move chacha to rust implementation

CMakeLists.txt

@@ -137,7 +137,6 @@ file(GLOB_RECURSE LIB_SRC
     ${CMAKE_CURRENT_SOURCE_DIR}/app/src/parser_impl.c
     ${CMAKE_CURRENT_SOURCE_DIR}/app/src/parser_impl_common.c
     ${CMAKE_CURRENT_SOURCE_DIR}/app/src/crypto_helper.c
-    ${CMAKE_CURRENT_SOURCE_DIR}/app/src/crypto_helper/chacha.c
 
     # ###
     ${CMAKE_CURRENT_SOURCE_DIR}/deps/blake2/ref/blake2b-ref.c
@@ -150,7 +149,6 @@ target_include_directories(app_lib PUBLIC
     ${CMAKE_CURRENT_SOURCE_DIR}/deps/ledger-zxlib/include
     ${CMAKE_CURRENT_SOURCE_DIR}/app/src
     ${CMAKE_CURRENT_SOURCE_DIR}/app/src/lib
-    ${CMAKE_CURRENT_SOURCE_DIR}/app/src/crypto_helper
     ${CMAKE_CURRENT_SOURCE_DIR}/app/src/common
     ${CMAKE_CURRENT_SOURCE_DIR}/app/rust/include
     ${CMAKE_CURRENT_SOURCE_DIR}/deps/blake2/ref

app/rust/Cargo.toml

@@ -14,6 +14,7 @@ crate-type = ["staticlib"]
 [dependencies]
 jubjub = { version = "0.10.0", default-features = false }
 blake2b_simd = { version = "1.0.0", default-features = false }
+chacha20poly1305 = { version = "0.10.1", default-features = false }
 
 [target.thumbv6m-none-eabi.dev-dependencies]
 panic-halt = "0.2.0"

app/rust/include/rslib.h

@@ -17,6 +17,10 @@ parser_error_t compute_sbar(const uint8_t s[KEY_LENGTH], const uint8_t r[KEY_LEN
                             uint8_t sbar[32]);
 parser_error_t shared_secret(uint8_t secret_key[32], uint8_t other_public_key[32], const uint8_t reference_public_key[32],
                              uint8_t output[32]);
+parser_error_t decrypt_note_encryption_keys(const uint8_t key[KEY_LENGTH], const uint8_t note_encryption_keys[80],
+                                            uint8_t output[ENCRYPTED_SHARED_KEY_SIZE]);
+parser_error_t decrypt_note(const uint8_t key[KEY_LENGTH], const uint8_t note[ENCRYPTED_NOTE_SIZE + MAC_SIZE],
+                            uint8_t output[ENCRYPTED_NOTE_SIZE]);
 #ifdef __cplusplus
 }
 #endif

app/rust/src/constants.rs

@@ -74,7 +74,7 @@ pub const MEMO_SIZE: usize = 32;
 pub const AMOUNT_VALUE_SIZE: usize = 8;
 pub const ASSET_ID_LENGTH: usize = 32;
 pub const PUBLIC_ADDRESS_SIZE: usize = 32;
-
+pub const EPHEMEREAL_PUBLIC_KEY_SIZE: usize = 32;
 pub const ENCRYPTED_NOTE_SIZE: usize =
     SCALAR_SIZE + MEMO_SIZE + AMOUNT_VALUE_SIZE + ASSET_ID_LENGTH + PUBLIC_ADDRESS_SIZE;
 

app/rust/src/lib.rs

@@ -19,9 +19,11 @@
 
 use core::panic::PanicInfo;
 
+use chacha20poly1305::{aead::generic_array::GenericArray, ChaCha20Poly1305, Key, KeyInit, Nonce};
 use constants::{
-    DIFFIE_HELLMAN_PERSONALIZATION, ENCRYPTED_NOTE_SIZE, ENCRYPTED_SHARED_KEY_SIZE, MAC_SIZE,
-    NOTE_ENCRYPTION_KEY_SIZE, SHARED_KEY_PERSONALIZATION, SPENDING_KEY_GENERATOR,
+    DIFFIE_HELLMAN_PERSONALIZATION, ENCRYPTED_NOTE_SIZE, ENCRYPTED_SHARED_KEY_SIZE,
+    EPHEMEREAL_PUBLIC_KEY_SIZE, MAC_SIZE, NOTE_ENCRYPTION_KEY_SIZE, SHARED_KEY_PERSONALIZATION,
+    SPENDING_KEY_GENERATOR,
 };
 mod constants;
 
@@ -150,6 +152,52 @@ pub extern "C" fn shared_secret(
     ParserError::ParserOk
 }
 
