CryptoSys API Library Manual

TDEA_HexMode

TDEA_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.

VB6/VBA Syntax

Public Declare Function TDEA_HexMode Lib "diCryptoSys.dll" (ByVal strOutput As String, ByVal strInput As String, ByVal strHexKey As String, ByVal bEncrypt As Boolean, ByVal strMode As String, ByVal strHexIV As String) As Long

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

Parameters

strOutput
[out] String of sufficient length to receive the output.
strInput
[in] String containing the input data in hexadecimal.
strHexKey
[in] String containing the key in hexadecimal.
bEncrypt
[in] Boolean direction flag: set as True to encrypt or False to decrypt.
strMode
[in] String 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.
strHexIV
[in] String containing the initialization vector (IV) in hexadecimal.

C/C++ Syntax

long _stdcall TDEA_HexMode(char *lpszOutput, const char *lpszInput, const char *lpszKey, int bEncrypt, const char *lpszMode, const char *lpszIV);

Returns (VB6/C)

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

.NET Equivalent

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

COM/ASP Equivalent

tdea.HexMode
Public Function HexMode(ByVal strInput As String, ByVal strHexKey As String, ByVal bEncrypt As Boolean, ByVal strMode As String, ByVal strHexIV As String) As String

See tdea.HexMode.

Remarks

The length of the input string strInput 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 key string strHexKey must be exactly 48 hex characters long (i.e. representing exactly 24 bytes). The initialization vector string strIV must be exactly 16 hex characters long (i.e. representing exactly 8 bytes) unless strMode is ECB, in which case strIV is ignored (use ""). Valid hexadecimal characters are [0-9A-Fa-f]. The output string strOutput must be set up with at least the same number of characters as the input string before calling. The variables strOutput and strInput should be different.

Example

    Dim nRet As Long
    Dim strOutput As String
    Dim strInput As String
    Dim strKey As String
    Dim strIV As String
    Dim bEncrypt As Boolean
    Dim sCorrect As String

    strInput = "5468697320736F6D652073616D706520636F6E74656E742E0808080808080808"
    strKey = "737C791F25EAD0E04629254352F7DC6291E5CB26917ADA32"
    strIV = "B36B6BFB6231084E"
    sCorrect = "d76fd1178fbd02f84231f5c1d2a2f74a4159482964f675248254223daf9af8e4"
    ' Set strOutput to be same length as strInput
    strOutput = String(Len(strInput), " ")

    Debug.Print "KY="; strKey
    Debug.Print "PT="; strInput
    nRet = TDEA_HexMode(strOutput, strInput, strKey, True, "CBC", strIV)
    Debug.Print "CT="; strOutput; nRet
    Debug.Print "OK="; sCorrect

    strInput = strOutput
    nRet = TDEA_HexMode(strOutput, strInput, strKey, DECRYPT, "CBC", strIV)
    Debug.Print "P'="; strOutput; nRet

This should result in output as follows:

KY=737C791F25EAD0E04629254352F7DC6291E5CB26917ADA32
PT=5468697320736F6D652073616D706520636F6E74656E742E0808080808080808
CT=D76FD1178FBD02F84231F5C1D2A2F74A4159482964F675248254223DAF9AF8E4 0
OK=d76fd1178fbd02f84231f5c1d2a2f74a4159482964f675248254223daf9af8e4
P'=5468697320736F6D652073616D706520636F6E74656E742E0808080808080808 0

See Also

TDEA_Hex

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