(Unicode C) Azure Key Vault Sign with a Certificate's Private Key

See more Azure Key Vault Examples

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

Note: This example requires Chilkat v9.5.0.96 or later.

For more information, see https://learn.microsoft.com/en-us/rest/api/keyvault/certificates/import-certificate/import-certificate?tabs=HTTP

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#include <C_CkJsonObjectW.h>
#include <C_CkStringBuilderW.h>
#include <C_CkHttpW.h>
#include <C_CkHttpResponseW.h>
#include <C_CkCertW.h>
#include <C_CkRsaW.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkJsonObjectW json;
    HCkStringBuilderW sb;
    const wchar_t *signedString;
    const wchar_t *hash_base64url;
    HCkJsonObjectW jsonBody;
    HCkHttpW http;
    const wchar_t *url;
    HCkHttpResponseW resp;
    int statusCode;
    HCkJsonObjectW jsonResp;
    HCkCertW cert;
    HCkRsaW rsa;
    BOOL valid;

    // 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.
    json = CkJsonObjectW_Create();
    CkJsonObjectW_UpdateString(json,L"client_id",L"APP_ID");
    CkJsonObjectW_UpdateString(json,L"client_secret",L"APP_PASSWORD");
    CkJsonObjectW_UpdateString(json,L"resource",L"https://vault.azure.net");
    CkJsonObjectW_UpdateString(json,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"
    sb = CkStringBuilderW_Create();
    signedString = L"This is a test";
    CkStringBuilderW_Append(sb,signedString);
    hash_base64url = CkStringBuilderW_getHash(sb,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..

    jsonBody = CkJsonObjectW_Create();
    CkJsonObjectW_UpdateString(jsonBody,L"alg",L"RS256");
    CkJsonObjectW_UpdateString(jsonBody,L"value",hash_base64url);

    http = CkHttpW_Create();

    // 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.
    CkHttpW_putAuthToken(http,CkJsonObjectW_emit(json));

    CkHttpW_SetUrlVar(http,L"certName",L"importCert01");
    CkHttpW_SetUrlVar(http,L"certVersion",L"7140c8755ed14839b5d86a9f7e7f0497");
    // Note: Replace "VAULT_NAME" with the name of your Azure key vault.
    url = L"https://VAULT_NAME.vault.azure.net/keys/{$certName}/{$certVersion}/sign?api-version=7.4";
    resp = CkHttpW_PostJson3(http,url,L"application/json",jsonBody);
    if (CkHttpW_getLastMethodSuccess(http) == FALSE) {
        // This means something failed before we got a response.
        wprintf(L"%s\n",CkHttpW_lastErrorText(http));
        CkJsonObjectW_Dispose(json);
        CkStringBuilderW_Dispose(sb);
        CkJsonObjectW_Dispose(jsonBody);
        CkHttpW_Dispose(http);
        return;
    }

    statusCode = CkHttpResponseW_getStatusCode(resp);

    jsonResp = CkJsonObjectW_Create();
    CkHttpResponseW_GetBodyJson(resp,jsonResp);
    CkHttpResponseW_Dispose(resp);

    CkJsonObjectW_putEmitCompact(jsonResp,FALSE);
    wprintf(L"%s\n",CkJsonObjectW_emit(jsonResp));

    if (statusCode != 200) {
        wprintf(L"Failed.\n");
        CkJsonObjectW_Dispose(json);
        CkStringBuilderW_Dispose(sb);
        CkJsonObjectW_Dispose(jsonBody);
        CkHttpW_Dispose(http);
        CkJsonObjectW_Dispose(jsonResp);
        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.
    // 
    cert = CkCertW_Create();
    success = CkCertW_LoadFromFile(cert,L"qa_data/certs/chilkat_code_signing_2024.cer");
    if (success == FALSE) {
        wprintf(L"%s\n",CkCertW_lastErrorText(cert));
        CkJsonObjectW_Dispose(json);
        CkStringBuilderW_Dispose(sb);
        CkJsonObjectW_Dispose(jsonBody);
        CkHttpW_Dispose(http);
        CkJsonObjectW_Dispose(jsonResp);
        CkCertW_Dispose(cert);
        return;
    }

    rsa = CkRsaW_Create();
    // Tell the RSA object to use the cert's public key.
    success = CkRsaW_SetX509Cert(rsa,cert,FALSE);
    if (success == FALSE) {
        wprintf(L"%s\n",CkRsaW_lastErrorText(rsa));
        CkJsonObjectW_Dispose(json);
        CkStringBuilderW_Dispose(sb);
        CkJsonObjectW_Dispose(jsonBody);
        CkHttpW_Dispose(http);
        CkJsonObjectW_Dispose(jsonResp);
        CkCertW_Dispose(cert);
        CkRsaW_Dispose(rsa);
        return;
    }

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


    CkJsonObjectW_Dispose(json);
    CkStringBuilderW_Dispose(sb);
    CkJsonObjectW_Dispose(jsonBody);
    CkHttpW_Dispose(http);
    CkJsonObjectW_Dispose(jsonResp);
    CkCertW_Dispose(cert);
    CkRsaW_Dispose(rsa);

    }