verify-install.sh

#!/bin/bash

REPO=lightningnetwork
PROJECT=lnd

RELEASE_URL=https://github.com/$REPO/$PROJECT/releases
API_URL=https://api.github.com/repos/$REPO/$PROJECT/releases
MANIFEST_SELECTOR=". | select(.name | test(\"manifest-v.*(\\\\.txt)$\")) | .name"
SIGNATURE_SELECTOR=". | select(.name | test(\"manifest-.*(\\\\.sig)$\")) | .name"
HEADER_JSON="Accept: application/json"
HEADER_GH_JSON="Accept: application/vnd.github.v3+json"

# All keys that can sign lnd releases. The key must be downloadable/importable
# from the URL given after the space.
KEYS=()
KEYS+=("F4FC70F07310028424EFC20A8E4256593F177720 https://keybase.io/guggero/pgp_keys.asc")
KEYS+=("15E7ECF257098A4EF91655EB4CA7FE54A6213C91 https://keybase.io/carlakirkcohen/pgp_keys.asc")
KEYS+=("9C8D61868A7C492003B2744EE7D737B67FA592C7 https://keybase.io/bitconner/pgp_keys.asc")
KEYS+=("E4D85299674B2D31FAA1892E372CBD7633C61696 https://keybase.io/roasbeef/pgp_keys.asc")
KEYS+=("729E9D9D92C75A5FBFEEE057B5DD717BEF7CA5B1 https://keybase.io/wpaulino/pgp_keys.asc")
KEYS+=("7E81EF6B9989A9CC93884803118759E83439A9B1 https://keybase.io/eugene_/pgp_keys.asc")
KEYS+=("7AB3D7F5911708842796513415BAADA29DA20D26 https://keybase.io/halseth/pgp_keys.asc")

function check_command() {
  echo -n "Checking if $1 is installed... "
  if ! command -v "$1"; then
    echo "ERROR: $1 is not installed or not in PATH!"
    exit 1
  fi
}

# By default we're picking up lnd and lncli from the system $PATH.
LND_BIN=$(which lnd)
LNCLI_BIN=$(which lncli)

# If exactly two parameters are specified, we expect the first one to be lnd and
# the second one to be lncli.
if [[ $# -eq 2 ]]; then
  LND_BIN=$(realpath $1)
  LNCLI_BIN=$(realpath $2)
  
  # Make sure both files actually exist.
  if [[ ! -f $LND_BIN ]]; then
    echo "ERROR: $LND_BIN not found!"
    exit 1
  fi
  if [[ ! -f $LNCLI_BIN ]]; then
    echo "ERROR: $LNCLI_BIN not found!"
    exit 1
  fi
elif [[ $# -eq 0 ]]; then
  # Make sure both binaries can be found and are executable.
  check_command lnd
  check_command lncli
else
  echo "ERROR: invalid number of parameters!"
  echo "Usage: verify-install.sh [lnd-binary lncli-binary]"
  exit 1
fi

check_command curl
check_command jq
check_command gpg

LND_VERSION=$($LND_BIN --version | cut -d'=' -f2)
LNCLI_VERSION=$($LNCLI_BIN --version | cut -d'=' -f2)

# Make this script compatible with both linux and *nix.
SHA_CMD="sha256sum"
if ! command -v "$SHA_CMD"; then
  if command -v "shasum"; then
    SHA_CMD="shasum -a 256"
  else
    echo "ERROR: no SHA256 sum binary installed!"
    exit 1
  fi
fi
LND_SUM=$($SHA_CMD $LND_BIN | cut -d' ' -f1)
LNCLI_SUM=$($SHA_CMD $LNCLI_BIN | cut -d' ' -f1)

echo "Detected lnd $LND_BIN version $LND_VERSION with SHA256 sum $LND_SUM"
echo "Detected lncli $LNCLI_BIN version $LNCLI_VERSION with SHA256 sum $LNCLI_SUM"

# Make sure lnd and lncli are installed with the same version and is an actual
# version string.
if [[ "$LNCLI_VERSION" != "$LND_VERSION" ]]; then
  echo "ERROR: Version $LNCLI_VERSION of lncli does not match $LND_VERSION of lnd!"
  exit 1
fi
version_regex="^v[[:digit:]]+\.[[:digit:]]+\.[[:digit:]]"
if [[ ! "$LND_VERSION" =~ $version_regex ]]; then
  echo "ERROR: Invalid version of lnd detected: $LND_VERSION"
  exit 1
fi

# Make sure the hash was actually calculated by looking at its length.
if [[ ${#LND_SUM} -ne 64 ]]; then
  echo "ERROR: Invalid hash for lnd: $LND_SUM!"
  exit 1
fi
if [[ ${#LNCLI_SUM} -ne 64 ]]; then
  echo "ERROR: Invalid hash for lncli: $LNCLI_SUM!"
  exit 1
fi

