Unicode C++

Azure Key Vault Sign with a Certificate's Private Key

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Signs a hash using the private key of a certificate previously imported to an Azure Key Vault. Unicode C++

#include <CkJsonObjectW.h>
#include <CkStringBuilderW.h>
#include <CkHttpW.h>
#include <CkHttpResponseW.h>
#include <CkCertW.h>
#include <CkRsaW.h>

void ChilkatSample(void)
    {
    bool success = false;

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

    // See Azure Key Vault Get Certificates for a more detailed explanation
    // for how Chilkat is automatically getting the OAuth2 access token for your application.

    // Provide information needed for Chilkat to automatically get an OAuth2 access token as needed.
    CkJsonObjectW json;
    json.UpdateString(L"client_id",L"APP_ID");
    json.UpdateString(L"client_secret",L"APP_PASSWORD");
    json.UpdateString(L"resource",L"https://vault.azure.net");
    json.UpdateString(L"token_endpoint",L"https://login.microsoftonline.com/TENANT_ID/oauth2/token");

    // In this example, we'll sign the SHA256 hash of the string "This is a test"
    CkStringBuilderW sb;
    const wchar_t *signedString = L"This is a test";
    sb.Append(signedString);
    const wchar_t *hash_base64url = sb.getHash(L"sha256",L"base64url",L"utf-8");

    // We're going to send a POST to the following URL:
    // POST {vaultBaseUrl}/keys/{key-or-cert-name}/{key-or-cert-version}/sign?api-version=7.4

    // For example:

    // POST https://VAULT_NAME.vault.azure.net/keys/CERT_NAME/CERT_VERSION/sign?api-version=7.4
    // 
    // {
    //   "alg": "RS512",
    //   "value": "RUE3Nzg4NTQ4QjQ5RjFFN0U2NzAyQzhDNEMwMkJDOTA1MTYyOTUzNjI5NDhBNzZDQTlFOTM1NDA2M0ZGMjk2Mg"
    // }

    // The alg can be one of the following
    // ES256  ECDSA using P-256 and SHA-256
    // ES256K ECDSA using P-256K and SHA-256
    // ES384  ECDSA using P-384 and SHA-384
    // ES512  ECDSA using P-521 and SHA-512
    // PS256  RSASSA-PSS using SHA-256 and MGF1 with SHA-256
    // PS384  RSASSA-PSS using SHA-384 and MGF1 with SHA-384
    // PS512  RSASSA-PSS using SHA-512 and MGF1 with SHA-512
    // RS256  RSASSA-PKCS1-v1_5 using SHA-256
    // RS384  RSASSA-PKCS1-v1_5 using SHA-384
    // RS512  RSASSA-PKCS1-v1_5 using SHA-512

    // The sample POST above uses SHA512.  We'll instead sign a SHA256 hash..

    CkJsonObjectW jsonBody;
    jsonBody.UpdateString(L"alg",L"RS256");
    jsonBody.UpdateString(L"value",hash_base64url);

    CkHttpW http;

    // Instead of providing an actual access token, we give Chilkat the information that allows it to 
    // automatically fetch the access token using the OAuth2 client credentials flow.
    http.put_AuthToken(json.emit());

    http.SetUrlVar(L"certName",L"importCert01");
    http.SetUrlVar(L"certVersion",L"7140c8755ed14839b5d86a9f7e7f0497");
    // Note: Replace "VAULT_NAME" with the name of your Azure key vault.
    const wchar_t *url = L"https://VAULT_NAME.vault.azure.net/keys/{$certName}/{$certVersion}/sign?api-version=7.4";
    CkHttpResponseW resp;
    success = http.HttpJson(L"POST",url,jsonBody,L"application/json",resp);
    if (success == false) {
        wprintf(L"%s\n",http.lastErrorText());
        return;
    }

    int statusCode = resp.get_StatusCode();

    CkJsonObjectW jsonResp;
    resp.GetBodyJson(jsonResp);

    jsonResp.put_EmitCompact(false);
    wprintf(L"%s\n",jsonResp.emit());

    if (statusCode != 200) {
        wprintf(L"Failed.\n");
        return;
    }

    // A successful response body contains JSON like this:
    // Note: Azure's documentation is not very clear, but base64url is the encoding, not "base64".
    // {
    //   "kid": "https://kvchilkat.vault.azure.net/keys/importCert01/7140c8755ed14839b5d86a9f7e7f0497",
    //   "value": "JzWd2YF21gjtW ... Em37hKOQ"
    // }

    // Let's validate the signature using the cert's public key.
    // This example will load the corresponding certificate from a local file and will verify the signature against the original data.
    // 
    CkCertW cert;
    success = cert.LoadFromFile(L"qa_data/certs/chilkat_code_signing_2024.cer");
    if (success == false) {
        wprintf(L"%s\n",cert.lastErrorText());
        return;
    }

    CkRsaW rsa;
    // Tell the RSA object to use the cert's public key.
    success = rsa.SetX509Cert(cert,false);
    if (success == false) {
        wprintf(L"%s\n",rsa.lastErrorText());
        return;
    }

    // Verify the signature using the cert's public key against the original string.
    rsa.put_EncodingMode(L"base64url");
    bool valid = rsa.VerifyStringENC(signedString,L"sha-256",jsonResp.stringOf(L"value"));
    wprintf(L"signature valid = %d\n",valid);
    }