Add support for STX (Blockstack) address

[vinhbhn]

Issue number

#295

Description

Add support for STX (Blockstack) address

Reference to the specification

• https://github.com/blockstack/c32check/blob/master/src/address.ts#L37&&L59
• https://blockstackdocs.netlify.app/faqs/allfaqs#what-is-a-public-stacks-wallet-address

Reference to the test address.

• https://github.com/blockstack/c32check/blob/master/tests/unitTests/src/index.ts#L461
• https://github.com/blockstack/c32check/blob/master/tests/unitTests/src/index.ts#L479
• https://github.com/blockstack/c32check/blob/master/tests/unitTests/src/index.ts#L500

List of features added/changed

• STX encoder, decoder

NOTE: If you are adding new coin address support, please make sure to add a reference link to README so that reviewer can verify.

How much has the filesize increased?

21kB

How Has This Been Tested?

STX address has the format: S + P or M (p2pkh or p2sh version) + hex_payload + hex_checksum
hex_checksum = sha256(sha256(p2pkh or p2sh version + hex_payload)).substring(0, 4)
Info

According to the 3 links I sent above, the hex_payload is a46ff88886c2ef9762d970b4d2c63678835bd39d which can be used both SP or SM addresses (if not using hex_checksum), so I decided to keep hex_payload and hex_checksum after that so I can use used for encoder

Checklist:

• My code follows the code style of this project.
• My code implements all the required features.
• I have specified correct coinTypes specified at Slip 44
• I have provided the reference link to the specification I implemented.
• I have provided enough explanation about how I provided the test address

[makoto]

There is a size increase from 370k to 438k

[vinhbhn]

There is a size increase from 370k to 438k

After editing, the file size increased by 21kb from 387kb to 408kb.

[vinhbhn]

Hey @makoto, can you review it?

[makoto]

Thanks for the contribution!