(VB.NET) Generate a CSR with keyUsage, extKeyUsage, and other Extensions

See more CSR Examples

Demonstrates how to generate a CSR containing a 1.2.840.113549.1.9.14 extensionRequest with the following extensions:

• 1.3.6.1.4.1.311.20.2 enrollCerttypeExtension
• 2.5.29.15 keyUsage
• 2.5.29.37 extKeyUsage
• 2.5.29.14 subjectKeyIdentifier

Chilkat .NET Downloads Chilkat .NET Framework Chilkat for .NET Core

' This requires the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

' This example will generate a secp256r1 ECDSA key for the CSR.
Dim ecc As New Chilkat.Ecc
Dim prng As New Chilkat.Prng

Dim privKey As Chilkat.PrivateKey = ecc.GenEccKey("secp256r1",prng)
If (ecc.LastMethodSuccess = False) Then
    Debug.WriteLine("Failed to generate a new ECDSA private key.")
    Exit Sub
End If


Dim csr As New Chilkat.Csr

' Add common CSR fields:
csr.CommonName = "mysubdomain.mydomain.com"
csr.Country = "GB"
csr.State = "Yorks"
csr.Locality = "York"
csr.Company = "Internet Widgits Pty Ltd"
csr.EmailAddress = "support@mydomain.com"

' Add the following 1.2.840.113549.1.9.14 extensionRequest
' Note: The easiest way to know the content and format of the XML to be added is to examine
' a pre-existing CSR with the same desired extensionRequest.  You can use Chilkat to
' get the extensionRequest from an existing CSR. 

' 
' Here is a sample extension request:

' <?xml version="1.0" encoding="utf-8"?>
' <set>
'     <sequence>
'         <sequence>
'             <oid>1.3.6.1.4.1.311.20.2</oid>
'             <asnOctets>
'                 <universal tag="30" constructed="0">AEUAbgBkAEUAbgB0AGkAdAB5AEMAbABpAGUAbgB0AEEAdQB0AGgAQwBlAHIAdABpAGYAaQBjAGEAdABl
' AF8AQwBTAFIAUABhAHMAcwB0AGgAcgBvAHUAZwBoAC8AVgAx</universal>
'             </asnOctets>
'         </sequence>
'         <sequence>
'             <oid>2.5.29.15</oid>
'             <bool>1</bool>
'             <asnOctets>
'                 <bits n="3">A0</bits>
'             </asnOctets>
'         </sequence>
'         <sequence>
'             <oid>2.5.29.37</oid>
'             <asnOctets>
'                 <sequence>
'                     <oid>1.3.6.1.5.5.7.3.3</oid>
'                 </sequence>
'             </asnOctets>
'         </sequence>
'         <sequence>
'             <oid>2.5.29.14</oid>
'             <asnOctets>
'                 <octets>MCzBMQAViXBz8IDt8LsgmJxJ4Xg=</octets>
'             </asnOctets>
'         </sequence>
'     </sequence>
' </set>

' Use this online tool to generate code from sample XML: 
' Generate Code to Create XML

' A few notes:
' The string "AEUAbgBkAEUAbgB0AGkAdAB5AEMAbABpAGUAbgB0AEEAdQB0AGgAQwBlAHIAdABpAGYAaQBjAGEAdABlAF8AQwBTAFIAUABhAHMAcwB0AGgAcgBvAHUAZwBoAC8AVgAx"
' is the base64 encoding of the utf-16be byte representation of the string "EndEntityClientAuthCertificate_CSRPassthrough/V1"

Dim s As String = "EndEntityClientAuthCertificate_CSRPassthrough/V1"
Dim bdTemp As New Chilkat.BinData
bdTemp.AppendString(s,"utf-16be")
Dim s_base64_utf16be As String = bdTemp.GetEncoded("base64")
' The string should be "AEUA....."
Debug.WriteLine(s_base64_utf16be)


' Here's the code to generate the above extension request.

Dim xml As New Chilkat.Xml
xml.Tag = "set"
xml.UpdateChildContent("sequence|sequence|oid","1.3.6.1.4.1.311.20.2")
xml.UpdateAttrAt("sequence|sequence|asnOctets|universal",True,"tag","30")
xml.UpdateAttrAt("sequence|sequence|asnOctets|universal",True,"constructed","0")
xml.UpdateChildContent("sequence|sequence|asnOctets|universal",s_base64_utf16be)
xml.UpdateChildContent("sequence|sequence[1]|oid","2.5.29.15")
xml.UpdateChildContent("sequence|sequence[1]|bool","1")
xml.UpdateAttrAt("sequence|sequence[1]|asnOctets|bits",True,"n","3")
' A0 is hex for decimal 160.
xml.UpdateChildContent("sequence|sequence[1]|asnOctets|bits","A0")
xml.UpdateChildContent("sequence|sequence[2]|oid","2.5.29.37")
xml.UpdateChildContent("sequence|sequence[2]|asnOctets|sequence|oid","1.3.6.1.5.5.7.3.3")

' This is the subjectKeyIdentifier extension.
' The string "MCzBMQAViXBz8IDt8LsgmJxJ4Xg=" is base64 that decodes to 20 bytes, which is a SHA1 hash.
' This is simply a hash of the DER of the public key.

Dim pubKey As Chilkat.PublicKey = privKey.GetPublicKey()
Dim bdPubKeyDer As New Chilkat.BinData
bdPubKeyDer.AppendEncoded(pubKey.GetEncoded(True,"base64"),"base64")
Dim ski As String = bdPubKeyDer.GetHash("sha1","base64")


xml.UpdateChildContent("sequence|sequence[3]|oid","2.5.29.14")
xml.UpdateChildContent("sequence|sequence[3]|asnOctets|octets",ski)

' Add the extension request to the CSR
csr.SetExtensionRequest(xml)

' Generate the CSR with the extension request
Dim csrPem As String = csr.GenCsrPem(privKey)
If (csr.LastMethodSuccess = False) Then
    Debug.WriteLine(csr.LastErrorText)

    Exit Sub
End If


Debug.WriteLine(csrPem)