How to generate a custom certificate that dotnet core recognizes as a valid certificate on Windows.
Note: This is an updated version that generates valid certificates on Windows, if using other OS the steps in this guide can be used down to question "Install as dev cert?", the installation of certificate need to be handle different on each OS. Use the original guide for generating certs with dotnet devcerts.
When running Litium Apps in containers (docker) the localhost domain will always point to the container itself and can't be used in the communication between the app and Litium. To solve the communication between the app and Litium, we will use a custom domain that resolves to the host of the container, see dns-resolver on shared dependencies.
To be able to use custom domain names with dotnet core's inbuilt webserver; Kestrel, you must generate your own certificate. In this article, we will use the testing domain name localtest.me. What is special with localtest.me domain is that all sub-domains will point to your local machine.
Before starting ensure that the following is installed:
- Docker client
- Powershell or Powershell Core
To be able to generate your own certificate you need to create two different templates, one for your local CA and one for the certificate.
Prepared files can be downloaded and are prefered to use, when copying from the browser sometimes the formatting of the content will be wrong that will make the generation to fail:
Create a file with the name ca.txt with the following content, this will be used as the input to the certificate generation. The content in the template can be changed to make it work for other domains that you want to use.
[ req ]
distinguished_name = req_distinguished_name
x509_extensions = v3_ca
[ req_distinguished_name ]
commonName = Common Name (e.g. server FQDN or YOUR name)
commonName_default = Dev CA
commonName_max = 64
[ v3_ca ]
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid:always,issuer
basicConstraints = critical,CA:true
nsComment = "Dev CA"
Create a file with the name localhost.txt with the following content, this will be used as the input to the certificate generation. The content in the template can be changed to make it work for other domains that you want to use.
[ req ]
distinguished_name = req_distinguished_name
x509_extensions = user_crt
req_extensions = v3_req
[ req_distinguished_name ]
commonName = Common Name (e.g. server FQDN or YOUR name)
commonName_default = localhost
commonName_max = 64
[ v3_req ]
subjectAltName = @alt_names
basicConstraints = critical, CA:false
keyUsage = nonRepudiation, digitalSignature, keyEncipherment
extendedKeyUsage = serverAuth
1.3.6.1.4.1.311.84.1.1 = DER:02
[ user_crt ]
nsCertType = client, email, objsign
nsComment = "dotnet DevCert"
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid,issuer
subjectAltName = @alt_names
extendedKeyUsage = serverAuth
1.3.6.1.4.1.311.84.1.1 = DER:02
[ alt_names ]
DNS.1 = localhost
DNS.2 = 127.0.0.1
DNS.3 = *.localtest.me
DNS.4 = *.docker.internal
When we have the certificate template we will use OpenSSL to generate the certificate, we will run the certificate generation inside docker and export the generated certificate.
Execute the following commands to generate the certificate and installing that as a developing certificate with the dev-certs tool. To succeed you need to accept the confirmation dialogs. If you want to use the certificate with IIS, run the scripts as administrator.
$p = $PSScriptRoot; if ("" -eq $p) { $p = (Get-Location) };
$s = [System.Guid]::NewGuid()
Write-Host "Generated password: $s" -ForegroundColor DarkGreen
Set-Content $p -Path $p/generated-secret.txt -NoNewline | Out-Null
Write-Host "Generating CA Key" -ForegroundColor DarkGreen
docker run --rm -t -it -v "$($p):/data:rw" alpine/openssl `
genrsa `
-des3 `
-out /data/generated-ca.key `
-passout pass:$s `
2048
if ($LASTEXITCODE -ne 0) { return; }
Write-Host "Generating CA cert" -ForegroundColor DarkGreen
docker run --rm -t -it -v "$($p):/data:rw" alpine/openssl `
req `
-x509 `
