(C) Create PKCS7 (CMS) EnvelopedData

Encrypt some data to a recipient by creating a PKCS7 (CMS) EnvelopedData structure. The data will be encrypted using a symmetric content-encryption algorithm (e.g., AES), and the randomly generated symmetric key will be encrypted using the recipient’s RSA public key extracted from their X.509 certificate.

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#include <C_CkCrypt2.h>
#include <C_CkCert.h>

void ChilkatSample(void)
    {
    HCkCrypt2 crypt;
    HCkCert cert;
    BOOL success;
    const char *toBeEncrypted;
    const char *result;

    crypt = CkCrypt2_Create();

    // Specify the encryption to be used.
    // "pki" indicates "Public Key Infrastructure" and will create a PKCS7 encrypted (enveloped-data) message.
    CkCrypt2_putCryptAlgorithm(crypt,"pki");
    CkCrypt2_putPkcs7CryptAlg(crypt,"aes");
    CkCrypt2_putKeyLength(crypt,256);
    CkCrypt2_putOaepHash(crypt,"sha256");
    CkCrypt2_putOaepPadding(crypt,TRUE);

    cert = CkCert_Create();

    // Use a certificate found in the Windows certificate store.
    success = CkCert_LoadByCommonName(cert,"My Certificate");
    if (success != TRUE) {
        printf("%s\n",CkCert_lastErrorText(cert));
        CkCrypt2_Dispose(crypt);
        CkCert_Dispose(cert);
        return;
    }

    // Tell the crypt object to use the certificate.
    CkCrypt2_SetEncryptCert(crypt,cert);

    toBeEncrypted = "This string is to be encrypted.";

    // Get the result in multi-line BASE64 MIME format.
    CkCrypt2_putEncodingMode(crypt,"base64_mime");
    CkCrypt2_putCharset(crypt,"utf-8");

    result = CkCrypt2_encryptStringENC(crypt,toBeEncrypted);
    if (success != TRUE) {
        printf("%s\n",CkCrypt2_lastErrorText(crypt));
        CkCrypt2_Dispose(crypt);
        CkCert_Dispose(cert);
        return;
    }

    // -------------------------------------------------------------------------
    // See the following example to decrypt what was created in this example
    // Decrypt PKCS7 (CMS) EnvelopedData
    // -------------------------------------------------------------------------

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

    // Sample output:

    // MIICSgYJKoZIhvcNAQcDoIICOzCCAjcCAQAxggHiMIIB3gIBADCBljCBgTELMAkGA1UEBhMCSVQx
    // EDAOBgNVBAgMB0JlcmdhbW8xGTAXBgNVBAcMEFBvbnRlIFNhbiBQaWV0cm8xFzAVBgNVBAoMDkFj
    // dGFsaXMgUy5wLkEuMSwwKgYDVQQDDCNBY3RhbGlzIENsaWVudCBBdXRoZW50aWNhdGlvbiBDQSBH
    // MwIQPCWvkSv8oQ7xRmEHJ6TzEDA8BgkqhkiG9w0BAQcwL6APMA0GCWCGSAFlAwQCAQUAoRwwGgYJ
    // KoZIhvcNAQEIMA0GCWCGSAFlAwQCAQUABIIBAKqHAPQNSsQoX7B2NH7QyEOWQRsSVs8oCHXmy8f4
    // MVZD2er3bvYUCIomxpwbLEAl14qjUIMynahooYGgqip7+4FqL301G+BVjZVfEhHWj+VI1dAWnWuL
    // VHlvc/pbQNBWqV8rKVJsNIsuAZkdj4WSwLVKxYkYX43B8fh/g71XN2DTJu7Z/824v48KBmgpQBOT
    // 2q7IcDGxNPAFN2p6eavIVGn2LvhEbf/Fszyj+GR5tMcnQP1BOLJ3s3JzUBbvj8hcZrF1Vhl9HnTU
    // YQx8G/KdW1mR+Wlhl3BWoK0LYKRTbnTx2BXOs0CY1SXOAdhKr01ZYjA+xW4nGzY0lfXS9QZjh9gw
    // TAYJKoZIhvcNAQcBMB0GCWCGSAFlAwQBKgQQw0xTbfmnt0zjWHo5SaQIp4AgxTVY9E/Ncqy6t+RM
    // 8y4c3Av62/wB8IpPUEmtM2OeuZo=


    CkCrypt2_Dispose(crypt);
    CkCert_Dispose(cert);

    }