(C) 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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#include <C_CkEcc.h>
#include <C_CkPrng.h>
#include <C_CkPrivateKey.h>
#include <C_CkCsr.h>
#include <C_CkBinData.h>
#include <C_CkXml.h>
#include <C_CkPublicKey.h>

void ChilkatSample(void)
    {
    HCkEcc ecc;
    HCkPrng prng;
    HCkPrivateKey privKey;
    HCkCsr csr;
    const char *s;
    HCkBinData bdTemp;
    const char *s_base64_utf16be;
    HCkXml xml;
    HCkPublicKey pubKey;
    HCkBinData bdPubKeyDer;
    const char *ski;
    const char *csrPem;

    // 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 = CkEcc_Create();
    prng = CkPrng_Create();

    privKey = CkEcc_GenEccKey(ecc,"secp256r1",prng);
    if (CkEcc_getLastMethodSuccess(ecc) == FALSE) {
        printf("Failed to generate a new ECDSA private key.\n");
        CkEcc_Dispose(ecc);
        CkPrng_Dispose(prng);
        return;
    }

    csr = CkCsr_Create();

    // Add common CSR fields:
    CkCsr_putCommonName(csr,"mysubdomain.mydomain.com");
    CkCsr_putCountry(csr,"GB");
    CkCsr_putState(csr,"Yorks");
    CkCsr_putLocality(csr,"York");
    CkCsr_putCompany(csr,"Internet Widgits Pty Ltd");
    CkCsr_putEmailAddress(csr,"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 = CkBinData_Create();
    CkBinData_AppendString(bdTemp,s,"utf-16be");
    s_base64_utf16be = CkBinData_getEncoded(bdTemp,"base64");
    // The string should be "AEUA....."
    printf("%s\n",s_base64_utf16be);

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

    xml = CkXml_Create();
    CkXml_putTag(xml,"set");
    CkXml_UpdateChildContent(xml,"sequence|sequence|oid","1.3.6.1.4.1.311.20.2");
    CkXml_UpdateAttrAt(xml,"sequence|sequence|asnOctets|universal",TRUE,"tag","30");
    CkXml_UpdateAttrAt(xml,"sequence|sequence|asnOctets|universal",TRUE,"constructed","0");
    CkXml_UpdateChildContent(xml,"sequence|sequence|asnOctets|universal",s_base64_utf16be);
    CkXml_UpdateChildContent(xml,"sequence|sequence[1]|oid","2.5.29.15");
    CkXml_UpdateChildContent(xml,"sequence|sequence[1]|bool","1");
    CkXml_UpdateAttrAt(xml,"sequence|sequence[1]|asnOctets|bits",TRUE,"n","3");
    // A0 is hex for decimal 160.
    CkXml_UpdateChildContent(xml,"sequence|sequence[1]|asnOctets|bits","A0");
    CkXml_UpdateChildContent(xml,"sequence|sequence[2]|oid","2.5.29.37");
    CkXml_UpdateChildContent(xml,"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 = CkPrivateKey_GetPublicKey(privKey);
    bdPubKeyDer = CkBinData_Create();
    CkBinData_AppendEncoded(bdPubKeyDer,CkPublicKey_getEncoded(pubKey,TRUE,"base64"),"base64");
    ski = CkBinData_getHash(bdPubKeyDer,"sha1","base64");
    CkPublicKey_Dispose(pubKey);

    CkXml_UpdateChildContent(xml,"sequence|sequence[3]|oid","2.5.29.14");
    CkXml_UpdateChildContent(xml,"sequence|sequence[3]|asnOctets|octets",ski);

    // Add the extension request to the CSR
    CkCsr_SetExtensionRequest(csr,xml);

    // Generate the CSR with the extension request
    csrPem = CkCsr_genCsrPem(csr,privKey);
    if (CkCsr_getLastMethodSuccess(csr) == FALSE) {
        printf("%s\n",CkCsr_lastErrorText(csr));
        CkPrivateKey_Dispose(privKey);
        CkEcc_Dispose(ecc);
        CkPrng_Dispose(prng);
        CkCsr_Dispose(csr);
        CkBinData_Dispose(bdTemp);
        CkXml_Dispose(xml);
        CkBinData_Dispose(bdPubKeyDer);
        return;
    }

    printf("%s\n",csrPem);

    CkPrivateKey_Dispose(privKey);


    CkEcc_Dispose(ecc);
    CkPrng_Dispose(prng);
    CkCsr_Dispose(csr);
    CkBinData_Dispose(bdTemp);
    CkXml_Dispose(xml);
    CkBinData_Dispose(bdPubKeyDer);

    }