Replace MethodIDs with ImageIDs (risc0#326)

.vscode/settings.json

@@ -28,6 +28,7 @@
     "iosfwd": "cpp",
     "vector": "cpp",
     "charconv": "cpp",
-    "stdexcept": "cpp"
+    "stdexcept": "cpp",
+    "array": "cpp"
   }
 }

Cargo.toml

@@ -27,6 +27,12 @@ lto = true
 [profile.dev]
 opt-level = 3
 
+[profile.dev.build-override]
+opt-level = 3
+
 [profile.release]
 debug = 1
 lto = true
+
+[profile.release.build-override]
+opt-level = 3

README.md

@@ -48,7 +48,7 @@ SDK support exists for Rust, C, and C++.
 First, the code to be proven must be compiled from its implementation language
 into a *method*.  A method is represented by a RISC-V ELF file with a special
 entry point that runs the code of the method.  Additionally, one can compute for
-a given method its *method ID* which is a special type of cryptographic hash of
+a given method its *image ID* which is a special type of cryptographic hash of
 the ELF file, and is required for verification.
 
 Next, the prover runs the method inside the zkVM.  The logical RISC-V machine
@@ -68,7 +68,7 @@ The verifier can then verify the receipt and examine the log. If any tampering
 was done to the journal or the seal, the receipt will fail to verify.
 Additionally, it is cryptographically infeasible to generate a valid receipt
 unless the output of the journal is the exactly correct output for some valid
-execution of the method whose method ID matches the receipt. In summary, the
+execution of the method whose image ID matches the receipt. In summary, the
 receipt acts as a zero knowledge proof of correct execution.
 
 Because the protocol is zero knowledge, the verifier cannot infer anything about
@@ -92,7 +92,7 @@ other manner of problems.  Caveat emptor.
 ## Getting Started
 
 To get started building applications using the zkVM in Rust, we provide a
-[starter template](https://github.com/risc0/risc0-rust-starter) and a 
+[starter template](https://github.com/risc0/risc0-rust-starter) and a
 number of [working examples](https://github.com/risc0/risc0-rust-examples/).
 
 ## Example

risc0/build/risc0.ld

@@ -21,10 +21,9 @@ EXTERN(__start)
 
 /* Must match risc0/zkvm/platform/src/memory.rs */
 MEMORY {
-  stack        : ORIGIN = 0x00000000, LENGTH =  16M
-  data    (RW) : ORIGIN = 0x01000000, LENGTH =  16M
-  heap         : ORIGIN = 0x02000000, LENGTH =  32M
-  input        : ORIGIN = 0x04000000, LENGTH =  32M
+  stack        : ORIGIN = 0x02000000, LENGTH =  16M
+  data    (RW) : ORIGIN = 0x03000000, LENGTH =  16M
+  heap         : ORIGIN = 0x04000000, LENGTH =  32M
   prog    (X)  : ORIGIN = 0x06000000, LENGTH =  32M
 }
 
@@ -47,17 +46,15 @@ SECTIONS {
 
   . = ALIGN(4);
 
-  .bss (NOLOAD) :  {
+  .bss (NOLOAD) : {
     __bss_begin = .;
     *(.sbss*)
     *(.gnu.linkonce.sb.*)
     *(.bss .bss.*)
     *(.gnu.linkonce.b.*)
     *(COMMON)
     . = ALIGN(4);
-    __result = .;
-    /* Result is 9 words * 4 = 36 bytes, 8 words for output, and 1 word for output size*/
-    __bss_end = . + 36;
+    __bss_end = .;
   } >data
 
   __bss_size = __bss_end - __bss_begin;

risc0/build/src/lib.rs

@@ -16,9 +16,9 @@
 //!
 //! In order for the host to execute guest code in the [RISC Zero
 //! zkVM](risc0_zkvm), the host must be provided a compiled RISC-V ELF file and
-//! the corresponding [MethodID](risc0_zkvm::MethodId). This crate
+//! the corresponding ImageID. This crate
 //! contains the functions needed to take zkVM guest code, build a corresponding
-//! ELF file and MethodID, and make the MethodID and a path to the ELF file
+//! ELF file and ImageID, and make the ImageID and a path to the ELF file
 //! available for the host to use.
 //!
 //! ## Using risc0-build to build guest methods
@@ -57,10 +57,10 @@
 //! include!(concat!(env!("OUT_DIR"), "/methods.rs"));
 //! ```
 //!
-//! This process will generate a method ID (`*_ID`) and the contents of an ELF
+//! This process will generate an image ID (`*_ID`) and the contents of an ELF
 //! file (`*_ELF`). The names will be derived from the name of the ELF
 //! binary, which will be converted to ALL_CAPS to comply with rust naming
-//! conventions. Thus, if a method binary is named `multiply`, the method ID
+//! conventions. Thus, if a method binary is named `multiply`, the image ID
 //! will be named `methods::MULTIPLY_ID` and the contents of the ELF file will
 //! be named `methods::MULTIPLY_ELF`. These are included at the beginning
 //! of the host-side code:
@@ -83,10 +83,10 @@ use std::{
 
 use cargo_metadata::{MetadataCommand, Package};
 use downloader::{Download, Downloader};
-use risc0_zkp::adapter::TapsProvider;
-use risc0_zkvm::{MethodId, DEFAULT_METHOD_ID_LIMIT};
+use risc0_zkvm::{sha::Digest, MemoryImage, Program};
+use risc0_zkvm_platform::{memory::MEM_SIZE, PAGE_SIZE};
 use serde::Deserialize;
-use sha2::{Digest, Sha256};
+use sha2::{Digest as ShaDigest, Sha256};
 use tempfile::tempdir_in;
 use zip::ZipArchive;
 
