VB.NET

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.

VB.NET

Dim success As Boolean = False

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

Dim crypt As New 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).
Dim cert1 As New Chilkat.Cert
success = cert1.LoadFromFile("qa_data/user1/cert_user1.pem")
' Assume success for the example, but make sure your application checks for success/failure...
crypt.AddEncryptCert(cert1)

Dim cert2 As New Chilkat.Cert
success = cert2.LoadFromFile("qa_data/user2/cert_user2.pem")
crypt.AddEncryptCert(cert2)

Dim cert3 As New Chilkat.Cert
success = cert3.LoadFromFile("qa_data/user3/cert_user3.pem")
crypt.AddEncryptCert(cert3)

' 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.
crypt.CryptAlgorithm = "pki"
crypt.Pkcs7CryptAlg = "aes"
crypt.KeyLength = 128
crypt.OaepHash = "sha256"
crypt.OaepPadding = True

' Load the file to be encrypted...
Dim fileData As New Chilkat.BinData
success = fileData.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.
success = crypt.EncryptBd(fileData)
If (success <> True) Then
    Debug.WriteLine(crypt.LastErrorText)
    Exit Sub
End If


' Save the PKCS7 encrypted message to a file..
success = fileData.WriteFile("qa_output/pkcs7_encrypted.p7")

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

Debug.WriteLine("OK.")