MuSig
Notice
The MuSig Module is an experimental feature. It is provided as a demonstration of Antara capabilities and of the MuSig concept. If you would like to use MuSig on a production-level Smart Chain, please reach out to the Komodo team on Discord.
The MuSig Antara Module implements a new type of multi-signature functionality. MuSig allows a blockchain to process multi-signature transactions in a more data-efficient manner. MuSig also keeps private the number of signers partaking in a multi-signature transaction.
This functionality is facilitated by MuSig's implementation of Schnorr Signature technology. Schnorr Signatures are unique in that each signature is 64 bytes in size, regardless of the number of signers in a transaction. Also, a multi-signature Schnorr Signature can be processed in one verification.
Schnorr Signatures differs from the existing multi-signature method (ECDSA), as the ECDSA method requires each signer of a transaction to be verified separately. Also, with the ECDSA method each set of signers must be collected into a final verification. The size of the ECDSA multi-signature transaction can vary according to the number of signers in the set, and this can disclose information that would otherwise remain private.
Therefore, Schnorr Signatures greatly reduce verification time and data-storage requirements, and enhance user privacy.
For further information, see this article. Also, the reader may refer to the comments in the following core komodod files, File 1 and File 2.
- Create a combined pubkey using the combine method
- From the response, take note of the
combined_pkandpkhashvalues
- From the response, take note of the
- Send coins to
combined_pkusing the send method- Decode the returned raw transaction using getrawtransaction
- From the decoded raw transaction, take note of the
sendtxidvalue
- Calculate the message that needs to be signed using the calcmsg method
- From the response, take note of
msg - This
msgneeds to be signed by all participating pubkeys
- From the response, take note of
- On each node create a session using the session method
- From the response on each node take note of the
commitmentvalue - Transfer each node's
commitmentvalue to each other node - Do not stop the
komododdaemon on any node from this point forward- The
komododdaemon stores thecommitmentvalue as a part of aglobal data structure - Should any
komododdaemon be stopped, the MuSig workflow must be restarted from the beginning
- The
- Also, execute the
sessionsmethod only once on each node
- From the response on each node take note of the
- On each node use the commit method
- Transfer each node's
noncevalue to each other node
- Transfer each node's
- On each node use the nonce method
- Transfer each node's
partialsigvalue to each other node
- Transfer each node's
- On each node execute the partialsig method
- Verify that the
combinedsigvalue of each node is the same as each other node by transferring onecombinedsigvalue on one node to all other nodes
- Verify that the
- On at least one node execute the verify method
- Use the returned output to verify that the
combinedsigvalue will be able to successfully execute thespendmethod for the desiredmsg
- Use the returned output to verify that the
- On one node execute the spend method and broadcast the returned raw transaction
The Antara Tutorials section features a full installation and walkthrough tutorial of the Musig module.
cclib calcmsg 18 '["sendtxid", "scriptPubKey"]'
The calcmsg method can be used by any one of the signers to initiate a spend transaction.
To calculate the msg value, this method requires a sendtxid and a scriptPubKey.
- The
sendtxidis the id of a transaction that added funds to thecombined_pkthrough the send method. - The
scriptPubKeyexpected here is of the type p2pk inhexform.
To create a scriptPubkey from a normal pubkey, add the characters 21 to the beginning of the pubkey string and the characters ac to the end of the string:
scriptPubkey = 21 + pubkey + ac
For example:
- The
pubkeyis:02f7597468703c1c5c8465dd6d43acaae697df9df30bed21494d193412a1ea193e - The associated
scriptPubkeyis:2102f7597468703c1c5c8465dd6d43acaae697df9df30bed21494d193412a1ea193eac
Usage of this method depends on the cclib method. The EVALCODE is 18.
| Name | Type | Description |
|---|---|---|
| sendtxid | (string) | the transaction id of the transaction created by the send method that was executed to fund the MuSig address; only the funds in the vout0 of the sendtxid are spent |
| scriptPubKey | (string) | a modified form of a pubkey; this is the pubkey that will receive the spent funds |
| Name | Type | Description |
|---|---|---|
| msg | (string) | the message that must be signed by all the signers for the final spend to succeed |
| result | (string) | whether the call executed successfully |
Command:
./komodo-cli -ac_name=MUSIG cclib calcmsg 18 '["09daa45cb6e17028f9568347291a993cbf29c152a527b53e9ac0925d4900c293","210225f1cbbda1a0c406bb8f6dc7a589d88b2f9e28cd4fdb3f59139f8aff1f5d270aac"]'
cclib combine 18 '[ "pubkey1", "pubkey2", .....]'
The combine method produces the combined pubkey ( combined_pk ) from all pubkeys provided.
