feat(composer)! avoid holding private key in env var (#1074)

## Summary
This PR changes the configuration env vars for composer to not hold the
contents of the private key for signing sequencer transactions.

## Background
It's undesirable to have the contents of a private key in an env var.

## Changes
Changed the existing env var to hold a path to a hex-encoded private key
file.

## Testing
Modified existing tests, and ran smoke test using local build of
composer.

## Breaking Changelist
- Removed `ASTRIA_COMPOSER_PRIVATE_KEY`
- Added `ASTRIA_COMPOSER_PRIVATE_KEY_FILE`

## Related Issues
Closes #993.

Cargo.toml

@@ -55,7 +55,9 @@ bytes = "1"
 celestia-tendermint = "0.32.1"
 celestia-types = "0.1.1"
 clap = "4.5.4"
-ed25519-consensus = "2.1.0"
+ed25519-consensus = { version = "2.1.0", default-features = false, features = [
+  "std",
+] }
 ethers = "2.0.11"
 futures = "0.3"
 hex = "0.4"

charts/evm-rollup/Chart.yaml

@@ -15,7 +15,7 @@ type: application
 # This is the chart version. This version number should be incremented each time you make changes
 # to the chart and its templates, including the app version.
 # Versions are expected to follow Semantic Versioning (https://semver.org/)
-version: 0.16.1
+version: 0.16.2
 
 # This is the version number of the application being deployed. This version number should be
 # incremented each time you make changes to the application. Versions are not expected to

charts/evm-rollup/templates/configmap.yaml

@@ -63,11 +63,12 @@ data:
   OTEL_EXPORTER_OTLP_HEADERS: "{{ .Values.config.rollup.otel.otlpHeaders }}"
   OTEL_EXPORTER_OTLP_TRACE_HEADERS: "{{ .Values.config.rollup.otel.traceHeaders }}"
   OTEL_SERVICE_NAME: "{{ tpl .Values.config.rollup.otel.serviceNamePrefix . }}-composer"
+  {{- if not .Values.global.dev }}
   {{- if not .Values.secretProvider.enabled }}
-  ASTRIA_COMPOSER_PRIVATE_KEY: "{{ .Values.config.sequencer.privateKey }}"
+  ASTRIA_COMPOSER_PRIVATE_KEY: "{{ .Values.config.sequencer.privateKey.devContent }}"
   {{- end }}
-  {{- if not .Values.global.dev }}
   {{- else }}
+  ASTRIA_COMPOSER_PRIVATE_KEY_FILE: "/var/secrets/{{ .Values.config.sequencer.privateKey.secret.filename }}"
   {{- end }}
 ---
 apiVersion: v1
@@ -259,3 +260,15 @@ metadata:
 data:
   VISUALIZER__SERVER__GRPC__ENABLED: "false"
   VISUALIZER__SERVER__HTTP__ADDR: "0.0.0.0:8151"
+---
+{{- if not .Values.secretProvider.enabled }}
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  namespace: {{ include "rollup.namespace" .  }}
+  name: sequencer-private-key
+data:
+  {{ .Values.config.sequencer.privateKey.secret.filename }}: |
+    {{ .Values.config.sequencer.privateKey.devContent }}
+---
+{{- end }}

charts/evm-rollup/templates/statefulsets.yaml

@@ -56,8 +56,8 @@ spec:
             {{- else }}
             - --state.scheme=path
             {{- end }}
-            {{ if .Values.config.rollup.metrics.enabled }} 
-            - --metrics 
+            {{ if .Values.config.rollup.metrics.enabled }}
+            - --metrics
             - --metrics.addr=0.0.0.0
             - --metrics.port={{ .Values.ports.metrics }}
             {{- end }}
@@ -79,12 +79,12 @@ spec:
               name: ws-rpc
             - containerPort: {{ .Values.ports.executionGRPC }}
               name: execution-grpc
-            {{- if .Values.config.rollup.metrics.enabled }} 
+            {{- if .Values.config.rollup.metrics.enabled }}
             - containerPort: {{ .Values.ports.metrics }}
               name: geth-metr
             {{- end }}
           resources:
-            {{- toYaml .Values.resources.geth | trim | nindent 12 }}     
+            {{- toYaml .Values.resources.geth | trim | nindent 12 }}
         - name: composer
           image: {{ include "composer.image" . }}
           command: [ "/usr/local/bin/astria-composer" ]
@@ -93,20 +93,10 @@ spec:
           envFrom:
             - configMapRef:
                 name: {{ .Values.config.rollup.name }}-composer-env
-          {{- if .Values.secretProvider.enabled }}
-          env:
-            - name: ASTRIA_COMPOSER_PRIVATE_KEY
-              valueFrom:
-                secretKeyRef:
-                  name: sequencer-private-key
-                  key: {{ .Values.secretProvider.secrets.sequencerPrivateKey.key }}
-          {{- end }}
           volumeMounts:
-          {{- if .Values.secretProvider.enabled }}
           - mountPath: "/var/secrets"
             name: sequencer-private-key
-          {{- end }}
-          {{- if .Values.config.rollup.metrics.enabled }} 
+          {{- if .Values.config.rollup.metrics.enabled }}
           ports:
             - containerPort: {{ .Values.ports.composerMetrics }}
               name: composer-metr
@@ -123,7 +113,7 @@ spec:
                 name: {{ .Values.config.rollup.name }}-conductor-env
           resources:
             {{- toYaml .Values.resources.conductor | trim | nindent 12 }}
-          {{- if .Values.config.rollup.metrics.enabled }} 
+          {{- if .Values.config.rollup.metrics.enabled }}
           ports:
             - containerPort: {{ .Values.ports.conductorMetrics }}
               name: conductor-metr
@@ -140,14 +130,17 @@ spec:
           {{- else }}
           emptyDir: {}
           {{- end }}
-        {{- if .Values.secretProvider.enabled }}
         - name: sequencer-private-key
+          {{- if .Values.secretProvider.enabled }}
           csi:
             driver: secrets-store.csi.k8s.io
             readOnly: true
             volumeAttributes:
               secretProviderClass: sequencer-private-key
-        {{- end }}
+          {{- else }}
+          configMap:
+            name: sequencer-private-key
+          {{- end }}
 ---
 {{- if .Values.config.blockscout.enabled }}
 apiVersion: apps/v1

