Move the scheme related primitives to dedicated modules

src/encryption.rs

@@ -2,8 +2,6 @@ use crate::canonicalization::{canonicalize, join_canonicalized_str};
 use crate::error::Result;
 use crate::kdf::derive_key;
 use crate::{storage, InputKeyMaterialList};
-use chacha20poly1305::aead::{Aead, KeyInit, Payload};
-use chacha20poly1305::{Key, XChaCha20Poly1305, XNonce};
 
 pub(crate) type DecryptionFunction = dyn Fn(&[u8], &EncryptedData, &str) -> Result<Vec<u8>>;
 pub(crate) type EncryptionFunction = dyn Fn(&[u8], &[u8], &str) -> Result<EncryptedData>;
@@ -34,36 +32,6 @@ pub fn encrypt(
 	Ok(storage::encode(ikm.id, &encrypted_data))
 }
 
-pub(crate) fn xchacha20poly1305_encrypt(
-	key: &[u8],
-	data: &[u8],
-	aad: &str,
-) -> Result<EncryptedData> {
-	// Adapt the key
-	let key = Key::from_slice(key);
-
-	// Generate a nonce
-	let mut nonce: [u8; 24] = [0; 24];
-	getrandom::getrandom(&mut nonce)?;
-	let nonce = XNonce::from_slice(&nonce);
-
-	// Prepare the payload
-	let payload = Payload {
-		msg: data,
-		aad: aad.as_bytes(),
-	};
-
-	// Encrypt the payload
-	let cipher = XChaCha20Poly1305::new(key);
-	let ciphertext = cipher.encrypt(nonce, payload)?;
-
-	// Return the result
-	Ok(EncryptedData {
-		nonce: nonce.to_vec(),
-		ciphertext,
-	})
-}
-
 pub fn decrypt(
 	ikml: &InputKeyMaterialList,
 	key_context: &[&str],
@@ -78,21 +46,6 @@ pub fn decrypt(
 	decryption_function(&key, &encrypted_data, &aad)
 }
 
-pub(crate) fn xchacha20poly1305_decrypt(
-	key: &[u8],
-	encrypted_data: &EncryptedData,
-	aad: &str,
-) -> Result<Vec<u8>> {
-	let key = Key::from_slice(key);
-	let nonce = XNonce::from_slice(&encrypted_data.nonce);
-	let payload = Payload {
-		msg: &encrypted_data.ciphertext,
-		aad: aad.as_bytes(),
-	};
-	let cipher = XChaCha20Poly1305::new(key);
-	Ok(cipher.decrypt(nonce, payload)?)
-}
-
 #[cfg(test)]
 mod tests {
 	use super::*;

src/kdf.rs

@@ -9,10 +9,6 @@ pub(crate) fn derive_key(ikm: &InputKeyMaterial, key_context: &[&str]) -> Vec<u8
 	kdf(&key_context, &ikm.content)
 }
 
-pub(crate) fn blake3_derive(context: &str, ikm: &[u8]) -> Vec<u8> {
-	blake3::derive_key(context, ikm).to_vec()
-}
-
 #[cfg(test)]
 mod tests {
 	use crate::ikm::InputKeyMaterial;
@@ -38,16 +34,4 @@ mod tests {
 			]
 		);
 	}
-
-	#[test]
-	fn blake3_derive() {
-		assert_eq!(
-			super::blake3_derive("this is a context", b"7b47db8f365e5b602fd956d35985e9e1"),
-			vec![
-				0xc4, 0xf4, 0x6c, 0xf2, 0x03, 0xd9, 0x2d, 0x7b, 0x72, 0xe8, 0xe7, 0x90, 0xa3, 0x62,
-				0x2a, 0xf4, 0x3c, 0x2a, 0xab, 0x27, 0xc6, 0xb1, 0x8b, 0x46, 0x9d, 0x40, 0x61, 0x56,
-				0x19, 0x76, 0x88, 0xc4
-			]
-		);
-	}
 }

src/scheme.rs

@@ -2,6 +2,9 @@ use crate::encryption::{DecryptionFunction, EncryptionFunction};
 use crate::kdf::KdfFunction;
 use crate::Error;
 
