feat: add decrypt_json_gcm for encrypted status storages

src/tests/utils/file_tests.rs

@@ -86,3 +86,27 @@ async fn encrypt_stream_starts_with_json_header_line() -> Result<()> {
 
     Ok(())
 }
+
+use crate::utils::file::decrypt_json_gcm;
+
+const VECTOR_KEY_B64: &str = "BwcHBwcHBwcHBwcHBwcHBwcHBwcHBwcHBwcHBwcHBwc=";
+const VECTOR_ENVELOPE_B64: &str = "AQIDBAUGBwgJCgsM4AfK9w7I2A7UDzMvpJaScfnUYAGDZgPWT5Chrp1pdzMPPQVpNjb6ZEiFea9YdWVFv1UEo9RGmmf+zYUv4I3gE4SU/SBrMwkCHEpJGJOzJtK3tSpJmzLVX3+7EeUNwp4qjZheL8p0pe1x6dRUtx3JmLjz1W/RhWd6zuReDItv6+0jg4CaPOHvFXBreaGNCTRslxbImD+lFBoEOvw8lsbH";
+const VECTOR_PLAINTEXT: &str = "[{\"id\":\"11111111-1111-1111-1111-111111111111\",\"config\":{\"bucket\":\"my-bucket\",\"accessKeyId\":\"AKIA\",\"secretAccessKey\":\"s3cr3t\"},\"provider\":\"s3\"}]";
+
+#[test]
+fn decrypt_json_gcm_decrypts_node_vector() {
+    let plaintext = decrypt_json_gcm(VECTOR_ENVELOPE_B64, VECTOR_KEY_B64).unwrap();
+    assert_eq!(String::from_utf8(plaintext).unwrap(), VECTOR_PLAINTEXT);
+}
+
+#[test]
+fn decrypt_json_gcm_rejects_wrong_key() {
+    let wrong_key = "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=";
+    assert!(decrypt_json_gcm(VECTOR_ENVELOPE_B64, wrong_key).is_err());
+}
+
+#[test]
+fn decrypt_json_gcm_rejects_short_input() {
+    // 8 bytes base64 -> shorter than nonce(12)+tag(16)
+    assert!(decrypt_json_gcm("AAAAAAAAAAA=", VECTOR_KEY_B64).is_err());
+}

src/utils/file.rs

@@ -175,3 +175,32 @@ pub async fn decrypt_file_stream_gcm(
     writer.flush().await?;
     Ok(())
 }
+
+/// Decrypt a base64 `nonce(12) ‖ ciphertext ‖ tag(16)` AES-256-GCM envelope
+/// using the raw master key (STANDARD base64). Returns the plaintext bytes.
+pub fn decrypt_json_gcm(ciphertext_b64: &str, master_key_b64: &str) -> Result<Vec<u8>> {
+    let master_key_bytes = general_purpose::STANDARD
+        .decode(master_key_b64)
+        .map_err(|_| anyhow::anyhow!("Invalid base64 master key"))?;
+
+    let data = general_purpose::STANDARD
+        .decode(ciphertext_b64)
+        .map_err(|_| anyhow::anyhow!("Invalid base64 ciphertext"))?;
+
+    if data.len() < 12 + 16 {
+        return Err(anyhow::anyhow!("Ciphertext too short"));
+    }
+
+    let key = Key::<Aes256Gcm>::try_from(master_key_bytes.as_slice())
+        .map_err(|_| anyhow::anyhow!("Invalid AES-256 key length"))?;
+    let cipher = Aes256Gcm::new(&key);
+
+    let nonce = Nonce::try_from(&data[..12])
+        .map_err(|_| anyhow::anyhow!("Invalid nonce length"))?;
+
+    let plaintext = cipher
+        .decrypt(&nonce, &data[12..])
+        .map_err(|e| anyhow::anyhow!("AES-GCM decryption failed: {:?}", e))?;
+
+    Ok(plaintext)
+}