Change PKI so that attestation certs are fully compliant. (#668)

* Change PKI so that attestation certs are fully compliant.

Initially we generated the smallest certificate possible.
Unfortunately sometimes attestation certificates are
thoroughly checked and the FIDO x509v3 extensions must be present.
This PR now creates a PKI (root CA and signing CA) with corresponding
CRLs and also allows to create multiple batch certificates for the keys
instead of a single one.
The latest generated batch cert/key is automatically symlinked so that
the previous documentation still holds.

* Change openssl options to support older versions

* OSX doesn't support long options

---------

Co-authored-by: kaczmarczyck <43844792+kaczmarczyck@users.noreply.github.com>
This commit is contained in:
Jean-Michel Picod
2023-12-18 10:47:46 +01:00
committed by GitHub
parent 5fdc6e0739
commit 6b8aa3aaf3
6 changed files with 389 additions and 52 deletions

View File

@@ -1,5 +1,5 @@
#!/bin/bash
# Copyright 2019 Google LLC
# Copyright 2019-2023 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
@@ -13,20 +13,19 @@
# See the License for the specific language governing permissions and
# limitations under the License.
generate_crypto_materials () {
# OpenSSL ext file location
local openssl_ext_file=tools/openssl.ext
generate_pki () {
# Curve parameters
local ecparams_file=crypto_data/ecparams.pem
# OpenSK AAGUID
local aaguid_file=crypto_data/aaguid.txt
# Root CA key pair and certificate
local ca_priv_key=crypto_data/opensk_ca.key
local ca_cert_name=crypto_data/opensk_ca
local ca_priv_key=crypto_data/ca/root-ca/private/root-ca.key
local ca_cert_name=crypto_data/ca/root-ca
# Attestation key pair and certificate that will be embedded into the
# firmware. The certificate will be signed by the Root CA.
local opensk_key=crypto_data/opensk.key
local opensk_cert_name=crypto_data/opensk_cert
# Signing CA key pair and certificate
local signing_ca_priv_key=crypto_data/ca/signing-ca/private/signing-ca.key
local signing_ca_cert_name=crypto_data/ca/signing-ca
# The upgrade private key is used for signing, the corresponding public key
# will be COSE encoded and embedded into the firmware.
@@ -36,6 +35,9 @@ generate_crypto_materials () {
# Allow invoker to override the command with a full path.
local openssl=${OPENSSL:-$(which openssl)}
# Print version for debug purposes
${openssl} version
# We need openssl command to continue
if [ ! -x "${openssl}" ]
then
@@ -47,55 +49,109 @@ generate_crypto_materials () {
set -e
force_generate="$1"
mkdir -p crypto_data
if [ ! -f "${ca_priv_key}" ]
ask_for_password="$2"
if [ "${force_generate}" = "Y" ]
then
"${openssl}" ecparam -genkey -name prime256v1 -out "${ca_priv_key}"
# Remove old OpenSK certs and CRL
rm -rf crypto_data/crl crypto_data/certs
fi
if [ ! -f "${ca_cert_name}.pem" ]
openssl_keypwd="-nodes"
openssl_batch="-batch"
if [ "${ask_for_password}" = "Y" ]
then
openssl_keypwd=""
openssl_batch=""
fi
# Create PKI directories
mkdir -p crypto_data/ca/root-ca/private crypto_data/ca/root-ca/db
mkdir -p crypto_data/ca/signing-ca/private crypto_data/ca/signing-ca/db
mkdir -p crypto_data/crl crypto_data/certs
chmod 700 crypto_data/ca/root-ca/private crypto_data/ca/signing-ca/private
# Prepare PKI databases
for fname in \
crypto_data/ca/root-ca/db/root-ca.db \
crypto_data/ca/root-ca/db/root-ca.db.attr \
crypto_data/ca/signing-ca/db/signing-ca.db \
crypto_data/ca/signing-ca/db/signing-ca.db.attr
do
if [ "${force_generate}" = "Y" -o ! -f "${fname}" ]
then
cp /dev/null "${fname}"
fi
done
# Initialize PKI serial numbers
for fname in \
crypto_data/ca/root-ca/db/root-ca.pem.srl \
crypto_data/ca/root-ca/db/root-ca.pem.srl \
crypto_data/ca/signing-ca/db/signing-ca.pem.srl \
crypto_data/ca/signing-ca/db/signing-ca.pem.srl
do
if [ "${force_generate}" = "Y" -o ! -f "${fname}" ]
then
echo 01 > "${fname}"
fi
done
# Generate AAGUID
if [ "${force_generate}" = "Y" -o ! -f "${aaguid_file}" ]
then
uuidgen > "${aaguid_file}"
fi
if [ ! -f "${ecparams_file}" ]
then
"${openssl}" ecparam -param_enc "named_curve" -name "prime256v1" -out "${ecparams_file}"
fi
if [ "${force_generate}" = "Y" -o ! -f "${ca_cert_name}.pem" ]
then
# Create root CA request and key pair
"${openssl}" req \
-new \
-key "${ca_priv_key}" \
