From 8b2989c417db9090913f1cb6074ae961f4c14d5e Mon Sep 17 00:00:00 2001
From: Divy Srivastava <dj.srivastava23@gmail.com>
Date: Wed, 2 Mar 2022 10:56:10 +0530
Subject: feat(ext/crypto): AES-GCM support for 128bit IVs (#13805)

---
 ext/crypto/encrypt.rs | 79 +++++++++++++++++++++++++++++++++------------------
 1 file changed, 51 insertions(+), 28 deletions(-)

(limited to 'ext/crypto/encrypt.rs')

diff --git a/ext/crypto/encrypt.rs b/ext/crypto/encrypt.rs
index f1d88438b..63f8af889 100644
--- a/ext/crypto/encrypt.rs
+++ b/ext/crypto/encrypt.rs
@@ -7,10 +7,12 @@ use aes::cipher::NewCipher;
 use aes::BlockEncrypt;
 use aes::NewBlockCipher;
 use aes_gcm::aead::generic_array::typenum::U12;
+use aes_gcm::aead::generic_array::typenum::U16;
+use aes_gcm::aead::generic_array::ArrayLength;
+use aes_gcm::aes::Aes128;
 use aes_gcm::aes::Aes192;
+use aes_gcm::aes::Aes256;
 use aes_gcm::AeadInPlace;
-use aes_gcm::Aes128Gcm;
-use aes_gcm::Aes256Gcm;
 use aes_gcm::NewAead;
 use aes_gcm::Nonce;
 use ctr::Ctr;
@@ -183,52 +185,73 @@ fn encrypt_aes_cbc(
   Ok(ciphertext)
 }
 
-fn encrypt_aes_gcm(
-  key: RawKeyData,
-  length: usize,
-  tag_length: usize,
+fn encrypt_aes_gcm_general<N: ArrayLength<u8>>(
+  key: &[u8],
   iv: Vec<u8>,
-  additional_data: Option<Vec<u8>>,
-  data: &[u8],
-) -> Result<Vec<u8>, AnyError> {
-  let key = key.as_secret_key()?;
-  let additional_data = additional_data.unwrap_or_default();
-
-  // Fixed 96-bit nonce
-  if iv.len() != 12 {
-    return Err(type_error("iv length not equal to 12"));
-  }
-
-  let nonce = Nonce::from_slice(&iv);
-
-  let mut ciphertext = data.to_vec();
+  length: usize,
+  ciphertext: &mut [u8],
+  additional_data: Vec<u8>,
+) -> Result<aes_gcm::Tag, AnyError> {
+  let nonce = Nonce::<N>::from_slice(&iv);
   let tag = match length {
     128 => {
-      let cipher = Aes128Gcm::new_from_slice(key)
+      let cipher = aes_gcm::AesGcm::<Aes128, N>::new_from_slice(key)
         .map_err(|_| operation_error("Encryption failed"))?;
       cipher
-        .encrypt_in_place_detached(nonce, &additional_data, &mut ciphertext)
+        .encrypt_in_place_detached(nonce, &additional_data, ciphertext)
         .map_err(|_| operation_error("Encryption failed"))?
     }
     192 => {
-      type Aes192Gcm = aes_gcm::AesGcm<Aes192, U12>;
-
-      let cipher = Aes192Gcm::new_from_slice(key)
+      let cipher = aes_gcm::AesGcm::<Aes192, N>::new_from_slice(key)
         .map_err(|_| operation_error("Encryption failed"))?;
       cipher
-        .encrypt_in_place_detached(nonce, &additional_data, &mut ciphertext)
+        .encrypt_in_place_detached(nonce, &additional_data, ciphertext)
         .map_err(|_| operation_error("Encryption failed"))?
     }
     256 => {
-      let cipher = Aes256Gcm::new_from_slice(key)
+      let cipher = aes_gcm::AesGcm::<Aes256, N>::new_from_slice(key)
         .map_err(|_| operation_error("Encryption failed"))?;
       cipher
-        .encrypt_in_place_detached(nonce, &additional_data, &mut ciphertext)
+        .encrypt_in_place_detached(nonce, &additional_data, ciphertext)
         .map_err(|_| operation_error("Encryption failed"))?
     }
     _ => return Err(type_error("invalid length")),
   };
 
+  Ok(tag)
+}
+
+fn encrypt_aes_gcm(
+  key: RawKeyData,
+  length: usize,
+  tag_length: usize,
+  iv: Vec<u8>,
+  additional_data: Option<Vec<u8>>,
+  data: &[u8],
+) -> Result<Vec<u8>, AnyError> {
+  let key = key.as_secret_key()?;
+  let additional_data = additional_data.unwrap_or_default();
+
+  let mut ciphertext = data.to_vec();
+  // Fixed 96-bit OR 128-bit nonce
+  let tag = match iv.len() {
+    12 => encrypt_aes_gcm_general::<U12>(
+      key,
+      iv,
+      length,
+      &mut ciphertext,
+      additional_data,
+    )?,
+    16 => encrypt_aes_gcm_general::<U16>(
+      key,
+      iv,
+      length,
+      &mut ciphertext,
+      additional_data,
+    )?,
+    _ => return Err(type_error("iv length not equal to 12 or 16")),
+  };
+
   // Truncated tag to the specified tag length.
   // `tag` is fixed to be 16 bytes long and (tag_length / 8) is always <= 16
   let tag = &tag[..(tag_length / 8)];
-- 
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