aesgcm refactoring + unit tests

crates/sp_client/src/aesgcm.rs

@@ -29,40 +29,57 @@ use rand::{thread_rng, RngCore};
 
 const HALFKEYSIZE: usize = SECRET_KEY_SIZE / 2;
 
-pub type HalfKey = [u8; HALFKEYSIZE];
+pub struct HalfKey([u8; HALFKEYSIZE]);
 
-pub enum EncryptionTarget {
-    Login(HalfKey),
+impl TryFrom<Vec<u8>> for HalfKey {
+    type Error = anyhow::Error;
+    fn try_from(value: Vec<u8>) -> std::prelude::v1::Result<Self, Error> {
+        if value.len() == HALFKEYSIZE {
+            let mut buf = [0u8; HALFKEYSIZE];
+            buf.copy_from_slice(&value);
+            Ok(HalfKey(buf))
+        } else {
+            Err(Error::msg("Invalid length for HalfKey"))
+        }
+    }
 }
 
-pub enum DecryptionTarget {
+impl HalfKey {
+    pub fn as_slice(&self) -> &[u8] {
+        &self.0
+    }
+
+    pub fn to_inner(&self) -> Vec<u8> {
+        self.0.to_vec()
+    }
+}
+
+pub enum Purpose {
     Login,
 }
 
-pub enum PlainText {
-    Login(HalfKey),
-}
-
 pub type CipherText = Vec<u8>;
 
+pub type EncryptedKey = Vec<u8>;
+
 pub struct Aes256Decryption {
-    target: DecryptionTarget,
+    pub purpose: Purpose,
+    cipher_text: CipherText,
     aes_key: [u8; 32],
     nonce: [u8; 12],
-    cipher_text: CipherText,
 }
 
 impl Aes256Decryption {
     pub fn new(
-        target: DecryptionTarget,
+        purpose: Purpose,
+        cipher_text: CipherText,
         encrypted_aes_key: Vec<u8>,
         shared_secret: SharedSecret,
-        cipher_text: CipherText,
     ) -> Result<Self> {
         if encrypted_aes_key.len() <= 12 {
             return Err(Error::msg("encrypted_aes_key is shorter than nonce length"));
-        }
-        // take the first 12 bytes form encrypted_aes_key as nonce
+        } // Actually we could probably test that if the remnant is not a multiple of 32, something's wrong
+          // take the first 12 bytes form encrypted_aes_key as nonce
         let (decrypt_key_nonce, encrypted_key) = encrypted_aes_key.split_at(12);
         // decrypt key with shared_secret obtained from transaction
         let decrypt_key_cipher = Aes256Gcm::new_from_slice(shared_secret.as_ref())
@@ -76,26 +93,29 @@ impl Aes256Decryption {
         let mut aes_key = [0u8; 32];
         aes_key.copy_from_slice(&aes_key_plain);
         if cipher_text.len() <= 12 {
-            return Err(Error::msg("cipher_text is shorter than nonce lenght"));
+            return Err(Error::msg("cipher_text is shorter than nonce length"));
         }
         let (message_nonce, message_cipher) = cipher_text.split_at(12);
         let mut nonce = [0u8; 12];
         nonce.copy_from_slice(message_nonce);
         Ok(Self {
-            target,
+            purpose,
+            cipher_text: message_cipher.to_vec(),
             aes_key,
             nonce,
-            cipher_text: message_cipher.to_vec(),
         })
     }
 
-    pub fn decrypt_with_key(&self) -> Result<PlainText> {
-        match self.target {
-            DecryptionTarget::Login => self.decrypt_login()
+    pub fn decrypt_with_key(&self) -> Result<Vec<u8>> {
+        match self.purpose {
+            Purpose::Login => {
+                let half_key = self.decrypt_login()?;
+                Ok(half_key.to_inner())
+            }
         }
     }
 
