#!/bin/bash

# Source: https://jamielinux.com/docs/openssl-certificate-authority/index.html

if [ -z "$1" ]; then
	echo "=x=> Path for your CA root is required!"
	exit 1
fi

CA_ROOT=$(realpath "$1")

# Intermediate directory
INTERMEDIATE_ROOT="$CA_ROOT/intermediate"

# Static config blanks

read -r -d '' OPENSSL_CA_CFG << EOM
# OpenSSL root CA configuration file.
# Auto-generated.

[ ca ]
# \`man ca\`
default_ca = CA_default

[ CA_default ]
# Directory and file locations.
dir               = $CA_ROOT
certs             = \$dir/certs
crl_dir           = \$dir/crl
new_certs_dir     = \$dir/newcerts
database          = \$dir/index.txt
serial            = \$dir/serial
RANDFILE          = \$dir/private/.rand

# The root key and root certificate.
private_key       = \$dir/private/ca.key.pem
certificate       = \$dir/certs/ca.cert.pem

# For certificate revocation lists.
crlnumber         = \$dir/crlnumber
crl               = \$dir/crl/ca.crl.pem
crl_extensions    = crl_ext
default_crl_days  = 30

# SHA-1 is deprecated, so use SHA-2 instead.
default_md        = sha256

name_opt          = ca_default
cert_opt          = ca_default
default_days      = 375
preserve          = no
policy            = policy_strict

[ policy_strict ]
# The root CA should only sign intermediate certificates that match.
# See the POLICY FORMAT section of \`man ca\`.
countryName             = match
stateOrProvinceName     = match
organizationName        = match
organizationalUnitName  = optional
commonName              = supplied
emailAddress            = optional

[ policy_loose ]
# Allow the intermediate CA to sign a more diverse range of certificates.
# See the POLICY FORMAT section of the \`ca\` man page.
countryName             = optional
stateOrProvinceName     = optional
localityName            = optional
organizationName        = optional
organizationalUnitName  = optional
commonName              = supplied
emailAddress            = optional

[ req ]
# Options for the \`req\` tool (\`man req\`).
default_bits        = 4096
distinguished_name  = req_distinguished_name
string_mask         = utf8only

# SHA-1 is deprecated, so use SHA-2 instead.
default_md          = sha256

# Extension to add when the -x509 option is used.
x509_extensions     = v3_ca

[ req_distinguished_name ]
# See <https://en.wikipedia.org/wiki/Certificate_signing_request>.
countryName                     = Country Name (2 letter code)
stateOrProvinceName             = State or Province Name
localityName                    = Locality Name
0.organizationName              = Organization Name
organizationalUnitName          = Organizational Unit Name
commonName                      = Common Name
emailAddress                    = Email Address

[ v3_ca ]
# Extensions for a typical CA (\`man x509v3_config\`).
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid:always,issuer
basicConstraints = critical, CA:true
keyUsage = critical, digitalSignature, cRLSign, keyCertSign

[ v3_intermediate_ca ]
# Extensions for a typical intermediate CA (\`man x509v3_config\`).
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid:always,issuer
basicConstraints = critical, CA:true, pathlen:0
keyUsage = critical, digitalSignature, cRLSign, keyCertSign

[ usr_cert ]
# Extensions for client certificates (\`man x509v3_config\`).
basicConstraints = CA:FALSE
nsCertType = client, email
nsComment = "OpenSSL Generated Client Certificate"
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid,issuer
keyUsage = critical, nonRepudiation, digitalSignature, keyEncipherment
extendedKeyUsage = clientAuth, emailProtection

[ server_cert ]
# Extensions for server certificates (\`man x509v3_config\`).
basicConstraints = CA:FALSE
nsCertType = server
nsComment = "OpenSSL Generated Server Certificate"
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid,issuer:always
keyUsage = critical, digitalSignature, keyEncipherment
extendedKeyUsage = serverAuth

[ crl_ext ]
# Extension for CRLs (\`man x509v3_config\`).
authorityKeyIdentifier=keyid:always

[ ocsp ]
# Extension for OCSP signing certificates (\`man ocsp\`).
basicConstraints = CA:FALSE
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid,issuer
keyUsage = critical, digitalSignature
extendedKeyUsage = critical, OCSPSigning

EOM

read -r -d '' OPENSSL_INTERMEDIATE_CFG << EOM
# OpenSSL intermediate CA configuration file.
# Auto-generated.

