Is a keyed-hash function that provides message authentication using the HMAC algorithm and the MD5 hash function.
Public Declare Function MD5_Hmac Lib "diCryptoSys.dll"
(ByVal strDigest As String, ByRef lpData As Byte, ByVal nDataLen As Long,
ByRef lpKey As Byte, ByVal nKeyLen As Long) As Long
nRet = MD5_Hmac(strDigest, abData(0), nDataLen, abKey(0), nKeyLen)
' Note the "(0)" after the byte array parameters
long __stdcall MD5_Hmac(char *szDigest, const unsigned char *textBytes, long textLen, const unsigned char *lpKeyBytes, long keyLen);
If successful, the return value is 0; otherwise it returns a non-zero error code.
Md5.Hmac Method (Byte[], Byte[])
szDigest must be at least 32 (API_MAX_MD5_CHARS) characters long (33 in a C program).
This example reproduces the three test vectors from RFC 2104.
Dim nRet As Long
Dim abData() As Byte
Dim abKey() As Byte
Dim i As Integer
Dim nDataLen As Long, nKeyLen As Long
Dim strDigest As String * 32
' Test No 1.
' Set key = 0x0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b
ReDim abKey(15)
For i = 0 To 15
abKey(i) = &HB
Next
' Convert string to byte array
abData() = StrConv("Hi There", vbFromUnicode)
nDataLen = UBound(abData) + 1
' Create HMAC digest
nRet = MD5_Hmac(strDigest, abData(0), nDataLen, abKey(0), 16)
Debug.Print 1; nRet; strDigest
' Test No 2.
abKey() = StrConv("Jefe", vbFromUnicode)
nKeyLen = UBound(abKey) + 1
abData() = StrConv("what do ya want for nothing?", vbFromUnicode)
nDataLen = UBound(abData) + 1
nRet = MD5_Hmac(strDigest, abData(0), nDataLen, abKey(0), nKeyLen)
Debug.Print 2; nRet; strDigest
' Test No 3.
ReDim abKey(15)
For i = 0 To 15
abKey(i) = &HAA
Next
ReDim abData(49)
For i = 0 To 49
abData(i) = &HDD
Next
nRet = MD5_Hmac(strDigest, abData(0), 50, abKey(0), 16)
Debug.Print 3; nRet; strDigest
This should result in output as follows:
1 0 9294727a3638bb1c13f48ef8158bfc9d 2 0 750c783e6ab0b503eaa86e310a5db738 3 0 56be34521d144c88dbb8c733f0e8b3f6
-