(Unicode C) Encrypt File to PKCS7 .p7m

Unicode C example to public-key encrypt a file creating a PKCS#7 .p7m file as output. Also demonstrates how to decrypt the .p7m to recover the original file.

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#include <C_CkCrypt2W.h>
#include <C_CkCertW.h>

void ChilkatSample(void)
    {
    HCkCrypt2W crypt;
    HCkCertW encryptCert;
    BOOL success;
    const wchar_t *inFile;
    const wchar_t *outFile;
    HCkCrypt2W decrypt;
    const wchar_t *pfxFilename;
    const wchar_t *pfxPassword;

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

    crypt = CkCrypt2W_Create();

    // Indicate the public-key encryption is to be used.
    // Do this by setting the encryption algorithm equal 
    // to "PKI" (an acroynm for public-key infrastructure).
    CkCrypt2W_putCryptAlgorithm(crypt,L"PKI");

    // Indicate the inner symmetric encryption algorithm to be used.
    // possible values are "aes", "des", "3des", and "rc2".
    // For this example, we'll use 256-bit AES encryption.
    CkCrypt2W_putPkcs7CryptAlg(crypt,L"aes");
    CkCrypt2W_putKeyLength(crypt,256);

    // To encrypt, only a certificate w/ public key is needed.
    // (The certificate w/ private key is required for decryption.)

    // The LoadFromFile method can load virtually any certificate format:
    // 1. DER encoded binary X.509 (.CER)
    // 2. Base-64 encoded X.509 (.CER)
    // 3. Cryptographic Message Syntax Standard - PKCS #7 Certificates (.P7B)
    // 4. PEM format
    encryptCert = CkCertW_Create();
    success = CkCertW_LoadFromFile(encryptCert,L"/Users/chilkat/testData/cer/acme.cer");
    if (success != TRUE) {
        wprintf(L"%s\n",CkCertW_lastErrorText(encryptCert));
        CkCrypt2W_Dispose(crypt);
        CkCertW_Dispose(encryptCert);
        return;
    }

    // Tell the crypt object to use the certificate for encrypting:
    CkCrypt2W_AddEncryptCert(crypt,encryptCert);

    // Encrypt a file, producing a .p7m as output.
    // The input file is unchanged, the output .p7m contains the encrypted
    // contents of the input file.
    inFile = L"/Users/chilkat/testData/pdf/sample.pdf";
    outFile = L"/Users/chilkat/testData/p7m/sample.pdf.p7m";
    success = CkCrypt2W_CkEncryptFile(crypt,inFile,outFile);
    if (success != TRUE) {
        wprintf(L"%s\n",CkCrypt2W_lastErrorText(crypt));
        CkCrypt2W_Dispose(crypt);
        CkCertW_Dispose(encryptCert);
        return;
    }

    // For demonstration purposes, a different instance of the object will be used
    // for decryption.
    decrypt = CkCrypt2W_Create();

    // To decrypt, the certificate w/ private key is required.  A PFX (also known
    // as PKCS#12) is a common secure container for certs and private keys.
    pfxFilename = L"/Users/chilkat/testData/pfx/acme.pfx";
    pfxPassword = L"secret";

    // Tell the component to look in the PFX file for certs and private keys.
    success = CkCrypt2W_AddPfxSourceFile(decrypt,pfxFilename,pfxPassword);
    if (success != TRUE) {
        wprintf(L"%s\n",CkCrypt2W_lastErrorText(decrypt));
        CkCrypt2W_Dispose(crypt);
        CkCertW_Dispose(encryptCert);
        CkCrypt2W_Dispose(decrypt);
        return;
    }

    // Tell the decrypt object that PKI (public key encryption) is to be used
    // for decryptiong.
    CkCrypt2W_putCryptAlgorithm(decrypt,L"PKI");
    // There is no need to set the Pkcs7Alg or KeyLength because this information
    // is contained within the .p7m

    // Decrypt the .p7m
    inFile = L"/Users/chilkat/testData/p7m/sample.pdf.p7m";
    outFile = L"/Users/chilkat/testData/pdf/recovered.pdf";
    success = CkCrypt2W_CkDecryptFile(decrypt,inFile,outFile);
    if (success == FALSE) {
        wprintf(L"%s\n",CkCrypt2W_lastErrorText(decrypt));
        CkCrypt2W_Dispose(crypt);
        CkCertW_Dispose(encryptCert);
        CkCrypt2W_Dispose(decrypt);
        return;
    }

    wprintf(L"Success!\n");


    CkCrypt2W_Dispose(crypt);
    CkCertW_Dispose(encryptCert);
    CkCrypt2W_Dispose(decrypt);

    }