Make signing and key generation C independent

.gitmodules

@@ -1,3 +0,0 @@
-[submodule "PQClean"]
-	path = PQClean
-	url = https://github.com/PQClean/PQClean.git

Cargo.toml

@@ -53,6 +53,11 @@ serde = { version = "1.0", features = [
 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 }
+rand = {version = "0.8.5"}
+num-complex = "0.4.4"
+num = "0.4.1"
+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

@@ -1,6 +1,5 @@
-use core::fmt;
-
 use super::{LOG_N, MODULUS, PK_LEN};
+use core::fmt;
 
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub enum FalconError {
@@ -9,13 +8,9 @@ pub enum FalconError {
     PubKeyDecodingInvalidCoefficient(u32),
     PubKeyDecodingInvalidLength(usize),
     PubKeyDecodingInvalidTag(u8),
-    SigDecodingTooBigHighBits(u32),
-    SigDecodingInvalidRemainder,
-    SigDecodingNonZeroUnusedBitsLastByte,
-    SigDecodingMinusZero,
-    SigDecodingIncorrectEncodingAlgorithm,
-    SigDecodingNotSupportedDegree(u8),
-    SigGenerationFailed,
+    InvalidEncodingLength,
+    InvalidHeaderFormat,
+    WrongVariant,
 }
 
 impl fmt::Display for FalconError {
@@ -35,22 +30,39 @@ impl fmt::Display for FalconError {
             PubKeyDecodingInvalidTag(byte) => {
                 write!(f, "Failed to decode public key: expected the first byte to be {LOG_N} but was {byte}")
             }
-            SigDecodingTooBigHighBits(m) => {
-                write!(f, "Failed to decode signature: high bits {m} exceed 2048")
+            InvalidEncodingLength => {
+                write!(f, "Failed to decode: length is different from the one expected")
             }
-            SigDecodingInvalidRemainder => {
-                write!(f, "Failed to decode signature: incorrect remaining data")
+            InvalidHeaderFormat => write!(f, "Invalid header format"),
+            WrongVariant => write!(f, "Wrong Falcon DSA variant"),
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl std::error::Error for FalconError {}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum FalconSerializationError {
+    TooBigHighBits(u32),
+    MinusZero,
+    NonZeroUnusedBitsLastByte,
+}
+
+impl fmt::Display for FalconSerializationError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        use FalconSerializationError::*;
+        match self {
+            TooBigHighBits(m) => {
+                write!(f, "Failed to decode signature: high bits {m} exceed 2048")
             }
-            SigDecodingNonZeroUnusedBitsLastByte => {
+            NonZeroUnusedBitsLastByte => {
                 write!(f, "Failed to decode signature: Non-zero unused bits in the last byte")
             }
-            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"),
+            MinusZero => write!(f, "Failed to decode signature: -0 is forbidden"),
         }
     }
 }
 
 #[cfg(feature = "std")]
-impl std::error::Error for FalconError {}
+impl std::error::Error for FalconSerializationError {}