CIPHER_Bytes

Encrypt or decrypt data in a byte array. The key and initialization vector are given as byte arrays.
@deprecated Use CIPHER_EncryptBytes or CIPHER_DecryptBytes instead.

VBA/VB6 Syntax

nRet = CIPHER_Bytes(fEncrypt, lpOutput(0), lpData(0), nDataLen, lpKey(0), lpIV(0), strAlgAndMode, nOptions) ' Note the "(0)" after the byte array parameters

C/C++ Syntax

Parameters

fEncrypt

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

lpOutput

[out] array of sufficient length to receive the output.

lpData

[in] array containing the input data.

nDataLen

[in] specifying the length of the input data in bytes.

lpKey

[in] array containing the key.

lpIV

[in] containing the initialization vector (IV), or zero (0) for ECB mode.

szAlgAndMode

[in] containing the block cipher algorithm and mode (see Specifying the algorithm and mode for generic block cipher functions).

nOptions

[in] option flags.

Returns (VBA/C)

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

.NET Equivalent

Cipher.Encrypt Method (Byte[], Byte[], Byte[], CipherAlgorithm, Mode)
Cipher.Decrypt Method (Byte[], Byte[], Byte[], CipherAlgorithm, Mode)

Remarks

The algorithm and mode must be specified using either the szAlgAndMode or nOptions parameter (see Specifying the algorithm and mode for generic block cipher functions). The length of key lpKey must be exactly the required key size, and the length of the IV, if required, exactly the block size. See Valid key and block sizes. Important: The output array lpOutput must be at least nDataLen bytes long. lpOutput and lpData may be the same.

For ECB and CBC modes, the length of the input data lpInput must be an exact multiple of the block size otherwise a BAD_LENGTH_ERROR error will result. It is the responsibility of the user to provide suitable padding before encrypting in those modes and to remove any padding after decrypting.

Example

Note that we convert the input data from hex strings to byte arrays in this example just for convenience so we can quickly demonstrate how the function works. In practice, since you are using the "Bytes" function, we assume your input data would already be in byte array form. If all your data strings are already in hex string format and you want the output in hex, then use CIPHER_Hex instead.

Dim nRet As Long
Dim strOutput As String
Dim strInput As String
Dim sCorrect As String
Dim abKey()  As Byte
Dim abInitV() As Byte
Dim abResult() As Byte
Dim abData() As Byte
Dim abCheck() As Byte
Dim nDataLen As Long

' Set up input in byte arrays
strInput = "Now is the time for all good men"
sCorrect = "C3153108A8DD340C0BCB1DFE8D25D2320EE0E66BD2BB4A313FB75C5638E9E177"
abKey = cnvBytesFromHexStr("0123456789ABCDEFF0E1D2C3B4A59687")
abInitV = cnvBytesFromHexStr("FEDCBA9876543210FEDCBA9876543210")
abData = StrConv(strInput, vbFromUnicode)
nDataLen = UBound(abData) - LBound(abData) + 1

' Pre-dimension output array
ReDim abResult(nDataLen - 1)

Debug.Print "KY=" & cnvHexStrFromBytes(abKey)
Debug.Print "IV=" & cnvHexStrFromBytes(abInitV)
Debug.Print "PT=" & strInput
Debug.Print "PT=" & cnvHexStrFromBytes(abData)
' Encrypt in one-off process (abResult <-- abData)
nRet = CIPHER_Bytes(ENCRYPT, abResult(0), abData(0), nDataLen, _
    abKey(0), abInitV(0), "aes128-cbc", 0)
Debug.Print "CIPHER_Bytes(ENCRYPT) returns " & nRet
Debug.Print "CT=" & cnvHexStrFromBytes(abResult)
Debug.Print "OK=" & sCorrect

' Now decrypt back (abCheck <-- abResult)
ReDim abCheck(nDataLen - 1)
nRet = CIPHER_Bytes(DECRYPT, abCheck(0), abResult(0), nDataLen, _
    abKey(0), abInitV(0), "", PKI_BC_AES128 + PKI_MODE_CBC)
Debug.Print "CIPHER_Bytes(DECRYPT) returns " & nRet
' And decode back from a byte array into a string
Debug.Print "P'=" & cnvHexStrFromBytes(abCheck)
strOutput = StrConv(abCheck(), vbUnicode)
Debug.Print "P'=" & strOutput

This should result in output as follows:

KY=0123456789ABCDEFF0E1D2C3B4A59687
IV=FEDCBA9876543210FEDCBA9876543210
PT=Now is the time for all good men
PT=4E6F77206973207468652074696D6520666F7220616C6C20676F6F64206D656E
CIPHER_Bytes(ENCRYPT) returns 0
CT=C3153108A8DD340C0BCB1DFE8D25D2320EE0E66BD2BB4A313FB75C5638E9E177
OK=C3153108A8DD340C0BCB1DFE8D25D2320EE0E66BD2BB4A313FB75C5638E9E177
CIPHER_Bytes(DECRYPT) returns 0
P'=4E6F77206973207468652074696D6520666F7220616C6C20676F6F64206D656E
P'=Now is the time for all good men

See Also

CIPHER_Hex

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