TDEA_File encrypts or decrypts a file
using a specified mode. The key and initialization vector
are passed as arrays of bytes. PKCS-5/7 padding is used.
Public Declare Function TDEA_File Lib "diCrPKI.dll"
(ByVal strFileOut As String, ByVal strFileIn As String, ByRef abKey As Byte,
ByVal fEncrypt As Long, ByVal strMode As String, ByRef abInitV As Byte) As Long
nRet = TDEA_File(strFileOut, strFileIn, abKey(0), fEncrypt, strMode, abInitV(0))
String with the full path name of the output
file to be created.String with the full path name of the input file
to be processed.Byte array containing the key.Boolean direction flag:
set as ENCRYPT (True) to encrypt or DECRYPT (False)
to decrypt.String specifying the confidentiality mode:Byte array containing the initialization vector (IV),
or zero (0) for ECB mode.
long _stdcall TDEA_File(const char *szFileOut, const char *szFileIn, const unsigned char *lpKey, long fEncrypt, const char *szMode, const unsigned char *lpIV);
Long: If successful, the return value is zero;
otherwise it returns a nonzero error code.
Tdea.FileEncrypt Method (String, String, Byte[], Mode, Byte[])
Tdea.FileDecrypt Method (String, String, Byte[], Mode, Byte[])
The key array abKey()
must be exactly 16 bytes long.
The initialization vector abInitV()
must be exactly the block size of 16 bytes long, except for ECB mode, where it is ignored (use 0).
The output file strFileOut will be overwritten without warning.
If there is an error [new in version 3.1], the output file will not exist.
The input and output files must not be the same.
In ECB and CBC modes, a padding string will be added or assumed according to the method outlined in Section 6.3 of
[CMS],
which is the same as the padding method in [PKCS7] section 10.3 and [PKCS5] section 6.1.1
and [RFC 1423] para 1.1.
Const MY_PATH As String = "C:\Test\"
Dim aKey() As Byte
Dim strFileOut As String
Dim strFileIn As String
Dim strFileChk As String
Dim nRet As Long
' Construct full path names to files
strFileIn = MY_PATH & "hello.txt"
strFileOut = MY_PATH & "hello.tdea.enc.dat"
strFileChk = MY_PATH & "hello.tdea.chk.txt"
' Create the key as an array of bytes
' This creates an array of 24 bytes {&HFE, &HDC, ... &H10}
aKey = cnvBytesFromHexStr("fedcba9876543210fedcba9876543210fedcba9876543210")
' Encrypt plaintext file to ciphertext
' Output file = 16-byte ciphertext file hello.enc
nRet = TDEA_File(strFileOut, strFileIn, aKey(0), ENCRYPT, "ECB", 0)
Debug.Print nRet
' Now decrypt it
nRet = TDEA_File(strFileChk, strFileOut, aKey(0), DECRYPT, "ECB", 0)
Debug.Print nRet