Clarify how to disable key path spending#43
Merged
sipa merged 1 commit intosipa:bip-schnorrfrom Aug 21, 2019
jonasnick:script-path-only
Merged
Clarify how to disable key path spending#43sipa merged 1 commit intosipa:bip-schnorrfrom jonasnick:script-path-only
sipa merged 1 commit intosipa:bip-schnorrfrom
jonasnick:script-path-only
Conversation
Owner
|
ack |
|
Shouldn't this be a random key for privacy? |
Author
|
@real-or-random yes, it is
|
|
Nevermind, I'm too stupid to read. |
Author
|
Updated the link to how to derive H to a newer commit which made the code snippet actually copy-and-pastable. |
|
ACK |
sipa
reviewed
Aug 15, 2019
| * When deciding between scripts with conditionals (<code>OP_IF</code> etc.) and splitting them up into multiple scripts (each corresponding to one execution path through the original script), it is generally preferable to pick the latter. | ||
| * When a single condition requires signatures with multiple keys, key aggregation techniques like MuSig can be used to combine them into a single key. The details are out of scope for this document, but note that this may complicate the signing procedure. | ||
| * If one or more of the spending conditions consist of just a single key (after aggregation), the most likely one should be made the internal key. If no such condition exists, it may be worthwhile adding one that consists of an aggregation of all keys participating in all scripts combined; effectively adding an "everyone agrees" branch. If that is inacceptable, pick as internal key a point with unknown discrete logarithm (TODO). | ||
| * If one or more of the spending conditions consist of just a single key (after aggregation), the most likely one should be made the internal key. If no such condition exists, it may be worthwhile adding one that consists of an aggregation of all keys participating in all scripts combined; effectively adding an "everyone agrees" branch. If that is inacceptable, pick as internal key a point with unknown discrete logarithm. One example of such a point is ''H = point(0x0250929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac0)'' which is [https://github.com/ElementsProject/secp256k1-zkp/blob/11af7015de624b010424273be3d91f117f172c82/src/modules/rangeproof/main_impl.h#L16 constructed] by taking the hash of the uncompressed DER serialization of secp256k1 generator ''G'' as X coordinate. In order to avoid leaking the information that key path spending is not possible it is recommended to pick a fresh integer ''r'' in the range ''0...n-1'' uniformly at random and use ''H + rG'' as internal key. It is possible to prove that this internal key is does not have a known discrete logarithm with respect to ''G'' by revealing ''r'' to a verifier who can then reconstruct how the internal key was created. |
Owner
There was a problem hiding this comment.
Nit: the elliptic curve point serialization is not DER; it's just the standard encoding for points. DER is only used for ECDSA signatures (and I hope nobody ever uses it for anything else...).
Author
There was a problem hiding this comment.
Sorry I just mindlessly copied the description from secp-zkp. Fixed.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
No description provided.