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MIME S/MIME Encryption Algorithm Properties

Demonstrates the properties that control S/MIME encryption: Pkcs7CryptAlg (the symmetric content-encryption algorithm), Pkcs7KeyLength (the content-encryption key length in bits), OaepPadding (whether RSAES-OAEP key transport is used instead of RSAES-PKCS1-v1_5), and the OAEP hash settings OaepHash and OaepMgfHash. The properties are configured before calling Encrypt.

Background. CMS/PKCS #7 encryption uses a symmetric algorithm to protect the content and an RSA key-transport scheme to protect the symmetric key. The defaults (aes, 128-bit, PKCS1-v1_5 padding) work broadly; these properties tune the algorithms and padding.

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Local $bSuccess = False

$oMime = ObjCreate("Chilkat.Mime")
$bSuccess = $oMime.SetBodyFromPlainText("This message will be encrypted.")
If ($bSuccess = False) Then
    ConsoleWrite($oMime.LastErrorText & @CRLF)
    Exit
EndIf

;  Pkcs7CryptAlg is the symmetric content-encryption algorithm.  Supported values are aes, aes-gcm,
;  des, 3des, and rc2.  The default is aes.
$oMime.Pkcs7CryptAlg = "aes"

;  Pkcs7KeyLength is the content-encryption key length in bits.  The default is 128.
$oMime.Pkcs7KeyLength = 256

;  OaepPadding selects the RSA key-transport padding.  The default is False (RSAES-PKCS1-v1_5).
;  Set True to use RSAES-OAEP, in which case the OAEP hash settings apply.
$oMime.OaepPadding = True
$oMime.OaepHash = "sha256"
$oMime.OaepMgfHash = "sha256"

;  Load the recipient certificate (public key is sufficient for encrypting).
$oCert = ObjCreate("Chilkat.Cert")
$bSuccess = $oCert.LoadFromFile("qa_data/recipient.cer")
If ($bSuccess = False) Then
    ConsoleWrite($oCert.LastErrorText & @CRLF)
    Exit
EndIf

;  Encrypt using the algorithm settings configured above.
$bSuccess = $oMime.Encrypt($oCert)
If ($bSuccess = False) Then
    ConsoleWrite($oMime.LastErrorText & @CRLF)
    Exit
EndIf

ConsoleWrite("Encrypted with " & $oMime.Pkcs7CryptAlg & " " & $oMime.Pkcs7KeyLength & "-bit key." & @CRLF)