Problem

The recommended quick install method downloads and executes a script directly from GitHub:

```bash curl -fsSL https://raw.githubusercontent.com/rtk-ai/rtk/refs/heads/master/install.sh | sh ```

Risks

1. Supply chain attack surface: If the GitHub repo is compromised (or a maintainer account is hijacked), every new install gets a backdoored binary. There is no integrity verification between download and execution.

2. MITM risk: While HTTPS protects against most MITM attacks, a compromised CA or DNS hijack could serve a malicious script. The script then downloads and installs a binary without verification.

3. No checksum verification: The installer downloads the tar.gz but does not verify a checksum or signature before extracting and installing.

`install.sh` lines 75-85:

```bash info "Downloading from: $DOWNLOAD_URL" if ! curl -fsSL "$DOWNLOAD_URL" -o "$ARCHIVE"; then error "Failed to download binary" fi

info "Extracting..." tar -xzf "$ARCHIVE" -C "$TEMP_DIR"

mkdir -p "$INSTALL_DIR" mv "${TEMP_DIR}/${BINARY_NAME}" "${INSTALL_DIR}/" ```

Proposed fixes

Short term: Add checksum verification

Publish SHA-256 checksums alongside each release and verify in the installer:

```bash

Download checksum

CHECKSUM=$(curl -fsSL "$DOWNLOAD_URL.sha256") echo "$CHECKSUM $ARCHIVE" | sha256sum --check ```

Medium term: Add GPG signature verification

Sign releases with a maintainer GPG key and verify in the installer.

Long term: Provide OS package manager installation as primary

The Homebrew installation (`brew install rtk`) already has integrity verification via Homebrew's formula system. Making this the primary recommendation would be more secure.

Comparison with industry best practices

• Rustup: Downloads a script but verifies GPG signatures on the binaries
• Homebrew: Verifies SHA-256 checksums in formula
• Nix: Cryptographic content-addressed store paths
• asdf: Verifies checksums against published hashes

Acceptance criteria

• Installer verifies binary integrity before installation
• Checksums or signatures are published with each release
• Documentation recommends verified installation methods first