diff --git a/.github/scripts/validate-signatures.sh b/.github/scripts/validate-signatures.sh
new file mode 100755
index 00000000..7afe683e
--- /dev/null
+++ b/.github/scripts/validate-signatures.sh
@@ -0,0 +1,172 @@
+#!/bin/bash
+set -euo pipefail
+
+# Configuration: Networks to validate
+NETWORKS=(
+  "mainnet"
+  "sepolia"
+  "sepolia-alpha"
+)
+
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+NC='\033[0m'
+
+VALIDATION_FAILED=0
+VALIDATION_PASSED=0
+
+echo "🔍 Validating task signatures..."
+
+# Build regex pattern from networks
+NETWORK_PATTERN=$(IFS='|'; echo "${NETWORKS[*]}")
+
+# Get changed task directories
+TASK_DIRS=$(git diff --name-only origin/main...HEAD \
+  | grep -E "^($NETWORK_PATTERN)/[^/]+/" \
+  | sed -E 's|^([^/]+/[^/]+)/.*|\1|' \
+  | sort -u || true)
+
+if [ -z "$TASK_DIRS" ]; then
+  echo "ℹ️  No task folders modified. Skipping validation."
+  exit 0
+fi
+
+echo "📋 Tasks to validate:"
+echo "$TASK_DIRS" | sed 's/^/   - /'
+echo ""
+
+base64_to_hex() {
+  echo "$1" | base64 -d | od -An -tx1 | tr -d ' \n'
+}
+
+# Validate a single signature file
+validate_signature_file() {
+  local sig_file="$1"
+  local computed_hash="$2"
+  local sig_name=$(basename "$sig_file" .json)
+
+  echo "🔍 Checking $sig_name..."
+
+  # Check if file exists
+  if [ ! -f "$sig_file" ]; then
+    echo -e "${RED}   ❌ Missing signature file${NC}"
+    return 1
+  fi
+
+  # Validate JSON
+  if ! jq empty "$sig_file" 2>/dev/null; then
+    echo -e "${RED}   ❌ Invalid JSON${NC}"
+    return 1
+  fi
+
+  # Check algorithm
+  local algorithm=$(jq -r '.messageSignature.messageDigest.algorithm // empty' "$sig_file")
+  if [ "$algorithm" != "SHA2_384" ]; then
+    echo -e "${RED}   ❌ Wrong algorithm: $algorithm (expected SHA2_384)${NC}"
+    return 1
+  fi
+
+  # Extract digest
+  local base64_digest=$(jq -r '.messageSignature.messageDigest.digest // empty' "$sig_file")
+  if [ -z "$base64_digest" ]; then
+    echo -e "${RED}   ❌ No digest found${NC}"
+    return 1
+  fi
+
+  # Compare hashes
+  local sig_hash=$(base64_to_hex "$base64_digest")
+  if [ "$computed_hash" = "$sig_hash" ]; then
+    echo -e "${GREEN}   ✓ Hash matches${NC}"
+    return 0
+  else
+    echo -e "${RED}   ❌ Hash mismatch${NC}"
+    echo -e "${RED}      Expected: $computed_hash${NC}"
+    echo -e "${RED}      Got:      $sig_hash${NC}"
+    return 1
+  fi
+}
+
+# Validate a task
+validate_task() {
+  local task_dir="$1"
+  local network=$(echo "$task_dir" | cut -d'/' -f1)
+  local task_name=$(echo "$task_dir" | cut -d'/' -f2)
+
+  echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+  echo "📦 Validating: $task_dir"
+  echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+
+  # Check task directory exists
+  if [ ! -d "$task_dir" ]; then
+    echo -e "${RED}❌ Task directory not found${NC}"
+    return 1
+  fi
+
+  # Create deterministic tarball
+  local temp_tar=$(mktemp)
+  trap "rm -f $temp_tar" EXIT
+
+  echo "📦 Creating deterministic tarball..."
+  if ! tar --sort=name \
+      --mtime='1970-01-01 00:00:00' \
+      --owner=0 --group=0 \
+      --numeric-owner \
+      -C "$network" \
+      -cf "$temp_tar" \
+      "$task_name/" 2>/dev/null; then
+    echo -e "${RED}❌ Failed to create tarball${NC}"
+    return 1
+  fi
+
+  # Compute hash
+  echo "🔐 Computing SHA2-384 hash..."
+  local computed_hash=$(openssl dgst -sha384 -binary "$temp_tar" | od -An -tx1 | tr -d ' \n')
+  echo "   Computed: $computed_hash"
+  echo ""
+
+  # Validate each signature file
+  local sig_dir="signatures/$network/$task_name"
+  local sig_files=("$sig_dir/author.json" "$sig_dir/base-facilitator.json" "$sig_dir/base-sc-facilitator.json")
+  local all_match=true
+
+  for sig_file in "${sig_files[@]}"; do
+    if ! validate_signature_file "$sig_file" "$computed_hash"; then
+      all_match=false
+    fi
+  done
+
+  echo ""
+  if [ "$all_match" = true ]; then
+    echo -e "${GREEN}✅ PASSED${NC}"
+    return 0
+  else
+    echo -e "${RED}❌ FAILED${NC}"
+    return 1
+  fi
+}
+
+# Validate all tasks
+while IFS= read -r task_dir; do
+  if validate_task "$task_dir"; then
+    VALIDATION_PASSED=$((VALIDATION_PASSED + 1))
+  else
+    VALIDATION_FAILED=$((VALIDATION_FAILED + 1))
+  fi
+  echo ""
+done <<< "$TASK_DIRS"
+
+# Print summary
+echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+echo "📊 Summary"
+echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+echo -e "   ${GREEN}Passed: $VALIDATION_PASSED${NC}"
+echo -e "   ${RED}Failed: $VALIDATION_FAILED${NC}"
+echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+
+if [ $VALIDATION_FAILED -gt 0 ]; then
+  echo -e "${RED}❌ Signature validation failed${NC}"
+  exit 1
+fi
+
+echo -e "${GREEN}✅ All signatures validated successfully${NC}"
+exit 0
diff --git a/.github/workflows/validate-task-signatures.yml b/.github/workflows/validate-task-signatures.yml
new file mode 100644
index 00000000..2eda304e
--- /dev/null
+++ b/.github/workflows/validate-task-signatures.yml
@@ -0,0 +1,39 @@
+name: Validate Task Signatures
+
+on:
+  pull_request:
+    paths:
+      - "mainnet/**"
+      - "sepolia/**"
+      - "sepolia-alpha/**"
+      - "signatures/**"
+
+permissions:
+  contents: read
+
+jobs:
+  validate-signatures:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Harden the runner (Audit all outbound calls)
+        uses: step-security/harden-runner@002fdce3c6a235733a90a27c80493a3241e56863 # v2.12.1
+        with:
+          egress-policy: audit
+
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          fetch-depth: 0
+          ref: ${{ github.event.pull_request.head.ref }}
+
+      - name: Fetch base branch
+        run: |
+          git fetch origin ${{ github.event.pull_request.base.ref }}:${{ github.event.pull_request.base.ref }}
+
+      - name: Install dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y jq
+
+      - name: Validate task signatures
+        run: |
+          bash .github/scripts/validate-signatures.sh