[ ca ]
# \`man ca\`
default_ca = CA_default

[ CA_default ]
# Directory and file locations.
dir               = $INTERMEDIATE_ROOT
certs             = \$dir/certs
crl_dir           = \$dir/crl
new_certs_dir     = \$dir/newcerts
database          = \$dir/index.txt
serial            = \$dir/serial
RANDFILE          = \$dir/private/.rand

# The root key and root certificate.
private_key       = \$dir/private/intermediate.key.pem
certificate       = \$dir/certs/intermediate.cert.pem

# For certificate revocation lists.
crlnumber         = \$dir/crlnumber
crl               = \$dir/crl/intermediate.crl.pem
crl_extensions    = crl_ext
default_crl_days  = 30

# SHA-1 is deprecated, so use SHA-2 instead.
default_md        = sha256

name_opt          = ca_default
cert_opt          = ca_default
default_days      = 375
preserve          = no
policy            = policy_loose

# Allow copying extensions from CSRs
copy_extensions   = copy

[ policy_strict ]
# The root CA should only sign intermediate certificates that match.
# See the POLICY FORMAT section of \`man ca\`.
countryName             = match
stateOrProvinceName     = match
organizationName        = match
organizationalUnitName  = optional
commonName              = supplied
emailAddress            = optional

[ policy_loose ]
# Allow the intermediate CA to sign a more diverse range of certificates.
# See the POLICY FORMAT section of the \`ca\` man page.
countryName             = optional
stateOrProvinceName     = optional
localityName            = optional
organizationName        = optional
organizationalUnitName  = optional
commonName              = supplied
emailAddress            = optional

[ req ]
# Options for the \`req\` tool (\`man req\`).
default_bits        = 4096
distinguished_name  = req_distinguished_name
string_mask         = utf8only

# SHA-1 is deprecated, so use SHA-2 instead.
default_md          = sha256

# Extension to add when the -x509 option is used.
x509_extensions     = v3_intermediate_ca

[ req_distinguished_name ]
# See <https://en.wikipedia.org/wiki/Certificate_signing_request>.
countryName                     = Country Name (2 letter code)
stateOrProvinceName             = State or Province Name
localityName                    = Locality Name
0.organizationName              = Organization Name
organizationalUnitName          = Organizational Unit Name
commonName                      = Common Name
emailAddress                    = Email Address

[ v3_ca ]
# Extensions for a typical CA (\`man x509v3_config\`).
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid:always,issuer
basicConstraints = critical, CA:true
keyUsage = critical, digitalSignature, cRLSign, keyCertSign

[ v3_intermediate_ca ]
# Extensions for a typical intermediate CA (\`man x509v3_config\`).
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid:always,issuer
basicConstraints = critical, CA:true, pathlen:0
keyUsage = critical, digitalSignature, cRLSign, keyCertSign

[ usr_cert ]
# Extensions for client certificates (\`man x509v3_config\`).
basicConstraints = CA:FALSE
nsCertType = client, email
nsComment = "OpenSSL Generated Client Certificate"
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid,issuer
keyUsage = critical, nonRepudiation, digitalSignature, keyEncipherment
extendedKeyUsage = clientAuth, emailProtection

[ server_cert ]
# Extensions for server certificates (\`man x509v3_config\`).
basicConstraints = CA:FALSE
nsCertType = server
nsComment = "OpenSSL Generated Server Certificate"
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid,issuer:always
keyUsage = critical, digitalSignature, keyEncipherment
extendedKeyUsage = serverAuth

[ crl_ext ]
# Extension for CRLs (\`man x509v3_config\`).
authorityKeyIdentifier=keyid:always

[ ocsp ]
# Extension for OCSP signing certificates (\`man ocsp\`).
basicConstraints = CA:FALSE
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid,issuer
keyUsage = critical, digitalSignature
extendedKeyUsage = critical, OCSPSigning

