Conditional Statements in Circom Circom is very strict with the usage of if-statements. The following rules must be followed: Signals cannot be used to alter the behavior of an if-statement. A signal...

Public and Private Inputs A public input in Circom is a signal in the witness that will be revealed to the verifier. For example, suppose we want to create a ZK proof that states: “we know the input...

Symbolic Variables in Circom A symbolic variable in Circom is a variable that has been assigned values from a signal. When a signal is assigned to a variable (thereby turning it into a symbolic...

Quadratic Constraints Circom Constraints A Rank 1 Constraint System has at most one multiplication between signals per constraint. This is called a "quadratic" constraint. Any constraint containing...

Circom Template Parameters, Variables, Loops, If Statements, Assert This chapter covers essential syntax, which you'll see in most Circom programs. With Circom, we're able to define a Rank 1...

Quin Selector The Quin Selector is a design pattern that allows us to use a signal as an index for an array of signals. As a prerequisite, we assume the reader has read the chapter on Conditional...

The Permutation Argument A permutation argument is a proof that two lists hold the same elements, but possibly in a different order. For example, is a permutation of and vice-versa. The permutation...

Introduction to ZK Circuits with Circom Circom is a programming language for creating Rank 1 Constraint Systems (R1CS) and populating the witness vector of the R1CS. The R1CS format is of interest...

Circom Components in a Loop Circom does not allow for components to be directly instantiated in a loop. For example, compiling the following code results in the error below. The workaround is to...

ERC-6909 Minimal Multi-Token Standard The ERC-6909 token standard is a streamlined alternative to the ERC-1155 token standard. The ERC-1155 standard introduced a multiple-token interface that allows...