Linux自建CA及签发证书

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一，环境准备

1， 创建所需目录 

cd /etc/pki/
mkdir CA
cd CA
mkdir certs crl newcerts private

2，创建所需文件

创建证书起始序列号

echo 01 > serial

创建CA 签发证书列表文件

touch index.txt

创建openssl配置文件

vi openssl.cnf

内容如下：

[ ca ]
# `man ca`
default_ca = CA_default

[ CA_default ]
# Directory and file locations.
dir               = /etc/pki/CA
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      = 365
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        = 2048
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_extensions = v3_req

[ 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

# Optionally, specify some defaults.
countryName_default             = CN
stateOrProvinceName_default     = China
localityName_default            =
0.organizationName_default      = Dp2u
#organizationalUnitName_default =
#emailAddress_default           =

[ v3_req ]

# Extensions to add to a certificate request

basicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, keyEncipherment
subjectAltName = @alt_names

[ alt_names ]
DNS.1 = dp2u.com
DNS.2 = *.dp2u.com

[ 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
subjectAltName = @alt_names

[ 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

二，签发步骤

1，生成 CA

1.1 生成CA私钥

openssl ecparam -genkey -name prime256v1 |openssl ec -out private/ca.key.pem

1.2 生成CA根证书

openssl req -config openssl.cnf -key private/ca.key.pem -new -x509 -days 7300 -sha256 -extensions v3_ca -out certs/ca.cert.pem

生成过程中需要填写几个参数，示例如下：

Country Name (2 letter code) [CN]:
State or Province Name [China]:
Locality Name []:Beijing
Organization Name [Dp2u]:
Organizational Unit Name []:Dp2u Root CA
Common Name []:Dp2uROOTCA 
Email Address []:ops@dp2u.com

2. 生成服务器证书

2.1 生成服务器私钥

openssl ecparam -genkey -name prime256v1 |openssl ec -out private/node1.key.pem

2.2 生成服务器证书请求文件

openssl req -config openssl.cnf -new -key private/node1.key.pem -out certs/node1.csr.pem

生成过程中也需要回答几个参数，示例如下：

Country Name (2 letter code) [CN]:
State or Province Name [China]:
Locality Name []:Beijing
Organization Name [Dp2u]:
Organizational Unit Name []:Node1
Common Name []:node1.dp2u.com
Email Address []:ops@dp2u.com

2.3 签发服务器证书

openssl ca -config openssl.cnf -extensions server_cert -days 1095 -md sha256 -in certs/node1.csr.pem -out certs/node1.cert.pem

输出示例如下：

Using configuration from openssl.cnf
Check that the request matches the signature
Signature ok
Certificate Details:
        Serial Number: 1 (0x1)
        Validity
            Not Before: Feb 20 03:27:00 2019 GMT
            Not After : Feb 19 03:27:00 2022 GMT
        Subject:
            countryName               = CN
            stateOrProvinceName       = China
            organizationName          = Dp2u
            organizationalUnitName    = Node1
            commonName                = node1.dp2u.com
            emailAddress              = ops@dp2u.com
        X509v3 extensions:
            X509v3 Basic Constraints: 
                CA:FALSE
            Netscape Cert Type: 
                SSL Server
            Netscape Comment: 
                OpenSSL Generated Server Certificate
            X509v3 Subject Key Identifier: 
                8F:A2:F7:D3:B0:09:85:D7:65:22:C8:66:C7:50:7A:37:12:7A:A5:20
            X509v3 Authority Key Identifier: 
                keyid:1B:22:83:F0:8F:4B:32:B6:54:03:1D:80:8F:03:72:F8:25:B9:5B:5E
                DirName:/C=CN/ST=China/L=Beijing/O=Dp2u/OU=Dp2u Root CA/CN=Dp2uROOTCA/emailAddress=ops@dp2u.com
                serial:FB:09:DF:58:48:31:4C:6B

            X509v3 Key Usage: critical
                Digital Signature, Key Encipherment
            X509v3 Extended Key Usage: 
                TLS Web Server Authentication
            X509v3 Subject Alternative Name: 
                DNS:dp2u.com, DNS:*.dp2u.com
Certificate is to be certified until Feb 19 03:27:00 2022 GMT (1095 days)
Sign the certificate? [y/n]:y


1 out of 1 certificate requests certified, commit? [y/n]y
Write out database with 1 new entries
Data Base Updated

回答两个y就可以签发出服务器证书了

至此ca和服务器证书都已生成完毕

CA的根证书是 certs/ca.cert.pem

CA的证书私钥是 private/ca.key.pem

服务器的证书是 certs/node1.cert.pem

服务器的证书私钥是 private/node1.key.pem

校验服务器证书：

openssl verify -verbose -CAfile /etc/pki/CA/certs/ca.cert.pem node1.cert.pem

从服务器证书导出服务器公钥

openssl x509 -pubkey -noout -in node1.cert.pem > node1.pubkey.pem