-    fn decrypt_login(&self) -> Result<PlainText> {
+    fn decrypt_login(&self) -> Result<HalfKey> {
         let cipher = Aes256Gcm::new(&self.aes_key.into());
         let plain = cipher
             .decrypt(&self.nonce.into(), &*self.cipher_text)
@@ -105,44 +125,70 @@ impl Aes256Decryption {
         }
         let mut key_half = [0u8; SECRET_KEY_SIZE / 2];
         key_half.copy_from_slice(&plain);
-        Ok(PlainText::Login(key_half))
+        Ok(HalfKey(key_half))
     }
 }
 
 pub struct Aes256Encryption {
-    pub target: EncryptionTarget,
+    pub purpose: Purpose,
+    plaintext: Vec<u8>,
     aes_key: [u8; 32],
     nonce: [u8; 12],
     shared_secrets: HashMap<Txid, HashMap<SilentPaymentAddress, SharedSecret>>,
 }
 
 impl Aes256Encryption {
-    pub fn new(target: EncryptionTarget) -> Result<Self> {
+    pub fn new(purpose: Purpose, plaintext: Vec<u8>) -> Result<Self> {
         let mut rng = thread_rng();
         let aes_key: [u8; 32] = Aes256Gcm::generate_key(&mut rng).into();
         let nonce: [u8; 12] = Aes256Gcm::generate_nonce(&mut rng).into();
-        Ok(Self {
-            target,
-            aes_key,
-            nonce,
-            shared_secrets: HashMap::new(),
-        })
+        Self::import_key(purpose, plaintext, aes_key, nonce)
     }
 
     pub fn set_shared_secret(
         &mut self,
         shared_secrets: HashMap<Txid, HashMap<SilentPaymentAddress, SharedSecret>>,
-    ) -> Result<()> {
-        unimplemented!();
+    ) {
+        self.shared_secrets = shared_secrets;
+    }
+
+    pub fn encrypt_keys_with_shared_secrets(
+        &self,
+    ) -> Result<HashMap<SilentPaymentAddress, EncryptedKey>> {
+        let mut res = HashMap::new();
+        let mut rng = thread_rng();
+
+        for (_, sp_address2shared_secret) in self.shared_secrets.iter() {
+            for (sp_address, shared_secret) in sp_address2shared_secret {
+                let cipher = Aes256Gcm::new_from_slice(shared_secret.as_ref())
+                    .map_err(|e| Error::msg(format!("{}", e)))?;
+                let nonce = Aes256Gcm::generate_nonce(&mut rng);
+                let encrypted_key = cipher
+                    .encrypt(&nonce, self.aes_key.as_slice())
+                    .map_err(|e| Error::msg(format!("{}", e)))?;
+
+                let mut ciphertext = Vec::<u8>::with_capacity(nonce.len() + encrypted_key.len());
+                ciphertext.extend(nonce);
+                ciphertext.extend(encrypted_key);
+
+                res.insert(sp_address.to_owned(), ciphertext);
+            }
+        }
+        Ok(res)
     }
 
     pub fn import_key(
-        target: EncryptionTarget,
+        purpose: Purpose,
+        plaintext: Vec<u8>,
         aes_key: [u8; 32],
         nonce: [u8; 12],
     ) -> Result<Self> {
+        if plaintext.len() == 0 {
+            return Err(Error::msg("Can't create encryption for an empty message"));
+        }
         Ok(Self {
-            target,
+            purpose,
+            plaintext,
             aes_key,
             nonce,
             shared_secrets: HashMap::new(),
@@ -150,15 +196,16 @@ impl Aes256Encryption {
     }
 
     pub fn encrypt_with_aes_key(&self) -> Result<CipherText> {
-        match self.target {
-            EncryptionTarget::Login(half_key) => self.encrypt_login(half_key),
+        match self.purpose {
+            Purpose::Login => self.encrypt_login(),
         }
     }
 
