B4X
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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Dim success As Boolean = False

'  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 ChilkatStringBuilder
sb.Initialize
Dim bCrlf As Boolean = True
sb.AppendLine("Content-Type: application/x-pkcs7-mime; name=" & Chr(34) & "smime.p7m" & Chr(34) & "; smime-type=" & Chr(34) & "enveloped-data" & Chr(34), bCrlf)
sb.AppendLine("someHeader1: Some value 1", bCrlf)
sb.AppendLine("someHeader2: Some value 2", bCrlf)
sb.AppendLine("Content-Disposition: attachment; filename=" & Chr(34) & "smime.p7m" & Chr(34), bCrlf)
sb.AppendLine("Content-Transfer-Encoding: base64", bCrlf)
sb.AppendLine("", bCrlf)
sb.AppendLine("MIIDvAYJKoZIhvcNAQcDoIIDrTCCA6kCAQAxggGgMIIBnAIBADB1MGgxCzAJBgNVBAYTAlVTMQsw", bCrlf)
sb.AppendLine("CQYDVQQIDAJJTDEQMA4GA1UEBwwHV2hlYXRvbjEhMB8GA1UECgwYSW50ZXJuZXQgV2lkZ2l0cyBQ", bCrlf)
sb.AppendLine("dHkgTHRkMRcwFQYDVQQDDA5DaGlsa2F0V2lkZ2V0cwIJAMRwugDmvniwMBwGCSqGSIb3DQEBBzAP", bCrlf)
sb.AppendLine("oA0wCwYJYIZIAWUDBAIBBIIBAFaUL1ga1bOrdqYKcMm+FHUacBvzfBxk0fnPA0AMBdN8BvTWT3CN", bCrlf)
sb.AppendLine("YuqBhjOGyq0FpYD9pVZybUuFMCVsVyIW2O62HnsOK58YaPEUUcdH2sI+yjqX9UAn0P0nVDSsVdeK", bCrlf)
sb.AppendLine("W8x9kMfZg+3UP+y1q+lu7VRJO3f2C9oLQpTkc4VW4n7UOcUI0waykLCjCTL8lFDb7/J3GeuMKyhH", bCrlf)
sb.AppendLine("5riNz50kpbzqn7m2Ks9yA+QmcTdXclclGFr2vwEUFzSdT2pxh/vaUrogCxkYWbQ2eV7vZg6O4kV0", bCrlf)
sb.AppendLine("aqHBqySkPTAzHKiHH8K8GVdlTuJ8350CpICa4T8w7/Ht5I7dyOPPKy4C+rVtrvcwggH+BgkqhkiG", bCrlf)
sb.AppendLine("9w0BBwEwHQYJYIZIAWUDBAECBBDTC2WNBN+z2I47/4Feu9YqgIIB0MZvl3nC/q/Wzil6HtfQTr12", bCrlf)
sb.AppendLine("Q5moHY+ORzAa1P9XvX2ZUFhW530mV395mQw/A4o4ekmX9eRPEZquYzZPLT8hNeZIuNdhpcSQUmad", bCrlf)
sb.AppendLine("rKnKkR0wKJ3jJ3LhOIohVBQSYs8kVDZKq6lJBIznlsurFelZoNEhyRschhteDZx5rb7fCe8c2+/O", bCrlf)
sb.AppendLine("DHxaqaHCAzm/Bd7kcg6FFfuTZy3tu0PgP5IsXN4OFA3kkvwjAs4XsVS8jdIcmDNBkYieE8WmJOIm", bCrlf)
sb.AppendLine("Mz7mh/CHWLgWfGKa0Dkb9RcbFgLwYNT3GzuXFw9XPbKkEZjEAtJajWbN6P0WQl96YYd9qZxUpGxZ", bCrlf)
sb.AppendLine("zjTHEYzViUdUXolfpLufttrRXyxN1RFWhNFMFbv66xYqklMSgpdM/Mbk+EuvX6eXayDPvDBpfYMw", bCrlf)
sb.AppendLine("NoRAzv1Ony2c0ez9rBemJICicxAzpuvHbRxdjYs63Dnv+TYgpBK12AxWWpPIjXvw0WQKgTC3Tg8s", bCrlf)
sb.AppendLine("EnuGhpENqso/clJBEBSn4+2WhYtYbdI5sVme67lvqQl1Xxy3r18SWaQbyDOwgYi1E+54lMDOxMy0", bCrlf)
sb.AppendLine("y0FPHk5pP45DnXWj+XORPp5LhuZr5mf62YOXSSUwR5P0cXy4Rc+pN5lhRQPCf5z2", bCrlf)

'  Load the encrypted MIME into the MIME object.
Dim mime As ChilkatMime
mime.Initialize
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
    Log(mime.LastErrorText)
    Return
End If


'  Decrypt.
success = mime.Decrypt
If success <> True Then
    Log(mime.LastErrorText)
    Return
End If


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

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

Dim cert As ChilkatCert
cert.Initialize("cert")
success = cert.LoadFromFile("qa_data/rsaes-oaep/cert.pem")

Dim privKey As ChilkatPrivateKey
privKey.Initialize("privKey")
success = privKey.LoadPemFile("qa_data/rsaes-oaep/privatekey.pem")

'  Decrypt using the cert + private key
Dim mime2 As ChilkatMime
mime2.Initialize
mime2.LoadMimeSb(sb)

success = mime2.Decrypt2(cert, privKey)
If success <> True Then
    Log(mime2.LastErrorText)
    Return
End If


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