remove use of EC_PUBLIC_KEY_LEN

diff --git a/src/rust/bitbox02-rust/src/secp256k1.rs b/src/rust/bitbox02-rust/src/secp256k1.rs
index 99be685..fc992d8 100644
--- a/src/rust/bitbox02-rust/src/secp256k1.rs
+++ b/src/rust/bitbox02-rust/src/secp256k1.rs
@@ -12,7 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+pub use bitcoin::secp256k1::constants::PUBLIC_KEY_SIZE;
 use bitcoin::secp256k1::{All, Secp256k1};
+
 use core::cell::OnceCell;
 use core::ops::Deref;
 
@@ -46,9 +48,6 @@ impl Deref for GlobalContext {
     }
 }
 
-/// Length of a compressed secp256k1 pubkey.
-const EC_PUBLIC_KEY_LEN: usize = 33;
-
 /// Sign message with private key using the given private key.
 ///
 /// Details about `host_nonce`, the host nonce contribution.  Instead of using plain rfc6979 to
@@ -91,13 +90,13 @@ pub fn secp256k1_sign(
 ///   host_nonce is passed to `secp256k1_sign()`. See `secp256k1_ecdsa_anti_exfil_host_commit()`.
 ///
 /// # Returns
-/// * `Ok([u8; EC_PUBLIC_KEY_LEN])` - EC_PUBLIC_KEY_LEN bytes compressed signer nonce pubkey on success
+/// * `Ok([u8; PUBLIC_KEY_SIZE])` - PUBLIC_KEY_SIZE bytes compressed signer nonce pubkey on success
 /// * `Err(())` on failure
 pub fn secp256k1_nonce_commit(
     private_key: &[u8; 32],
     msg: &[u8; 32],
     host_commitment: &[u8; 32],
-) -> Result<[u8; EC_PUBLIC_KEY_LEN], ()> {
+) -> Result<[u8; PUBLIC_KEY_SIZE], ()> {
     bitbox02::secp256k1::_secp256k1_nonce_commit(SECP256K1, private_key, msg, host_commitment)
 }
 
diff --git a/src/rust/bitbox02-sys/build.rs b/src/rust/bitbox02-sys/build.rs
index 1b95113..f80e02a 100644
--- a/src/rust/bitbox02-sys/build.rs
+++ b/src/rust/bitbox02-sys/build.rs
@@ -21,7 +21,6 @@ const ALLOWLIST_VARS: &[&str] = &[
     "BASE58_CHECKSUM_LEN",
     "BIP32_SERIALIZED_LEN",
     "BIP39_WORDLIST_LEN",
-    "EC_PUBLIC_KEY_LEN",
     "font_font_a_11X10",
     "font_font_a_9X9",
     "font_monogram_5X9",
diff --git a/src/rust/bitbox02/src/secp256k1.rs b/src/rust/bitbox02/src/secp256k1.rs
index 5138961..8a151ba 100644
--- a/src/rust/bitbox02/src/secp256k1.rs
+++ b/src/rust/bitbox02/src/secp256k1.rs
@@ -14,14 +14,12 @@
 
 use bitcoin::secp256k1::ffi::CPtr;
 
+pub use bitcoin::secp256k1::constants::PUBLIC_KEY_SIZE;
 use bitcoin::secp256k1::{All, Secp256k1};
 
 use alloc::vec::Vec;
 use core::mem::MaybeUninit;
 
-/// Length of a compressed secp256k1 pubkey.
-pub const EC_PUBLIC_KEY_LEN: usize = 33;
-
 pub struct SignResult {
     pub signature: [u8; 64],
     pub recid: u8,
@@ -71,7 +69,7 @@ pub fn _secp256k1_nonce_commit(
     private_key: &[u8; 32],
     msg: &[u8; 32],
     host_commitment: &[u8; 32],
-) -> Result<[u8; EC_PUBLIC_KEY_LEN], ()> {
+) -> Result<[u8; PUBLIC_KEY_SIZE], ()> {
     let mut signer_commitment = MaybeUninit::<bitbox02_sys::secp256k1_ecdsa_s2c_opening>::uninit();
     if unsafe {
         bitbox02_sys::secp256k1_ecdsa_anti_exfil_signer_commit(
@@ -86,7 +84,7 @@ pub fn _secp256k1_nonce_commit(
         return Err(());
     }
 
-    let mut out = [0u8; EC_PUBLIC_KEY_LEN];
+    let mut out = [0u8; PUBLIC_KEY_SIZE];
     if unsafe {
         bitbox02_sys::secp256k1_ecdsa_s2c_opening_serialize(
             secp.ctx().as_ptr().cast(),