-    fn encrypt_login(&self, plaintext: HalfKey) -> Result<CipherText> {
+    fn encrypt_login(&self) -> Result<CipherText> {
+        let half_key: HalfKey = self.plaintext.clone().try_into()?;
         let cipher = Aes256Gcm::new(&self.aes_key.into());
         let cipher_text = cipher
-            .encrypt(&self.nonce.into(), plaintext.as_slice())
+            .encrypt(&self.nonce.into(), half_key.as_slice())
             .map_err(|e| Error::msg(format!("{}", e)))?;
         let mut res = Vec::with_capacity(self.nonce.len() + cipher_text.len());
         res.extend_from_slice(&self.nonce);
@@ -166,3 +213,183 @@ impl Aes256Encryption {
         Ok(res)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use std::str::FromStr;
+
+    use super::*;
+
+    const ALICE_SP_ADDRESS: &str = "tsp1qqw3lqr6xravz9nf8ntazgwwl0fqv47kfjdxsnxs6eutavqfwyv5q6qk97mmyf6dtkdyzqlu2zv6h9j2ggclk7vn705q5u2phglpq7yw3dg5rwpdz";
+    const BOB_SP_ADDRESS: &str = "tsp1qq2hlsgrj0gz8kcfkf9flqw5llz0u2vr04telqndku9mcqm6dl4fhvq60t8r78srrf56w9yr7w9e9dusc2wjqc30up6fjwnh9mw3e3veqegdmtf08";
+    const TRANSACTION: &str = "4e6d03dec558e1b6624f813bf2da7cd8d8fb1c2296684c08cf38724dcfd8d10b";
+    const ALICE_SHARED_SECRET: &str = "ccf02d364c2641ca129a3fdf49de57b705896e233f7ba6d738991993ea7e2106";
+    const BOB_SHARED_SECRET: &str = "15ef3e377fb842e81de52dbaaea8ba30aeb051a81043ee19264afd27353da521";
+
+    #[test]
+    fn new_aes_empty_plaintext() {
+        let plaintext = Vec::new();
+        let aes_enc = Aes256Encryption::new(Purpose::Login, plaintext);
+
+        assert!(aes_enc.is_err());
+    }
+
+    #[test]
+    fn aes_encrypt_login_invalid_length() {
+        let plaintext = "example";
+        let aes_enc_short = Aes256Encryption::new(Purpose::Login, plaintext.as_bytes().to_vec());
+
+        assert!(aes_enc_short.is_ok());
+
+        let cipher = aes_enc_short.unwrap().encrypt_with_aes_key();
+
+        assert!(cipher.is_err());
+
+        let plaintext = [1u8; 64];
+        let aes_enc_long = Aes256Encryption::new(Purpose::Login, plaintext.to_vec());
+
+        assert!(aes_enc_long.is_ok());
+
+        let cipher = aes_enc_long.unwrap().encrypt_with_aes_key();
+
+        assert!(cipher.is_err());
+    }
+
+    #[test]
+    fn aes_encrypt_login() {
+        let plaintext = [1u8; HALFKEYSIZE];
+        let aes_enc = Aes256Encryption::new(Purpose::Login, plaintext.to_vec());
+
+        assert!(aes_enc.is_ok());
+
+        let cipher = aes_enc.unwrap().encrypt_with_aes_key();
+
+        assert!(cipher.is_ok());
+    }
+
+    #[test]
+    fn aes_encrypt_key() {
+        let plaintext = [1u8; HALFKEYSIZE];
+        let mut aes_enc = Aes256Encryption::new(Purpose::Login, plaintext.to_vec()).unwrap();
+
+        let mut shared_secrets: HashMap<Txid, _> = HashMap::new();
+        let mut sp_address2shared_secrets: HashMap<SilentPaymentAddress, SharedSecret> =
+            HashMap::new();
+        sp_address2shared_secrets.insert(
+            ALICE_SP_ADDRESS.try_into().unwrap(),
+            SharedSecret::from_str(ALICE_SHARED_SECRET).unwrap(),
+        );
+        shared_secrets.insert(
+            Txid::from_str(TRANSACTION).unwrap(),
+            sp_address2shared_secrets,
+        );
+
+        aes_enc.set_shared_secret(shared_secrets);
+
