Technical background of version 0 Skycoin addresses

How to Validate a Skycoin Address

Golang:

• Use the cipher.DecodeBase58Address from package cipher: https://godoc.org/github.com/skycoin/skycoin/src/cipher#DecodeBase58Address

Python:

• Use pyskycoin. The function is skycoin.cipher__DecodeBase58Address.

Javascript/other languages:

• You can make a POST request to https://node.skycoin.net/api/v2/address/verify (or use any Skycoin API node of your choice). See https://github.com/skycoin/skycoin/blob/develop/src/api/README.md#verify-an-address for the API docs
• Make language bindings to libskycoin
• Construct a validator in the native language (requires these libraries: sha256, ripemd160, base58).

Differences between Skycoin and Bitcoin addresses

Skycoin addresses are similar version 1 Bitcoin addresses, with these differences:

• The Skycoin address hash is calculated as ripemd160(sha256(sha256(pubkey))) whereas the Bitcoin address hash is ripemd160(sha256(pubkey))
• The Skycoin address version byte is placed last, whereas the Bitcoin address version byte is placed first
• The Skycoin address checksum is calculated as sha256(address+version), whereas the Bitcoin address checksum is calculated as sha256(sha256(version+address))

Technical background

The following is adapted from https://en.bitcoin.it/wiki/Technical_background_of_version_1_Bitcoin_addresses

A Skycoin address is a 160-bit hash of the public portion of a public/private ECDSA keypair. Using public-key cryptography, you can "sign" data with your private key and anyone who knows your public key can verify that the signature is valid.

A new keypair is generated for each receiving address, deterministically from the wallet's seed. The public key, private key, address and the seed needed to generate them are stored in the wallet data file (saved in ~/.skycoin/wallets by default). The seed and private keys are encrypted if the wallet is encrypted, but public data is left visible. If you lose your seed and the wallet file or you forget the password to your encrypted wallet, then you cannot recover your coins. Best practice is to retain the seed. It is ok to lose the wallet file as long as you have the seed.

Skycoin allows you to create as many addresses as you want.

Skycoin addresses contain a built-in check code (checksum), so it's generally not possible to send Skycoins to a mistyped address. However, it is possible that the address is mistyped but still valid. If no one owns it, any coins sent to that address will be lost forever.

Hash values and the checksum data are converted to an alpha-numeric representation using a custom scheme: the Base58Check encoding scheme. Under Base58Check, addresses can contain all alphanumeric characters except 0, O, I, and l. Due to the base58 encoding scheme, addresses can be 25-34 characters in length, but most addresses are 33 or 34 characters long. The underlying byte representation of an address is still a fixed length of 25 bytes (20 bytes for the ripemd160 hash, 1 byte for the version, 4 bytes for the checksum).

How to create a Skycoin address

0. Having a private ECDSA key

   7e4c9fbbbbb21be96fd496653b81036bab6e599a10557c790d1aa4d29c461ab9

1. Take the corresponding public key generated with it

   03a4e90c34b9f359364b01f2136f1ff850d648d56da2f4b4aed6cbb6fede346831

2. Perform SHA-256 hashing on the public key

   e6958adc2f9f3260b269d14842bde2e3da9dad93d310c9dab547a547e60fe885

3. Perform SHA-256 hashing on the result of the previous SHA-256 hash

   a8015a9b10fd68c55539a4fee83e9976b0efe808c6666780f9d30ae8c80be1fd

4. Perform RIPEMD-160 hashing on the result of SHA-256

   d690c4ca95e00522b34d8c5d4f618a0255f370df

5. Add version byte at the end of the RIPEMD-160 hash (version is 0x00 in this example)

   d690c4ca95e00522b34d8c5d4f618a0255f370df00

6. Perform SHA-256 hash on the extended RIPEMD-160 result

   d643b43ea9a97c0840c32e95a1d967b8fa3f5345207b72e5cc3714622f777dd5

7. Take the first 4 bytes of the previous SHA-256 hash. This is the address checksum

   d643b43e

8. Add the 4 checksum bytes from stage 7 at the end of extended RIPEMD-160 hash from stage 4. This is the 25-byte binary Bitcoin Address.

   d690c4ca95e00522b34d8c5d4f618a0255f370df00d643b43e

9. Convert the result from a byte string into a base58 string

   2VLXYmAWYnX5MMCfRwAvt46YyEk2X7TvrS9

These values were generated by this script: https://gist.github.com/gz-c/7f9018a8742133280685671bfcff80b6