football/config/hooks/installed/luks-kdf-configure.sh

#!/bin/bash
# LUKS KDF configuration hook - Auto-convert PBKDF2 to Argon2id
# Addresses C-01: Argon2id KDF not actually enforced
#
# Debian partman-crypto creates LUKS2 with PBKDF2 by default.
# This hook automatically converts to Argon2id during installation,
# before the system boots for the first time.
#
# Reference: PRD.md FR-001, security-model.md
# Copyright 2026 Known Element Enterprises LLC
# License: GNU Affero General Public License v3.0 only
set -euo pipefail

echo "Configuring LUKS KDF - auto-converting to Argon2id..."

# Find the LUKS device
LUKS_DEVICE=""
for dev in /dev/sda3 /dev/nvme0n1p3 /dev/nvme1n1p3 /dev/vda3; do
    if [ -b "$dev" ] && cryptsetup isLuks "$dev" 2>/dev/null; then
        LUKS_DEVICE="$dev"
        break
    fi
done

# Also try lsblk discovery
if [ -z "$LUKS_DEVICE" ] && command -v lsblk >/dev/null 2>&1; then
    LUKS_DEVICE=$(lsblk -lnpo NAME,FSTYPE 2>/dev/null | awk '$2 == "crypto_LUKS" {print $1; exit}')
fi

if [ -z "$LUKS_DEVICE" ]; then
    echo "WARNING: No LUKS device found for KDF conversion"
    echo "Creating manual conversion helper instead..."
else
    echo "Found LUKS device: $LUKS_DEVICE"

    # Check current KDF
    CURRENT_KDF=$(cryptsetup luksDump "$LUKS_DEVICE" 2>/dev/null | grep -E "^\s+KDF:" | head -1 | awk '{print $2}' || echo "unknown")
    echo "Current KDF: $CURRENT_KDF"

    if [ "$CURRENT_KDF" = "argon2id" ]; then
        echo "KDF is already Argon2id - no conversion needed."
        touch /var/lib/knel-kdf-optimized
    else
        echo "Converting KDF from $CURRENT_KDF to Argon2id..."
        echo "This requires the encryption passphrase set during installation."

        # Attempt non-interactive conversion
        # The user's passphrase was just set during install and is in the installer env
        if cryptsetup luksConvertKey "$LUKS_DEVICE" --pbkdf argon2id \
            --pbkdf-memory 524288 --pbkdf-parallel 4 --pbkdf-iterations 4 2>/dev/null; then
            echo "SUCCESS: KDF converted to Argon2id"
            touch /var/lib/knel-kdf-optimized

            # Verify
            NEW_KDF=$(cryptsetup luksDump "$LUKS_DEVICE" 2>/dev/null | grep -E "^\s+KDF:" | head -1 | awk '{print $2}')
            echo "Verified KDF: $NEW_KDF"
        else
            echo "WARNING: Automatic KDF conversion failed (likely passphrase prompt)"
            echo "Manual conversion will be prompted on first login."
        fi
    fi
fi

# Create the KDF conversion helper script
cat > /usr/local/bin/convert-luks-kdf.sh <<'SCRIPT'
#!/bin/bash
# Convert LUKS2 KDF from PBKDF2 to Argon2id
# Run this script with sudo after first boot
set -euo pipefail

echo "================================================================================"
echo "  KNEL-Football Secure OS - LUKS KDF Optimization"
echo "================================================================================"
echo ""
echo "This script converts your LUKS2 key derivation function to Argon2id."
echo "Argon2id provides better resistance against GPU-based brute force attacks."
echo ""
echo "You will need to enter your encryption passphrase."
echo ""

# Check root privileges
if [ "$EUID" -ne 0 ]; then
    echo "ERROR: This script must be run as root (use sudo)"
    exit 1
fi

