Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Adds page pseudorandom number generation algorithm #963

Merged
merged 4 commits into from
Jul 1, 2019
Merged

Adds page pseudorandom number generation algorithm #963

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
0274c2f
Adds page pseudorandom number generation algo
s-ben Jun 29, 2019
a89b20b
Add matheusd video
s-ben Jun 29, 2019
da9af41
Address davecgh feedback
s-ben Jun 29, 2019
087bf3c
Fix link syntax
s-ben Jun 29, 2019
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
8 changes: 8 additions & 0 deletions docs/research/ticket-selection-algorithm.md
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,8 @@
# <img class="dcr-icon" src="/img/dcr-icons/QuestionTicket.svg" /> Ticket Selection Algorithm

Every block, 5 tickets are pseudorandomly selected from the ticket pool to [vote](../proof-of-stake/overview.md). Below is a high-level description of the ticket selection algorithm. A more detailed, low-level walkthrough of the ticket selection code can be found in this [video](https://www.youtube.com/watch?v=eysGWVhDFWY).

## Pseudorandom number generation

Tickets are selected from the ticket pool using a deterministic [Pseudorandom Number Generator (PRNG)](https://en.wikipedia.org/wiki/Pseudorandom_number_generator). It is deterministic because the seed input to the PRNG is derived from the hash of the previous block (the block being voted on). Specifically, the seed is a serialization of the [header](../advanced/block-header-specifications.md) of the previous block suffixed with a constant derived from the hex representation of the mathematical constant Pi (𝜋), which acts as a publicly verifiable Nothing-Up-My-Sleeve ([NUMS](https://en.wikipedia.org/wiki/Nothing-up-my-sleeve_number)) constant. All eligible tickets in the ticket pool (also referred to as live tickets) are hashed using the [BLAKE-256](blake-256-hash-function.md) hash function and sorted [lexicographically](https://en.wikipedia.org/wiki/Lexicographical_order) by their hash to generate a [total order](https://en.wikipedia.org/wiki/Total_order). Finally, uniformly random values constrained by the number of total eligible tickets as an upper bound are produced and used as indices into the total order.

1 change: 1 addition & 0 deletions mkdocs.yml
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -134,6 +134,7 @@ nav:
- 'Script Extensions': 'research/script-extensions.md'
- 'Signature Script Isolation and Fraud Proofs': 'research/signature-script-isolation-and-fraud-proofs.md'
- 'Transaction Extensions': 'research/transaction-extensions.md'
- 'Ticket Selection Algorithm': 'research/ticket-selection-algorithm.md'
- 'Schnorr Signatures': 'research/schnorr-signatures.md'
- 'Miscellaneous Improvements': 'research/miscellaneous-improvements.md'
- Contributing:
Expand Down