EOM

deployFiles () {
	echo "Deploying a Certificate Authority to $CA_ROOT"
	echo ''

	if [ ! -d "$CA_ROOT" ]; then
		# Create directory
		mkdir -p "$CA_ROOT"

		# Create sub-directories
		mkdir -p "$CA_ROOT/private" "$CA_ROOT/csr" "$CA_ROOT/certs" "$CA_ROOT/newcerts"
		touch "$CA_ROOT/index.txt"
		echo 1000 > "$CA_ROOT/serial"

		chmod 700 "$CA_ROOT/private"
		echo "$OPENSSL_CA_CFG" > "$CA_ROOT/openssl.cfg"
	fi

	if [ ! -d "$INTERMEDIATE_ROOT" ]; then
		mkdir -p "$INTERMEDIATE_ROOT/private" "$INTERMEDIATE_ROOT/csr" "$INTERMEDIATE_ROOT/certs" "$INTERMEDIATE_ROOT/newcerts"
		touch "$INTERMEDIATE_ROOT/index.txt"
		echo 1000 > "$INTERMEDIATE_ROOT/serial"

		chmod 700 "$INTERMEDIATE_ROOT/private"
		echo "$OPENSSL_INTERMEDIATE_CFG" > "$INTERMEDIATE_ROOT/openssl.cfg"
	fi
}

generateRootPair () {
	############################
	# GENERATING ROOT KEY PAIR #
	############################

	echo '==> Starting the generation of the root key pair.'
	echo '==> Please fill in the appropriate information asked.'
	echo ''

	# Set CWD
	cd "$CA_ROOT"

	# CA Root Private Key
	if [ ! -e "$CA_ROOT/private/ca.key.pem" ]; then
		echo '=> Generating CA key.. Please enter a strong passphrase.'
		echo ''
		openssl genrsa -aes256 -out private/ca.key.pem 4096
	else
		echo '=> Root CA key exists, skipping..'
	fi

	if [ ! -e "$CA_ROOT/private/ca.key.pem" ]; then
		echo '=x=> Root CA key was not generated!'
		return 1
	fi
	chmod 400 private/ca.key.pem

	# CA Root Certificate
	if [ ! -e "$CA_ROOT/certs/ca.cert.pem" ]; then
		echo '=> Generating CA certificate..'
		echo ''
		openssl req -config "$CA_ROOT/openssl.cfg" \
		  -key private/ca.key.pem \
		  -new -x509 -days 7300 -sha256 -extensions v3_ca \
		  -out certs/ca.cert.pem
	else
		echo '=> Root certificate exists, skipping..'
	fi

	if [ ! -e "$CA_ROOT/certs/ca.cert.pem" ]; then
		echo '=x=> Root certificate was not generated!'
		return 1
	fi
	chmod 444 certs/ca.cert.pem

	# Print info
	openssl x509 -noout -text -in certs/ca.cert.pem

	echo '==> Root key pair generated.'
	echo ''
}

generateIntermediate () {
	if [ ! -e "$CA_ROOT/certs/ca.cert.pem" ]; then
		echo '=x=> Could not generate intermediate certificate.'
		echo '=x=> CA certificate is missing!'
		return 1
	fi

	####################################
	# GENERATING INTERMEDIATE KEY PAIR #
	####################################

	cd "$CA_ROOT"

	echo '==> Starting the generation of the intermediate key pair.'
	echo '==> This is used to sign server and user certificates.'
	echo '==> Please fill in the appropriate information asked.'
	echo ''

	if [ ! -e "$CA_ROOT/intermediate/private/intermediate.key.pem" ]; then
		# Key
		echo '=> Generating intermediate key.. Please enter a strong passphrase.'
		echo ''
		openssl genrsa -aes256 \
		    -out intermediate/private/intermediate.key.pem 4096
	else
		echo '=> Intermediate certificate key exists, skipping..'
	fi

	if [ ! -e "$CA_ROOT/intermediate/private/intermediate.key.pem" ]; then
		echo '=x=> Intermediate certificate key was not generated!'
		return 1
	fi

	chmod 400 intermediate/private/intermediate.key.pem

	if [ -e "$CA_ROOT/intermediate/csr/intermediate.csr.pem" ]; then
		rm -f intermediate/csr/intermediate.csr.pem
		rm -f intermediate/certs/intermediate.cert.pem
	fi

