add key management module to shim

Author: rphmeier

sugondat-shim/src/key.rs

@@ -0,0 +1,24 @@
+//! Key management: sr25519 account key used for signing blob submission
+//! transactions.
+
+use subxt_signer::sr25519::{Seed, Keypair};
+use std::path::Path;
+
+/// Load a key from the provided file path.
+///
+/// The file should contain a hex-encoded 32-byte seed used to generate
+/// the underlying schnorrkel private key.
+pub fn load_key_from_file<P: AsRef<Path>>(path: P) -> anyhow::Result<Keypair> {
+    let raw = hex::decode(std::fs::read(path)?)?;
+    let mut seed: Seed = Seed::default();
+    if raw.len() <= seed.len() {
+        anyhow::bail!("Keyfile length invalid")
+    }
+    seed.copy_from_slice(&raw[..]);
+    Ok(Keypair::from_seed(seed)?)
+}
+
+/// The default dev key.
+pub fn alice() -> Keypair {
+    subxt_signer::sr25519::dev::alice()
+}

sugondat-shim/src/main.rs

@@ -1,6 +1,7 @@
 mod adapters;
 mod cli;
 mod cmd;
+mod key;
 mod sugondat_rpc;
 
 #[tokio::main]