+
+
This page is for organizations who want to be able to create and send name operation transactions to the blockchain(s) Blockstack supports.
+It describes the transaction formats for the Bitcoin blockchain.
+
+
+
+
+
+
Each Bitcoin transaction for Blockstack contains signatures from two sets of keys: the name owner, and the payer. The owner scriptSig and scriptPubKey fields are generated from the key(s) that own the given name. The payer scriptSig and scriptPubKey fields are used to subsidize the operation. The owner keys do not pay for any operations; the owner keys only control the minimum amount of BTC required to make the transaction standard. The payer keys only pay for the transaction’s fees, and (when required) they pay the name fee.
+
+
This construction is meant to allow the payer to be wholly separate from the owner. The principal that owns the name can fund their own transactions, or they can create a signed transaction that carries out the desired operation and request some other principal (e.g. a parent organization) to actually pay for and broadcast the transaction.
+
+
The general transaction layout is as follows:
+
+
+
+
+ | Inputs |
+ Outputs |
+
+
+
+
+ | Owner scriptSig (1) |
+ OP_RETURN <payload> (2) |
+
+
+ | Payment scriptSig |
+ Owner scriptPubKey (3) |
+
+
+ | Payment scriptSig… (4) |
+ |
+
+
+ | … (4) |
+ … (5) |
+
+
+
+
+
(1) The owner scriptSig is always the first input.
+(2) The OP_RETURN script that describes the name operation is always the first output.
+(3) The owner scriptPubKey is always the second output.
+(4) The payer can use as many payment inputs as (s)he likes.
+(5) At most one output will be the “change” scriptPubKey for the payer.
+Different operations require different outputs.
+
+
+
+
Each Blockstack transaction in Bitcoin describes the name operation within an OP_RETURN output. It encodes name ownership, name fees, and payments as scriptPubKey outputs. The specific operations are described below.
+
+
Each OP_RETURN payload always starts with the two-byte string id (called the “magic” bytes in this document), followed by a one-byte op that describes the operation.
+
+
NAME_PREORDER
+
+
Op: ?
+
+
Description: This transaction commits to the hash of a name. It is the first
+transaction of two transactions that must be sent to register a name in BNS.
+
+
Example: 6730ae09574d5935ffabe3dd63a9341ea54fafae62fde36c27738e9ee9c4e889
+
+
OP_RETURN wire format:
+
0 2 3 23 39
+ |-----|--|--------------------------------------------------|--------------|
+ magic op hash_name(name.ns_id,script_pubkey,register_addr) consensus hash
+
+
+
+
Inputs:
+
+
+
Outputs:
+
+ OP_RETURN payload- Payment
scriptPubkey script for change
+ p2pkh scriptPubkey to the burn address (0x00000000000000000000000000000000000000)
+
+
Notes:
+
+ register_addr is a base58check-encoded ripemd160(sha256(pubkey)) (i.e. an address). This address must not have been used before in the underlying blockchain.script_pubkey is either a p2pkh or p2sh compiled Bitcoin script for the payer’s address.
+
+
NAME_REGISTRATION
+
+
Op: :
+
+
Description: This transaction reveals the name whose hash was announced by a
+previous NAME_PREORDER. It is the second of two transactions that must be
+sent to register a name in BNS.
+
+
Example: 55b8b42fc3e3d23cbc0f07d38edae6a451dfc512b770fd7903725f9e465b2925
+
+
OP_RETURN wire format (2 variations allowed):
+
+
Variation 1:
+
0 2 3 39
+ |----|--|-----------------------------|
+ magic op name.ns_id (37 bytes)
+
+
+
+
Variation 2:
+
0 2 3 39 59
+ |----|--|----------------------------------|-------------------|
+ magic op name.ns_id (37 bytes, 0-padded) value
+
+
+
+
Inputs:
+
+
+
Outputs:
+
+ OP_RETURN payloadscriptPubkey for the owner’s addressscriptPubkey for the payer’s change
+
+
Notes:
+
+
+ - Variation 1 simply registers the name. Variation 2 will register the name and
+set a name value simultaneously. This is used in practice to set a zone file
+hash for a name without the extra
NAME_UPDATE transaction.
+ - Both variations are supported. Variation 1 was designed for the time when
+Bitcoin only supported 40-byte
OP_RETURN outputs.
+
+
+
NAME_RENEWAL
+
+
Op: :
+
+
Description: This transaction renews a name in BNS. The name must still be
+registered and not expired, and owned by the transaction sender.