+fn decrypt<const SIZE: usize>(
+    key: &[u8; 32],
+    ciphertext: &[u8],
+    plaintext: &mut [u8; SIZE],
+) -> ParserError {
+    use chacha20poly1305::AeadInPlace;
+
+    // Check if the ciphertext length is sufficient
+    if ciphertext.len() < SIZE {
+        return ParserError::ParserUnexpectedError; // Return an error if insufficient data
+    }
+
+    let decryptor = ChaCha20Poly1305::new(Key::from_slice(key));
+
+    plaintext.copy_from_slice(&ciphertext[..SIZE]);
+
+    // Attempt decryption
+    match decryptor.decrypt_in_place_detached(
+        &Nonce::default(),
+        &[],
+        plaintext,
+        ciphertext[SIZE..].into(),
+    ) {
+        Ok(_) => ParserError::ParserOk,
+        Err(_) => ParserError::ParserUnexpectedError, // Handle decryption failure
+    }
+}
+
+#[no_mangle]
+pub extern "C" fn decrypt_note_encryption_keys(
+    key: &[u8; 32],
+    ciphertext: &[u8; NOTE_ENCRYPTION_KEY_SIZE],
+    output: &mut [u8; ENCRYPTED_SHARED_KEY_SIZE],
+) -> ParserError {
+    decrypt::<ENCRYPTED_SHARED_KEY_SIZE>(key, ciphertext, output)
+}
+
+#[no_mangle]
+pub extern "C" fn decrypt_note(
+    shared_key: &[u8; 32],
+    ciphertext: &[u8; ENCRYPTED_NOTE_SIZE + MAC_SIZE],
+    output: &mut [u8; ENCRYPTED_NOTE_SIZE],
+) -> ParserError {
+    decrypt::<ENCRYPTED_NOTE_SIZE>(shared_key, ciphertext, output)
+}
+
 #[cfg(not(test))]
 #[panic_handler]
 fn panic(_info: &PanicInfo) -> ! {

app/src/crypto_helper.c

@@ -18,7 +18,6 @@
 #include <string.h>
 
 #include "coin.h"
-#include "crypto_helper/chacha.h"
 #include "keys_personalizations.h"
 #include "rslib.h"
 #include "zxformat.h"
@@ -271,12 +270,7 @@ parser_error_t crypto_decrypt_merkle_note(parser_tx_t *txObj, const uint8_t *m_n
 
     // Decrypt the note encryption keys
     uint8_t note_encryption_key[ENCRYPTED_SHARED_KEY_SIZE] = {0};
-    uint8_t cc_nonce[CHACHA_NONCE_SIZE] = {0};
-    CHECK_ERROR(chacha(note_encryption_key, sizeof(note_encryption_key), m_note + NOTE_ENCRYPTION_KEYS_OFFSET,
-                       ENCRYPTED_SHARED_KEY_SIZE, encryption_key, cc_nonce, 1));
-#if defined(LEDGER_SPECIFIC)
-        io_seproxyhal_io_heartbeat();
-#endif
+    CHECK_ERROR(decrypt_note_encryption_keys(encryption_key, m_note + NOTE_ENCRYPTION_KEYS_OFFSET, note_encryption_key));
     CHECK_APP_CANARY()
 
     // Extract public address and secret key from the note encryption key
@@ -289,17 +283,14 @@ parser_error_t crypto_decrypt_merkle_note(parser_tx_t *txObj, const uint8_t *m_n
     uint8_t shared_key[32] = {0};
     const uint8_t *ephemeral_public_key = m_note + VALUE_COMMITMENT_SIZE + NOTE_COMMITMENT_SIZE;
     CHECK_ERROR(shared_secret(secret_key, public_address, ephemeral_public_key, shared_key));
-#if defined(LEDGER_SPECIFIC)
-        io_seproxyhal_io_heartbeat();
-#endif
     CHECK_APP_CANARY()
 
     // Finally decrypt the note
     uint8_t plain_text[ENCRYPTED_NOTE_SIZE] = {0};
-    CHECK_ERROR(chacha(plain_text, sizeof(plain_text), m_note + ENCRYPTED_NOTE_OFFSET, ENCRYPTED_NOTE_SIZE, shared_key,
-                       cc_nonce, 1));
+    CHECK_ERROR(decrypt_note(shared_key, m_note + ENCRYPTED_NOTE_OFFSET, plain_text));
+
 #if defined(LEDGER_SPECIFIC)
-        io_seproxyhal_io_heartbeat();
+    io_seproxyhal_io_heartbeat();
 #endif
     CHECK_APP_CANARY()
     // Fill the txObj with the decrypted note