-config tools/openssl/root-ca.conf \
-out "${ca_cert_name}.csr" \
-subj "/CN=OpenSK CA"
"${openssl}" x509 \
-trustout \
-req \
-days 7305 \
-keyout "${ca_priv_key}" \
"${openssl_keypwd}" \
"${openssl_batch}" \
-newkey "ec:${ecparams_file}"
# Make root CA certificate
"${openssl}" ca \
-selfsign \
-config tools/openssl/root-ca.conf \
"${openssl_batch}" \
-in "${ca_cert_name}.csr" \
-signkey "${ca_priv_key}" \
-outform pem \
-out "${ca_cert_name}.pem" \
-sha256
-extensions root_ca_ext
fi
if [ "${force_generate}" = "Y" -o ! -f "${opensk_key}" ]
then
"${openssl}" ecparam -genkey -name prime256v1 -out "${opensk_key}"
fi
if [ "${force_generate}" = "Y" -o ! -f "${opensk_cert_name}.pem" ]
if [ "${force_generate}" = "Y" -o ! -f "${signing_ca_cert_name}.pem" ]
then
# Create signing CA request
"${openssl}" req \
-new \
-key "${opensk_key}" \
-out "${opensk_cert_name}.csr" \
-subj "/C=US/O=OpenSK/OU=Authenticator Attestation/CN=OpenSK Hacker Edition"
"${openssl}" x509 \
-req \
-days 3652 \
-in "${opensk_cert_name}.csr" \
-CA "${ca_cert_name}.pem" \
-extfile "${openssl_ext_file}" \
-CAkey "${ca_priv_key}" \
-CAcreateserial \
-outform pem \
-out "${opensk_cert_name}.pem" \
-sha256
-config tools/openssl/signing-ca.conf \
-out "${signing_ca_cert_name}.csr" \
-keyout "${signing_ca_priv_key}" \
"${openssl_keypwd}" \
"${openssl_batch}" \
-newkey "ec:${ecparams_file}"
# Make signing CA certificate
"${openssl}" ca \
-config tools/openssl/root-ca.conf \
"${openssl_batch}" \
-in "${signing_ca_cert_name}.csr" \
-out "${signing_ca_cert_name}.pem" \
-extensions signing_ca_ext
fi
# Create firmware update key pair
if [ "${force_generate}" = "Y" -o ! -f "${opensk_upgrade}" ]
then
"${openssl}" ecparam -genkey -name prime256v1 -out "${opensk_upgrade}"
@@ -106,11 +162,88 @@ generate_crypto_materials () {
then
"${openssl}" ec -in "${opensk_upgrade}" -pubout -out "${opensk_upgrade_pub}"
fi
if [ "${force_generate}" = "Y" -o ! -f "${aaguid_file}" ]
then
uuidgen > "${aaguid_file}"
fi
}
generate_crypto_materials "$1"
generate_new_batch () {
local openssl=${OPENSSL:-$(which openssl)}
# Curve parameters
local ecparams_file=crypto_data/ecparams.pem
# OpenSK AAGUID
local aaguid_file=crypto_data/aaguid.txt
set -e
# We need openssl command to continue
if [ ! -x "${openssl}" ]
then
echo "Missing openssl command. Try to specify its full path using OPENSSL environment variable."
exit 1
fi
if [ ! -f "${ecparams_file}" ]
then
echo "Missing curve parameters. Has the PKI been generated?"
exit 1
fi
if [ ! -f "${aaguid_file}" ]
then
echo "Missing AAGUID file."
exit 1
fi
batch_id=$(uuidgen | tr -d '-')
aaguid=$(tr -d '-' < "${aaguid_file}")
# Attestation key pair and certificate that will be embedded into the
# firmware. The certificate will be signed by the Root CA.
local opensk_key=certs/${batch_id}.key
local opensk_cert_name=certs/${batch_id}
# x509v3 extension values are passed through environment variables.
export OPENSK_AAGUID="${aaguid}"
# Comma separated values of supported transport for the batch attestation certificate.
# 0=BTC, 1=BLE, 2=USB, 3=NFC
# Default to USB only
export OPENSK_TRANSPORT="${OPENSK_TRANSPORT:-2}" # comma separated values. 1=BLE, 2=USB, 3=NFC
ask_for_password="$1"
openssl_keypwd="-nodes"
openssl_batch="-batch"
if [ "${ask_for_password}" = "Y" ]
then
openssl_keypwd=""
openssl_batch=""
fi
# Generate certificate request for the current batch
"${openssl}" req \
-new \
-config "tools/openssl/opensk.conf" \
-keyout "crypto_data/${opensk_key}" \
-out "crypto_data/${opensk_cert_name}.csr" \
"${openssl_keypwd}" \
"${openssl_batch}" \
-newkey "ec:${ecparams_file}"
# Sign it using signing-CA and injecting the AAGUID as an extension
"${openssl}" ca \
-config "tools/openssl/signing-ca.conf" \
"${openssl_batch}" \
-in "crypto_data/${opensk_cert_name}.csr" \
-out "crypto_data/${opensk_cert_name}.pem" \
-extensions "fido_key_ext"
# Force symlink to the latest batch
ln -s -f "${opensk_cert_name}.pem" crypto_data/opensk_cert.pem
ln -s -f "${opensk_key}" crypto_data/opensk.key
}
if [ "X${1}" != "X" ]
then
ask_for_password=${2:-N}
generate_pki $1 $ask_for_password
if [ "$1" = "Y" -o ! -f "crypto_data/opensk.key" -o ! -f "crypto_data/opensk_cert.pem" ]
then
generate_new_batch $ask_for_password
fi
fi