(C) Get Public Key from CSR

Demonstrates how to get the public key from a CSR.

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#include <C_CkPem.h>
#include <C_CkAsn.h>
#include <C_CkXml.h>
#include <C_CkBinData.h>
#include <C_CkPublicKey.h>

void ChilkatSample(void)
    {
    HCkPem pem;
    const char *noPassword;
    BOOL success;
    const char *strBase64;
    HCkAsn asn;
    HCkXml xml;
    const char *strModulusHex;
    HCkBinData bd;
    const char *modulus64;
    HCkXml xmlPubKey;
    HCkPublicKey pubkey;
    BOOL preferPkcs1;

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

    pem = CkPem_Create();

    // No password is required.  Pass an empty password string..
    noPassword = "";
    success = CkPem_LoadPemFile(pem,"qa_data/csr/csr2.pem",noPassword);
    if (success != TRUE) {
        printf("%s\n",CkPem_lastErrorText(pem));
        CkPem_Dispose(pem);
        return;
    }

    strBase64 = CkPem_getEncodedItem(pem,"csr","","base64",0);

    asn = CkAsn_Create();
    success = CkAsn_LoadEncoded(asn,strBase64,"base64");
    if (success != TRUE) {
        printf("%s\n",CkAsn_lastErrorText(asn));
        CkPem_Dispose(pem);
        CkAsn_Dispose(asn);
        return;
    }

    // Convert the ASN.1 to XML.
    xml = CkXml_Create();
    success = CkXml_LoadXml(xml,CkAsn_asnToXml(asn));
    printf("%s\n",CkXml_getXml(xml));
    printf("----\n");

    strModulusHex = CkXml_getChildContent(xml,"bits");
    printf("strModulusHex = %s\n",strModulusHex);
    printf("----\n");

    // We need the modulus as base64.
    bd = CkBinData_Create();
    CkBinData_AppendEncoded(bd,strModulusHex,"hex");
    modulus64 = CkBinData_getEncoded(bd,"base64");
    printf("modulus64 = %s\n",modulus64);
    printf("----\n");

    // Build the XML for the public key.
    xmlPubKey = CkXml_Create();
    CkXml_putTag(xmlPubKey,"RSAPublicKey");
    CkXml_UpdateChildContent(xmlPubKey,"Modulus",modulus64);
    // The RSA exponent will always be decimal 65537 (base64 = AQAB)
    CkXml_UpdateChildContent(xmlPubKey,"Exponent","AQAB");

    printf("RSA public key as XML:\n");
    printf("%s\n",CkXml_getXml(xmlPubKey));
    printf("----\n");

    // Load the XML into a Chilkat public key object.
    pubkey = CkPublicKey_Create();
    success = CkPublicKey_LoadFromString(pubkey,CkXml_getXml(xmlPubKey));
    if (success != TRUE) {
        printf("%s\n",CkPublicKey_lastErrorText(pubkey));
        CkPem_Dispose(pem);
        CkAsn_Dispose(asn);
        CkXml_Dispose(xml);
        CkBinData_Dispose(bd);
        CkXml_Dispose(xmlPubKey);
        CkPublicKey_Dispose(pubkey);
        return;
    }

    // Show the public key as PEM.
    preferPkcs1 = TRUE;
    printf("%s\n",CkPublicKey_getPem(pubkey,preferPkcs1));


    CkPem_Dispose(pem);
    CkAsn_Dispose(asn);
    CkXml_Dispose(xml);
    CkBinData_Dispose(bd);
    CkXml_Dispose(xmlPubKey);
    CkPublicKey_Dispose(pubkey);

    }