	# Certificate Signing Request (CSR)
	echo '=> Generating intermediate CSR..'
	echo ''
	openssl req -config "$INTERMEDIATE_ROOT/openssl.cfg" -new -sha256 \
	    -key intermediate/private/intermediate.key.pem \
	    -out intermediate/csr/intermediate.csr.pem

	if [ ! -e "$CA_ROOT/intermediate/csr/intermediate.csr.pem" ]; then
		echo '=x=> Intermediate signing request was not generated!'
		return 1
	fi

	echo '=> Singing the intermediate certificate. Please answer yes in order to continue.'
	echo ''
	openssl ca -config "$CA_ROOT/openssl.cfg" -extensions v3_intermediate_ca \
	      -days 3650 -notext -md sha256 \
	      -in intermediate/csr/intermediate.csr.pem \
	      -out intermediate/certs/intermediate.cert.pem

	if [ ! -e "$CA_ROOT/intermediate/certs/intermediate.cert.pem" ]; then
		echo '=x=> Intermediate certificate was not signed!'
		return 1
	fi

	chmod 444 intermediate/certs/intermediate.cert.pem

	# Print info
	openssl x509 -noout -text \
	      -in intermediate/certs/intermediate.cert.pem

	openssl verify -CAfile certs/ca.cert.pem \
	      intermediate/certs/intermediate.cert.pem

	# Generate Certificate Chain
	cat intermediate/certs/intermediate.cert.pem \
	    certs/ca.cert.pem > intermediate/certs/ca-chain.cert.pem

	chmod 444 intermediate/certs/ca-chain.cert.pem

	echo '==> Intermediate key pair generated.'
	echo "==> Your CA (Certificate Authority) is \"$INTERMEDIATE_ROOT/certs/ca-chain.cert.pem\""
}

createCertificate() {
	if [ ! -e "$CA_ROOT" ]; then
		echo "=x=> Certificate root was not found."
		return 1
	elif [ ! -e "$INTERMEDIATE_ROOT/openssl.cfg" ]; then
		echo "=x=> Intermediate certificate configuration was not found."
		return 1
	fi

	if [ -z "$1" ]; then
		echo "=x=> Please provide a name for this certificate."
		return 1
	fi

	if [ -z "$2" ] || [ "$2" != "server_cert" ] && [ "$2" != "usr_cert" ]; then
		echo "=x=> Type must be one of server_cert or usr_cert. If you're unsure about this, use 'usr_cert'."
		return 1
	fi

	cd "$CA_ROOT"

	# Custom configuration file
	local CSRCFG="$INTERMEDIATE_ROOT/openssl.cfg"
	if [ -n $3 ]; then
		CSRCFG="$3"
	fi

	# Generate the key if it does not exist
	if [ ! -e "$INTERMEDIATE_ROOT/private/$1.key.pem" ]; then
		echo "==> Generating key for \"$1\""
		echo ''

		openssl genrsa -out "$INTERMEDIATE_ROOT/private/$1.key.pem" 4096
		chmod 400 "$INTERMEDIATE_ROOT/private/$1.key.pem"

		if [ ! -e "$INTERMEDIATE_ROOT/private/$1.key.pem" ]; then
			echo "=x=> Key was not created!"
			return 1
		fi
	fi

	echo "==> Generating CSR for \"$1\""
	echo ''

	openssl req -config "$CSRCFG" \
	    -key "$INTERMEDIATE_ROOT/private/$1.key.pem" \
	    -new -sha256 -out "$INTERMEDIATE_ROOT/csr/$1.csr.pem"

	if [ ! -e "$INTERMEDIATE_ROOT/csr/$1.csr.pem" ]; then
		echo "=x=> CSR was not created!"
		return 1
	fi

	echo "==> Generating certificate for \"$1\""
	echo ''

	openssl ca -config "$INTERMEDIATE_ROOT/openssl.cfg" \
	    -extensions "$2" -days 375 -notext -md sha256 \
	    -in "$INTERMEDIATE_ROOT/csr/$1.csr.pem" \
	    -out "$INTERMEDIATE_ROOT/certs/$1.cert.pem"

