(PowerShell) 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 Assemblies

Add-Type -Path "C:\chilkat\ChilkatDotNet47-9.5.0-x64\ChilkatDotNet47.dll"

# 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.
$ecc = New-Object Chilkat.Ecc
$prng = New-Object Chilkat.Prng

$privKey = $ecc.GenEccKey("secp256r1",$prng)
if ($ecc.LastMethodSuccess -eq $false) {
    $("Failed to generate a new ECDSA private key.")
    exit
}

$csr = New-Object 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"

$s = "EndEntityClientAuthCertificate_CSRPassthrough/V1"
$bdTemp = New-Object Chilkat.BinData
$bdTemp.AppendString($s,"utf-16be")
$s_base64_utf16be = $bdTemp.GetEncoded("base64")
# The string should be "AEUA....."
$($s_base64_utf16be)

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

$xml = New-Object 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.

$pubKey = $privKey.GetPublicKey()
$bdPubKeyDer = New-Object Chilkat.BinData
$bdPubKeyDer.AppendEncoded($pubKey.GetEncoded($true,"base64"),"base64")
$ski = $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
$csrPem = $csr.GenCsrPem($privKey)
if ($csr.LastMethodSuccess -eq $false) {
    $($csr.LastErrorText)

    exit
}

$($csrPem)