go-R1CS-Compiler

README

go-R1CS Compiler

UNDER CONSTRUCTION

Circuit Language A subset of Golang (with slight modifications), suitable for the creation of Non-Interactive Succinct Arguments, such as zkSNARKs. This projects goal is to provide a compiler that translates Go-code into R1CS, which is the compilation target and starting point for various zkSNARK constructions.

-This compiler currently supports the creation of Groth16 zkSNARKs.

-Comes with JS graph rendering support to visualize the generated arithmetic circuit if needed.

Language

main

as in Go, every program starts with the function 'main'

func main(){
#this is a comment
}

main can be fed with an arbitrary amount of single arguments and n-dimensional static size arrays of single values. Main does not support functions as inputs.

func main(a bool,b [2]uint32, c field, d uint64){

}

Declare public inputs

In order to declare, which of the Main-Function inputs will be part of the public statement of the SNARK, write

func main(a bool,b [2][3]uint32, c field, d uint64){
    public{
        a, 
        b[1][1],
        c
    }
}

variables

Variable assignment and overloading follows the same logic as in Golang:

    var a = 42*17  # is now a field type element
    # var a = x*x   -> Error- variable a already declared
    # a = true   -> type missmatch. Field expected, got bool
    var b = uint32(235)

    #declare array
    var c = [2]uint32{b,b+2}
    
    #declare function. Functions can return functions or take them as arguments
    var d = func(x field, b func()(bool) , c [4]bool)( func()(field)) {
               return 42
            }

}

Function preloading

At this point we extended Go by this cool functionality. One now can partially preload a function

func main(x field){
    var multiply = func(a field,b field)(field){return a*b}
    var multiplyBy5 = multiply(5)
    multiplyBy5(x) #is now the same as multiply(5,x) 
}

Operations

Operator	Description	Remark
+	addition
*	multiplication
-	subtraction
/	division
**	exponentiation	*
<<	left shift	*
>>	right-shift	*
<<<	rotate-left	*
>>>	rotate-right	*
&	bitwise-and
|	bitwise-or
^	bitwise-xor
==	equality
!=	un-equality

*rhs must be fixed at compile-time

if-else if-else

in order to create braching conditions, write:

if expression1{ 
    ...
}else if expression2{
    ...
}else if expression3{
    ...
}else{
    ...
}

note that we currently only support static decidable branching conditions

arrays

tba.

SNARK stuff

euquality assertion gate

in order to create an equality assertion constraint write

equal(expression1,expression2)

example: in order to prove knowledge of a square root of some input y, write

func main(x field,y field){
   public{y}
   equal(x*x,y)
}

split

to split a value into its bit representatives write

SPLIT(x)

now the i'th bit of x can be accessed with x[i], where x[0] is the least significant bit