Visual FoxPro

Encrypt a file to a PKCS7 encrypted message using multiple certificates from different users

See more Encryption Examples

Demonstrates how to encrypt a file to a PKCS7 encrypted message using multiple certificates from different users. Any one of the users can decrypt using his/her own certificate + private key.

Note: When doing public key encryption, it is the public key that is used to encrypt. The private key is required for decryption.

Visual FoxPro

LOCAL lnSuccess
LOCAL loCrypt
LOCAL loCert1
LOCAL loCert2
LOCAL loCert3
LOCAL loFileData

lnSuccess = 0

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

loCrypt = CreateObject('Chilkat.Crypt2')

* Tell the crypt object to use 3 certificates.
* Do this by calling AddEncryptCert for each certificate.

* Load a 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.AddEncryptCert(loCert1)

loCert2 = CreateObject('Chilkat.Cert')
lnSuccess = loCert2.LoadFromFile("qa_data/user2/cert_user2.pem")
loCrypt.AddEncryptCert(loCert2)

loCert3 = CreateObject('Chilkat.Cert')
lnSuccess = loCert3.LoadFromFile("qa_data/user3/cert_user3.pem")
loCrypt.AddEncryptCert(loCert3)

* 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-128 for the
* bulk encryption.
loCrypt.CryptAlgorithm = "pki"
loCrypt.Pkcs7CryptAlg = "aes"
loCrypt.KeyLength = 128
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 loCert2
    RELEASE loCert3
    RELEASE loFileData
    CANCEL
ENDIF

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

* Now indicate that the PKCS7 output is to be returned in the base64 encoding.
loCrypt.EncodingMode = "base64"

? "OK."

RELEASE loCrypt
RELEASE loCert1
RELEASE loCert2
RELEASE loCert3
RELEASE loFileData