(Xojo Plugin) Duplicate openssl req -newkey rsa:2048 -nodes -keyout mydomain.pem -out mydomain.csr

Demonstrates how to duplicate this OpenSSL command:

openssl req -newkey rsa:2048 -nodes -keyout mydomain.pem -out mydomain.csr

This command creates 2 files:

mydomain.csr: this is the file to send to DigiCert or Let's Encrypt (or any other CA)
mydomain.pem: this is the private key of the domain.

The second file is needed to pair with the certificate that will later be received from the CA.

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

Dim rsa As New Chilkat.Rsa

// Generate a 2048-bit key.  Chilkat RSA supports
// key sizes ranging from 512 bits to 8192 bits.
Dim success As Boolean
success = rsa.GenerateKey(2048)
If (success <> True) Then
    System.DebugLog(rsa.LastErrorText)
    Return
End If

Dim privKey As Chilkat.PrivateKey
privKey = rsa.ExportPrivateKeyObj()

// Save the private key to unencrypted PKCS8 PEM
success = privKey.SavePkcs8PemFile("mydomain.pem")

// (alternatively) Save the private key to encrypted PKCS8 PEM
success = privKey.SavePkcs8EncryptedPemFile("myPassword","mydomain_enc.pem")

// We'll need the private key's modulus for the CSR.
// The modulus is not something that needs to be protected.  Most people don't realize
// that a public key is actually just a subset of the private key.  The public parts of
// an RSA private key are the modulus and exponent.  The exponent is always 65537.
Dim privKeyXml As New Chilkat.Xml
success = privKeyXml.LoadXml(privKey.GetXml())

// Get the modulus in base64 format:
Dim keyModulus As String
keyModulus = privKeyXml.GetChildContent("Modulus")

// --------------------------------------------------------------------------------
// Now build the CSR using Chilkat's ASN.1 API.
// The keyModulus will be embedded within the ASN.1.

// A new ASN.1 object is automatically a SEQUENCE.
// Given that the CSR's root item is a SEQUENCE, we can use
// this as the root of our CSR.
Dim asnRoot As New Chilkat.Asn

// Beneath the root, we have a SEQUENCE (the certificate request info), 
// another SEQUENCE (the algorithm identifier), and a BITSTRING (the signature data)

success = asnRoot.AppendSequence()
success = asnRoot.AppendSequence()

// ----------------------------------
// Build the Certificate Request Info
// ----------------------------------
Dim asnCertReqInfo As Chilkat.Asn
asnCertReqInfo = asnRoot.GetSubItem(0)
success = asnCertReqInfo.AppendInt(0)

// Build the Subject part of the Certificate Request Info
Dim asnCertSubject As Chilkat.Asn
asnCertSubject = asnCertReqInfo.AppendSequenceR()

// Add each subject part..
Dim asnTemp As Chilkat.Asn
asnTemp = asnCertSubject.AppendSetR()
success = asnTemp.AppendSequence2()
// AppendSequence2 updates the internal reference to the newly appended SEQUENCE.
// The OID and printable string are added to the SEQUENCE.
success = asnTemp.AppendOid("2.5.4.6")
success = asnTemp.AppendString("printable","US")

asnTemp = asnCertSubject.AppendSetR()
success = asnTemp.AppendSequence2()
success = asnTemp.AppendOid("2.5.4.8")
success = asnTemp.AppendString("utf8","Utah")

asnTemp = asnCertSubject.AppendSetR()
success = asnTemp.AppendSequence2()
success = asnTemp.AppendOid("2.5.4.7")
success = asnTemp.AppendString("utf8","Lindon")

asnTemp = asnCertSubject.AppendSetR()
success = asnTemp.AppendSequence2()
success = asnTemp.AppendOid("2.5.4.10")
success = asnTemp.AppendString("utf8","DigiCert Inc.")

asnTemp = asnCertSubject.AppendSetR()
success = asnTemp.AppendSequence2()
success = asnTemp.AppendOid("2.5.4.11")
success = asnTemp.AppendString("utf8","DigiCert")

asnTemp = asnCertSubject.AppendSetR()
success = asnTemp.AppendSequence2()
success = asnTemp.AppendOid("2.5.4.3")
success = asnTemp.AppendString("utf8","example.digicert.com")

// Build the Public Key Info part of the Certificate Request Info
Dim asnPubKeyInfo As Chilkat.Asn
asnPubKeyInfo = asnCertReqInfo.AppendSequenceR()

Dim asnPubKeyAlgId As Chilkat.Asn
asnPubKeyAlgId = asnPubKeyInfo.AppendSequenceR()
success = asnPubKeyAlgId.AppendOid("1.2.840.113549.1.1.1")
success = asnPubKeyAlgId.AppendNull()

// The public key itself is a BIT STRING, but the bit string is composed of ASN.1
// for the RSA public key.  We'll first build the RSA ASN.1 for the public key
// (containing the 2048 bit modulus and exponent), and encoded it to DER, and then add
// the DER bytes as a BIT STRING (as a sub-item of asnPubKeyInfo)

// This is already a SEQUENCE..
Dim asnRsaKey As New Chilkat.Asn

// The RSA modulus is a big integer.
success = asnRsaKey.AppendBigInt(keyModulus,"base64")
success = asnRsaKey.AppendInt(65537)

Dim rsaKeyDerBase64 As String
rsaKeyDerBase64 = asnRsaKey.GetEncodedDer("base64")

// Now add the RSA key DER as a BIT STRING.
success = asnPubKeyInfo.AppendBits(rsaKeyDerBase64,"base64")

// The last part of the certificate request info is an empty context-specific constructed item
// with a tag equal to 0.
success = asnCertReqInfo.AppendContextConstructed(0)

// Get the DER of the asnCertReqInfo.  
// This will be signed using the RSA private key.
Dim bdDer As New Chilkat.BinData
success = asnCertReqInfo.WriteBd(bdDer)

// Add the signature to the ASN.1
Dim bdSig As New Chilkat.BinData
success = rsa.SignBd(bdDer,"SHA1",bdSig)
success = asnRoot.AppendBits(bdSig.GetEncoded("base64"),"base64")

// ----------------------------------
// Finally, add the algorithm identifier, which is the 2nd sub-item under the root.
// ----------------------------------
Dim asnAlgId As Chilkat.Asn
asnAlgId = asnRoot.GetSubItem(1)
success = asnAlgId.AppendOid("1.2.840.113549.1.1.5")
success = asnAlgId.AppendNull()

// Write the CSR to a DER encoded binary file:
success = asnRoot.WriteBinaryDer("qa_output/mydomain.csr")
If (success <> True) Then
    System.DebugLog(asnRoot.LastErrorText)
    Return
End If

// It is also possible to get the CSR in base64 format:
Dim csrBase64 As String
csrBase64 = asnRoot.GetEncodedDer("base64")

System.DebugLog("Base64 CSR:")
System.DebugLog(csrBase64)