charts/evm-rollup/values.yaml

@@ -173,7 +173,11 @@ config:
     # Private key which is used for wrapping txs for sequencer submission
     # Note: When secretProvider.enabled is true the secret provided by
     #       `sequencerPrivateKey` is used instead of this value.
-    privateKey: "2bd806c97f0e00af1a1fc3328fa763a9269723c8db8fac4f93af71db186d6e90"
+    privateKey:
+      devContent: "2bd806c97f0e00af1a1fc3328fa763a9269723c8db8fac4f93af71db186d6e90"
+      secret:
+        filename: "key.hex"
+        resourceName: "projects/$PROJECT_ID/secrets/sequencerPrivateKey/versions/latest"
 
   celestia:
     # if config.rollup.executionLevel is NOT 'SoftOnly' AND celestia-node is not enabled

crates/astria-cli/src/commands/sequencer.rs

@@ -1,4 +1,5 @@
 use astria_core::{
+    crypto::SigningKey,
     primitive::v1::asset,
     protocol::transaction::v1alpha1::{
         action::{
@@ -31,10 +32,7 @@ use color_eyre::{
         Context,
     },
 };
-use ed25519_consensus::{
-    SigningKey,
-    VerificationKeyBytes,
-};
+use ed25519_consensus::VerificationKeyBytes;
 use rand::rngs::OsRng;
 
 use crate::cli::sequencer::{

crates/astria-composer/Cargo.toml

@@ -21,7 +21,6 @@ telemetry = { package = "astria-telemetry", path = "../astria-telemetry", featur
 ] }
 
 pin-project-lite = "0.2.13"
-secrecy = { version = "0.8", features = ["serde"] }
 tonic-health = "0.10.2"
 
 async-trait = { workspace = true }
@@ -70,6 +69,7 @@ test_utils = { package = "astria-test-utils", path = "../astria-test-utils", fea
   "geth",
 ] }
 insta = { workspace = true, features = ["json"] }
+tempfile = { workspace = true }
 tokio-test = { workspace = true }
 astria-core = { path = "../astria-core", features = ["client"] }
 tendermint-rpc = { workspace = true }

crates/astria-composer/local.env.example

@@ -35,9 +35,9 @@ ASTRIA_COMPOSER_SEQUENCER_CHAIN_ID="astria-dev-1"
 # names are sha256 hashed and used as the `rollup_id` in `SequenceAction`s
 ASTRIA_COMPOSER_ROLLUPS="astriachain::ws://127.0.0.1:8545"
 
-# Private key for the sequencer account used for signing transactions
-# Must be a hex-encoded 32-byte array (64-character hex string)
-ASTRIA_COMPOSER_PRIVATE_KEY="2bd806c97f0e00af1a1fc3328fa763a9269723c8db8fac4f93af71db186d6e90"
+# The path to the file storing the private key for the sequencer account used for signing
+# transactions. The file should contain a hex-encoded Ed25519 secret key.
+ASTRIA_COMPOSER_PRIVATE_KEY_FILE=/path/to/priv_sequencer_key.json
 
 # Block time in milliseconds, used to force submitting of finished bundles.
 # Should match the sequencer node configuration for 'timeout_commit', as

crates/astria-composer/src/composer.rs

@@ -120,7 +120,7 @@ impl Composer {
         let (executor, executor_handle) = executor::Builder {
             sequencer_url: cfg.sequencer_url.clone(),
             sequencer_chain_id: cfg.sequencer_chain_id.clone(),
-            private_key: cfg.private_key.clone(),
+            private_key_file: cfg.private_key_file.clone(),
             block_time_ms: cfg.block_time_ms,
             max_bytes_per_bundle: cfg.max_bytes_per_bundle,
             bundle_queue_capacity: cfg.bundle_queue_capacity,

crates/astria-composer/src/config.rs

@@ -1,14 +1,8 @@
 use std::net::SocketAddr;
 
