Move the canonicalize function to a dedicated module

src/canonicalization.rs

@@ -0,0 +1,44 @@
+use base64ct::{Base64UrlUnpadded, Encoding};
+
+const CANONICALIZATION_BUFFER_SIZE: usize = 1024;
+const CANONICALIZATION_SEPARATOR: &str = ":";
+
+pub(crate) fn canonicalize(key_context: &[&str]) -> String {
+	match key_context.len() {
+		0 => String::new(),
+		1 => key_context[0].to_string(),
+		_ => {
+			let mut ret = String::with_capacity(CANONICALIZATION_BUFFER_SIZE);
+			for (i, ctx_elem) in key_context.iter().enumerate() {
+				if i != 0 {
+					ret += CANONICALIZATION_SEPARATOR;
+				}
+				ret += &Base64UrlUnpadded::encode_string(ctx_elem.as_bytes());
+			}
+			ret
+		}
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+
+	#[test]
+	fn canonicalize_empty() {
+		let canon = canonicalize(&[]);
+		assert_eq!(canon, String::new());
+	}
+
+	#[test]
+	fn canonicalize_one() {
+		let canon = canonicalize(&["test"]);
+		assert_eq!(&canon, "test");
+	}
+
+	#[test]
+	fn canonicalize_many() {
+		let canon = canonicalize(&["test", "bis", "ter", ""]);
+		assert_eq!(&canon, "dGVzdA:Ymlz:dGVy:");
+	}
+}

src/kdf.rs

@@ -1,28 +1,8 @@
+use crate::canonicalization::canonicalize;
 use crate::ikm::InputKeyMaterial;
-use base64ct::{Base64UrlUnpadded, Encoding};
 
 pub(crate) type KdfFunction = dyn Fn(&str, &[u8]) -> Vec<u8>;
 
-const CANONICALIZATION_BUFFER_SIZE: usize = 1024;
-const CANONICALIZATION_SEPARATOR: &str = ":";
-
-fn canonicalize(key_context: &[&str]) -> String {
-	match key_context.len() {
-		0 => String::new(),
-		1 => key_context[0].to_string(),
-		_ => {
-			let mut ret = String::with_capacity(CANONICALIZATION_BUFFER_SIZE);
-			for (i, ctx_elem) in key_context.iter().enumerate() {
-				if i != 0 {
-					ret += CANONICALIZATION_SEPARATOR;
-				}
-				ret += &Base64UrlUnpadded::encode_string(ctx_elem.as_bytes());
-			}
-			ret
-		}
-	}
-}
-
 pub(crate) fn derive_key(ikm: &InputKeyMaterial, key_context: &[&str]) -> Vec<u8> {
 	let key_context = canonicalize(key_context);
 	let kdf = ikm.scheme.get_kdf();
@@ -32,26 +12,3 @@ pub(crate) fn derive_key(ikm: &InputKeyMaterial, key_context: &[&str]) -> Vec<u8
 pub(crate) fn blake3_derive(context: &str, ikm: &[u8]) -> Vec<u8> {
 	blake3::derive_key(context, ikm).to_vec()
 }
-
-#[cfg(test)]
-mod tests {
-	use super::*;
-
-	#[test]
-	fn canonicalize_empty() {
-		let canon = canonicalize(&[]);
-		assert_eq!(canon, String::new());
-	}
-
-	#[test]
-	fn canonicalize_one() {
-		let canon = canonicalize(&["test"]);
-		assert_eq!(&canon, "test");
-	}
-
-	#[test]
-	fn canonicalize_many() {
-		let canon = canonicalize(&["test", "bis", "ter", ""]);
-		assert_eq!(&canon, "dGVzdA:Ymlz:dGVy:");
-	}
-}

src/lib.rs

@@ -1,3 +1,4 @@
+mod canonicalization;
 #[cfg(feature = "encryption")]
 mod encryption;
 mod error;