+mod blake3;
+mod xchacha20poly1305;
+
 pub(crate) type SchemeSerializeType = u32;
 
 #[derive(Copy, Clone, Debug, PartialEq)]
@@ -12,14 +15,14 @@ pub enum Scheme {
 impl Scheme {
 	pub(crate) fn get_kdf(&self) -> Box<KdfFunction> {
 		match self {
-			Scheme::XChaCha20Poly1305WithBlake3 => Box::new(crate::kdf::blake3_derive),
+			Scheme::XChaCha20Poly1305WithBlake3 => Box::new(blake3::blake3_derive),
 		}
 	}
 
 	pub(crate) fn get_decryption(&self) -> Box<DecryptionFunction> {
 		match self {
 			Scheme::XChaCha20Poly1305WithBlake3 => {
-				Box::new(crate::encryption::xchacha20poly1305_decrypt)
+				Box::new(xchacha20poly1305::xchacha20poly1305_decrypt)
 			}
 		}
 	}
@@ -27,7 +30,7 @@ impl Scheme {
 	pub(crate) fn get_encryption(&self) -> Box<EncryptionFunction> {
 		match self {
 			Scheme::XChaCha20Poly1305WithBlake3 => {
-				Box::new(crate::encryption::xchacha20poly1305_encrypt)
+				Box::new(xchacha20poly1305::xchacha20poly1305_encrypt)
 			}
 		}
 	}

src/scheme/blake3.rs

@@ -0,0 +1,18 @@
+pub(crate) fn blake3_derive(context: &str, ikm: &[u8]) -> Vec<u8> {
+	blake3::derive_key(context, ikm).to_vec()
+}
+
+#[cfg(test)]
+mod tests {
+	#[test]
+	fn blake3_derive() {
+		assert_eq!(
+			super::blake3_derive("this is a context", b"7b47db8f365e5b602fd956d35985e9e1"),
+			vec![
+				0xc4, 0xf4, 0x6c, 0xf2, 0x03, 0xd9, 0x2d, 0x7b, 0x72, 0xe8, 0xe7, 0x90, 0xa3, 0x62,
+				0x2a, 0xf4, 0x3c, 0x2a, 0xab, 0x27, 0xc6, 0xb1, 0x8b, 0x46, 0x9d, 0x40, 0x61, 0x56,
+				0x19, 0x76, 0x88, 0xc4
+			]
+		);
+	}
+}

src/scheme/xchacha20poly1305.rs

@@ -0,0 +1,49 @@
+use crate::encryption::EncryptedData;
+use crate::error::Result;
+use chacha20poly1305::aead::{Aead, KeyInit, Payload};
+use chacha20poly1305::{Key, XChaCha20Poly1305, XNonce};
+
+pub(crate) fn xchacha20poly1305_encrypt(
+	key: &[u8],
+	data: &[u8],
+	aad: &str,
+) -> Result<EncryptedData> {
+	// Adapt the key
+	let key = Key::from_slice(key);
+
+	// Generate a nonce
+	let mut nonce: [u8; 24] = [0; 24];
+	getrandom::getrandom(&mut nonce)?;
+	let nonce = XNonce::from_slice(&nonce);
+
+	// Prepare the payload
+	let payload = Payload {
+		msg: data,
+		aad: aad.as_bytes(),
+	};
+
+	// Encrypt the payload
+	let cipher = XChaCha20Poly1305::new(key);
+	let ciphertext = cipher.encrypt(nonce, payload)?;
+
+	// Return the result
+	Ok(EncryptedData {
+		nonce: nonce.to_vec(),
+		ciphertext,
+	})
+}
+
+pub(crate) fn xchacha20poly1305_decrypt(
+	key: &[u8],
+	encrypted_data: &EncryptedData,
+	aad: &str,
+) -> Result<Vec<u8>> {
+	let key = Key::from_slice(key);
+	let nonce = XNonce::from_slice(&encrypted_data.nonce);
+	let payload = Payload {
+		msg: &encrypted_data.ciphertext,
+		aad: aad.as_bytes(),
+	};
+	let cipher = XChaCha20Poly1305::new(key);
+	Ok(cipher.decrypt(nonce, payload)?)
+}