+
+
Example: e543211b18e5d29fd3de7c0242cb017115f6a22ad5c6d51cf39e2b87447b7e65
+
+
OP_RETURN wire format (2 variations allowed):
+
+
Variation 1:
+
0 2 3 39
+ |----|--|-----------------------------|
+ magic op name.ns_id (37 bytes)
+
+
+
+
Variation 2:
+
0 2 3 39 59
+ |----|--|----------------------------------|-------------------|
+ magic op name.ns_id (37 bytes, 0-padded) value
+
+
+
+
Inputs:
+
+
+
+
Outputs:
+
+
+ OP_RETURN payloadscriptPubkey for the owner’s addess. This can be a different address than
+the current name owner (in which case, the name is renewed and transferred).scriptPubkey for the payer’s changescriptPubkey for the burn address (to pay the name cost)
+
+
Notes:
+
+
+ - This transaction is identical to a
NAME_REGISTRATION, except for the presence of the fourth output that pays for the name cost (to the burn address).
+ - Variation 1 simply renews the name. Variation 2 will both renew the name and
+set a new name value (in practice, the hash of a new zone file).
+ - Both variations are supported. Variation 1 was designed for the time when
+Bitcoin only supported 40-byte
OP_RETURN outputs.
+ - This operation can be used to transfer a name to a new address by setting the
+second output (the first
scriptPubkey) to be the scriptPubkey of the new
+owner key.
+
+
+
NAME_UPDATE
+
+
Op: +
+
+
Description: This transaction sets the name state for a name to the given
+value. In practice, this is used to announce new DNS zone file hashes to the Atlas
+network.
+
+
Example: e2029990fa75e9fc642f149dad196ac6b64b9c4a6db254f23a580b7508fc34d7
+
+
OP_RETURN wire format:
+
0 2 3 19 39
+ |-----|--|-----------------------------------|-----------------------|
+ magic op hash128(name.ns_id,consensus hash) zone file hash
+
+
+
+
Note that hash128(name.ns_id, consensus hash) is the first 16 bytes of a SHA256 hash over the name concatenated to the hexadecimal string of the consensus hash (not the bytes corresponding to that hex string).
+See the Method Glossary below.
+
+
Example: hash128("jude.id" + "8d8762c37d82360b84cf4d87f32f7754") == "d1062edb9ec9c85ad1aca6d37f2f5793".
+
+
Inputs:
+
+ - owner
scriptSig
+ - payment
scriptSig’s
+
+
+
Outputs:
+
+ OP_RETURN payload- owner’s
scriptPubkey
+ - payment
scriptPubkey change
+
+
+
NAME_TRANSFER
+
+
Op: >
+
+
Description: This transaction changes the public key hash that owns the name in
+BNS.
+
+
Example: 7a0a3bb7d39b89c3638abc369c85b5c028d0a55d7804ba1953ff19b0125f3c24
+
+
OP_RETURN wire format:
+
0 2 3 4 20 36
+ |-----|--|----|-------------------|---------------|
+ magic op keep hash128(name.ns_id) consensus hash
+ data?
+
+
+
+
Inputs:
+
+
+ - Owner
scriptSig
+ - Payment
scriptSig’s
+
+
+
Outputs:
+
+
+ OP_RETURN payload- new name owner’s
scriptPubkey
+ - old name owner’s
scriptPubkey
+ - payment
scriptPubkey change
+
+
+
Notes:
+
+
+ - The
keep data? byte controls whether or not the name’s 20-byte value is preserved. This value is either > to preserve it, or ~ to delete it.
+
+
+
NAME_REVOKE
+
+
Op: ~
+
+
Description: This transaction destroys a registered name. Its name state value
+in BNS will be cleared, and no further transactions will be able to affect the
+name until it expires (if its namespace allows it to expire at all).
+
+
Example: eb2e84a45cf411e528185a98cd5fb45ed349843a83d39fd4dff2de47adad8c8f
+
+
OP_RETURN wire format:
+
0 2 3 39
+ |----|--|-----------------------------|
+ magic op name.ns_id (37 bytes)
+
+
+
+
Inputs:
+
+
+ - owner
scriptSig
+ - payment
scriptSig’s
+
+
+
Outputs:
+
+
+ OP_RETURN payload- owner
scriptPubkey
+ - payment
scriptPubkey change
+
+
+
ANNOUNCE
+
+
Op: #
+
+
Description: This transaction does not affect any names in BNS, but it allows a
+user to send a message to other BNS nodes. In order for the message to be
+received, the following must be true:
+
+
+ - The sender must have a BNS name
+ - The BNS nodes must list the sender’s BNS name as being a “trusted message
+sender”
+ - The message must have already been propagated through the Atlas
+network. This transaction references it by content hash.