+        let sp_address2encrypted_keys = aes_enc.encrypt_keys_with_shared_secrets();
+
+        assert!(sp_address2encrypted_keys.is_ok());
+
+        let encrypted_key = sp_address2encrypted_keys
+            .unwrap()
+            .get(&ALICE_SP_ADDRESS.try_into().unwrap())
+            .cloned();
+
+        let ciphertext = aes_enc.encrypt_with_aes_key();
+
+        assert!(ciphertext.is_ok());
+
+        let aes_dec = Aes256Decryption::new(
+            Purpose::Login,
+            ciphertext.unwrap(),
+            encrypted_key.unwrap(),
+            SharedSecret::from_str(ALICE_SHARED_SECRET).unwrap(),
+        );
+
+        assert!(aes_dec.is_ok());
+
+        let retrieved_plain = aes_dec.unwrap().decrypt_with_key();
+
+        assert!(retrieved_plain.is_ok());
+
+        assert!(retrieved_plain.unwrap() == plaintext);
+    }
+
+    #[test]
+    fn aes_encrypt_key_many() {
+        let plaintext = [1u8; HALFKEYSIZE];
+        let mut aes_enc = Aes256Encryption::new(Purpose::Login, plaintext.to_vec()).unwrap();
+
+        let mut shared_secrets: HashMap<Txid, _> = HashMap::new();
+        let mut sp_address2shared_secrets: HashMap<SilentPaymentAddress, SharedSecret> =
+            HashMap::new();
+        sp_address2shared_secrets.insert(
+            ALICE_SP_ADDRESS.try_into().unwrap(),
+            SharedSecret::from_str(ALICE_SHARED_SECRET).unwrap(),
+        );
+        sp_address2shared_secrets.insert(
+            BOB_SP_ADDRESS.try_into().unwrap(),
+            SharedSecret::from_str(BOB_SHARED_SECRET).unwrap(),
+        );
+        shared_secrets.insert(
+            Txid::from_str(TRANSACTION).unwrap(),
+            sp_address2shared_secrets,
+        );
+
+        aes_enc.set_shared_secret(shared_secrets);
+
+        let mut sp_address2encrypted_keys = aes_enc.encrypt_keys_with_shared_secrets();
+
+        assert!(sp_address2encrypted_keys.is_ok());
+
+        // Alice
+        let encrypted_key = sp_address2encrypted_keys.as_mut()
+            .unwrap()
+            .get(&ALICE_SP_ADDRESS.try_into().unwrap())
+            .cloned();
+
+        let ciphertext = aes_enc.encrypt_with_aes_key();
+
+        assert!(ciphertext.is_ok());
+
+        let aes_dec = Aes256Decryption::new(
+            Purpose::Login,
+            ciphertext.unwrap(),
+            encrypted_key.unwrap(),
+            SharedSecret::from_str(ALICE_SHARED_SECRET).unwrap(),
+        );
+
+        assert!(aes_dec.is_ok());
+
+        let retrieved_plain = aes_dec.unwrap().decrypt_with_key();
+
+        assert!(retrieved_plain.is_ok());
+
+        assert!(retrieved_plain.unwrap() == plaintext);
+        
+        // Bob 
+        let encrypted_key = sp_address2encrypted_keys
+            .unwrap()
+            .get(&BOB_SP_ADDRESS.try_into().unwrap())
+            .cloned();
+
+        let ciphertext = aes_enc.encrypt_with_aes_key();
+
+        assert!(ciphertext.is_ok());
+
+        let aes_dec = Aes256Decryption::new(
+            Purpose::Login,
+            ciphertext.unwrap(),
+            encrypted_key.unwrap(),
+            SharedSecret::from_str(BOB_SHARED_SECRET).unwrap(),
+        );
+
+        assert!(aes_dec.is_ok());
+
+        let retrieved_plain = aes_dec.unwrap().decrypt_with_key();
+
+        assert!(retrieved_plain.is_ok());
+
+        assert!(retrieved_plain.unwrap() == plaintext);
+    }
+}