	if [ ! -e "$INTERMEDIATE_ROOT/certs/$1.cert.pem" ]; then
		echo "=x=> Certificate was not created!"
		return 1
	fi

	chmod 444 "$INTERMEDIATE_ROOT/certs/$1.cert.pem"

	echo "==> Done."
	echo "==> Key:  $INTERMEDIATE_ROOT/private/$1.key.pem"
	echo "==> Cert: $INTERMEDIATE_ROOT/certs/$1.cert.pem"
}

revokeCertificate() {
	if [ ! -e "$CA_ROOT" ]; then
		echo "=x=> Certificate root was not found."
		return 1
	elif [ ! -e "$INTERMEDIATE_ROOT/openssl.cfg" ]; then
		echo "=x=> Intermediate certificate configuration was not found."
		return 1
	fi

	if [ -z "$1" ]; then
		echo "=x=> Please provide a name for a certificate to revoke."
		return 1
	fi

	cd "$CA_ROOT"

	echo "==> Revoking certificate"

	openssl ca -config "$INTERMEDIATE_ROOT/openssl.cfg" \
	    -revoke "$INTERMEDIATE_ROOT/certs/$1.cert.pem"

	echo "==> Done."
}

printInfo () {
	if [ ! -e "$CA_ROOT" ]; then
		echo "=x=> Certificate root was not found."
		return 1
	elif [ ! -e "$INTERMEDIATE_ROOT/openssl.cfg" ]; then
		echo "=x=> Intermediate certificate configuration was not found."
		return 1
	fi

	if [ -n "$1" ]; then
		openssl x509 -noout -text -in "$CA_ROOT/intermediate/certs/$1.cert.pem"
		return 0
	fi

	echo "=> Root certificate"
	openssl x509 -noout -text -in "$CA_ROOT/certs/ca.cert.pem"

	echo "=> Intermediate certificate"
	openssl x509 -noout -text \
	      -in "$CA_ROOT/intermediate/certs/intermediate.cert.pem"

	openssl verify -CAfile "$CA_ROOT/certs/ca.cert.pem" \
	      "$CA_ROOT/intermediate/certs/intermediate.cert.pem"

	echo ""
	echo "==> Paths"
	echo "Root: $CA_ROOT"
	echo "Intermediate: $CA_ROOT/intermediate"
	echo ""

	echo "Root Key: $CA_ROOT/private/ca.key.pem"
	echo "Root Cert: $CA_ROOT/certs/ca.cert.pem"

	echo "CA Key: $CA_ROOT/intermediate/private/intermediate.key.pem"
	echo "Chain: $CA_ROOT/intermediate/certs/ca-chain.cert.pem"
	echo ""
}

printHelp () {
	echo "Usage: ./ca <CA Path> info | wizard | root | intm | revoke [<name>] | new [<name>] [ server_cert | usr_cert ] [ openssl.cfg ]"
	echo -e "    info\t- Print information about your CA"
	echo -e "    wizard\t- Create a new CA"
	echo -e "    root\t- Generate root certificate. For use when wizard fails."
	echo -e "    intm\t- Generate intermediate certificate. For use when wizard fails."
	echo -e "    new \t- Create a new certificate signed with your CA. Can also be used for renewal."
	echo -e "    revoke\t- Revoke a certificate by name"
}

set -e
case "$2" in
	"info")
		printInfo $3
	;;
	"wizard" | "generate" | "newca")
		echo "==> Proceeding with full generation for path $1"
		deployFiles
		generateRootPair
		generateIntermediate
		printInfo
	;;
	"files")
		deployFiles
	;;
	"rootpair" | "root")
		generateRootPair
	;;
	"intermediate" | "intm")
		generateIntermediate
	;;
	"certificate" | "cert" | "new" | "renew")
		createCertificate $3 $4 $5
	;;
	"revoke")
		revokeCertificate $3
	;;
	"help")
		printHelp
	;;
	*)
		echo "Usage: ./ca <CA Path> info | wizard | root | intm | revoke [<name>] | new [<name>] [ server_cert | usr_cert ] [ openssl.cfg ]"
	;;
esac