-new `
-nodes `
-key /data/generated-ca.key `
-sha256 `
-days 3650 `
-out /data/generated-ca.pem `
-subj "/CN=Dev CA" `
-config /data/ca.txt `
-passin pass:$s
if ($LASTEXITCODE -ne 0) { return; }
if ($DebugPreference -eq "Continue") {
Write-Host "Display CA cert" -ForegroundColor DarkGreen
docker run --rm -t -it -v "$($p):/data:rw" alpine/openssl `
x509 -text -noout -in /data/generated-ca.pem
if ($LASTEXITCODE -ne 0) { return; }
}
Write-Host "Generating dev key" -ForegroundColor DarkGreen
docker run --rm -t -it -v "$($p):/data:rw" alpine/openssl `
genrsa `
-out /data/generated-localhost.key `
-passout pass:$s `
2048
if ($LASTEXITCODE -ne 0) { return; }
Write-Host "Generating dev cert" -ForegroundColor DarkGreen
docker run --rm -t -it -v "$($p):/data:rw" alpine/openssl `
req `
-new `
-key /data/generated-localhost.key `
-out /data/generated-localhost.csr `
-config /data/localhost.txt `
-subj "/CN=localhost"
if ($LASTEXITCODE -ne 0) { return; }
if ($DebugPreference -eq "Continue") {
Write-Host "Display dev csr" -ForegroundColor DarkGreen
docker run --rm -t -it -v "$($p):/data:rw" alpine/openssl `
req -text -noout -verify -in /data/generated-localhost.csr
if ($LASTEXITCODE -ne 0) { return; }
}
Write-Host "Signing dev cert" -ForegroundColor DarkGreen
docker run --rm -t -it -v "$($p):/data:rw" alpine/openssl `
x509 `
-req `
-days 3650 `
-CA /data/generated-ca.pem `
-CAkey /data/generated-ca.key `
-CAcreateserial `
-in /data/generated-localhost.csr `
-out /data/generated-localhost.crt `
-extensions user_crt `
-extfile /data/localhost.txt `
-passin pass:$s
if ($LASTEXITCODE -ne 0) { return; }
if ($DebugPreference -eq "Continue") {
Write-Host "Display dev cert" -ForegroundColor DarkGreen
docker run --rm -t -it -v "$($p):/data:rw" alpine/openssl `
x509 -text -noout -in /data/generated-localhost.crt
if ($LASTEXITCODE -ne 0) { return; }
}
Write-Host "Exporting dev cert" -ForegroundColor DarkGreen
docker run --rm -t -it -v "$($p):/data:rw" alpine/openssl `
pkcs12 -export `
-out /data/generated-localhost.pfx `
-inkey /data/generated-localhost.key `
-in /data/generated-localhost.crt `
-name "ASP.NET Core HTTPS development certificate" `
-passout pass:$s
if ($LASTEXITCODE -ne 0) { return; }
if ($DebugPreference -eq "Continue") {
Write-Host "Display dev pfx" -ForegroundColor DarkGreen
docker run --rm -t -it -v "$($p):/data:rw" alpine/openssl `
pkcs12 -info -in /data/generated-localhost.pfx -passin pass:$s -nokeys -nocerts
if ($LASTEXITCODE -ne 0) { return; }
}
if ($env:Os -eq "Windows_NT" -or $IsWindows) {
$r = (Read-Host -Prompt "Install as dev cert? [Y/n]")
if ("" -eq $r -or "y" -eq $r -or "Y" -eq $r) {
$sp = (ConvertTo-SecureString $s -AsPlainText -Force)
Import-Certificate `
-FilePath $p/generated-ca.pem `
-CertStoreLocation cert:\CurrentUser\Root
if ($LASTEXITCODE -ne 0) { return; }
Import-PfxCertificate `
-FilePath $p/generated-localhost.pfx `
-Password $sp `
-Exportable `
-CertStoreLocation cert:\CurrentUser\My
if ($LASTEXITCODE -ne 0) { return; }
dotnet dev-certs https --trust
if ($LASTEXITCODE -ne 0) { return; }
if (Test-Path "$Env:APPDATA\ASP.NET\Https") {
Remove-Item "$Env:APPDATA\ASP.NET\Https\*"
if ($LASTEXITCODE -ne 0) { return; }
}
$myWindowsID = [System.Security.Principal.WindowsIdentity]::GetCurrent();
$myWindowsPrincipal = New-Object System.Security.Principal.WindowsPrincipal($myWindowsID);
$adminRole = [System.Security.Principal.WindowsBuiltInRole]::Administrator;
if ($myWindowsPrincipal.IsInRole($adminRole)) {
$r = (Read-Host -Prompt "Install machine wide to be used with IIS? [Y/n]")
if ("" -eq $r -or "y" -eq $r -or "Y" -eq $r) {
$sp = (ConvertTo-SecureString $s -AsPlainText -Force)
Import-Certificate `
-FilePath ./generated-ca.pem `
-CertStoreLocation cert:\LocalMachine\Root
if ($LASTEXITCODE -ne 0) { return; }
Import-PfxCertificate `
-FilePath ./generated-localhost.pfx `
-Password $sp `
-CertStoreLocation cert:\LocalMachine\My
if ($LASTEXITCODE -ne 0) { return; }
}
}
}
Remove-Item -Path "$($p)/generated-*" -Recurse -Force | Out-Null
}
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