Creating SSL Certificate with Custom CA

Creating Default OpenSSL Config File

Creating Custom Root CA

Creating the CA key:
openssl genrsa -des3 -out root-CA.key 4096
Note: remove -des option to create key without password

Creating self sign CA certificate

openssl req -x509 -new -nodes -key root-CA.key -sha256 -days 3650 -out root-CA.crt `
    -subj "/C=ID/O=Dev lab/CN=Dev lab Root CA" `
    -addext 'keyUsage = cRLSign, keyCertSign, digitalSignature' `
    -addext 'extendedKeyUsage = critical, serverAuth, clientAuth, codeSigning, emailProtection, timeStamping' `
    -addext 'subjectKeyIdentifier=hash' `
    -addext 'authorityKeyIdentifier=keyid:always,issuer:always' `
    -addext "basicConstraints = critical, CA:TRUE"

Explanations:

subj
create unattended answer subject
basicConstraints
CA:TRUE means it's issuer
keyUsage
determine what's this cert for: certificate signing (keyCertSign), CRL signing (cRLSign), digital signature
extendedKeyUsage
an extended version of keyUsage: server authentication (serverAuth), client authentication (clientAuth), file/code signing (codeSigning), S/MIME signing (emailProtection), time stamping
subjectKeyIdentifier
identifier of this cert
authoritykKeyIdentifier

the identifier which signs the cert, if it's root cert, then it should be itself

Shorter version

openssl req -config openssl.cnf -x509 -new -nodes -key root-CA.key -out root-CA.crt -days 3650 -extensions ca_cert -subj "/C=ID/O=Dev Lab/CN=Dev Lab Root CA"

Reference: OpenSSL man page

Inspect root CA certificate
openssl x509 -noout -text -in root-CA.crt

Convert into PKCS12 (.pfx) format
openssl pkcs12 -export -name "Root CA" -out root-CA.pfx -inkey root-CA.key -in root-CA.crt
Then import the pfx file into local machine placed under Trusted Root Certification Authorities

Creating Intermediate CA

Creating the intermedia CA key
openssl genrsa -out server-CA.key 4096

Creating intermediate certificate request

openssl req -new -key server-CA.key -out server-CA.csr -subj "/C=ID/O=Dev Lab/OU=Development/CN=Dev Lab Server CA"

Sign the intermedia CA certificate's request with CA's key and cert:
openssl x509 -extfile openssl.cnf -req -in server-CA.csr -CA root-CA.crt -CAkey root-CA.key -CAcreateserial -out server-CA.crt -extensions ica_cert -days 3650

Inspect root CA certificate
openssl x509 -noout -text -in server-CA.crt

Convert into PKCS12 format
openssl pkcs12 -export -name "Dev lab Server CA" -inkey server-CA.key -in server-CA.crt -out server-CA.pfx
Then import the pfx file into local machine placed under Intermediate Certification Authorities

Creating User Certificate

Creating the certificate key
openssl genrsa -out dev.lab.key 2048

Before moving on, the openssl config is configured to accept subject alternate name from environment variable named SAN (see line 176), so you need to configure first, otherwise, it will fail: $Env:SAN = 'DNS:*.dev.lab, DNS:dev.lab'. You can set it to the same as CN if you don't want to assign it to wilcard domain. We can also assign it to IP address as follows: $Env:SAN = 'DNS:*.dev.lab,DNS:dev.lab,DNS:localhost,IP:127.0.0.1'. After that, we can continue to create certificate request

openssl req -new -key dev.lab.key -out dev.lab.csr -subj "/C=ID/ST=Jakarta/O=Dev Home/OU=Development/CN=*.dev.lab"

Sign the certificate request using server CA's key and certificate

openssl x509 -extfile openssl.cnf -extensions web_cert -req -CA server-CA.crt `
    -CAkey server-CA.key -CAcreateserial -days 365 `
    -in dev.lab.csr -out dev.lab.crt

Convert into PKCS12 format
openssl pkcs12 -export -name "dev.lab Certificate" -inkey dev.lab.key -in dev.lab.crt -out dev.lab.pfx

Import the .pfx file into local machine using default location.

Creating S/MIME Certificate

Creating the certificate key

openssl genrsa -out iroel-email.key 2048

Creating certificate request
openssl req -new -key iroel-email.key -out iroel-email.csr -subj "/C=ID/ST=Jakarta/CN=Fakhrulhilal Maktum/[email protected]" -addext "subjectAltName = email:[email protected], email:[email protected]"

Sign the certificate request using server CA's key and certificate

$Env:SAN = 'email:[email protected], email:[email protected]'
openssl x509 -extfile openssl.cnf -extensions smime_cert -req -CA server-CA.crt `
    -CAkey server-CA.key -CAcreateserial -setalias "Dev email certificate" `
    -in iroel-email.csr -out iroel-email.crt -trustout -days 365

Convert into PKCS12 format
openssl pkcs12 -export -name "wilcard.dev.lab Certificate" -inkey dev.lab.key -in dev.lab.crt -out dev.lab.pfx

Import the .pfx file into local machine using default location.

Installing Certificates

Installing CAs' Certificate

Install root certificate (root-CA.crt) to Trusted Root Certification Authorities in machine level
Install intermediate certificate (server-CA.crt) to Intermediate Certification Authorities

Install IIS Express Certificate

Install the certificate in Local Machine wide and in default location (Personal). Run this powershell with administrator privilege. Friendly name is -name parameter value when converting into PKCS12 format.

$Ports = @(44351)
$PfxPassword = 'pfx_password'
#$Certificate = Get-ChildItem Cert:\LocalMachine\My | ?{ $_.FriendlyName -eq 'localhost' }
$Certificate = Get-PfxCertificate -FilePath .\dev.lab.pfx -Password (ConvertTo-SecureString -String $PfxPassword -AsPlainText)
$IisExpress = Get-CimInstance Win32_Product -Filter 'Name like "IIS%Express%"'
$Ports | %{ 
    netsh http delete sslcert ipport=0.0.0.0:$Port
    netsh http add sslcert ipport=0.0.0.0:$Port  certhash="$($Certificate.Thumbprint)"  appid="$($IisExpress.IdentifyingNumber)"
}

Installing Kestrel Certificate

Using environment variable
ASPNETCORE_Kestrel__Certificates__Default__Path = path to pfx file
ASPNETCORE_Kestrel__Certificates__Default__Password = pfx's password
Using appsettings.json
json { "Kestrel": { "Certificates": { "Default": { "Path": "path/to/pfx/file", "Password": "pfx's password", /* or using .crt and key file */ /* "Path": "path/to/crt/file", "KeyPath": "path/to/key/file" */ } } } }
Reference: Configure endpoints for the ASP.NET Core Kestrel web server
Using dotnet tool: dotnet dev-certs https --clean -i .\dev.lab.pfx -p the_password