Ubuntu OpenSSL如何配置CA

在Ubuntu上配置OpenSSL作为CA（证书颁发机构）涉及几个步骤。以下是一个基本的指南：

1. 安装OpenSSL

首先，确保你已经安装了OpenSSL。如果没有安装，可以使用以下命令进行安装：

sudo apt update
sudo apt install openssl

2. 创建CA目录结构

创建一个目录来存放CA的文件，并设置适当的权限：

mkdir -p /etc/ssl/CA
chmod 700 /etc/ssl/CA

3. 创建CA配置文件

创建一个CA配置文件/etc/ssl/openssl.cnf，并添加以下内容：

[ ca ]
default_ca = CA_default

[ CA_default ]
dir               = /etc/ssl/CA
certs             = $dir/certs
crl_dir           = $dir/crl
new_certs_dir     = $dir/newcerts
database          = $dir/index.txt
serial            = $dir/serial
RANDFILE          = $dir/private/.rand

private_key       = $dir/private/ca.key
certificate       = $dir/cacert.pem

crlnumber         = $dir/crlnumber
crl               = $dir/crl.pem
crl_extensions    = crl_ext
default_crl_days  = 30

default_md        = sha256

name_opt          = ca_default
cert_opt          = ca_default
default_days      = 3650
preserve          = no
policy            = policy_strict

[ policy_strict ]
countryName             = match
stateOrProvinceName     = match
organizationName        = match
organizationalUnitName  = optional
commonName              = supplied
emailAddress            = optional

[ req ]
default_bits        = 2048
distinguished_name  = req_distinguished_name
string_mask         = utf8only

[ req_distinguished_name ]
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 ]
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid:always,issuer
basicConstraints = critical, CA:true
keyUsage = critical, digitalSignature, cRLSign, keyCertSign

4. 创建CA私钥

生成CA的私钥：

sudo openssl genpkey -algorithm RSA -out /etc/ssl/CA/private/ca.key -aes256
sudo chmod 400 /etc/ssl/CA/private/ca.key

5. 创建CA证书

使用私钥生成CA证书：

sudo openssl req -config /etc/ssl/openssl.cnf -key /etc/ssl/CA/private/ca.key -new -x509 -days 3650 -sha256 -extensions v3_ca -out /etc/ssl/CA/cacert.pem
sudo chmod 444 /etc/ssl/CA/cacert.pem

6. 创建证书索引文件和序列号文件

创建证书索引文件和序列号文件：

echo 1000 > /etc/ssl/CA/serial
touch /etc/ssl/CA/index.txt

7. 创建CRL文件

创建一个空的CRL文件：

sudo openssl ca -gencrl -out /etc/ssl/CA/crl.pem

8. 验证CA配置

验证CA配置是否正确：

sudo openssl ca -config /etc/ssl/openssl.cnf -extensions v3_ca -days 3650 -notext -md sha256

9. 使用CA签发证书

现在你可以使用这个CA来签发证书。创建一个请求文件request.pem：

sudo openssl req -new -keyout server.key -out request.pem -subj "/C=US/ST=State/L=City/O=Organization/CN=CommonName"

然后使用CA签发证书：

sudo openssl ca -config /etc/ssl/openssl.cnf -extensions server_cert -days 365 -notext -md sha256 -in request.pem -out server.crt

10. 验证签发的证书

验证签发的证书：

sudo openssl x509 -in server.crt -text -noout

通过以上步骤，你就可以在Ubuntu上配置一个基本的OpenSSL CA，并使用它来签发证书。