CryptoSys PKI Toolkit Manual

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 "diCrPKI.dll" (ByVal strOutput As String, ByVal strInput As String, ByVal strKey As String, ByVal fEncrypt As Long, ByVal strMode As String, ByVal strIV As String) As Long

nRet = TDEA_HexMode(strOutput, strInput, strKey, fEncrypt, strMode, strIV)

Parameters

strOutput
[out] String of sufficient length to receive the output.
strInput
[in] String containing the input data in hex format.
strKey
[in] String containing the key in hex format.
fEncrypt
[in] Boolean direction flag: set as ENCRYPT (True) to encrypt or DECRYPT (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.
strIV
[in] String containing the initialization vector (IV), if required, in hex format.

C/C++ Syntax

long _stdcall TDEA_HexMode(char *szOutput, const char *szInput, const char *szKey, long fEncrypt, const char *szMode, const char *szIV);

Returns (VB6/C)

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

.NET Equivalent

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

Remarks

For ECB and CBC modes, the length of the input string strInput must be a multiple of 16 hex characters long (i.e. representing a multiple of 8 bytes) otherwise an error will result. The key string strKey must be exactly 48 hex characters long (i.e. representing exactly 24 bytes/192 bits). The initialization vector string strIV must be exactly 16 hex characters long (i.e. representing exactly the block size of 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 the same number of characters as the input string before calling. The variables strOutput and strInput should be different.

Example

This example is from Section 8.1 of [SMIME-EX].

Dim nRet As Long
Dim sOutput As String
Dim sInput As String
Dim sKey As String
Dim sInitV As String
Dim sCorrect As String

sInput = "5468697320736F6D652073616D706520636F6E74656E742E0808080808080808"
'         T h i s _ s o m e _ s a m p e _ c o n t e n t . (padding 8 x 08)
sKey = "737C791F25EAD0E04629254352F7DC6291E5CB26917ADA32"
sInitV = "B36B6BFB6231084E"
sCorrect = "d76fd1178fbd02f84231f5c1d2a2f74a4159482964f675248254223daf9af8e4"
' Set sOutput to be same length as sInput
sOutput = String(Len(sInput), " ")

Debug.Print "KY=" & sKey
Debug.Print "PT=" & sInput
nRet = TDEA_HexMode(sOutput, sInput, sKey, ENCRYPT, "CBC", sInitV)
Debug.Print "CT=" & sOutput & nRet
Debug.Print "OK=" & sCorrect

sInput = sOutput
nRet = TDEA_HexMode(sOutput, sInput, sKey, DECRYPT, "CBC", sInitV)
Debug.Print "P'=" & sOutput & nRet

This should result in output as follows:

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

See Also

TDEA_BytesMode TDEA_B64Mode

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