使用 OpenSSL 生成 CA 与服务端客户端证书

准备默认 OpenSSL 配置文件于当前目录。此配置文件在 linux 系统下通常位于 /etc/pki/tls/openssl.cnf，在 mac 系统下通常位于 /System/Library/OpenSSL/openssl.cnf。

如果存在，则直接拷贝到当前目录，例如 cp /etc/pki/tls/openssl.cnf ./my-openssl.cnf。如果不存在可以使用下面的命令来创建。

cat > my-openssl.cnf << EOF
[ ca ]
default_ca = CA_default
[ CA_default ]
x509_extensions = usr_cert
[ req ]
default_bits        = 2048
default_md          = sha256
default_keyfile     = privkey.pem
distinguished_name  = req_distinguished_name
attributes          = req_attributes
x509_extensions     = v3_ca
string_mask         = utf8only
[ req_distinguished_name ]
[ req_attributes ]
[ usr_cert ]
basicConstraints       = CA:FALSE
nsComment              = "OpenSSL Generated Certificate"
subjectKeyIdentifier   = hash
authorityKeyIdentifier = keyid,issuer
[ v3_ca ]
subjectKeyIdentifier   = hash
authorityKeyIdentifier = keyid:always,issuer
basicConstraints       = CA:true
EOF

生成默认 ca:

1 2	openssl genrsa -out ca.key 2048 openssl req -x509 -new -nodes -key ca.key -subj "/CN=example.ca.com" -days 5000 -out ca.crt

生成 Server 证书:

openssl genrsa -out server.key 2048

openssl req -new -sha256 -key server.key \
    -subj "/C=XX/ST=DEFAULT/L=DEFAULT/O=DEFAULT/CN=server.com" \
    -reqexts SAN \
    -config <(cat my-openssl.cnf <(printf "\n[SAN]\nsubjectAltName=DNS:localhost,IP:127.0.0.1,DNS:example.server.com")) \
    -out server.csr

openssl x509 -req -days 365 -sha256 \
	-in server.csr -CA ca.crt -CAkey ca.key -CAcreateserial \
	-extfile <(printf "subjectAltName=DNS:localhost,IP:127.0.0.1,DNS:example.server.com") \
	-out server.crt

生成 Client的证书:

openssl genrsa -out client.key 2048
openssl req -new -sha256 -key client.key \
    -subj "/C=XX/ST=DEFAULT/L=DEFAULT/O=DEFAULT/CN=client.com" \
    -reqexts SAN \
    -config <(cat my-openssl.cnf <(printf "\n[SAN]\nsubjectAltName=DNS:client.com,DNS:example.client.com")) \
    -out client.csr

openssl x509 -req -days 365 -sha256 \
    -in client.csr -CA ca.crt -CAkey ca.key -CAcreateserial \
	-extfile <(printf "subjectAltName=DNS:client.com,DNS:example.client.com") \
	-out client.crt

在本例中，server.crt 和 client.crt 都是由默认 ca 签发的，因此他们对默认 ca 是合法的。