B4X

Create PKCS7 (CMS) EnvelopedData

Encrypt some data to a recipient by creating a PKCS7 (CMS) EnvelopedData structure. The data will be encrypted using a symmetric content-encryption algorithm (e.g., AES), and the randomly generated symmetric key will be encrypted using the recipient’s RSA public key extracted from their X.509 certificate. B4X

Dim success As Boolean = False

Dim crypt As ChilkatCrypt2
crypt.Initialize("crypt")

'  Specify the encryption to be used.
'  "pki" indicates "Public Key Infrastructure" and will create a PKCS7 encrypted (enveloped-data) message.
crypt.CryptAlgorithm = "pki"
crypt.Pkcs7CryptAlg = "aes"
crypt.KeyLength = 256
crypt.OaepHash = "sha256"
crypt.OaepPadding = True

Dim cert As ChilkatCert
cert.Initialize("cert")

'  Use a certificate found in the Windows certificate store.
success = cert.LoadByCommonName("My Certificate")
If success <> True Then
    Log(cert.LastErrorText)
    Return
End If


'  Tell the crypt object to use the certificate.
crypt.SetEncryptCert(cert)

Dim toBeEncrypted As String = "This string is to be encrypted."

'  Get the result in multi-line BASE64 MIME format.
crypt.EncodingMode = "base64_mime"
crypt.Charset = "utf-8"

Dim result As String = crypt.EncryptStringENC(toBeEncrypted)
If success <> True Then
    Log(crypt.LastErrorText)
    Return
End If


'  -------------------------------------------------------------------------
'  See the following example to decrypt what was created in this example
'  Decrypt PKCS7 (CMS) EnvelopedData
'  -------------------------------------------------------------------------

Log(result)

'  Sample output:

'  MIICSgYJKoZIhvcNAQcDoIICOzCCAjcCAQAxggHiMIIB3gIBADCBljCBgTELMAkGA1UEBhMCSVQx
'  EDAOBgNVBAgMB0JlcmdhbW8xGTAXBgNVBAcMEFBvbnRlIFNhbiBQaWV0cm8xFzAVBgNVBAoMDkFj
'  dGFsaXMgUy5wLkEuMSwwKgYDVQQDDCNBY3RhbGlzIENsaWVudCBBdXRoZW50aWNhdGlvbiBDQSBH
'  MwIQPCWvkSv8oQ7xRmEHJ6TzEDA8BgkqhkiG9w0BAQcwL6APMA0GCWCGSAFlAwQCAQUAoRwwGgYJ
'  KoZIhvcNAQEIMA0GCWCGSAFlAwQCAQUABIIBAKqHAPQNSsQoX7B2NH7QyEOWQRsSVs8oCHXmy8f4
'  MVZD2er3bvYUCIomxpwbLEAl14qjUIMynahooYGgqip7+4FqL301G+BVjZVfEhHWj+VI1dAWnWuL
'  VHlvc/pbQNBWqV8rKVJsNIsuAZkdj4WSwLVKxYkYX43B8fh/g71XN2DTJu7Z/824v48KBmgpQBOT
'  2q7IcDGxNPAFN2p6eavIVGn2LvhEbf/Fszyj+GR5tMcnQP1BOLJ3s3JzUBbvj8hcZrF1Vhl9HnTU
'  YQx8G/KdW1mR+Wlhl3BWoK0LYKRTbnTx2BXOs0CY1SXOAdhKr01ZYjA+xW4nGzY0lfXS9QZjh9gw
'  TAYJKoZIhvcNAQcBMB0GCWCGSAFlAwQBKgQQw0xTbfmnt0zjWHo5SaQIp4AgxTVY9E/Ncqy6t+RM
'  8y4c3Av62/wB8IpPUEmtM2OeuZo=