(Visual FoxPro) Encrypt a File to a PKCS7 (CMS) Message

Shows how to encrypt a file into a PKCS7 encrypted message using the recipient's certificate. Public-key encryption requires no private key. However, the recipient's private key is necessary for decryption.

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

LOCAL loCrypt
LOCAL loCert1
LOCAL lnSuccess
LOCAL loFileData

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

loCrypt = CreateObject('Chilkat.Crypt2')

* Load the recipient's digital certificate. 
* We don't need the private key for encryption.
* Only the public key is needed (which is included in a certificate).
loCert1 = CreateObject('Chilkat.Cert')
lnSuccess = loCert1.LoadFromFile("qa_data/user1/cert_user1.pem")
* Assume success for the example, but make sure your application checks for success/failure...
loCrypt.SetEncryptCert(loCert1)

* Indicate that we want PKI encryption (i.e. public-key infrastructure)
* to produce a CMS message (Cryptographic Message Syntax/PKCS7),
* that is be created with RSAES-OAEP padding, SHA256, and AES-256 for the
* bulk encryption.
loCrypt.CryptAlgorithm = "pki"
loCrypt.Pkcs7CryptAlg = "aes"
loCrypt.KeyLength = 256
loCrypt.OaepHash = "sha256"
loCrypt.OaepPadding = 1

* Load the file to be encrypted...
loFileData = CreateObject('Chilkat.BinData')
lnSuccess = loFileData.LoadFile("qa_data/jpg/penguins.jpg")
* Your app should check for success/failure..

* Encrypt the data.  The contents of the fileData object are replaced with the PKCS7 encrypted message.
lnSuccess = loCrypt.EncryptBd(loFileData)
IF (lnSuccess <> 1) THEN
    ? loCrypt.LastErrorText
    RELEASE loCrypt
    RELEASE loCert1
    RELEASE loFileData
    CANCEL
ENDIF

* Save the PKCS7 encrypted message to a file..
lnSuccess = loFileData.WriteFile("qa_output/pkcs7_encrypted.p7")

? "OK."

RELEASE loCrypt
RELEASE loCert1
RELEASE loFileData