B4X

Encrypt File using X.509 Certificate using AES in CBC Mode

See more Encryption Examples

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.) B4X

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 ChilkatCrypt2
crypt.Initialize("crypt")

'  Use public-key cryptography for encryption.
crypt.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.
Dim cert As ChilkatCert
cert.Initialize("cert")
success = cert.LoadFromFile("qa_data/certs/testCert.cer")
If success <> True Then
    Log(cert.LastErrorText)
    Return
End If


success = crypt.SetEncryptCert(cert)
If success <> True Then
    Log(crypt.LastErrorText)
    Return
End If


'  Indicate the underlying bulk encryption algorithm to be used:
crypt.Pkcs7CryptAlg = "aes"
crypt.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 True to
'  use RSAES_OAEP.  (We'll leave it set at the default value of False)
crypt.OaepPadding = False

'  Everything is specified.  Now just encrypt...
'  The output is PKCS7 in binary DER format.
success = crypt.CkEncryptFile("qa_data/hamlet.xml", "qa_output/hamlet.p7")
If success <> True Then
    Log(crypt.LastErrorText)
    Return
End If


Log("Finished.")