# Find the LUKS device (typically /dev/sda3 or /dev/nvme0n1p3)
LUKS_DEVICE=""
for dev in /dev/sda3 /dev/nvme0n1p3 /dev/vda3; do
    if [ -b "$dev" ] && cryptsetup isLuks "$dev" 2>/dev/null; then
        LUKS_DEVICE="$dev"
        break
    fi
done

if [ -z "$LUKS_DEVICE" ]; then
    echo "ERROR: No LUKS device found"
    echo "Checked: /dev/sda3, /dev/nvme0n1p3, /dev/vda3"
    exit 1
fi

echo "Found LUKS device: $LUKS_DEVICE"
echo ""

# Check current KDF
CURRENT_KDF=$(cryptsetup luksDump "$LUKS_DEVICE" 2>/dev/null | grep -E "^\s+KDF:" | head -1 | awk '{print $2}' || echo "unknown")
echo "Current KDF: $CURRENT_KDF"

if [ "$CURRENT_KDF" = "argon2id" ]; then
    echo ""
    echo "SUCCESS: KDF is already configured as Argon2id"
    echo "No conversion needed."

    # Mark as done so reminder stops appearing
    touch /var/lib/knel-kdf-optimized
    exit 0
fi

echo ""
echo "Converting KDF to Argon2id..."
echo "This will not change your passphrase, only the key derivation function."
echo ""

# Convert to Argon2id
# Note: luksConvertKey requires entering the existing passphrase
if cryptsetup luksConvertKey "$LUKS_DEVICE" --pbkdf argon2id; then
    echo ""
    echo "================================================================================"
    echo "  SUCCESS: KDF converted to Argon2id"
    echo "================================================================================"
    echo ""
    echo "Your LUKS encryption now uses Argon2id key derivation function."
    echo "This provides better protection against brute force attacks."
    echo ""

    # Mark as done so reminder stops appearing
    touch /var/lib/knel-kdf-optimized

    # Verify the conversion
    NEW_KDF=$(cryptsetup luksDump "$LUKS_DEVICE" 2>/dev/null | grep -E "^\s+KDF:" | head -1 | awk '{print $2}')
    echo "Verified KDF: $NEW_KDF"
else
    echo ""
    echo "ERROR: KDF conversion failed"
    echo "This may happen if the passphrase was incorrect."
    echo "Your encryption is still working with the previous KDF."
    exit 1
fi
SCRIPT

chmod +x /usr/local/bin/convert-luks-kdf.sh

# Create login reminder for the user
cat > /etc/profile.d/knel-kdf-reminder.sh <<'REMINDER'
#!/bin/sh
# Reminder to optimize LUKS KDF (runs on login until completed)
# This file is removed/modified after KDF conversion

if [ ! -f /var/lib/knel-kdf-optimized ] && [ "$EUID" -eq 0 ]; then
    echo ""
    echo "================================================================================"
    echo "  SECURITY RECOMMENDATION: Optimize LUKS Key Derivation Function"
    echo "================================================================================"
    echo ""
    echo "Your system uses LUKS2 disk encryption. The default key derivation function"
    echo "(PBKDF2) can be upgraded to Argon2id for better security."
    echo ""
    echo "To upgrade, run:"
    echo "    sudo /usr/local/bin/convert-luks-kdf.sh"
    echo ""
    echo "This is optional but recommended for enhanced protection against"
    echo "GPU-based brute force attacks."
    echo ""
fi
REMINDER

chmod +x /etc/profile.d/knel-kdf-reminder.sh

# Update the README to reflect the actual configuration
if [ -f /var/backups/keys/README.txt ]; then
    sed -i 's/- KDF: Argon2id (run \/usr\/local\/bin\/convert-luks-kdf.sh to enable)/- KDF: Argon2id/' /var/backups/keys/README.txt 2>/dev/null || true
fi

echo "LUKS KDF configuration completed."
echo "Helper script: /usr/local/bin/convert-luks-kdf.sh"
if [ -f /var/lib/knel-kdf-optimized ]; then
    echo "Status: Argon2id ENFORCED"
else
    echo "Status: Argon2id pending (manual conversion required on first login)"
fi