(Lianja) 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

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// 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.
loEcc = createobject("CkEcc")
loPrng = createobject("CkPrng")

loPrivKey = loEcc.GenEccKey("secp256r1",loPrng)
if (loEcc.LastMethodSuccess = .F.) then
    ? "Failed to generate a new ECDSA private key."
    release loEcc
    release loPrng
    return
endif

loCsr = createobject("CkCsr")

// Add common CSR fields:
loCsr.CommonName = "mysubdomain.mydomain.com"
loCsr.Country = "GB"
loCsr.State = "Yorks"
loCsr.Locality = "York"
loCsr.Company = "Internet Widgits Pty Ltd"
loCsr.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"
loBdTemp = createobject("CkBinData")
loBdTemp.AppendString(s,"utf-16be")
lcS_base64_utf16be = loBdTemp.GetEncoded("base64")
// The string should be "AEUA....."
? lcS_base64_utf16be

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

loXml = createobject("CkXml")
loXml.Tag = "set"
loXml.UpdateChildContent("sequence|sequence|oid","1.3.6.1.4.1.311.20.2")
loXml.UpdateAttrAt("sequence|sequence|asnOctets|universal",.T.,"tag","30")
loXml.UpdateAttrAt("sequence|sequence|asnOctets|universal",.T.,"constructed","0")
loXml.UpdateChildContent("sequence|sequence|asnOctets|universal",lcS_base64_utf16be)
loXml.UpdateChildContent("sequence|sequence[1]|oid","2.5.29.15")
loXml.UpdateChildContent("sequence|sequence[1]|bool","1")
loXml.UpdateAttrAt("sequence|sequence[1]|asnOctets|bits",.T.,"n","3")
// A0 is hex for decimal 160.
loXml.UpdateChildContent("sequence|sequence[1]|asnOctets|bits","A0")
loXml.UpdateChildContent("sequence|sequence[2]|oid","2.5.29.37")
loXml.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.

loPubKey = loPrivKey.GetPublicKey()
loBdPubKeyDer = createobject("CkBinData")
loBdPubKeyDer.AppendEncoded(loPubKey.GetEncoded(.T.,"base64"),"base64")
lcSki = loBdPubKeyDer.GetHash("sha1","base64")
release loPubKey

loXml.UpdateChildContent("sequence|sequence[3]|oid","2.5.29.14")
loXml.UpdateChildContent("sequence|sequence[3]|asnOctets|octets",lcSki)

// Add the extension request to the CSR
loCsr.SetExtensionRequest(loXml)

// Generate the CSR with the extension request
lcCsrPem = loCsr.GenCsrPem(loPrivKey)
if (loCsr.LastMethodSuccess = .F.) then
    ? loCsr.LastErrorText
    release loPrivKey
    release loEcc
    release loPrng
    release loCsr
    release loBdTemp
    release loXml
    release loBdPubKeyDer
    return
endif

? lcCsrPem

release loPrivKey


release loEcc
release loPrng
release loCsr
release loBdTemp
release loXml
release loBdPubKeyDer