TDEA_B64Mode

Encrypts or decrypts data represented as a base64 string using a specified mode. The key and initialization vector are represented as base64 strings.

VBA/VB6 Syntax

nRet = TDEA_B64Mode(strOutput, strInput, strKey, bEncrypt, strMode, strIV)

C/C++ Syntax

Parameters

szOutput

[out] of sufficient length to receive the output.

szInput

[in] containing the input data in base64.

szKey

[in] containing the key in base64.

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), if required, in base64.

Returns (VBA/C)

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

.NET Equivalent

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

Remarks

The length of the input string szInput must represent a multiple of the block size (8 bytes) when decoded. If not, an error will be returned. The initialization vector string szIV must represent exactly 8 bytes unless szMode is ECB, in which case szIV is ignored (use ""). The key szKey must represent exactly 24 bytes, the required key length. 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 strKey As String
Dim strIV As String
Dim bEncrypt As Boolean
Dim sCorrect As String

' Key is 0x737C791F25EAD0E04629254352F7DC6291E5CB26917ADA32
strKey = "c3x5HyXq0OBGKSVDUvfcYpHlyyaRetoy"
' IV is 0xB36B6BFB6231084E
strIV = "s2tr+2IxCE4="
' 0x5468697320736F6D652073616D706520636F6E74656E742E0808080808080808
'  "T h i s _ s o m e _ s a m p e _ c o n t e n t ." (padding 8 x 08)
strInput = "VGhpcyBzb21lIHNhbXBlIGNvbnRlbnQuCAgICAgICAg="
sCorrect = "12/RF4+9AvhCMfXB0qL3SkFZSClk9nUkglQiPa+a+OQ="

' Set strOutput to be same length as strInput
strOutput = String(Len(strInput), " ")

Debug.Print "KY=" & strKey
Debug.Print "IV=" & strIV
Debug.Print "PT=" & strInput
nRet = TDEA_B64Mode(strOutput, strInput, strKey, ENCRYPT, "CBC", strIV)
Debug.Print "CT=" & strOutput; nRet
Debug.Print "OK=" & sCorrect

strInput = strOutput
nRet = TDEA_B64Mode(strOutput, strInput, strKey, DECRYPT, "CBC", strIV)
Debug.Print "P'=" & strOutput; nRet

This should result in output as follows:

KY=c3x5HyXq0OBGKSVDUvfcYpHlyyaRetoy
IV=s2tr+2IxCE4=
PT=VGhpcyBzb21lIHNhbXBlIGNvbnRlbnQuCAgICAgICAg=
CT=12/RF4+9AvhCMfXB0qL3SkFZSClk9nUkglQiPa+a+OQ= 0 
OK=12/RF4+9AvhCMfXB0qL3SkFZSClk9nUkglQiPa+a+OQ=
P'=VGhpcyBzb21lIHNhbXBlIGNvbnRlbnQuCAgICAgICAg= 0 

See Also

TDEA_HexMode TDEA_BytesMode

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