR89hu

Convert the SS58 address from base 58 to hex

Base 58: 13QTQGKNCoGz8PkMCUEPfRGhtcTrTGBLo56wpCyYfyAR89hu
Hex: 006a5bfc392d5479b306d85c1e03766207b5443466f8e4668eedb97c26918e2e79259c

Note that the public key component is still the same, while the Network-ID and the Checksum is changed (Network id is now set to 0x00, i.e. the Polkadot prefix here)

---

You can find another example here