Merge branch 'master' of euphorik.ch:rup into master

[rup.git] / backend / src / crypto.rs

diff --git a/backend/src/crypto.rs b/backend/src/crypto.rs
new file mode 100644 (file)
index 0000000..16fbaa0
--- /dev/null
+++ b/backend/src/crypto.rs
@@ -0,0 +1,127 @@
+use openssl::{symm, sha::sha256};\r
+use rand::prelude::*;\r
+\r
+#[derive(Debug)]\r
+pub enum KeyError {\r
+    UnableToDecodeBase64Key,\r
+    WrongKeyLength,\r
+}\r
+\r
+#[derive(Debug)]\r
+pub enum EncryptError {\r
+    KeyError(KeyError),\r
+    UnsupportedVersion(u8),\r
+    UnableToEncrypt,\r
+}\r
+\r
+#[derive(Debug)]\r
+pub enum DecryptError {\r
+    KeyError(KeyError),\r
+    UnableToParseVersion,\r
+    UnsupportedVersion(u8),\r
+    MessageToShort,\r
+    UnableToDecodeBase64Message,\r
+    UnableToDecrypt,\r
+    UnableToDecodeMessageAsUTF8String,\r
+    HashMismatch,\r
+}\r
+\r
+fn decode_key(key: &str) -> Result<Vec<u8>, KeyError> {\r
+    match base64::decode(key) {\r
+        Ok(k) => if k.len() != 16 { Err(KeyError::WrongKeyLength) } else { Ok(k) },\r
+        Err(_e) => Err(KeyError::UnableToDecodeBase64Key)\r
+    }\r
+}\r
+\r
+/// Return a random key encoded in base64.\r
+pub fn generate_key() -> String {\r
+    let key = rand::thread_rng().gen::<[u8; 16]>();\r
+    base64::encode(key)\r
+}\r
+\r
+/// Encrypt the given text with the given key (first version). The key length must be 128 bits encoded in base64.\r
+/// Ouput formats:\r
+/// * 'version' = 1: "1" + base_64(<IV> + hash(message) + aes(message))\r
+/// * 'version' = 2: "2" + base_64(<IV> + aes(hash(message) + message))\r
+/// IV: 16 bytes randomized.\r
+/// Mode : CBC.\r
+pub fn encrypt(key: &str, plain_text: &str, version: u8) -> Result<String, EncryptError> {\r
+    let key_as_bytes = decode_key(key).map_err(EncryptError::KeyError)?;\r
+\r
+    let text_as_bytes = plain_text.as_bytes();\r
+    let hash_text = sha256(&text_as_bytes);\r
+    let iv = rand::thread_rng().gen::<[u8; 16]>();\r
+\r
+    let cipher_text =\r
+        if version == 1 {\r
+            symm::encrypt(symm::Cipher::aes_128_cbc(), &key_as_bytes, Some(&iv), text_as_bytes)\r
+                .map_err(|_e| EncryptError::UnableToEncrypt)?\r
+        } else if version == 2 {\r
+            symm::encrypt(symm::Cipher::aes_128_cbc(), &key_as_bytes, Some(&iv), &[&hash_text, text_as_bytes].concat())\r
+                .map_err(|_e| EncryptError::UnableToEncrypt)?\r
+        } else {\r
+            return Err(EncryptError::UnsupportedVersion(version))\r
+        };\r
+\r
+    let mut result: Vec<u8> = Vec::new();\r
+    result.extend(&iv);\r
+\r
+    if version == 1 {\r
+        result.extend(&hash_text);\r
+    }\r
+\r
+    result.extend(&cipher_text);\r
+\r
+    Ok(version.to_string() + &base64::encode(&result))\r
+}\r
+\r
+/// Decrypt the given text with the given key. The key length must be 128 bits encoded in base64.\r
+/// Input formats:\r
+/// * version 1: "1" + base_64(<IV> + hash(message) + aes(message))\r
+/// * version 2: "2" + base_64(<IV> + aes(hash(message) + message))\r
+pub fn decrypt(key: &str, cipher_text: &str) -> Result<String, DecryptError> {\r
+    let key_as_bytes = decode_key(key).map_err(DecryptError::KeyError)?;\r
+\r
+    // Can't decrypt a message with the wrong version.\r
+    let first_char = &cipher_text[..1];\r
+    let version: u8 = first_char.parse().map_err(|_e| DecryptError::UnableToParseVersion)?;\r
+\r
+    if version != 1 && version != 2 {\r
+        return Err(DecryptError::UnsupportedVersion(version))\r
+    }\r
+\r
+    let cipher_text_bytes =\r
+        base64::decode(&cipher_text.as_bytes()[1..])\r
+            .map_err(|_e| DecryptError::UnableToDecodeBase64Message)?;\r
+\r
+    if cipher_text_bytes.len() <= 48 { return Err(DecryptError::MessageToShort) }\r
+\r
+    let iv = &cipher_text_bytes[0..16];\r
+\r
+    let (plain_message_bytes, hash) =\r
+        if version == 1 {\r
+            let encrypted_message = &cipher_text_bytes[48..];\r
+            (\r
+                symm::decrypt(symm::Cipher::aes_128_cbc(), &key_as_bytes, Some(iv), encrypted_message)\r
+                    .map_err(|_e| DecryptError::UnableToDecrypt)?,\r
+                cipher_text_bytes[16..48].to_vec()\r
+            )\r
+        } else {\r
+            let encrypted_message = &cipher_text_bytes[16..];\r
+            let plain_text =\r
+                symm::decrypt(symm::Cipher::aes_128_cbc(), &key_as_bytes, Some(iv), encrypted_message)\r
+                    .map_err(|_e| DecryptError::UnableToDecrypt)?;\r
+            (\r
+                plain_text[32..].to_vec(),\r
+                plain_text[0..32].to_vec()\r
+            )\r
+        };\r
+\r
+    if sha256(&plain_message_bytes) != hash[..] { return Err(DecryptError::HashMismatch) }\r
+\r
+    let plain_message =\r
+        String::from_utf8(plain_message_bytes)\r
+            .map_err(|_e| DecryptError::UnableToDecodeMessageAsUTF8String)?;\r
+\r
+    Ok(plain_message)\r
+}\r