Alephium Namespace - Addresses

CAIP-10

For context, see the CAIP-10 specification.

Rationale

An address on Alephium is a unique identifier that represents an account or a contract. All networks share the same address format.

There are 4 different address types on Alephium:

• 0x00 - Pay to public key hash (P2PKH)
• 0x01 - Pay to multiple public key Hash (P2MPKH)
• 0x02 - Pay to script hash (P2SH)
• 0x03 - Pay to contract (P2C)

For each address type, content bytes are defined as follows:

• P2PKH - serialized public key hash
• P2MPKH - serialized public key hashes and multisig threshold
• P2SH - serialized script hash
• P2C - serialized contract id

Hash algorithm used is blake2b.

Constructing an address:

• address = address type || content bytes

Each address on Alephium belongs to a group, which can be derived deterministically from the address.

The algorithm for deriving group information from P2PKH, P2MPKH and P2SH address are similar:

1. Take the relevant bytes from the address. For P2PKH and P2SH address, take the content bytes directly. For P2MPKH address, take the part of the content bytes corresponding to the first public key hash.
2. Hash the relevant bytes from step 1 using the djb2 hash algorithm and perform a bitwise OR operation to the hashed value with 1.
3. Take the result from step 2, perform bitwise XOR operation on its last 4 bytes to get an one byte integer.
4. The group number is the remainder of this one byte integer dividing the total number of groups, which is currently 4 on Alephium.

For P2C address, group number is encoded directly as its last byte of its content bytes.

A Typescript implementation of the logic to derive group information from address can be found here.

Syntax

The native Alephium address encoding is a [Base58][]-encoded string of the type defined above. CAIP-10 simply uses an entire native address as the account_address component.

Test Cases

# P2PKH address
alephium:0_mainnet:15EM5rGtt7dPRZScE4Z9oL2EDfj84JnoSgq3NNgdcGFyu

# P2MPKH address
alephium:0_testnet:2jW1n2icPtc55Cdm8TF9FjGH681cWthsaZW3gaUFekFZepJoeyY3ZbY7y5SCtAjyCjLL24c4L2Vnfv3KDdAypCddfAY

# P2C address
alephium:2_mainnet:26j4viXkBzJd5SaDtQzyGM6joqoECmajncT4QS3tmT9hb

# P2SH address
alephium:0_testnet:ibsc1yJLJxxVcsPfSDJoR3mzrasrZq2Rn63dFQGcDAYE

References

• Alephium Documentation
• base58btc

Copyright

Copyright and related rights waived via CC0.

Citation

Please cite this document as:

Hongchao Liu, "namespaces/alephium-caip10: Alephium Namespace - Addresses [DRAFT]," Chain Agnostic Namespaces, alephium-caip10, June 2024 / June 2024. [Online serial]. Available: https://github.com/ChainAgnostic/namespaces/alephium-caip10.md