Usage of this method depends upon the cclib method. The EVALCODE is 18.
| Name | Type | Description |
|---|---|---|
| pubkey1, pubkey2, .... | (string) | the pubkeys of all the signers of the MuSig address |
| Name | Type | Description |
|---|---|---|
| pkhash | (string) | the 32-byte hash of the original public keys |
| combined_pk | (string) | the combined pubkey of all the signers |
| result | (string) | whether the call executed successfully |
Command:
./komodo-cli -ac_name=MUSIG cclib combine 18 '["0225f1cbbda1a0c406bb8f6dc7a589d88b2f9e28cd4fdb3f59139f8aff1f5d270a","02d3431950c2f0f9654217b6ce3d44468d3a9ca7255741767fdeee7c5ec6b47567"]'
cclib commit 18 '["pkhash", ind, "commitment"]'
The commit method produces a nonce for each set of index and commitment values provided.
The returned nonce must be shared with all corresponding nodes.
Usage of this method depends on the cclib method. The EVALCODE is 18.
| Name | Type | Description |
|---|---|---|
| pkhash | (string) | the 32-byte hash of the original public keys |
| ind | (decimal number) | the index of the node, whose commitment is being added to the global data structure |
| commitment | (string) | the commitment value produced by the node with index ind |
| Name | Type | Description |
|---|---|---|
| added_index | (decimal number) | the index of the node whose commitment is added |
| myind | (decimal number) | the index of the node on which this method is executed |
| nonce | (string) | the nonce value produced by the node on which this method is executed |
| result | (string) | whether the call executed successfully |
Command:
./komodo-cli -ac_name=MUSIG cclib commit 18 '["8897e150bfb07d3f967ffadb4b0f3c84ea73a94c0d715c4b7e6d9c816c5113a9",1,"2854473733147ebdbf2fb70b956c8086c9d7659ca0093627fe0371098f8bc003"]'
cclib nonce 18 '["pkhash", ind, "nonce"]'
The nonce method produces a partialsig for each set of index and nonce value provided.
The returned partialsig must be shared with all corresponding nodes.
Usage of this method depends on the cclib method. The EVALCODE is 18.
| Name | Type | Description |
|---|---|---|
| pkhash | (string) | the 32-byte hash of the original public keys |
| ind | (decimal number) | the index of the node, whose nonce is being added to the global data structure |
| nonce | (string) | the nonce value produced by the node with index ind |
| Name | Type | Description |
|---|---|---|
| added_index | (decimal number) | the index of the node whose nonce is added |
| myind | (decimal number) | the index of the node on which this method is executed |
| partialsig | (string) | the partialsig value produced by the node on which this method is executed |
| result | (string) | whether the call executed successfully |
Command:
./komodo-cli -ac_name=MUSIG cclib nonce 18 '["8897e150bfb07d3f967ffadb4b0f3c84ea73a94c0d715c4b7e6d9c816c5113a9",1,"02402fe26abd7ed2cf22d872a6b22ced4309aac8ec273b9c89e0f8f5b77f1574db"]'
cclib partialsig 18 '["pkhash", ind, "partialsig"]'
The partialsig method produces a combinedsig for each set of index and nonce values provided.
The returned combinedsig must be shared with all corresponding nodes.
Usage of this method depends on the cclib method. The EVALCODE is 18.
| Name | Type | Description |
|---|---|---|
| pkhash | (string) | the 32-byte hash of the original public keys |
| ind | (decimal number) | the index of the node, whose partialsig is now added to the global data structure |
| partialsig | (string) | the partialsig value produced by the node with index ind |
| Name | Type | Description |
|---|---|---|
| added_index | (decimal number) | the index of the node whose partialsig is added |
| myind | (decimal number) | the index of the node on which this method is executed |
| combinedsig | (string) | the combinedsig value produced by the node on which this method is executed |
| result | (string) | whether the call executed successfully |
Command:
./komodo-cli -ac_name=MUSIG cclib partialsig 18 '["8897e150bfb07d3f967ffadb4b0f3c84ea73a94c0d715c4b7e6d9c816c5113a9",1,"9e964dfd402f973ea1e9407e19918b1c3897ff6544d60dcdb19cfb0e5bc4c0c1"]'
cclib send 18 '["combined_pk", amount]'
The send method allows any node on the network to fund the combined_pk with the specified amount .
The returned transaction id is called the sendtxid. It is used as a parameter for the methods calcmsg and spend.
Usage of this method depends upon the cclib method. The EVALCODE is 18.
| Name | Type | Description |
|---|---|---|
| combined_pk | (string) | the combined pubkey of all the signers |
| amount | (number) | the amount of coins to be sent to the combined_pk |
| Name | Type | Description |
|---|---|---|
| hex | (string) | the send_transaction in raw-transaction format, provided in hexadecimal |
| txid | (string) | the transaction id of the send transaction |
| result | (string) | whether the call executed successfully |
Command:
./komodo-cli -ac_name=MUSIG cclib send 18 '["03d31479e789014a96ba6dd60d50210045aa8292fe693f293d44615929f04cf57a",1]'
cclib session 18 '["myindex", "numsigners", "combined_pk", "pkhash", "msg"]'
The session method creates a global data structure on each node on which the method is executed. The method also adds a commitment to sign the msg message provided.
