Support loading keys from Polkadot-JS accounts. (#1661)

* Import key pair from JSON.

* Get secret.

* Fix JSON decryption.

* Fix error handling.

* Fix warnings.

* Add polkadot-js links.

* Fix packages.

* Fix json feature.

* Add copyright message.

* Update Cargo.toml

Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>

* Improve error handling.

* Expect that provided parameters are valid.

* Add Scrypt parameters comment from JS implementation.

* Fix expect() message

* Make from_ed25519_bytes() pub(crate)

* Rename json feature to polkadot-js-compat

* Add comment about polkadot-js-compat dependencies.

Co-authored-by: James Wilson <james@jsdw.me>

* Add decrypt_json() public method.

* json.rs -> polkadot_js_compat.rs

* Simplify JSON structs.

* Only declare from_ed25519_bytes() with polkadot-js-compat

* Move decrypt_json() to top of file.

* Don't enable new crates on std feature

* Avoid enabling a couple of existing optional crates on std feature

---------

Co-authored-by: Jonathan Brown <jbrown@acuity.network>
Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>
Co-authored-by: James Wilson <james@jsdw.me>

Cargo.toml

@@ -162,6 +162,9 @@ keccak-hash = { version = "0.10.0", default-features = false }
 secrecy = "0.8.0"
 sha2 = { version = "0.10.8", default-features = false }
 zeroize = { version = "1", default-features = false }
+base64 = { version = "0.22.1", default-features = false }
+scrypt = { version = "0.11.0", default-features = false }
+crypto_secretbox = { version = "0.1.1", default-features = false }
 
 [profile.dev.package.smoldot-light]
 opt-level = 2

signer/Cargo.toml

@@ -23,8 +23,13 @@ std = [
     "sha2/std",
     "hmac/std",
     "bip39/std",
-    "schnorrkel/std",
-    "secp256k1/std",
+    "schnorrkel?/std",
+    "secp256k1?/std",
+    "serde?/std",
+    "serde_json?/std",
+    "base64?/std",
+    "scrypt?/std",
+    "crypto_secretbox?/std",
 ]
 
 # Pick the signer implementation(s) you need by enabling the
@@ -35,6 +40,9 @@ sr25519 = ["schnorrkel"]
 ecdsa = ["secp256k1"]
 unstable-eth = ["keccak-hash", "ecdsa", "secp256k1", "bip32"]
 
+# Enable support for loading key pairs from polkadot-js json.
+polkadot-js-compat = ["std", "subxt", "sr25519", "base64", "scrypt", "crypto_secretbox", "serde", "serde_json"]
+
 # Make the keypair algorithms here compatible with Subxt's Signer trait,
 # so that they can be used to sign transactions for compatible chains.
 subxt = ["dep:subxt-core"]
@@ -66,6 +74,13 @@ secp256k1 = { workspace = true, optional = true, features = [
 ] }
 keccak-hash = { workspace = true, optional = true }
 
+# These are used if the polkadot-js-compat feature is enabled
+serde = { workspace = true, optional = true }
+serde_json = { workspace = true, optional = true }
+base64 = { workspace = true, optional = true, features = ["alloc"] }
+scrypt = { workspace = true, default-features = false, optional = true }
+crypto_secretbox = { workspace = true, optional = true, features = ["alloc", "salsa20"] }
+
 # We only pull this in to enable the JS flag for schnorrkel to use.
 getrandom = { workspace = true, optional = true }
 
@@ -86,4 +101,4 @@ rustdoc-args = ["--cfg", "docsrs"]
 defalt-features = true
 
 [lints]
-workspace = true
+workspace = true

signer/src/lib.rs

@@ -37,6 +37,11 @@ pub mod ecdsa;
 #[cfg_attr(docsrs, doc(cfg(feature = "unstable-eth")))]
 pub mod eth;
 
+/// A polkadot-js account json loader.
+#[cfg(feature = "polkadot-js-compat")]
+#[cfg_attr(docsrs, doc(cfg(feature = "polkadot-js-compat")))]
+pub mod polkadot_js_compat;
+
 // Re-export useful bits and pieces for generating a Pair from a phrase,
 // namely the Mnemonic struct.
 pub use bip39;