From 518c1026ff26f6fb2627a0ef639207b088512911 Mon Sep 17 00:00:00 2001
From: Alexandr Kitaev <makavity231@gmail.com>
Date: Fri, 10 May 2024 20:53:11 +0300
Subject: [PATCH] fix no_std

---
 bign256/src/ecdsa/verifying.rs | 3 +++
 bign256/src/lib.rs             | 5 ++---
 bign256/src/public_key.rs      | 7 ++++---
 bign256/src/secret_key.rs      | 2 +-
 4 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/bign256/src/ecdsa/verifying.rs b/bign256/src/ecdsa/verifying.rs
index 63442f3df..51cab3356 100644
--- a/bign256/src/ecdsa/verifying.rs
+++ b/bign256/src/ecdsa/verifying.rs
@@ -14,6 +14,9 @@
 //! 9. Return YES.
 //! ```
 
+#[cfg(feature = "alloc")]
+use alloc::boxed::Box;
+
 use super::{Signature, BELT_OID};
 use crate::{
     AffinePoint, BignP256, EncodedPoint, FieldBytes, Hash, ProjectivePoint, PublicKey, Scalar,
diff --git a/bign256/src/lib.rs b/bign256/src/lib.rs
index a74cfd6fe..99ba984e8 100644
--- a/bign256/src/lib.rs
+++ b/bign256/src/lib.rs
@@ -1,5 +1,4 @@
-// #![no_std]
-// #![no_std]
+#![no_std]
 #![cfg_attr(docsrs, feature(doc_auto_cfg))]
 #![doc = include_str!("../README.md")]
 #![doc(
@@ -58,7 +57,7 @@ const ALGORITHM_OID: pkcs8::ObjectIdentifier =
     pkcs8::ObjectIdentifier::new_unwrap("1.2.112.0.2.0.34.101.45.2.1");
 
 #[cfg(feature = "ecdsa")]
-type Hash = belt_hash::digest::Output<belt_hash::BeltHash>;
+type Hash = digest::Output<belt_hash::BeltHash>;
 
 /// Order of BIGN P-256's elliptic curve group (i.e. scalar modulus) in hexadecimal.
 const ORDER_HEX: &str = "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFD95C8ED60DFB4DFC7E5ABF99263D6607";
diff --git a/bign256/src/public_key.rs b/bign256/src/public_key.rs
index 68530c73f..c2209293d 100644
--- a/bign256/src/public_key.rs
+++ b/bign256/src/public_key.rs
@@ -1,7 +1,8 @@
 //! Public key types and traits
 
-use core::fmt::Display;
-use core::str::FromStr;
+#[cfg(feature = "alloc")]
+use alloc::{boxed::Box, fmt};
+use core::{fmt::Display, str::FromStr};
 
 use elliptic_curve::{
     array::Array,
@@ -198,7 +199,7 @@ impl FromStr for PublicKey {
 
 #[cfg(feature = "pem")]
 impl Display for PublicKey {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(
             f,
             "{}",
diff --git a/bign256/src/secret_key.rs b/bign256/src/secret_key.rs
index f4e70a1a3..00d111b9b 100644
--- a/bign256/src/secret_key.rs
+++ b/bign256/src/secret_key.rs
@@ -142,7 +142,7 @@ impl TryFrom<pkcs8::PrivateKeyInfo<'_>> for SecretKey {
 #[cfg(feature = "pem")]
 impl FromStr for SecretKey {
     type Err = Error;
-    fn from_str(s: &str) -> std::result::Result<Self, Error> {
+    fn from_str(s: &str) -> core::result::Result<Self, Error> {
         Self::from_pkcs8_pem(s).map_err(|_| Error)
     }
 }