sejong.jeonjo@gmail.com

참고하면 좋은 Web Docs:

https://www.lesstif.com/software-architect/openssl-command-tip-7635159.html#OpenSSL%EC%9E%90%EC%A3%BC%EC%93%B0%EB%8A%94%EB%AA%85%EB%A0%B9%EC%96%B4(command)%EB%B0%8F%EC%82%AC%EC%9A%A9%EB%B2%95,tip%EC%A0%95%EB%A6%AC-%EC%9D%B8%EC%A6%9D%EC%84%9C%EC%A0%95%EB%B3%B4%EB%B3%B4%EA%B8%B0

openssl command cheat sheet

## Certificate Expiry 확인
$  openssl x509 -in my.crt -noout -enddate | cut -c10-40

## File 내용 확인
$ openssl rsa  -noout -text -in myprivate.key    # private key file
$ openssl req  -noout -text -in myreq.csr        # singing request file
$ openssl x509 -noout -text -in mycert.crt       # certificate file

## cerficate과 private key가 쌍이 맞는지 확인
$ openssl rsa  -in myprivate.key -modulus -noout | openssl md5
$ openssl x509 -in mycert.crt    -modulus -noout | openssl md5
$ openssl req  -in myreq.csr     -modulus -noout | openssl md5

Private Key를 생성하고,  Signing 요청하는 것은 아래 내용을 참고할 것!

Certficate 파일과 Private Key 파일의 Format 변환(DER/PEM)은 아래 내용을 참고할 것!

공인된 CA가 아닌, 내가 CA가 되서 openssl 명령을 이용하여 Private Key를 Signing하고 Certificate을 생성하는 절차를 알아보자.

(2~3년에 한번씩 하는 작업이라서 메모하지 않으면 잊는다. 잘 메모해야지.. ㅠㅠ)

아래 예시 순서대로 따라서 실행하면 된다.

CA Certificate, Server Certificate 만들기

######################################################################
## 1)   Generate a Certificate Authority Certificate (CA Certificate)
######################################################################

##
## 1-a) Generate a CA certificate private key
##
$  openssl genrsa -out ca.key 4096

##
## 1-b) Generate the CA certificate
##
$  openssl req -x509 -new -nodes -sha512 -days 3650 \
    -subj "/C=CN/ST=Seoul/L=Seoul/O=AndrewInc/OU=Personal/CN=sejong.cluster" \
    -key ca.key \
    -out ca.crt



######################################################################
## 2)   Generate a Server Certificate
######################################################################

##
## 2-a) Generate a private key
##
$  openssl genrsa -out sejong.cluster.key 4096

##
## 2-b) Generate a certificate signing request (CSR).
##
$  openssl req -sha512 -new \
    -subj "/C=CN/ST=Seoul/L=Seoul/O=AndrewInc/OU=Personal/CN=sejong.cluster" \
    -key sejong.cluster.key \
    -out sejong.cluster.csr

##
## 2-c) Generate an x509 v3 extension file.
##
$  cat << EOF > v3.ext

authorityKeyIdentifier=keyid,issuer
basicConstraints=CA:FALSE
keyUsage = digitalSignature, nonRepudiation, keyEncipherment, dataEncipherment
extendedKeyUsage = serverAuth
subjectAltName = @alt_names

[alt_names]
DNS.1=sejong.cluster
DNS.2=sejong
DNS.3=registry
DNS.4=registry.sejong.cluster
DNS.5=10.1.4.51
DNS.6=registry.andrewinc.co.kr
EOF

$

##
## 2-d) Use the v3.ext file to generate a certificate for your server host.
##
$  openssl x509 -req -sha512 -days 3650 \
    -extfile v3.ext \
    -CA ca.crt -CAkey ca.key -CAcreateserial \
    -in sejong.cluster.csr \
    -out sejong.cluster.crt



######################################################################
## 3)   Merge the intermediate certificate with your own certificate 
##      to create a certificate bundle
######################################################################
## 참고로, 아래 명령은 Ubuntu에서만 가능한 명령이다. 
$  cp sejong.cluster.crt /usr/local/share/ca-certificates/sejong.cluster.crt
$  update-ca-certificates

## CentOS, Red Hat(RHEL)을 사용한다면, 위 명령 대신 아래 명령을 수행해야 한다.
$  cp sejong.cluster.crt /etc/pki/ca-trust/source/anchors/sejong.cluster.crt
$  update-ca-trust

Server Certificate  내용 확인

$  openssl x509 -in /usr/local/share/ca-certificates/sejong.cluster.crt -noout -text

Certificate:
    Data:
        Version: 3 (0x2)
        ... 중간 생략 ...
        Signature Algorithm: sha512WithRSAEncryption
        Issuer: C = KR, ST = Seoul, L = Seoul, O = MyCompany OU = Personal, CN = sejong.cluster
        Validity
            Not Before: Dec 21 04:08:37 2022 GMT
            Not After : Dec 18 04:08:37 2032 GMT
        Subject: C = KR, ST = Seoul, L = Seoul, O = MyCompany, OU = Personal, CN = sejong.cluster
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (4096 bit)
                Modulus:
                    00:bd:07:06:cb:ee:e9:0b:5a:51:bb:cc:a3:5c:a0:
                    ... 중간 생략 ...
                    ad:18:05
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Authority Key Identifier:
                ... 중간 생략 ...
            X509v3 Basic Constraints:
                ... 중간 생략 ...
            X509v3 Key Usage:
                Digital Signature, Non Repudiation, Key Encipherment, Data Encipherment
            X509v3 Extended Key Usage:
                TLS Web Server Authentication
            X509v3 Subject Alternative Name:
                DNS:sejong.cluster, DNS:sejong, DNS:registry, DNS:registry.sejong.cluster, DNS:10.1.4.51
            X509v3 Subject Key Identifier:
                ... 중간 생략 ...
    Signature Algorithm: sha512WithRSAEncryption
    Signature Value:
        82:b9:5d:81:e7:90:85:20:08:8a:da:bb:a7:fc:30:fb:62:bf:
        ... 중간 생략 ...
        b4:64:b7:45:98:37:e8:f4
        
$