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Latest revision as of 01:04, 7 June 2010

CryptoSetKeyInfo

Result$ = CryptoSetKeyInfo(Algorithm$, KeyLength, Key$, IV$)

CryptoSetKeyInfo function

Syntax: result-string = CryptoSetKeyInfo(Algorithm$, KeySize, Key$, IV$)

Discussion: The CryptoSetKeyInfo function is used to specify an algorithm and all of the parameters required for use with the Encrypt/Decrypt functions. The result-string will return "+OK" if the function is successful or if a error occurs, "-ERR" followed by a description of the error.

Algorithms: The CryptoSetKeyInfo function currently supports 2 algorithms, 3DES and AES. Each of these algorithms has specific requirements as to the supported Key size and IV (Initial Vector) size as follows:

3DES - Triple Data Encryption Standard: Wiki

• Key Size: 24 bytes (192 bits must be supplied although only 168 bits are used - parity bit is discarded).
• IV Size: 8 Bytes

AES - Advanced Encryption Standard: Wiki

• Key Size: 16, 24, or 32 bytes (128, 192, 256 bits)
• IV Size: 16 Bytes

History: This function is available in Comet32 only.

Example:

Set Algorithm$ = "3DES"
Set KeySize = 192			! 3DES(168) requires 192 bits (parity bit is dropped)
Set BlockSize = 8			! 3DES block size is always 8

Length DYNAMIC & Local Key$
Length DYNAMIC & Local IV$
Length DYNAMIC & Local ErrResult$
Length DYNAMIC & Local Encr$, Decr$
Length DYNAMIC & Local Data$

Print (cs);(et)
Print "Testing: Algorithm: ";Algorithm$;", Key Size: ";KeySize;", Block Size: ";BlockSize
Print ""

Print "Enter something to encrypt:"
Input Data$
If (Data$ NE "")
   Key$ = CryptoGenerateRandom(KeySize/8) ! Generate a key
   IV$ = CryptoGenerateRandom(BlockSize)  ! Generate a IV

   ! Pass info to crypto sub-system
   ErrResult$ = CryptoSetKeyInfo(Algorithm$, KeySize, Key$, IV$)
   If (ErrResult$ EQ "+OK")
      Encr$ = Encrypt(Data$, "")
      Decr$ = Decrypt(Encr$, "")

      Print "Before:";Data$
      Print "After:";Decr$
   Else
      Print "CryptoSetKeyInfo failed: ";ErrResult$
   EndIf

   ! For compatibility in other programs, when done reset algorithm back to old default (RC4)
   ErrResult$ = CryptoSetKeyInfo("", 0, "", "")
   Wait
Endif

Stop