Derives a key of any length from a password using the PBKDF2 algorithm from PKCS #5 with the salt and output derived key encoded in hexadecimal.
Public Declare Function PBE_Kdf2Hex Lib "diCryptoSys.dll"
(ByVal strOutput As String, ByVal nMaxChars As Long, ByVal nKeyBytes As Long,
ByVal strPwd As String, ByVal strSaltHex As String,
ByVal nCount As Long, ByVal nOptions As Long) As Long
nRet = PBE_Kdf2Hex(strDerivedKey, nMaxChars, nKeyLen, strPassword, strSaltHex, nCount, nOptions)
String to receive the hexadecimal-encoded derived key.Long specifying the maximum number of characters in strOutput.Long specifying the size of the required key in bytes.String containing the password.String containing the salt in hex format.Long specifying the required iteration count.Long Option flags. Select one of:
long _stdcall PBE_Kdf2Hex(char *szOutput, long nOutChars, long dkBytes, const char *szPwd, const char *szSaltHex, long count, long reserved);
Long: If successful, the return value is 0;
otherwise it returns a non-zero error code.
Pbe.Kdf2 Method (Int32, String, String, Int32)
pbe.DKF2FromString
Public Function DKF2FromString(ByVal nBytes As Long, ByVal strPassword As String, ByVal strSaltHex As String, nCount As Long) As String
See pbe.DKF2FromString.
The output string strOutput should be pre-dimensioned to be at least double the
required key length in bytes. (Hint: specify nMaxChars as Len(strOutput)).
The seed strSaltHex is specified in hex format and can be any even number of hex digits in length.
The password strPassword is normal text, not hexadecimal.
Dim strDerivedKey As String Dim nKeyLen As Long Dim strPassword As String Dim strSaltHex As String Dim nCount As Long Dim nRet As Long strPassword = "password" ' NB normal text, not hex ' Set 8-byte salt = 78 57 8E 5A 5D 63 CB 06 strSaltHex = "78578E5A5D63CB06" ' Iteration count is 2048 nCount = 2048 ' Pre-dimension output string for derived key to ' required length of 24 bytes i.e. 48 hex chars ' (Don't forget to do this) nKeyLen = 24 strDerivedKey = String(2 * nKeyLen, " ") ' Derive PBKDF2 key using function from CryptoSys API nRet = PBE_Kdf2Hex(strDerivedKey, Len(strDerivedKey), nKeyLen, _ strPassword, strSaltHex, nCount, 0) ' Check against test vector Debug.Print "Derived key = " & strDerivedKey Debug.Print "Correct key = BFDE6BE94DF7E11DD409BCE20A0255EC327CB936FFE93643"
This should result in output as follows:
Derived key = BFDE6BE94DF7E11DD409BCE20A0255EC327CB936FFE93643 Correct key = BFDE6BE94DF7E11DD409BCE20A0255EC327CB936FFE93643