Usage of this method depends on the cclib method. The EVALCODE is 18.
| Name | Type | Description |
|---|---|---|
| myindex | (decimal number) | the index of the node that is running this method; each node must be assigned a unique index from the set: {0,1,2,3, ... , (numsigners - 1)} |
| numsigners | (decimal number) | the total number of signers participating |
| combined_pk | (string) | the combined pubkey of all the signers |
| pkhash | (string) | the 32-byte hash of the original public keys |
| msg | (string) | the message that needs to be signed by all the signers for the final spend to succeed |
| Name | Type | Description |
|---|---|---|
| myind | (decimal number) | the index of the node on which this method is executed |
| numsigners | (decimal number) | the total number of signers participating |
| commitment | (string) | the commitment value produced by the node for this msg and session |
| result | (string) | whether the call executed successfully |
Command:
./komodo-cli -ac_name=MUSIG cclib session 18 '[0,2,"03d31479e789014a96ba6dd60d50210045aa8292fe693f293d44615929f04cf57a","8897e150bfb07d3f967ffadb4b0f3c84ea73a94c0d715c4b7e6d9c816c5113a9","3ef43614242afd3c57e02a75a3bc99342fea7c731f6190b791c0f99826789603"]'
cclib spend 18 '["sendtxid", "combinedsig", "scriptPubKey"]'
The spend method spends coins to the indicated scriptPubKey.
The scriptPubKey expected here is of the type p2pk in hex form.
To create a scriptPubkey from a normal pubkey, add the characters 21 to the beginning of the pubkey string and the characters ac to the end of the string:
scriptPubkey = 21 + pubkey + ac
For example:
- The
pubkeyis:02f7597468703c1c5c8465dd6d43acaae697df9df30bed21494d193412a1ea193e - The associated
scriptPubkeyis:2102f7597468703c1c5c8465dd6d43acaae697df9df30bed21494d193412a1ea193eac
The method generates a raw transaction which must then be broadcast using sendrawtransaction.
Usage of this method depends on the cclib method. The EVALCODE is 18.
| Name | Type | Description |
|---|---|---|
| sendtxid | (string) | the transaction id of the transaction created by the send method used to fund the MuSig address; only the funds in the vout0 of the sendtxid are spent |
| combinedsig | (string) | the combined signature produced by all the signers |
| scriptPubKey | (string) | a modified form of a pubkey to which funds are to be spent |
| Name | Type | Description |
|---|---|---|
| msg | (string) | the message that needs to be signed by all the signers for the final spend to succeed |
| combined_pk | (string) | the combined pubkey of all the signers |
| combinedsig | (string) | the combined signature produced by all the signers |
| hex | (string) | the spend transaction in raw-transaction format, provided in hexadecimal |
| txid | (string) | the transaction id of the spend transaction |
| result | (string) | whether the call executed successfully |
Command:
./komodo-cli -ac_name=MUSIG cclib spend 18 '["09daa45cb6e17028f9568347291a993cbf29c152a527b53e9ac0925d4900c293","210225f1cbbda1a0c406bb8f6dc7a589d88b2f9e28cd4fdb3f59139f8aff1f5d270aac","4b3a9b2b162802bc6c2cca2d22e70ab1cf738a9d4f5692f4f881d0cce0319c137b27889bb562602c94e163729c4168120a4ab41a8e936909e832e6af09e758f2"]'
cclib verify 18 '["msg", "combined_pk", "combinedsig"]'
The verify method verifies that the combinedsig is able to spend the funds owned by combined_pk. The funds in question are those which were referenced in the creation of the msg value.
Usage of this method depends on the cclib method. The EVALCODE is 18.
| Name | Type | Description |
|---|---|---|
| msg | (string) | the message that needs to be signed by all the signers for the final spend to succeed |
| combined_pk | (string) | the combined pubkey of all the signers |
| combinedsig | (string) | the combinedsig value produced by the node on which this method is executed |
| Name | Type | Description |
|---|---|---|
| msg | (string) | the message that needs to be signed by all the signers for the final spend to succeed |
| combinedsig | (string) | the combinedsig value produced by the node on which this method is executed |
| combined_pk | (string) | the combined pubkey of all the signers |
| result | (string) | whether the call executed successfully |
Command:
./komodo-cli -ac_name=MUSIG cclib verify 18 '["3ef43614242afd3c57e02a75a3bc99342fea7c731f6190b791c0f99826789603","03d31479e789014a96ba6dd60d50210045aa8292fe693f293d44615929f04cf57a","4b3a9b2b162802bc6c2cca2d22e70ab1cf738a9d4f5692f4f881d0cce0319c137b27889bb562602c94e163729c4168120a4ab41a8e936909e832e6af09e758f2"]'