+
+
+
OP_RETURN wire format:
+
+
0 2 3 23
+ |----|--|-----------------------------|
+ magic op ripemd160(sha256(message))
+
+
+
+
Inputs:
+
+
+ - The payer
scriptSig’s
+
+
+
Outputs:
+
+
+ OP_RETURN payload- change
scriptPubKey
+
+
+
Notes:
+
+
+ - The payer key should be an owner key for an existing name, since Blockstack users can subscribe to announcements from specific name-owners.
+
+
+
NAMESPACE_PREORDER
+
+
Op: *
+
+
Description: This transaction announces the hash of a new namespace. It is the
+first of three transactions that must be sent to create a namespace.
+
+
Example: 5f00b8e609821edd6f3369ee4ee86e03ea34b890e242236cdb66ef6c9c6a1b28
+
+
OP_RETURN wire format:
+
0 2 3 23 39
+ |-----|---|-----------------------------------------|----------------|
+ magic op hash_name(ns_id,script_pubkey,reveal_addr) consensus hash
+
+
+
+
Inputs:
+
+
+ - Namespace payer
scriptSig
+
+
+
Outputs:
+
+
+ OP_RETURN payload- Namespace payer
scriptPubkey change address
+ p2pkh script to the burn address 1111111111111111111114oLvT2, whose public key hash is 0x00000000000000000000000000000000
+
+
Notes:
+
+
+ - The
reveal_addr field is the address of the namespace revealer public key. The revealer private key will be used to generate NAME_IMPORT transactions.
+
+
+
NAMESPACE_REVEAL
+
+
Op: &
+
+
Description: This transaction reveals the namespace ID and namespace rules
+for a previously-anounced namespace hash (sent by a previous NAMESPACE_PREORDER).
+
+
Example: ab54b1c1dd5332dc86b24ca2f88b8ca0068485edf0c322416d104c5b84133a32
+
+
OP_RETURN wire format:
+
0 2 3 7 8 9 10 11 12 13 14 15 16 17 18 20 39
+ |-----|---|--------|-----|-----|----|----|----|----|----|-----|-----|-----|--------|----------|-------------------------|
+ magic op life coeff. base 1-2 3-4 5-6 7-8 9-10 11-12 13-14 15-16 nonalpha version namespace ID
+ bucket exponents no-vowel
+ discounts
+
+
+
+
Inputs:
+
+
+ - Namespace payer
scriptSigs
+
+
+
Outputs:
+
+
+ OP_RETURN payload- namespace revealer
scriptPubkey
+ - namespace payer change
scriptPubkey
+
+
+
Notes:
+
+
+ - This transaction must be sent within 1 day of the
NAMESPACE_PREORDER
+ - The second output (with the namespace revealer) must be a
p2pkh script
+ - The address of the second output must be the
reveal_addr in the NAMESPACE_PREORDER
+
+
+
Pricing:
+
+
The rules for a namespace are as follows:
+
+
+ - a name can fall into one of 16 buckets, measured by length. Bucket 16 incorporates all names at least 16 characters long.
+ - the pricing structure applies a multiplicative penalty for having numeric characters, or punctuation characters.
+ - the price of a name in a bucket is ((coeff) * (base) ^ (bucket exponent)) / ((numeric discount multiplier) * (punctuation discount multiplier))
+
+
+
Example:
+
+ - base = 10
+ - coeff = 2
+ - nonalpha discount: 10
+ - no-vowel discount: 10
+ - buckets 1, 2: 9
+ - buckets 3, 4, 5, 6: 8
+ - buckets 7, 8, 9, 10, 11, 12, 13, 14: 7
+ - buckets 15, 16+:
+
+
+
With the above example configuration, the following are true:
+
+
+ - The price of “john” would be 2 * 10^8, since “john” falls into bucket 4 and has no punctuation or numerics.
