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

Document boolean constraint requirement for gates. #87

Open
wants to merge 1 commit into
base: master
Choose a base branch
from
Open

Document boolean constraint requirement for gates. #87

Changes from all commits
Commits
Show all changes
1 commit
Select commit
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
13 changes: 13 additions & 0 deletions circuits/gates.circom
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,14 @@
*/
pragma circom 2.0.0;

/*
Boolean logic gates.

Inputs generally must be constrained to 0 or 1, using Num2Bits or a*(a-1) === 0 etc.
Most languages extend boolean logic to non boolean types, but using non-booleans here will lead to subtle soundness bugs.
*/

// Requires binary inputs: [2,2] -> -4, should be 0
template XOR() {
signal input a;
signal input b;
Expand All @@ -26,6 +34,7 @@ template XOR() {
out <== a + b - 2*a*b;
}

// Applies to non-binary numbers: gives non-zero output iff both inputs are non-zero because a and b are coprime with p
template AND() {
signal input a;
signal input b;
Expand All @@ -34,6 +43,7 @@ template AND() {
out <== a*b;
}

// Requires binary inputs: [2,2] -> 0, should be non-zero
template OR() {
signal input a;
signal input b;
Expand All @@ -42,13 +52,15 @@ template OR() {
out <== a + b - a*b;
}

// Requires binary inputs: 2 -> -1, should be 0
template NOT() {
signal input in;
signal output out;

out <== 1 + in - 2*in;
}

// Requires binary inputs: [2,1] -> -1, should be 0
template NAND() {
signal input a;
signal input b;
Expand All @@ -57,6 +69,7 @@ template NAND() {
out <== 1 - a*b;
}

// Requires binary inputs: [2,1] -> 0, should be non-zero
template NOR() {
signal input a;
signal input b;
Expand Down