diff --git a/Cargo.lock b/Cargo.lock
index 3915fc3..5cae4bd 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -195,6 +195,12 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "lazy_static"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
+
 [[package]]
 name = "libc"
 version = "0.2.158"
@@ -223,15 +229,6 @@ version = "1.19.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3fdb12b2476b595f9358c5161aa467c2438859caa136dec86c26fdd2efe17b92"
 
-[[package]]
-name = "ppv-lite86"
-version = "0.2.20"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "77957b295656769bb8ad2b6a6b09d897d94f05c41b069aede1fcdaa675eaea04"
-dependencies = [
- "zerocopy",
-]
-
 [[package]]
 name = "proc-macro2"
 version = "1.0.86"
@@ -250,36 +247,6 @@ dependencies = [
  "proc-macro2",
 ]
 
-[[package]]
-name = "rand"
-version = "0.8.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
-dependencies = [
- "libc",
- "rand_chacha",
- "rand_core",
-]
-
-[[package]]
-name = "rand_chacha"
-version = "0.3.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
-dependencies = [
- "ppv-lite86",
- "rand_core",
-]
-
-[[package]]
-name = "rand_core"
-version = "0.6.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
-dependencies = [
- "getrandom",
-]
-
 [[package]]
 name = "same-file"
 version = "1.0.6"
@@ -320,12 +287,12 @@ dependencies = [
 
 [[package]]
 name = "tc_tea"
-version = "0.1.4"
+version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cab26285e70ee5cbec8582c76b8124dfe65b564b43dad14b9caca6fd127d66d2"
+checksum = "0e0fb162058ad530c29c7e283ae3ca72d5188d8e7275c079f7622b3e053a547b"
 dependencies = [
- "rand",
- "rand_chacha",
+ "byteorder",
+ "thiserror",
 ]
 
 [[package]]
@@ -391,6 +358,7 @@ dependencies = [
  "anyhow",
  "byteorder",
  "itertools",
+ "lazy_static",
  "tc_tea",
  "thiserror",
  "umc_utils",
@@ -624,24 +592,3 @@ name = "windows_x86_64_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
-
-[[package]]
-name = "zerocopy"
-version = "0.7.35"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1b9b4fd18abc82b8136838da5d50bae7bdea537c574d8dc1a34ed098d6c166f0"
-dependencies = [
- "byteorder",
- "zerocopy-derive",
-]
-
-[[package]]
-name = "zerocopy-derive"
-version = "0.7.35"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fa4f8080344d4671fb4e831a13ad1e68092748387dfc4f55e356242fae12ce3e"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn",
-]
diff --git a/um_crypto/qmc/Cargo.toml b/um_crypto/qmc/Cargo.toml
index 8d0bc02..5b053d3 100644
--- a/um_crypto/qmc/Cargo.toml
+++ b/um_crypto/qmc/Cargo.toml
@@ -7,6 +7,7 @@ edition = "2021"
 anyhow = "1.0.86"
 byteorder = "1.5.0"
 itertools = "0.13.0"
-tc_tea = { version = "0.1.4", default-features = false, features = [] }
+lazy_static = "1.5.0"
+tc_tea = { version = "0.2.0", default-features = false }
 thiserror = "1.0.63"
 umc_utils = { path = "../utils" }
diff --git a/um_crypto/qmc/src/ekey.rs b/um_crypto/qmc/src/ekey.rs
index 8d138fb..644acb8 100644
--- a/um_crypto/qmc/src/ekey.rs
+++ b/um_crypto/qmc/src/ekey.rs
@@ -1,6 +1,8 @@
 use anyhow::Result;
 use itertools::Itertools;
+use lazy_static::lazy_static;
 use std::ops::Mul;
+use tc_tea::TcTeaError;
 use thiserror::Error;
 use umc_utils::base64;
 
@@ -13,14 +15,18 @@ const EKEY_V2_KEY2: [u8; 16] = [
     0x2A, 0x2A, 0x23, 0x21, 0x28, 0x23, 0x24, 0x25, 0x26, 0x5E, 0x61, 0x31, 0x63, 0x5A, 0x2C, 0x54,
 ];
 
-#[derive(Debug, Clone, PartialEq, Error)]
+lazy_static! {
+    static ref EKEY_SIMPLE_KEY: [u8; 8] = make_simple_key::<8>();
+}
+
+#[derive(Debug, PartialEq, Error)]
 pub enum EKeyDecryptError {
     #[error("EKey is too short for decryption")]
     EKeyTooShort,
-    #[error("Error when decrypting ekey v1")]
-    FailDecryptV1,
-    #[error("Error when decrypting ekey v2")]
-    FailDecryptV2,
+    #[error("Error when decrypting ekey v1: {0}")]
+    FailDecryptV1(TcTeaError),
+    #[error("Error when decrypting ekey v2: {0}")]
+    FailDecryptV2(TcTeaError),
 }
 
 fn make_simple_key<const N: usize>() -> [u8; N] {
@@ -44,21 +50,21 @@ pub fn decrypt_v1(ekey: &[u8]) -> Result<Box<[u8]>> {
     let ekey = base64::decode(ekey)?;
     let (header, cipher) = ekey.split_at(8);
 
-    let simple_key = make_simple_key::<8>();
-    let tea_key = simple_key
+    // tea_key: interleave a byte from each stream
+    let tea_key = EKEY_SIMPLE_KEY
         .iter()
         .zip(header)
-        .flat_map(|(&simple_part, &header_part)| [simple_part, header_part])
-        .collect::<Vec<_>>();
+        .flat_map(|(&simple_key_part, &header_part)| [simple_key_part, header_part])
+        .collect_vec();
 
-    let plaintext = tc_tea::decrypt(cipher, tea_key).ok_or(EKeyDecryptError::FailDecryptV1)?;
+    let plaintext = tc_tea::decrypt(cipher, tea_key).map_err(EKeyDecryptError::FailDecryptV1)?;
     Ok([header, &plaintext].concat().into())
 }
 
 pub fn decrypt_v2(ekey: &[u8]) -> Result<Box<[u8]>> {
     let ekey = base64::decode(ekey)?;
-    let ekey = tc_tea::decrypt(ekey, EKEY_V2_KEY1).ok_or(EKeyDecryptError::FailDecryptV2)?;
-    let ekey = tc_tea::decrypt(ekey, EKEY_V2_KEY2).ok_or(EKeyDecryptError::FailDecryptV2)?;
+    let ekey = tc_tea::decrypt(ekey, EKEY_V2_KEY1).map_err(EKeyDecryptError::FailDecryptV2)?;
+    let ekey = tc_tea::decrypt(ekey, EKEY_V2_KEY2).map_err(EKeyDecryptError::FailDecryptV2)?;
     let ekey = ekey.iter().take_while(|&&b| b != 0).copied().collect_vec();
 
     decrypt_v1(&ekey)