+ - The price of “john1” would be 2 * 10^6, since “john1” falls into bucket 5 but has a number (and thus receives a 10x discount)
+ - The price of “john_1” would be 2 * 10^6, since “john_1” falls into bucket 6 but has a number and punctuation (and thus receives a 10x discount)
+ - The price of “j0hn_1” would be 2 * 10^5, since “j0hn_1” falls into bucket 6 but has a number and punctuation and lacks vowels (and thus receives a 100x discount)
+
+
+
NAME_IMPORT
+
+
Op: ;
+
+
Description: This transaction registers a name and some name state into a
+namespace that has been revealed, but not been launched. Only the namespace
+creator can import names. See the namespace creation
+tutorial for details.
+
+
Example: c698ac4b4a61c90b2c93dababde867dea359f971e2efcf415c37c9a4d9c4f312
+
+
OP_RETURN wire format:
+
0 2 3 39
+ |----|--|-----------------------------|
+ magic op name.ns_id (37 bytes)
+
+
+
+
Inputs:
+
+
+ - The namespace reveal
scriptSig (with the namespace revealer’s public key), or one of its first 300 extended public keys
+ - Any payment inputs
+
+
+
Outputs:
+
+
+ OP_RETURN payload- recipient
scriptPubKey
+ - zone file hash (using the 20-byte hash in a standard
p2pkh script)
+ - payment change
scriptPubKey
+
+
+
Notes:
+
+
+ - These transactions can only be sent between the
NAMESPACE_REVEAL and NAMESPACE_READY.
+ - The first
NAME_IMPORT transaction must have a scriptSig input that matches the NAMESPACE_REVEAL’s second output (i.e. the reveal output).
+ - Any subsequent
NAME_IMPORT transactions may have a scriptSig input whose public key is one of the first 300 extended public keys from the NAMESPACE_REVEAL’s scriptSig public key.
+
+
+
NAMESPACE_READY
+
+
Op: !
+
+
Description: This transaction launches a namesapce. Only the namespace creator
+can send this transaction. Once sent, anyone can register names in the
+namespace.
+
+
Example: 2bf9a97e3081886f96c4def36d99a677059fafdbd6bdb6d626c0608a1e286032
+
+
OP_RETURN wire format:
+
+ 0 2 3 4 23
+ |-----|--|--|------------|
+ magic op . ns_id
+
+
+
+
Inputs:
+
+ - Namespace revealer’s
scriptSigs
+
+
+
Outputs:
+
+ OP_RETURN payload- Change output to the namespace revealer’s
p2pkh script
+
+
+
Notes:
+
+ - This transaction must be sent within 1 year of the corresponding
NAMESPACE_REVEAL to be accepted.
+
+
+
Method Glossary
+
+
Some hashing primitives are used to construct the wire-format representation of each name operation. They are enumerated here:
+
+
B40_REGEX = '^[a-z0-9\-_.+]*$'
+
+def is_b40(s):
+ return isinstance(s, str) and re.match(B40_REGEX, s) is not None
+
+def b40_to_bin(s):
+ if not is_b40(s):
+ raise ValueError('{} must only contain characters in the b40 char set'.format(s))
+ return unhexlify(charset_to_hex(s, B40_CHARS))
+
+def hexpad(x):
+ return ('0' * (len(x) % 2)) + x
+
+def charset_to_hex(s, original_charset):
+ return hexpad(change_charset(s, original_charset, B16_CHARS))
+
+def bin_hash160(s, hex_format=False):
+ """ s is in hex or binary format
+ """
+ if hex_format and is_hex(s):
+ s = unhexlify(s)
+ return hashlib.new('ripemd160', bin_sha256(s)).digest()
+
+def hex_hash160(s, hex_format=False):
+ """ s is in hex or binary format
+ """
+ if hex_format and is_hex(s):
+ s = unhexlify(s)
+ return hexlify(bin_hash160(s))
+
+def hash_name(name, script_pubkey, register_addr=None):
+ """
+ Generate the hash over a name and hex-string script pubkey.
+ Returns the hex-encoded string RIPEMD160(SHA256(x)), where
+ x is the byte string composed of the concatenation of the
+ binary
+ """
+ bin_name = b40_to_bin(name)
+ name_and_pubkey = bin_name + unhexlify(script_pubkey)
+
+ if register_addr is not None:
+ name_and_pubkey += str(register_addr)
+
+ # make hex-encoded hash
+ return hex_hash160(name_and_pubkey)
+
+def hash128(data):
+ """
+ Hash a string of data by taking its 256-bit sha256 and truncating it to the
+ first 16 bytes
+ """
+ return hexlify(bin_sha256(data)[0:16])
+
+
+
+
+
+