BLF_HexMode

Encrypts or decrypts data represented as a hexadecimal string using a specified mode. The key and initialization vector are represented as a hexadecimal string.

VBA/VB6 Syntax

nRet = BLF_HexMode(strOutput, strInput, strHexKey, bEncrypt, strMode, strHexIV)

C/C++ Syntax

Parameters

szOutput

[out] of sufficient length to receive the output.

szInput

[in] containing the input data in hexadecimal.

szKey

[in] containing the key in hexadecimal.

fEncrypt

[in] direction flag: set as ENCRYPT (True) to encrypt or DECRYPT (False) to decrypt.

szMode

[in] specifying the confidentiality mode:
"ECB" for Electronic Codebook mode,
"CBC" for Cipher Block Chaining mode,
"CFB" for 64-bit Cipher Feedback mode,
"OFB" for Output Feedback mode, or
"CTR" for Counter mode.

szIV

[in] containing the initialization vector (IV) in hexadecimal.

Returns (VBA/C)

If successful, the return value is 0; otherwise it returns a non-zero error code.

.NET Equivalent

Blowfish.Encrypt Method (String, String, Mode, String)
Blowfish.Decrypt Method (String, String, Mode, String)

COM/ASP Equivalent

See blf.HexMode.

Remarks

The length of the input string szInput must be a multiple of 16 hex characters long (i.e. representing a multiple of 8 bytes). If not, an error code will be returned.. The initialization vector string szIV must be exactly 16 hex characters long (i.e. representing exactly 8 bytes) unless szMode is ECB, in which case szIV is ignored (use ""). The key szKey can be any even length between 2 and 112 hexadecimal characters. Valid hexadecimal characters are [0-9A-Fa-f]. The output string szOutput must be set up with at least the same number of characters as the input string before calling. The variables szOutput and szInput should be different.

Example

    Dim nRet As Long
    Dim strOutput As String
    Dim strInput As String
    Dim strHexKey As String
    Dim strHexIV As String
    Dim sCorrect As String

    ' "7654321 Now is the time for " padded to 32 bytes with 4 nulls
    strInput = "37363534333231204E6F77206973207468652074696D6520666F722000000000"
    sCorrect = "6B77B4D63006DEE605B156E27403979358DEB9E7154616D959F1652BD5FF92CC"
    strHexKey = "0123456789ABCDEFF0E1D2C3B4A59687"
    strHexIV = "FEDCBA9876543210"
    ' Set strOutput to be same length as strInput
    strOutput = String(Len(strInput), " ")

    Debug.Print "KY=" & strHexKey
    Debug.Print "IV=" & strHexIV
    Debug.Print "PT=" & strInput
    ' Encrypt in one-off process
    nRet = BLF_HexMode(strOutput, strInput, strHexKey, ENCRYPT, "CBC", strHexIV)
    Debug.Print "CT=" & strOutput, nRet
    Debug.Print "OK=" & sCorrect

    ' Now decrypt back to plain text
    strInput = strOutput
    nRet = BLF_HexMode(strOutput, strInput, strHexKey, DECRYPT, "CBC", strHexIV)
    Debug.Print "P'=" & strOutput, nRet

This should result in output as follows:

KY=0123456789ABCDEFF0E1D2C3B4A59687
IV=FEDCBA9876543210
PT=37363534333231204E6F77206973207468652074696D6520666F722000000000
CT=6B77B4D63006DEE605B156E27403979358DEB9E7154616D959F1652BD5FF92CC    0
OK=6B77B4D63006DEE605B156E27403979358DEB9E7154616D959F1652BD5FF92CC
P'=37363534333231204E6F77206973207468652074696D6520666F722000000000    0

See Also

BLF_Hex

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