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

Demonstrates how to decrypt MIME what was encrypted with RSAES-OAEP with SHA256 and AES-128 content encryption.

In actuality, we don't really need to know in advance the various algorithms used to encrypt the MIME. When decrypting, the information about the algorithms required are embedded in the PCKS7 message itself, and this tells a decryptor what it should use.

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

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

' We begin with this 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

Dim sb As Chilkat.StringBuilder
Set sb = Chilkat.NewStringBuilder

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

' Load the encrypted MIME into the MIME object.
Dim mime As Chilkat.Mime
Set mime = Chilkat.NewMime
success = mime.LoadMimeSb(sb)

' Provide the required cert + private key from a PFX (.pfx/.p12) file.
success = mime.AddPfxSourceFile("qa_data/rsaes-oaep/cert_plus_privatekey.pfx","PFX_PASSWORD")
If (success <> True) Then
    Debug.Print mime.LastErrorText
    Exit Sub
End If

' Decrypt.
success = mime.Decrypt()
If (success <> True) Then
    Debug.Print mime.LastErrorText
    Exit Sub
End If

' Examine the decrypted MIME.
Debug.Print mime.GetMime()
Debug.Print "Decrypt test 1 succeeded."

' -----------------------------------------------------------
' Now let's decrypt another way..
' We have the same cert and private key in PEM files..

Dim cert As Chilkat.Cert
Set cert = Chilkat.NewCert
success = cert.LoadFromFile("qa_data/rsaes-oaep/cert.pem")

Dim privKey As Chilkat.PrivateKey
Set privKey = Chilkat.NewPrivateKey
success = privKey.LoadPemFile("qa_data/rsaes-oaep/privatekey.pem")

' Decrypt using the cert + private key
Dim mime2 As Chilkat.Mime
Set mime2 = Chilkat.NewMime
success = mime2.LoadMimeSb(sb)

success = mime2.Decrypt2(cert,privKey)
If (success <> True) Then
    Debug.Print mime2.LastErrorText
    Exit Sub
End If

' Examine the decrypted MIME.
Debug.Print mime2.GetMime()
Debug.Print "Decrypt test 2 succeeded."