Building signal-cli from Source

Clone the repository and execute the Gradle wrapper to compile the distribution package. Ensure your environment runs Java Development Kit 21, as lower versions trigger plugin resolution failures related to GraalVM native tools. Network instability during dependency fetching often results in resource download exceptions; verifying proxy settings or retrying resolves these transient issues.

# Repository retrieval and build sequence
REPO_DIR="signal-cli-source"
git clone https://github.com/AsamK/signal-cli "$REPO_DIR"
cd "$REPO_DIR"

./gradlew clean build installDist

Validate the installation by invoking the help flag within the generated binary directory.

Adapting Configuration for Private Infrastructure

When routing traffic through a custom Signal backend, two configuration layers require adjustment: Java-level endpoint definitions and cryptographic trust stores.

Modify lib/src/main/java/org/asamk/signal/manager/config/LiveConfig.java to override default routing addresses. Update the following static fields to match your infrastructure:

• URL, CDN_URL, CDN2_URL, CDN3_URL, STORAGE_URL, SIGNAL_SVR2_URL
• Cryptographic parameters: UNIDENTIFIED_SENDER_TRUST_ROOT, zkGroupServerPublicParams, genericServerPublicParams, backupServerPublicParams

The client performs strict certificate validation against lib/src/main/resources/org/asamk/signal/manager/config/whisper.store. An unmodified trust store will trigger an SSLHandshakeException indicating a missing certification path. To integrate your server's TLS certificate into the required BKS format:

1. Acquire the Bouncy Castle provider JAR (bcprov-jdk18on-1.80.jar).
2. Export your server's full certificate chain (e.g., fullchain.pem).
3. Convert and import the certificate using the hardcoded passphrase whisper:

# Convert PEM to BKS keystore
CERT_ALIAS="signal-tls-cert"
CERT_FILE="./fullchain.pem"
KEYSTORE_PATH="./whisper.store"
PROVIDER_JAR="./bcprov-jdk18on-1.80.jar"

keytool \
  -importcert \
  -alias "$CERT_ALIAS" \
  -file "$CERT_FILE" \
  -keystore "$KEYSTORE_PATH" \
  -storetype BKS \
  -providerclass org.bouncycastle.jce.provider.BouncyCastleProvider \
  -providerpath "$PROVIDER_JAR" \
  -storepass whisper \
  -noprompt

Replace the original trust store and recompile the distribution.

Operational Workflow

The command-line interface supports user registration, verification, status queries, message transmission, and profile management. Consult the official documentation and man page for exhaustive command syntax.

Registration & Verification

# Initialize new identity
SIGNAL_CLI_BIN="./build/install/signal-cli/bin/signal-cli"
USER_PHONE="+8613311111111"

"$SIGNAL_CLI_BIN" -u "$USER_PHONE" register

# Confirm received verification code
"$SIGNAL_CLI_BIN" -u "$USER_PHONE" verify "XXXX-XXX"

Directory & Status Queries Traditional phone number lookups may return authentication errors on certain networks. Username-based resolution typically succeeds under standard configurations.

TARGET_USER="s131.01"

# Phone lookup (may yield 401 Unauthorized on specific deployments)
"$SIGNAL_CLI_BIN" -u "$USER_PHONE" getUserStatus +8613111111111

# Username lookup (preferred method)
"$SIGNAL_CLI_BIN" -u "$USER_PHONE" getUserStatus --username "$TARGET_USER"

Messaging & Profile Management Dispatch a plaintext payload to the target identifier:

MESSAGE_PAYLOAD="System initialization complete."
"$SIGNAL_CLI_BIN" -u "$USER_PHONE" send -m "$MESSAGE_PAYLOAD" -u "$TARGET_USER"

Once accepetd on the receiving end, establish a unique display name and handle for discoverability:

DISPLAY_NAME="dev-node-01"
HANDLE_ALIAS="admin.signal"

"$SIGNAL_CLI_BIN" -u "$USER_PHONE" updateAccount -n "$HANDLE_ALIAS"
"$SIGNAL_CLI_BIN" -u "$USER_PHONE" updateProfile --name "$DISPLAY_NAME"

Monitor incoming traffic streams using the dedicated listener command:

"$SIGNAL_CLI_BIN" -u "$USER_PHONE" receive

This output stream renders rich media payloads, including standardized emoji sequences, directly within terminal emulators supporting Unicode rendering.