zcash_keys: Enable no_std usage.

Cargo.toml

@@ -49,23 +49,22 @@ pczt = { version = "0.0", path = "pczt" }
 
 # Shielded protocols
 bellman = { version = "0.14", default-features = false, features = ["groth16"] }
-ff = "0.13"
+ff = { version = "0.13", default-features = false }
 group = "0.13"
-incrementalmerkletree = "0.7"
+incrementalmerkletree = { version = "0.7.1", default-features = false }
 shardtree = "0.5"
 zcash_spec = "0.1"
 
 # Payment protocols
 # - Sapling
-bitvec = "1"
-blake2s_simd = "1"
+bitvec = { version = "1", default-features = false, features = ["alloc"] }
+blake2s_simd = { version = "1", default-features = false }
 bls12_381 = "0.8"
 jubjub = "0.10"
 redjubjub = "0.7"
 sapling = { package = "sapling-crypto", version = "0.3", default-features = false }
 
 # - Orchard
-nonempty = "0.7"
 orchard = { version = "0.10", default-features = false }
 pasta_curves = "0.5"
 
@@ -75,12 +74,13 @@ ripemd = { version = "0.1", default-features = false }
 secp256k1 = { version = "0.27", default-features = false, features = ["alloc"] }
 transparent = { package = "zcash_transparent", version = "0.0", path = "zcash_transparent", default-features = false }
 
-# Boilerplate
+# Boilerplate & missing stdlib
 getset = "0.1"
+nonempty = { version = "0.10", default-features = false }
 
 # CSPRNG
-rand = "0.8"
-rand_core = "0.6"
+rand = { version = "0.8", default-features = false }
+rand_core = { version = "0.6", default-features = false }
 
 # Currency conversions
 rust_decimal = { version = "1.35", default-features = false, features = ["serde"] }
@@ -100,7 +100,7 @@ byteorder = "1"
 hex = { version = "0.4", default-features = false, features = ["alloc"] }
 percent-encoding = "2.1.0"
 postcard = { version = "1", features = ["alloc"] }
-serde = { version = "1", features = ["derive"] }
+serde = { version = "1", default-features = false, features = ["derive"] }
 serde_json = "1"
 
 # HTTP
@@ -111,8 +111,8 @@ tokio-rustls = "0.24"
 webpki-roots = "0.25"
 
 # Logging and metrics
-memuse = "0.2.1"
-tracing = "0.1"
+memuse = { version = "0.2.2", default-features = false }
+tracing = { version = "0.1", default-features = false }
 
 # No-std support
 core2 = { version = "0.3", default-features = false, features = ["alloc"] }
@@ -166,7 +166,7 @@ trait-variant = "0.1"
 
 # ZIP 32
 aes = "0.8"
-fpe = "0.6"
+fpe = { version = "0.6", default-features = false, features = ["alloc"] }
 zip32 = { version = "0.1.1", default-features = false }
 
 [profile.release]
@@ -195,5 +195,6 @@ debug = true
 unexpected_cfgs = { level = "warn", check-cfg = ['cfg(zcash_unstable, values("zfuture"))'] }
 
 [patch.crates-io]
-orchard = { git = "https://github.com/zcash/orchard.git", rev = "7a44e3279b5747819022c4d8f4474fa79b2d9746" }
+nonempty = { git = "https://github.com/nuttycom/nonempty.git", rev = "090815ca02ff969d23c6331f9f5b1e4c7720160a" }
+orchard = { git = "https://github.com/zcash/orchard.git", rev = "1d60917a6092ff4628e8cf89538f7cd5b339110d" }
 sapling-crypto = { git = "https://github.com/zcash/sapling-crypto.git", rev = "e47d57f5c9c46f05740328f8ef9601f6d697cf34" }

zcash_keys/CHANGELOG.md

@@ -6,6 +6,10 @@ and this library adheres to Rust's notion of
 
 ## [Unreleased]
 
+### Added
+- `no-std` compatibility (`alloc` is required). A default-enabled `std` feature
+  flag has been added gating the `std::error::Error` usage.
+
 ### Changed
 - Migrated to `bech32 0.11`.
 - The `UnifiedAddressRequest` argument to the following methods is now optional:

zcash_keys/Cargo.toml

@@ -33,6 +33,7 @@ rand_core.workspace = true
 # - Encodings
 bech32.workspace = true
 bs58.workspace = true
+core2.workspace = true
 
