From aafb7077691b497c36db92ecc226fd6823487f20 Mon Sep 17 00:00:00 2001
From: jrconlin <me+crypt@jrconlin.com>
Date: Tue, 30 Apr 2019 13:09:52 -0700
Subject: [PATCH] feat: Add convenience functions for encrypt/decrypt

Closes #25
---
 Cargo.toml |  7 +++---
 src/lib.rs | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 66 insertions(+), 9 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 0342df1..88e4465 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "ece"
-version = "0.1.3"
+version = "0.2.0"
 authors = ["Edouard Oger <eoger@fastmail.com>", "JR Conlin <jrconlin@gmail.com>"]
 license = "MPL-2.0"
 edition = "2018"
@@ -13,14 +13,13 @@ byteorder = "1.3"
 failure = "0.1"
 failure_derive = "0.1"
 base64 = "0.10"
+hex = "0.3"
 hkdf = { version = "0.7", optional = true }
 lazy_static = { version = "1.2", optional = true }
 openssl = { version = "0.10", optional = true }
+rand = "0.6"
 sha2 = { version = "0.8", optional = true }
 
-[dev-dependencies]
-hex = "0.3"
-
 [features]
 default = ["backend-openssl"]
 backend-openssl = ["openssl", "lazy_static", "hkdf", "sha2"]
diff --git a/src/lib.rs b/src/lib.rs
index 09e0686..f8cebbe 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -9,6 +9,10 @@ mod crypto_backend;
 mod crypto_backends;
 mod error;
 
+use hex;
+use rand;
+use rand::Rng;
+
 pub use crate::{
     aes128gcm::Aes128GcmEceWebPush,
     aesgcm::{AesGcmEceWebPush, AesGcmEncryptedBlock},
@@ -21,6 +25,7 @@ pub type Aes128GcmEceWebPushImpl = aes128gcm::Aes128GcmEceWebPush<crypto_backend
 pub type AesGcmEceWebPushImpl = aesgcm::AesGcmEceWebPush<crypto_backends::CryptoImpl>;
 pub use crate::crypto_backends::{CryptoImpl, LocalKeyPairImpl, RemoteKeyPairImpl};
 
+/// Generate a local ECE key pair and auth nonce.
 pub fn generate_keypair_and_auth_secret(
 ) -> Result<(LocalKeyPairImpl, [u8; ECE_WEBPUSH_AUTH_SECRET_LENGTH])> {
     let local_key_pair = LocalKeyPairImpl::generate_random()?;
@@ -29,6 +34,44 @@ pub fn generate_keypair_and_auth_secret(
     Ok((local_key_pair, auth_secret))
 }
 
+/// Encrypt a block using default AES128GCM encoding.
+///
+/// param remote_pub &str - The remote public key in hex encoded format
+/// param remote_auth &str - The remote authorization token in hex encoded format
+/// param salt &[u8] - The locally generated random salt
+/// param data &[u8] - The data to encrypt
+///
+pub fn encrypt(remote_pub: &str, remote_auth: &str, salt: &[u8], data: &[u8]) -> Result<Vec<u8>> {
+    let remote_decode = hex::decode(remote_pub).map_err(|_| error::ErrorKind::DecodeError)?;
+    let remote_key = crypto_backends::CryptoImpl::public_key_from_raw(remote_decode.as_slice())?;
+    let local_key = LocalKeyPairImpl::generate_random()?;
+    let auth_secret = hex::decode(remote_auth).map_err(|_| error::ErrorKind::DecodeError)?;
+    // TODO: randomize pad.
+    let mut rng = rand::thread_rng();
+    let pad = rng.gen_range(1, 4096 - data.len());
+    let params = WebPushParams::new(4096, pad, Vec::from(salt));
+    Aes128GcmEceWebPushImpl::encrypt_with_keys(
+        &local_key,
+        &remote_key,
+        &auth_secret.as_slice(),
+        data,
+        params,
+    )
+}
+
+/// Decrypt a block using default AES128GCM encoding.
+///
+/// param local_priv &str - The locally generated Private key as a raw, hex encoded string
+/// param auth &str - The locally generated auth token as a hex encoded string (this value was shared with the encryptor)
+/// param data &[u8] - The encrypted data block
+///
+pub fn decrypt(local_priv: &str, auth: &str, data: &[u8]) -> Result<Vec<u8>> {
+    let priv_key = hex::decode(local_priv).unwrap();
+    let priv_key = LocalKeyPairImpl::new(priv_key.as_slice()).unwrap();
+    let auth_secret = hex::decode(auth).unwrap();
+    Aes128GcmEceWebPushImpl::decrypt(&priv_key, &auth_secret.as_slice(), data)
+}
+
 #[cfg(test)]
 mod aes128gcm_tests {
     extern crate hex;
@@ -70,11 +113,7 @@ mod aes128gcm_tests {
     }
 
     fn try_decrypt(priv_key: &str, auth_secret: &str, payload: &str) -> Result<String> {
-        let priv_key = hex::decode(priv_key).unwrap();
-        let priv_key = LocalKeyPairImpl::new(&priv_key)?;
-        let auth_secret = hex::decode(auth_secret).unwrap();
-        let payload = hex::decode(payload).unwrap();
-        let plaintext = Aes128GcmEceWebPushImpl::decrypt(&priv_key, &auth_secret, &payload)?;
+        let plaintext = decrypt(priv_key, auth_secret, &hex::decode(payload).unwrap())?;
         Ok(String::from_utf8(plaintext).unwrap())
     }
 
@@ -100,6 +139,25 @@ mod aes128gcm_tests {
         assert_eq!(decrypted, plaintext);
     }
 
+    #[test]
+    fn test_conv_fn() -> Result<()> {
+        let (local_key, auth) = generate_keypair_and_auth_secret()?;
+        let hex_auth = hex::encode(auth);
+        let plaintext = b"Mary had a little lamb, with some nice mint jelly";
+        let mut salt = vec![0u8; 16];
+        CryptoImpl::random(&mut salt)?;
+        let encoded = encrypt(
+            &hex::encode(local_key.pub_as_raw()?),
+            &hex_auth,
+            &salt,
+            plaintext,
+        )
+        .unwrap();
+        let decoded = decrypt(&hex::encode(local_key.to_raw()), &hex_auth, &encoded)?;
+        assert_eq!(decoded, plaintext.to_vec());
+        Ok(())
+    }
+
     #[test]
     fn try_encrypt_ietf_rfc() {
         let ciphertext = try_encrypt(