broadvilks / PixieZKVM

A simple virtual machine whose execution can be proven in ZERO-KNOWLEDGE. Showcases the intricacies of: Trace Generation | Cross-Table Lookups | RangeChecks | Recursive Proofs / Proof Aggregation

PixieZKVM

A toy, simple an playful ZERO-KNOWLEDGE / STARK based ZKVM to showcase the intricacies of | Trace Generation | Cross-Table Lookups | RangeChecks | Proof Composition.

VM description

• Single byte-only addressible memory of range: 0x00 to 0xFF. All addresses are Read-Write (no Read-only memory).
• No Stack, No Heap, No Allocator.
• CPU instruction set described below, 2 registers: r0, r1 each capable of storing one byte at a time.
• Harvard CPU architecture, no self-modifying code.

Instruction Set

This VM intends to support the smallest subset of instructions to describe the major design elements of ZKVMs with as less of fluff as possible. For this, the following instructions are chosen to be implemented:

• ADD: ADD r1 r2 Adds registers r1 and r2 such that r1 = r1 + r2.
• SUB: SUB r1 r2 Subtracts registers r1 and r2 such that r1 = r1 - r2.
• MUL: MUL r1 r2 Multiplies registers r1 and r2 such that r1 = r1 * r2.
• DIV: DIV r1 r2 Divides registers r1 and r2 such that r1 = r1 / r2.
• SHL: BSL r1 r2 BitShifts r1 by r2 to the left.
• SHR: SHR r1 r2 BitShift analog towards the right.
• JZ: JZ r1 0x10 Jump to 0x10 if value in r1 is zero.
• JNZ: JNZ r1 0x10 Jump to 0x10 if value in r1 is not zero.
• LB: LB r1 0x10 Loads a single byte at 0x10 into register r1.
• SB: SB r1 0x10 Stores a single byte in register r1 to memory location 0x10.

Program Writing

Since our instruction set and VM description is bespoke, we do not have compilation toolkit from any programming language for PixieZKVM. All programs are built by hand in assembly format.

Testing the Project

Clone and test:

git clone [e-mail]:supragya/PixieZKVM.git
cargo test