 # - Transparent protocols
 bip32 = { workspace = true, optional = true }
@@ -58,7 +59,7 @@ proptest = { workspace = true, optional = true }
 # Dependencies used internally:
 # (Breaking upgrades to these are usually backwards-compatible, but check MSRVs.)
 # - Documentation
-document-features.workspace = true
+document-features = { workspace = true, optional = true }
 
 # - Encodings
 byteorder = { workspace = true, optional = true }
@@ -75,6 +76,9 @@ zcash_address = { workspace = true, features = ["test-dependencies"] }
 zcash_primitives = { workspace = true, features = ["test-dependencies"] }
 
 [features]
+default = ["std"]
+std = ["dep:document-features"]
+
 ## Enables use of transparent key parts and addresses
 transparent-inputs = ["dep:bip32", "zcash_primitives/transparent-inputs"]
 

zcash_keys/src/address.rs

@@ -1,5 +1,8 @@
 //! Structs for handling supported address types.
 
+use alloc::vec::Vec;
+use alloc::string::{String, ToString};
+
 use transparent::address::TransparentAddress;
 use zcash_address::{
     unified::{self, Container, Encoding, Typecode},
@@ -215,7 +218,7 @@ impl UnifiedAddress {
 
     /// Returns the set of receiver typecodes.
     pub fn receiver_types(&self) -> Vec<Typecode> {
-        let result = std::iter::empty();
+        let result = core::iter::empty();
         #[cfg(feature = "orchard")]
         let result = result.chain(self.orchard.map(|_| Typecode::Orchard));
         #[cfg(feature = "sapling")]

zcash_keys/src/encoding.rs

@@ -5,20 +5,23 @@
 
 use crate::address::UnifiedAddress;
 use bs58::{self, decode::Error as Bs58Error};
-use std::fmt;
+use core::fmt;
+use alloc::borrow::ToOwned;
+use alloc::string::{String, ToString};
 
 use transparent::address::TransparentAddress;
 use zcash_address::unified::{self, Encoding};
 use zcash_protocol::consensus::{self, NetworkConstants};
 
 #[cfg(feature = "sapling")]
 use {
+    alloc::vec::Vec,
     bech32::{
         primitives::decode::{CheckedHrpstring, CheckedHrpstringError},
         Bech32, Hrp,
     },
     sapling::zip32::{ExtendedFullViewingKey, ExtendedSpendingKey},
-    std::io::{self, Write},
+    core2::io::{self, Write},
     zcash_protocol::consensus::NetworkType,
 };
 
@@ -73,7 +76,7 @@ impl fmt::Display for Bech32DecodeError {
     }
 }
 
-#[cfg(feature = "sapling")]
+#[cfg(all(feature = "sapling", feature = "std"))]
 impl std::error::Error for Bech32DecodeError {}
 
 #[cfg(feature = "sapling")]
@@ -95,7 +98,7 @@ where
 /// A trait for encoding and decoding Zcash addresses.
 pub trait AddressCodec<P>
 where
-    Self: std::marker::Sized,
+    Self: core::marker::Sized,
 {
     type Error;
 
@@ -132,6 +135,7 @@ impl fmt::Display for TransparentCodecError {
     }
 }
 
+#[cfg(feature = "std")]
 impl std::error::Error for TransparentCodecError {}
 
 impl<P: consensus::Parameters> AddressCodec<P> for TransparentAddress {