-use secrecy::{
-    zeroize::ZeroizeOnDrop,
-    ExposeSecret as _,
-    SecretString,
-};
 use serde::{
     Deserialize,
     Serialize,
-    Serializer,
 };
 
 // this is a config, may have many boolean values
@@ -31,9 +25,8 @@ pub struct Config {
     /// A list of <rollup_name>::<url> pairs
     pub rollups: String,
 
-    /// Private key for the sequencer account used for signing transactions
-    #[serde(serialize_with = "serialize_private_key")]
-    pub private_key: SecretString,
+    /// Path to private key for the sequencer account used for signing transactions
+    pub private_key_file: String,
 
     /// Sequencer block time in milliseconds
     #[serde(alias = "max_submit_interval_ms")]
@@ -69,22 +62,6 @@ impl config::Config for Config {
     const PREFIX: &'static str = "ASTRIA_COMPOSER_";
 }
 
-impl ZeroizeOnDrop for Config {}
-
-fn serialize_private_key<S>(key: &SecretString, s: S) -> Result<S::Ok, S::Error>
-where
-    S: Serializer,
-{
-    use serde::ser::Error as _;
-    let mut raw_key = key.expose_secret().clone().into_bytes();
-    if let Some(sub_slice) = raw_key.get_mut(4..) {
-        sub_slice.fill(b'#');
-    }
-    let sanitized_key = std::str::from_utf8(&raw_key)
-        .map_err(|_| S::Error::custom("private key hex contained non-ascii characters"))?;
-    s.serialize_str(sanitized_key)
-}
-
 #[cfg(test)]
 mod tests {
     use super::Config;

crates/astria-composer/src/executor/builder.rs

@@ -1,21 +1,18 @@
-use std::time::Duration;
+use std::{
+    fs,
+    path::Path,
+    time::Duration,
+};
 
 use astria_core::{
+    crypto::SigningKey,
     primitive::v1::Address,
     protocol::transaction::v1alpha1::action::SequenceAction,
 };
-use astria_eyre::{
+use astria_eyre::eyre::{
+    self,
     eyre,
-    eyre::{
-        eyre,
-        WrapErr as _,
-    },
-};
-use ed25519_consensus::SigningKey;
-use secrecy::{
-    ExposeSecret,
-    SecretString,
-    Zeroize,
+    WrapErr as _,
 };
 use tokio::sync::watch;
 use tokio_util::sync::CancellationToken;
@@ -28,7 +25,7 @@ use crate::{
 pub(crate) struct Builder {
     pub(crate) sequencer_url: String,
     pub(crate) sequencer_chain_id: String,
-    pub(crate) private_key: SecretString,
+    pub(crate) private_key_file: String,
     pub(crate) block_time_ms: u64,
     pub(crate) max_bytes_per_bundle: usize,
     pub(crate) bundle_queue_capacity: usize,
@@ -40,7 +37,7 @@ impl Builder {
         let Self {
             sequencer_url,
             sequencer_chain_id,
-            private_key,
+            private_key_file,
             block_time_ms,
             max_bytes_per_bundle,
             bundle_queue_capacity,
@@ -49,12 +46,10 @@ impl Builder {
         let sequencer_client = sequencer_client::HttpClient::new(sequencer_url.as_str())
             .wrap_err("failed constructing sequencer client")?;
         let (status, _) = watch::channel(Status::new());
-        let mut private_key_bytes: [u8; 32] = hex::decode(private_key.expose_secret())
-            .wrap_err("failed to decode private key bytes from hex string")?
-            .try_into()
-            .map_err(|_| eyre!("invalid private key length; must be 32 bytes"))?;
-        let sequencer_key = SigningKey::from(private_key_bytes);
-        private_key_bytes.zeroize();
+
+        let sequencer_key = read_signing_key_from_file(&private_key_file).wrap_err_with(|| {
+            format!("failed reading signing key from file at path `{private_key_file}`")
+        })?;
 
         let sequencer_address = Address::from_verification_key(sequencer_key.verification_key());
 
@@ -78,3 +73,11 @@ impl Builder {
         ))
     }
 }
+
+fn read_signing_key_from_file<P: AsRef<Path>>(path: P) -> eyre::Result<SigningKey> {
+    let private_key_hex = fs::read_to_string(path)?;
+    let private_key_bytes: [u8; 32] = hex::decode(private_key_hex.trim())?
+        .try_into()
+        .map_err(|_| eyre!("invalid private key length; must be 32 bytes"))?;
+    Ok(SigningKey::from(private_key_bytes))
+}