(Visual FoxPro) Encrypt File using X.509 Certificate using AES in CBC Mode

Demonstrates how to encrypt a file using an X.509 Certificate's public key, where the underlying bulk encryption algorithm is 128-bit AES in CBC mode. (The underlying bulk encryption algorithm can be specified to be other algorithms/strengths.)

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

LOCAL loCrypt
LOCAL loCert
LOCAL lnSuccess

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

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

* Use public-key cryptography for encryption.
loCrypt.CryptAlgorithm = "pki"

* Get an X.509 certificate to use for encrypting.
* Note: Chilkat provides many different ways of loading a certificate, from many different formats,
* or if on Windows, from the installed certificates on the system.
* This example simply loads a certificate from a file.
* Also, for encryption, only the public key is needed.  Digital certificates embed the public key
* within the X.509 format itself.  Therefore, if you have a certificate, you also have the public key.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Cert')
loCert = CreateObject('Chilkat.Cert')
lnSuccess = loCert.LoadFromFile("qa_data/certs/testCert.cer")
IF (lnSuccess <> 1) THEN
    ? loCert.LastErrorText
    RELEASE loCrypt
    RELEASE loCert
    CANCEL
ENDIF

lnSuccess = loCrypt.SetEncryptCert(loCert)
IF (lnSuccess <> 1) THEN
    ? loCrypt.LastErrorText
    RELEASE loCrypt
    RELEASE loCert
    CANCEL
ENDIF

* Indicate the underlying bulk encryption algorithm to be used:
loCrypt.Pkcs7CryptAlg = "aes"
loCrypt.KeyLength = 128

* Note: When doing public-key encryption the underlying bulk symmetric cipher mode will always be CBC. (at least with Chilkat...)

* There's one last option that could be set.  If is the RSA encryption encryption/padding scheme. 
* By default, RSAES_PKCS1-V1_5 is used.  If desired, the OaepPadding property could be set to 1 to
* use RSAES_OAEP.  (We'll leave it set at the default value of 0)
loCrypt.OaepPadding = 0

* Everything is specified.  Now just encrypt...
* The output is PKCS7 in binary DER format.
lnSuccess = loCrypt.CkEncryptFile("qa_data/hamlet.xml","qa_output/hamlet.p7")
IF (lnSuccess <> 1) THEN
    ? loCrypt.LastErrorText
    RELEASE loCrypt
    RELEASE loCert
    CANCEL
ENDIF

? "Finished."

RELEASE loCrypt
RELEASE loCert