(Visual FoxPro) Encrypt File to PKCS7 .p7m

Visual FoxPro 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.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL loCrypt
LOCAL loEncryptCert
LOCAL lnSuccess
LOCAL lcInFile
LOCAL lcOutFile
LOCAL loDecrypt
LOCAL lcPfxFilename
LOCAL lcPfxPassword

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

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Crypt2')
loCrypt = CreateObject('Chilkat.Crypt2')

* 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).
loCrypt.CryptAlgorithm = "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.
loCrypt.Pkcs7CryptAlg = "aes"
loCrypt.KeyLength = 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
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Cert')
loEncryptCert = CreateObject('Chilkat.Cert')
lnSuccess = loEncryptCert.LoadFromFile("/Users/chilkat/testData/cer/acme.cer")
IF (lnSuccess <> 1) THEN
    ? loEncryptCert.LastErrorText
    RELEASE loCrypt
    RELEASE loEncryptCert
    CANCEL
ENDIF

* Tell the crypt object to use the certificate for encrypting:
loCrypt.AddEncryptCert(loEncryptCert)

* Encrypt a file, producing a .p7m as output.
* The input file is unchanged, the output .p7m contains the encrypted
* contents of the input file.
lcInFile = "/Users/chilkat/testData/pdf/sample.pdf"
lcOutFile = "/Users/chilkat/testData/p7m/sample.pdf.p7m"
lnSuccess = loCrypt.CkEncryptFile(lcInFile,lcOutFile)
IF (lnSuccess <> 1) THEN
    ? loCrypt.LastErrorText
    RELEASE loCrypt
    RELEASE loEncryptCert
    CANCEL
ENDIF

* For demonstration purposes, a different instance of the object will be used
* for decryption.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Crypt2')
loDecrypt = CreateObject('Chilkat.Crypt2')

* 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.
lcPfxFilename = "/Users/chilkat/testData/pfx/acme.pfx"
lcPfxPassword = "secret"

* Tell the component to look in the PFX file for certs and private keys.
lnSuccess = loDecrypt.AddPfxSourceFile(lcPfxFilename,lcPfxPassword)
IF (lnSuccess <> 1) THEN
    ? loDecrypt.LastErrorText
    RELEASE loCrypt
    RELEASE loEncryptCert
    RELEASE loDecrypt
    CANCEL
ENDIF

* Tell the decrypt object that PKI (public key encryption) is to be used
* for decryptiong.
loDecrypt.CryptAlgorithm = "PKI"
* There is no need to set the Pkcs7Alg or KeyLength because this information
* is contained within the .p7m

* Decrypt the .p7m
lcInFile = "/Users/chilkat/testData/p7m/sample.pdf.p7m"
lcOutFile = "/Users/chilkat/testData/pdf/recovered.pdf"
lnSuccess = loDecrypt.CkDecryptFile(lcInFile,lcOutFile)
IF (lnSuccess = 0) THEN
    ? loDecrypt.LastErrorText
    RELEASE loCrypt
    RELEASE loEncryptCert
    RELEASE loDecrypt
    CANCEL
ENDIF

? "Success!"

RELEASE loCrypt
RELEASE loEncryptCert
RELEASE loDecrypt