feat: make signing and key generation C independent

Cargo.toml

@@ -53,6 +53,11 @@ serde = { version = "1.0", features = ["derive"], default-features = false, opti
 winter_crypto = { version = "0.8", package = "winter-crypto", default-features = false }
 winter_math = { version = "0.8", package = "winter-math", default-features = false }
 winter_utils = { version = "0.8", package = "winter-utils", default-features = false }
+num-complex = "0.4.4"
+num = "0.4.1"
+rand = "0.8.5"
+sha3 = "0.10.8"
+hex = "0.4.3"
 
 [dev-dependencies]
 seq-macro = { version = "0.3" }

build.rs

@@ -1,39 +1,8 @@
 fn main() {
-    #[cfg(feature = "std")]
-    compile_rpo_falcon();
-
     #[cfg(target_feature = "sve")]
     compile_arch_arm64_sve();
 }
 
-#[cfg(feature = "std")]
-fn compile_rpo_falcon() {
-    use std::path::PathBuf;
-
-    const RPO_FALCON_PATH: &str = "src/dsa/rpo_falcon512/falcon_c";
-
-    println!("cargo:rerun-if-changed={RPO_FALCON_PATH}/falcon.h");
-    println!("cargo:rerun-if-changed={RPO_FALCON_PATH}/falcon.c");
-    println!("cargo:rerun-if-changed={RPO_FALCON_PATH}/rpo.h");
-    println!("cargo:rerun-if-changed={RPO_FALCON_PATH}/rpo.c");
-
-    let target_dir: PathBuf = ["PQClean", "crypto_sign", "falcon-512", "clean"].iter().collect();
-    let common_dir: PathBuf = ["PQClean", "common"].iter().collect();
-
-    let scheme_files = glob::glob(target_dir.join("*.c").to_str().unwrap()).unwrap();
-    let common_files = glob::glob(common_dir.join("*.c").to_str().unwrap()).unwrap();
-
-    cc::Build::new()
-        .include(&common_dir)
-        .include(target_dir)
-        .files(scheme_files.into_iter().map(|p| p.unwrap().to_string_lossy().into_owned()))
-        .files(common_files.into_iter().map(|p| p.unwrap().to_string_lossy().into_owned()))
-        .file(format!("{RPO_FALCON_PATH}/falcon.c"))
-        .file(format!("{RPO_FALCON_PATH}/rpo.c"))
-        .flag("-O3")
-        .compile("rpo_falcon512");
-}
-
 #[cfg(target_feature = "sve")]
 fn compile_arch_arm64_sve() {
     const RPO_SVE_PATH: &str = "arch/arm64-sve/rpo";

src/dsa/rpo_falcon512/error.rs

@@ -15,7 +15,9 @@ pub enum FalconError {
     SigDecodingMinusZero,
     SigDecodingIncorrectEncodingAlgorithm,
     SigDecodingNotSupportedDegree(u8),
-    SigGenerationFailed,
+    BadEncodingLength,
+    InvalidHeaderFormat,
+    WrongVariant,
 }
 
 impl fmt::Display for FalconError {
@@ -47,7 +49,9 @@ impl fmt::Display for FalconError {
             SigDecodingMinusZero => write!(f, "Failed to decode signature: -0 is forbidden"),
             SigDecodingIncorrectEncodingAlgorithm => write!(f, "Failed to decode signature: not supported encoding algorithm"),
             SigDecodingNotSupportedDegree(log_n) => write!(f, "Failed to decode signature: only supported irreducible polynomial degree is 512, 2^{log_n} was provided"),
-            SigGenerationFailed => write!(f, "Failed to generate a signature"),
+            BadEncodingLength => write!(f, "Failed to decode: length is different from the one expected"),
+            InvalidHeaderFormat => write!(f, "Invalid header format"),
+            WrongVariant => write!(f, "Wrong Falcon DSA variant"),
         }
     }
 }