The AES cipher is currently implemented by the Microsoft Enhanced RSA and AES Cryptographic Provider
on Windows XP and 2003 only. On Windows XP, the actual registry name of the CSP is
Microsoft Enhanced RSA and AES Cryptographic Provider (Prototype).
AES is currently implemented in three key lengths: 128 bits, 192 bits and 256 bits. Accordingly,
the AspEncrypt library defines
the following constants to designate these key lengths:
calgAES128 (26126)
calgAES192 (26127)
calgAES256 (26128)
These constants (or their numeric equivalents) are to be passed to the methods GenerateKey,
GenerateKeyFromPassword and ImportRawKey as an Algorithm argument.
The following code snippet encrypts a string with a password-derived 256-bit AES key on Windows 2003.
On Windows XP, the code would be the same except that the CSP name passed to OpenContextEx would have to be appended
with the word (Prototype).
<!--METADATA TYPE="TypeLib" UUID="{B72DF063-28A4-11D3-BF19-009027438003}"-->
<%
Set CM = Server.CreateObject("Persits.CryptoManager")
Set context = CM.OpenContextEx("Microsoft Enhanced RSA and AES Cryptographic Provider", "", True)
' Generate 256-bit AES key
Set Key = context.GenerateKeyFromPassword("password", , calgAES256 )
' Encrypt text
Set Blob = Key.EncryptText("Some text")
%>
Using a Pre-set Key
The following code snippet takes a pre-set 128-bit AES key and encrypts a binary string with it.
The values for the key and string were taken from the AES specifications to verify the correctness of
encryption:
<!--METADATA TYPE="TypeLib" UUID="{B72DF063-28A4-11D3-BF19-009027438003}"-->
<%
Set CM = Server.CreateObject("Persits.CryptoManager")
Set context = CM.OpenContextEx("Microsoft Enhanced RSA and AES Cryptographic Provider", "", True)
' Blob containing raw bits of key
Set KeyBlob = CM.CreateBlob
KeyBlob.Hex = "00010203050607080A0B0C0D0F101112"
' Import key bits into CryptoKey object, set cipher mode
Set key = context.ImportRawKey(KeyBlob, calgAES128, True)
key.Mode = ccmECB
' Binary plain text
Set blob = CM.CreateBlob
blob.Hex = "506812A45F08C889B97F5980038B8359"
' Encrypt, display result in Hex
Set ResBlob = key.EncryptBinary(blob)
Response.Write ResBlob.Hex
%>