# If we're inside the docker image, there should be a shasums.txt file in the
# root directory. If that's the case, we first want to make sure we still have
# the same hash as we did when building the image.
if [[ -f /shasums.txt ]]; then
  if ! grep -q "$LND_SUM" /shasums.txt; then
    echo "ERROR: Hash $LND_SUM for lnd not found in /shasums.txt: "
    cat /shasums.txt
    exit 1
  fi
  if ! grep -q "$LNCLI_SUM" /shasums.txt; then
    echo "ERROR: Hash $LNCLI_SUM for lnd not found in /shasums.txt: "
    cat /shasums.txt
    exit 1
  fi
fi

# Import all the signing keys.
for key in "${KEYS[@]}"; do
  KEY_ID=$(echo $key | cut -d' ' -f1)
  IMPORT_URL=$(echo $key | cut -d' ' -f2)
  echo "Downloading and importing key $KEY_ID from $IMPORT_URL"
  curl -L -s $IMPORT_URL | gpg --import

  # Make sure we actually imported the correct key.
  if ! gpg --list-key "$KEY_ID"; then
    echo "ERROR: Imported key from $IMPORT_URL doesn't match ID $KEY_ID."
  fi
done

echo ""

# Download the JSON of the release itself. That'll contain the release ID we need for the next call.
RELEASE_JSON=$(curl -L -s -H "$HEADER_JSON" "$RELEASE_URL/$LND_VERSION")

TAG_NAME=$(echo $RELEASE_JSON | jq -r '.tag_name')
RELEASE_ID=$(echo $RELEASE_JSON | jq -r '.id')
echo "Release $TAG_NAME found with ID $RELEASE_ID"

# Now download the asset list and filter by the manifest and the signatures.
ASSETS=$(curl -L -s -H "$HEADER_GH_JSON" "$API_URL/$RELEASE_ID" | jq -c '.assets[]')
MANIFEST=$(echo $ASSETS | jq -r "$MANIFEST_SELECTOR")
SIGNATURES=$(echo $ASSETS | jq -r "$SIGNATURE_SELECTOR")

# Download the main "manifest-*.txt" and all "manifest-*.sig" files containing
# the detached signatures.
TEMP_DIR=$(mktemp -d /tmp/lnd-sig-verification-XXXXXX)
echo "Downloading $MANIFEST"
curl -L -s -o "$TEMP_DIR/$MANIFEST" "$RELEASE_URL/download/$LND_VERSION/$MANIFEST"

for signature in $SIGNATURES; do
  echo "Downloading $signature"
  curl -L -s -o "$TEMP_DIR/$signature" "$RELEASE_URL/download/$LND_VERSION/$signature"
done

echo ""
cd $TEMP_DIR || exit 1

# Before we even look at the content of the manifest, we first want to make sure
# the signatures actually sign that exact manifest.
NUM_CHECKS=0
for signature in $SIGNATURES; do
  echo "Verifying $signature"
  if gpg --verify "$signature" "$MANIFEST" 2>&1 | grep -q "Good signature"; then
    echo "Signature for $signature appears valid: "
    gpg --verify "$signature" "$MANIFEST" 2>&1 | grep "using"
  elif gpg --verify "$signature" 2>&1 | grep -q "No public key"; then
    echo "Unable to verify signature $signature, no key available, skipping"
    continue
  else
    echo "ERROR: Did not get valid signature for $MANIFEST in $signature!"
    echo "  The developer signature $signature disagrees on the expected"
    echo "  release binaries in $MANIFEST. The release may have been faulty or"
    echo "  was backdoored."
    exit 1
  fi

  echo "Verified $signature against $MANIFEST"
  ((NUM_CHECKS=NUM_CHECKS+1))
done

# We want at least five signatures (out of seven public keys) that sign the
# hashes of the binaries we have installed. If we arrive here without exiting,
# it means no signature manifests were uploaded (yet) with the correct naming
# pattern.
MIN_REQUIRED_SIGNATURES=5
if [[ $NUM_CHECKS -lt $MIN_REQUIRED_SIGNATURES ]]; then
  echo "ERROR: Not enough valid signatures found!"
  echo "  Valid signatures found: $NUM_CHECKS"
  echo "  Valid signatures required: $MIN_REQUIRED_SIGNATURES"
  echo
  echo "  Make sure the release $LND_VERSION contains the required "
  echo "  number of signatures on the manifest, or wait until more "
  echo "  signatures have been added to the release."
  exit 1
fi

# Then make sure that the hash of the installed binaries can be found in the
# manifest that we now have verified the signatures for.
if ! grep -q "^$LND_SUM" "$MANIFEST"; then
  echo "ERROR: Hash $LND_SUM for lnd not found in $MANIFEST: "
  cat "$MANIFEST"
  echo "  The expected release binaries have been verified with the developer "
  echo "  signatures. Your binary's hash does not match the expected release "
  echo "  binary hashes. Make sure you're using an official binary."
  exit 1
fi

if ! grep -q "^$LNCLI_SUM" "$MANIFEST"; then
  echo "ERROR: Hash $LNCLI_SUM for lncli not found in $MANIFEST: "
  cat "$MANIFEST"
  echo "  The expected release binaries have been verified with the developer "
  echo "  signatures. Your binary's hash does not match the expected release "
  echo "  binary hashes. Make sure you're using an official binary."
  exit 1
fi

echo ""
echo "SUCCESS! Verified lnd and lncli against $MANIFEST signed by $NUM_CHECKS developers."