PureBasic Forums - English

Code: Select all

;No Unicode!!!

String$ = "Hello this is a test for AES"
Debug String$
Debug "Len: " + Len(String$)           ;28, we need 32
*CipheredString   = AllocateMemory(Len(String$) + 1)  ;with Zero_Byte
*DecipheredString = AllocateMemory(Len(String$) + 1)  ;with Zero_Byte
  
AESEncoder(@String$, *CipheredString, Len(String$), ?KeyPB, 128, 0, #PB_Cipher_ECB)
Debug "Ciphered: "+PeekS(*CipheredString)
    
For i = 0 To Len(String$) - 1
  If i % 16 = 0
    Debug "=========================================="     ;Optik
  EndIf
  Debug Hex(PeekA(*CipheredString + i))
Next

AESDecoder(*CipheredString, *DecipheredString, Len(String$), ?KeyPB, 128, 0, #PB_Cipher_ECB)
Debug "Deciphered: " + PeekS(*DecipheredString)

Debug "=========================================="
Debug "Internal:"
String1$ = Space(32)
For i = 0 To Len(String$) - 1
  PokeA(@String1$ + i, PeekA(@String$ + i))
Next

;Length of last Block is 12 -> we need 4 Bytes
PokeA(@String1$ + 28, $5)    ;copy Bytes from the Block before last Block into last Block (see Debug-Output)
PokeA(@String1$ + 29, $31)
PokeA(@String1$ + 30, $c8)
PokeA(@String1$ + 31, $94)

*CipheredString1   = AllocateMemory(Len(String1$) + 1)     ;with Zero_Byte
*DecipheredString1 = AllocateMemory(Len(String1$) + 1)     ;with Zero_Byte

AESEncoder(@String1$, *CipheredString1, Len(String1$), ?KeyPB, 128, 0, #PB_Cipher_ECB)
;Debug "Ciphered: " + PeekS(*CipheredString1)
    
For i = 0 To Len(String1$) - 1
  If i % 16 = 0
    Debug "=========================================="
  EndIf
  Debug Hex(PeekA(*CipheredString1 + i))
Next
If i % 16 = 0
  Debug "=========================================="
EndIf

;now change the last Block with the Block before and set old Length
Buffer = AllocateMemory(32)
CopyMemory(*CipheredString1, Buffer + 16, 16)
CopyMemory(*CipheredString1 + 16, Buffer, 16)
For i = 0 To 31
  If i % 16 = 0
    Debug "=========================================="
  EndIf
  Debug Hex(PeekA(Buffer + i))
Next
If i % 16 = 0
  Debug "=========================================="
EndIf

PokeB(Buffer + 28, 0)        ;set old String-Length

For i = 0 To 27
  If i % 16 = 0
    Debug "=========================================="
  EndIf
  Debug Hex(PeekA(Buffer + i))
Next
If i % 16 = 0
  Debug "=========================================="
EndIf

AESDecoder(Buffer, *DecipheredString1, Len(String$), ?KeyPB, 128, 0, #PB_Cipher_ECB)
Debug "Deciphered: " + PeekS(*DecipheredString1)

DataSection
  KeyPB:
    Data.b $06, $a9, $21, $40, $36, $b8, $a1, $5b, $51, $2e, $03, $d5, $34, $12, $00, $06
EndDataSection

Code: Select all

; This code demonstrates the standard decryption with PB AES - CTS of encrypted data which is not divisible by 16

; ECB Mode

EnableExplicit
Define iv$=Space(8)
Define key$=Space(8)
Define test$="Hello World, i hope you are well !" ; StringByteLength
Define ByteLength=StringByteLength(test$)
Define difference=ByteLength%16
If Bytelength<16
  MessageRequester("Hint", "PB AES supports not bytelength < 16"+#LF$+#LF$+
                           "You can fix this with a QAES module"+#LF$+
  "https://www.purebasic.fr/english/viewtopic.php?f=12&t=76780")
  End
  EndIf
AESEncoder(@test$, @test$, ByteLength, @key$, 128, @iv$, #PB_Cipher_ECB) ; We encrypt the characters

If difference
Define *buffer_0=AllocateMemory(16) ; We create a buffer for the last incomplete block
Define *buffer_1=AllocateMemory(16) ; We create a buffer for the last block
Define *buffer_2=AllocateMemory(ByteLength)

CopyMemory(@test$+ByteLength-difference, *buffer_0, difference)
CopyMemory(@test$+ByteLength-difference-16, *buffer_0, 16)

AESDecoder(*buffer_0, *buffer_0, 16, @key$, 128, @iv$, #PB_Cipher_ECB) ; Decrypt difference bytes

CopyMemory(*buffer_0+difference, *buffer_1+difference, 16-difference)
CopyMemory(@test$+ByteLength-difference, *buffer_1, difference)

AESDecoder(*buffer_1, *buffer_1, 16, @key$, 128, @iv$, #PB_Cipher_ECB) ; Decrypt the second to last block

FillMemory(*buffer_0+difference, 16-difference)

AESDecoder(@test$, @test$, Bytelength-16-difference, @key$, 128, @iv$, #PB_Cipher_ECB) ; Decrypt the second to last block
test$=Left(test$, (Bytelength-16-difference)/SizeOf(character))

Debug test$+PeekS(*buffer_1)+PeekS(*buffer_0)
Else
AESDecoder(@test$, @test$, Bytelength, @key$, 128, @iv$, #PB_Cipher_ECB) ; Decrypt the second to last block
Debug test$
EndIf