CIPHER_File

Encrypts/decrypts a file using specified block cipher algorithm and mode.

VB6/VBA

Debug.Print "Testing CIPHER_File ..."
Const MY_PATH As String = ""
Dim abKey() As Byte
Dim abIV() As Byte
Dim strFileEnc 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"
strFileEnc = MY_PATH & "hello.aes128.enc.dat"
strFileChk = MY_PATH & "hello.aes128.chk.txt"

' Create the key as an array of bytes
' This creates an array of 16 bytes {&HFE, &HDC, ... &H10}
abKey = cnvBytesFromHexStr("fedcba9876543210fedcba9876543210")
' Create the IV at random
ReDim abIV(PKI_BLK_AES_BYTES - 1)
Call RNG_Bytes(abIV(0), PKI_BLK_AES_BYTES, "", 0)
' Display the IV (this needs to be communicated separately to the recipient)
Debug.Print "IV=" & cnvHexStrFromBytes(abIV)

' Encrypt plaintext file to ciphertext using AES-128 in counter (CTR) mode
' (This will create a file of exactly the same size as the input)
nRet = CIPHER_File(ENCRYPT, strFileEnc, strFileIn, abKey(0), abIV(0), "aes128-ctr", 0)
Debug.Print "CIPHER_File(ENCRYPT) returns " & nRet

' Now decrypt it
nRet = CIPHER_File(DECRYPT, strFileChk, strFileEnc, abKey(0), abIV(0), "aes128-ctr", 0)
Debug.Print "CIPHER_File(DECRYPT) returns " & nRet

Output

Testing CIPHER_File ...
IV=33BE3982D3537B8AD891E703F88AE902
CIPHER_File(ENCRYPT) returns 0
CIPHER_File(DECRYPT) returns 0

VB.NET

Console.WriteLine("Testing CIPHER_File ...")
Const MY_PATH As String = ""
Dim abKey() As Byte
Dim abIV() As Byte
Dim strFileEnc As String
Dim strFileIn As String
Dim strFileChk As String
Dim nRet As Integer

' Construct full path names to files
strFileIn = MY_PATH & "hello.txt"
strFileEnc = MY_PATH & "hello.aes128.enc.dat"
strFileChk = MY_PATH & "hello.aes128.chk.txt"

' Create the key as an array of bytes
' This creates an array of 16 bytes {&HFE, &HDC, ... &H10}
abKey = Cnv.FromHex("fedcba9876543210fedcba9876543210")
' Create the IV at random
''ReDim abIV(PKI_BLK_AES_BYTES - 1)
'abIV = Rng.Bytes(Tdea.BlockSize)  ' WRONG!
abIV = Rng.Bytes(Cipher.BlockBytes(CipherAlgorithm.Aes128))  ' OR ``Rng.Bytes(16)``
' Display the IV (this needs to be communicated separately to the recipient)
Console.WriteLine("IV=" & Cnv.ToHex(abIV))

' Encrypt plaintext file to ciphertext using AES-128 in counter (CTR) mode
' (This will create a file of exactly the same size as the input)
nRet = Cipher.FileEncrypt(strFileEnc, strFileIn, abKey, abIV, CipherAlgorithm.Aes128, Mode.CTR)
Console.WriteLine("CIPHER_File(ENCRYPT) returns " & nRet)

' Now decrypt it
nRet = Cipher.FileDecrypt(strFileChk, strFileEnc, abKey, abIV, CipherAlgorithm.Aes128, Mode.CTR)
Console.WriteLine("CIPHER_File(DECRYPT) returns " & nRet)

Remarks

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