(Excel) Encrypt MIME using RSAES-OAEP with SHA256 and AES-128 content encryption

Demonstrates how to encrypt MIME using RSAES-OAEP with SHA256 and AES-128 content encryption.

Note: This example requires Chilkat v9.5.0.67 or greater.

Download Excel Class Modules Chilkat Excel Class Modules

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

Dim mime As Chilkat.Mime
Set mime = Chilkat.NewMime

' Create a MIME message to encrypt.
Dim success As Boolean
success = mime.NewMultipartMixed()
success = mime.AddHeaderField("someHeader1","Some value 1")
success = mime.AddHeaderField("someHeader2","Some value 2")

Dim part0 As Chilkat.Mime
Set part0 = Chilkat.NewMime
success = part0.AddHeaderField("hdrA","Some value A")
success = part0.AddHeaderField("hdrB","Some value B")
part0.ContentType = "text/plain"
part0.SetBody "This is the plain-text body."

Dim part1 As Chilkat.Mime
Set part1 = Chilkat.NewMime
success = part1.AddHeaderField("hdrX","Some value X")
success = part1.AddHeaderField("hdrY","Some value Y")
part1.ContentType = "text/xml"
part1.SetBody "<a>This is the XML body</a>"

success = mime.AppendPart(part0)
success = mime.AppendPart(part1)

' The MIME to be encrypted:
Dim sbMime As Chilkat.StringBuilder
Set sbMime = Chilkat.NewStringBuilder
success = mime.GetMimeSb(sbMime)
Debug.Print sbMime.GetAsString()

' 	Content-Type: multipart/mixed; boundary="------------080303020600020604010008"
' 	someHeader1: Some value 1
' 	someHeader2: Some value 2
' 
' 	--------------080303020600020604010008
' 	hdrA: Some value A
' 	hdrB: Some value B
' 	Content-Type: text/plain
' 
' 	This is the plain-text body.
' 	--------------080303020600020604010008
' 	hdrX: Some value X
' 	hdrY: Some value Y
' 	Content-Type: text/xml
' 
' 	<a>This is the XML body</a>
' 	--------------080303020600020604010008--
' 

' Load an RSA-based certificate.
' (Encrypting MIME only requires the public key.  Decrypting MIME requires the private key.)
Dim cert As Chilkat.Cert
Set cert = Chilkat.NewCert
success = cert.LoadFromFile("qa_data/rsaes-oaep/cert.pem")
If (success <> True) Then
    Debug.Print cert.LastErrorText
    Exit Sub
End If

' Set the email object properties to indicate the desired encryption.
mime.Pkcs7CryptAlg = "aes"
' If AES-256 is desired, set the following property to 256.
mime.Pkcs7KeyLength = 128
mime.OaepPadding = True
' Other choices for the OAEP hash algorithm are "sha1", "sha384", and "sha512"
mime.OaepHash = "sha256"

' Encrypt the MIME (to create S/MIME, which stands for "Secure MIME")
success = mime.Encrypt(cert)
If (success <> True) Then
    Debug.Print mime.LastErrorText
    Exit Sub
End If

Debug.Print "---------------"
Debug.Print "Encrypted MIME:"
Debug.Print "---------------"
Debug.Print mime.GetMime()

Debug.Print "Success."

' ---------------------------------------------------
' This is sample output for RSAES-OAEP encrypted MIME:
' ---------------------------------------------------

' Content-Type: application/x-pkcs7-mime; name="smime.p7m"; smime-type="enveloped-data"
' someHeader1: Some value 1
' someHeader2: Some value 2
' Content-Disposition: attachment; filename="smime.p7m"
' Content-Transfer-Encoding: base64
' 
' MIIDvAYJKoZIhvcNAQcDoIIDrTCCA6kCAQAxggGgMIIBnAIBADB1MGgxCzAJBgNVBAYTAlVTMQsw
' CQYDVQQIDAJJTDEQMA4GA1UEBwwHV2hlYXRvbjEhMB8GA1UECgwYSW50ZXJuZXQgV2lkZ2l0cyBQ
' dHkgTHRkMRcwFQYDVQQDDA5DaGlsa2F0V2lkZ2V0cwIJAMRwugDmvniwMBwGCSqGSIb3DQEBBzAP
' oA0wCwYJYIZIAWUDBAIBBIIBAFaUL1ga1bOrdqYKcMm+FHUacBvzfBxk0fnPA0AMBdN8BvTWT3CN
' YuqBhjOGyq0FpYD9pVZybUuFMCVsVyIW2O62HnsOK58YaPEUUcdH2sI+yjqX9UAn0P0nVDSsVdeK
' W8x9kMfZg+3UP+y1q+lu7VRJO3f2C9oLQpTkc4VW4n7UOcUI0waykLCjCTL8lFDb7/J3GeuMKyhH
' 5riNz50kpbzqn7m2Ks9yA+QmcTdXclclGFr2vwEUFzSdT2pxh/vaUrogCxkYWbQ2eV7vZg6O4kV0
' aqHBqySkPTAzHKiHH8K8GVdlTuJ8350CpICa4T8w7/Ht5I7dyOPPKy4C+rVtrvcwggH+BgkqhkiG
' 9w0BBwEwHQYJYIZIAWUDBAECBBDTC2WNBN+z2I47/4Feu9YqgIIB0MZvl3nC/q/Wzil6HtfQTr12
' Q5moHY+ORzAa1P9XvX2ZUFhW530mV395mQw/A4o4ekmX9eRPEZquYzZPLT8hNeZIuNdhpcSQUmad
' rKnKkR0wKJ3jJ3LhOIohVBQSYs8kVDZKq6lJBIznlsurFelZoNEhyRschhteDZx5rb7fCe8c2+/O
' DHxaqaHCAzm/Bd7kcg6FFfuTZy3tu0PgP5IsXN4OFA3kkvwjAs4XsVS8jdIcmDNBkYieE8WmJOIm
' Mz7mh/CHWLgWfGKa0Dkb9RcbFgLwYNT3GzuXFw9XPbKkEZjEAtJajWbN6P0WQl96YYd9qZxUpGxZ
' zjTHEYzViUdUXolfpLufttrRXyxN1RFWhNFMFbv66xYqklMSgpdM/Mbk+EuvX6eXayDPvDBpfYMw
' NoRAzv1Ony2c0ez9rBemJICicxAzpuvHbRxdjYs63Dnv+TYgpBK12AxWWpPIjXvw0WQKgTC3Tg8s
' EnuGhpENqso/clJBEBSn4+2WhYtYbdI5sVme67lvqQl1Xxy3r18SWaQbyDOwgYi1E+54lMDOxMy0
' y0FPHk5pP45DnXWj+XORPp5LhuZr5mf62YOXSSUwR5P0cXy4Rc+pN5lhRQPCf5z2