@@ -112,7 +112,7 @@ struct Risc0Method {
 }
 
 impl Risc0Method {
-    fn make_method_id(&self, code_limit: usize) -> MethodId {
+    fn make_image_id(&self) -> Digest {
         if !self.elf_path.exists() {
             eprintln!(
                 "RISC-V method was not found at: {:?}",
@@ -121,57 +121,21 @@ impl Risc0Method {
             std::process::exit(-1);
         }
 
-        let method_id_path = self.elf_path.with_extension("id");
-        let elf_sha_path = self.elf_path.with_extension("sha");
-        let elf_contents = std::fs::read(&self.elf_path).unwrap();
-
-        let elf_sha = Sha256::new()
-            // Method ID calculation is slow, so only recalculate it if we
-            // actually get a different ELF file.
-            .chain_update(&elf_contents)
-            // Take into account the current circuit; if the circuit
-            // changes, the Method ID will change as well.
-            .chain_update(format!(
-                "{:?}",
-                risc0_circuit_rv32im::CircuitImpl.get_taps()
-            ))
-            // If the Method ID version changes, we need to recreate the Method ID.
-            .chain_update(format!("{}", MethodId::VERSION))
-            .finalize();
-
-        let elf_sha_hex: String = elf_sha
-            .as_slice()
-            .iter()
-            .map(|x| format!("{:02x}", x))
-            .collect();
-
-        if method_id_path.exists() {
-            if let Ok(cached_sha) = std::fs::read(&elf_sha_path) {
-                if cached_sha == elf_sha.as_slice() {
-                    println!("MethodID for {} ({}) up to date", self.name, elf_sha_hex);
-                    let buf = std::fs::read(&method_id_path).unwrap();
-                    return MethodId::from_slice(&buf).unwrap();
-                }
-            }
-        }
-
-        println!("Computing MethodID for {} ({:})!", self.name, elf_sha_hex);
-        let method_id = MethodId::compute_with_limit(&elf_contents, code_limit).unwrap();
-        std::fs::write(method_id_path, method_id.as_slice()).unwrap();
-        std::fs::write(elf_sha_path, elf_sha).unwrap();
-        method_id
+        let elf = fs::read(&self.elf_path).unwrap();
+        let program = Program::load_elf(&elf, MEM_SIZE as u32).unwrap();
+        let image = MemoryImage::new(&program, PAGE_SIZE as u32);
+        image.root
     }
 
-    fn rust_def(&self, code_limit: usize) -> String {
+    fn rust_def(&self) -> String {
         let elf_path = self.elf_path.display();
         let upper = self.name.to_uppercase();
-        let method_id = self.make_method_id(code_limit);
-        let method_id = method_id.as_slice();
+        let image_id = self.make_image_id();
         let elf_contents = std::fs::read(&self.elf_path).unwrap();
         format!(
             r##"
 pub const {upper}_ELF: &'static [u8] = &{elf_contents:?};
-pub const {upper}_ID: &'static [u8] = &{method_id:?};
+pub const {upper}_ID: &'static str = r#"{image_id:?}"#;
 pub const {upper}_PATH: &'static str = r#"{elf_path}"#;
             "##
         )
@@ -497,11 +461,6 @@ fn build_guest_package<P>(
 /// Options defining how to embed a guest package in
 /// [`embed_methods_with_options`].
 pub struct GuestOptions {
-    /// The maximum number of cycles (in units of powers of 2) supported by a
-    /// MethodID. The bigger this value is the longer it takes to compute a
-    /// MethodID.
-    pub code_limit: usize,
-
     /// Features for cargo to build the guest with.
     pub features: Vec<String>,
 
@@ -512,7 +471,6 @@ pub struct GuestOptions {
 impl Default for GuestOptions {
     fn default() -> Self {
         GuestOptions {
-            code_limit: DEFAULT_METHOD_ID_LIMIT,
             features: vec![],
             std: true,
         }
@@ -554,7 +512,7 @@ pub fn embed_methods_with_options(mut guest_pkg_to_options: HashMap<&str, GuestO
 
         for method in guest_methods(&guest_pkg, &out_dir) {
             methods_file
-                .write_all(method.rust_def(guest_options.code_limit).as_bytes())
+                .write_all(method.rust_def().as_bytes())
                 .unwrap();
         }
     }
@@ -575,7 +533,7 @@ pub fn embed_methods_with_options(mut guest_pkg_to_options: HashMap<&str, GuestO
 /// listing the relative paths that contain riscv guest method
 /// packages.
 ///
-/// To access the generated method IDs and ELF filenames, include the
+/// To access the generated image IDs and ELF filenames, include the
 /// generated methods.rs:
 ///
 /// ```text
@@ -584,7 +542,7 @@ pub fn embed_methods_with_options(mut guest_pkg_to_options: HashMap<&str, GuestO
 ///
 /// To conform to rust's naming conventions, the constants are mapped
 /// to uppercase.  For instance, if you have a method named
-/// "my_method", the method ID and elf contents will be defined as
+/// "my_method", the image ID and elf contents will be defined as
 /// "MY_METHOD_ID" and "MY_METHOD_ELF" respectively.
 pub fn embed_methods() {
     embed_methods_with_options(HashMap::new())