From 0073c153d257986e3260cac181bea80b50af789b Mon Sep 17 00:00:00 2001
From: Julien Cretin <cretin@google.com>
Date: Thu, 4 Jun 2020 14:32:04 +0200
Subject: [PATCH] Propagate the NBYTES constant from Int256 to SecKey

---
 libraries/crypto/src/ecdsa.rs | 6 ++++--
 src/ctap/storage.rs           | 2 +-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/libraries/crypto/src/ecdsa.rs b/libraries/crypto/src/ecdsa.rs
index 966552d..8b4329a 100644
--- a/libraries/crypto/src/ecdsa.rs
+++ b/libraries/crypto/src/ecdsa.rs
@@ -22,6 +22,8 @@ use super::{Hash256, HashBlockSize64Bytes};
 use alloc::vec::Vec;
 use core::marker::PhantomData;
 
+pub use super::ec::int256::NBYTES;
+
 #[derive(Clone, PartialEq)]
 #[cfg_attr(feature = "derive_debug", derive(Debug))]
 pub struct SecKey {
@@ -140,7 +142,7 @@ impl SecKey {
         }
     }
 
-    pub fn from_bytes(bytes: &[u8; 32]) -> Option<SecKey> {
+    pub fn from_bytes(bytes: &[u8; NBYTES]) -> Option<SecKey> {
         let k = NonZeroExponentP256::from_int_checked(Int256::from_bin(bytes));
         // The branching here is fine because all this reveals is whether the key was invalid.
         if bool::from(k.is_none()) {
@@ -150,7 +152,7 @@ impl SecKey {
         Some(SecKey { k })
     }
 
-    pub fn to_bytes(&self, bytes: &mut [u8; 32]) {
+    pub fn to_bytes(&self, bytes: &mut [u8; NBYTES]) {
         self.k.to_int().to_bin(bytes);
     }
 }
diff --git a/src/ctap/storage.rs b/src/ctap/storage.rs
index 452bff6..c138660 100644
--- a/src/ctap/storage.rs
+++ b/src/ctap/storage.rs
@@ -62,7 +62,7 @@ const AAGUID: usize = 7;
 const NUM_TAGS: usize = 8;
 
 const MAX_PIN_RETRIES: u8 = 6;
-const ATTESTATION_PRIVATE_KEY_LENGTH: usize = 32;
+const ATTESTATION_PRIVATE_KEY_LENGTH: usize = crypto::ecdsa::NBYTES;
 const AAGUID_LENGTH: usize = 16;
 
 #[derive(PartialEq, Eq, PartialOrd, Ord)]