Every name and subdomain in BNS has a DID. The encoding is slightly different for subdomains, so the software can determine which code-path to take.
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For on-chain BNS names, the
{address}is the same as the Bitcoin address that owns the name. Currently, both version byte 0 and version byte 5 addresses are supported (i.e. addresses starting with1or3, meaningp2pkhandp2shaddresses). -
For off-chain BNS subdomains, the
{address}has version byte 63 for subdomains owned by a single private key, and version byte 50 for subdomains owned by a m-of-n set of private keys. That is, subdomain DID addresses start withSorM, respectively.
The {index} field for a subdomain’s DID is distinct from the {index} field
for a BNS name’s DID, even if the same created both names and subdomains.
For example, the name abcdefgh123456.id has the DID did:stack:v0:16EMaNw3pkn3v6f2BgnSSs53zAKH4Q8YJg-0,
because it was the first name created by 16EMaNw3pkn3v6f2BgnSSs53zAKH4Q8YJg.
However, 16EMaNw3pkn3v6f2BgnSSs53zAKH4Q8YJg also created jude.statism.id
as its first subdomain name. The DID for jude.statism.id is
did:stack:v0:SSXMcDiCZ7yFSQSUj7mWzmDcdwYhq97p2i-0. Note that the address
SSXMcDiCZ7yFSQSUj7mWzmDcdwYhq97p2i encodes the same public key hash as the address
16EMaNw3pkn3v6f2BgnSSs53zAKH4Q8YJg (the only difference between these two
strings is that the first is base58check-encoded with version byte 0, and the
second is encoded with version byte 63).
You can see this play out in practice with the following code snippit:
>>> import blockstack
>>> blockstack.lib.client.get_name_record('jude.statism.id', hostport='https://node.blockstack.org:6263')['address']
u'16EMaNw3pkn3v6f2BgnSSs53zAKH4Q8YJg'
>>> import virtualchain
>>> virtualchain.address_reencode('16EMaNw3pkn3v6f2BgnSSs53zAKH4Q8YJg', version_byte=63)
'SSXMcDiCZ7yFSQSUj7mWzmDcdwYhq97p2i'
>>> blockstack.lib.client.resolve_DID('did:stack:v0:SSXMcDiCZ7yFSQSUj7mWzmDcdwYhq97p2i-0', hostport='https://node.blockstack.org:6263')
{'public_key': '020fadbbcea0ff3b05f03195b41cd991d7a0af8bd38559943aec99cbdaf0b22cc8'}
