AES128_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 = AES128_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 128-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

Aes128.Encrypt Method (String, String, Mode, String, EncodingBase)
Aes128.Decrypt Method (String, String, Mode, String, EncodingBase)

Remarks

The length of the input string szInput must represent a multiple of the block size (16 bytes) when decoded. If not, an error will be returned. The initialization vector string szIV must represent exactly 16 bytes unless szMode is ECB, in which case szIV is ignored (use ""). The key szKey must also represent exactly 16 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

This example is the same data as for AES128_HexMode, except the data is in base64 format.

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

' Case #4: Encrypting 64 bytes (4 blocks) using AES-CBC with 128-bit key
' Key       : 0x56e47a38c5598974bc46903dba290349
strKey = "VuR6OMVZiXS8RpA9uikDSQ=="
' IV        : 0x8ce82eefbea0da3c44699ed7db51b7d9
strIV = "jOgu776g2jxEaZ7X21G32Q=="
' Plaintext : 0xa0a1a2a3a4a5a6a7a8a9aaabacadaeaf
'               b0b1b2b3b4b5b6b7b8b9babbbcbdbebf
'               c0c1c2c3c4c5c6c7c8c9cacbcccdcecf
'               d0d1d2d3d4d5d6d7d8d9dadbdcdddedf
strInput = "oKGio6SlpqeoqaqrrK2ur7CxsrO0tba3uLm6u7y9vr/" _
& "AwcLDxMXGx8jJysvMzc7P0NHS09TV1tfY2drb3N3e3w=="
' Ciphertext: 0xc30e32ffedc0774e6aff6af0869f71aa
'               0f3af07a9a31a9c684db207eb0ef8e4e
'               35907aa632c3ffdf868bb7b29d3d46ad
'               83ce9f9a102ee99d49a53e87f4c3da55
sCorrect = "ww4y/+3Ad05q/2rwhp9xqg868HqaManGhNsgfrDvjk" _
& "41kHqmMsP/34aLt7KdPUatg86fmhAu6Z1JpT6H9MPaVQ=="

' 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 = AES128_B64Mode(strOutput, strInput, strKey, ENCRYPT, "CBC", strIV)
Debug.Print "CT=" & strOutput & nRet
Debug.Print "OK=" & sCorrect

strInput = strOutput
nRet = AES128_B64Mode(strOutput, strInput, strKey, DECRYPT, "CBC", strIV)
Debug.Print "P'=" & strOutput; nRet

This should result in output as follows:

KY=VuR6OMVZiXS8RpA9uikDSQ==
IV=jOgu776g2jxEaZ7X21G32Q==
PT=oKGio6SlpqeoqaqrrK2ur7CxsrO0tba3uLm6u7y9vr/
AwcLDxMXGx8jJysvMzc7P0NHS09TV1tfY2drb3N3e3w==
CT=ww4y/+3Ad05q/2rwhp9xqg868HqaManGhNsgfrDvjk
41kHqmMsP/34aLt7KdPUatg86fmhAu6Z1JpT6H9MPaVQ== 0 
OK=ww4y/+3Ad05q/2rwhp9xqg868HqaManGhNsgfrDvjk
41kHqmMsP/34aLt7KdPUatg86fmhAu6Z1JpT6H9MPaVQ==
P'=oKGio6SlpqeoqaqrrK2ur7CxsrO0tba3uLm6u7y9vr/
AwcLDxMXGx8jJysvMzc7P0NHS09TV1tfY2drb3N3e3w== 0 

See Also

AES128_HexMode AES128_BytesMode

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