Creates a SHA-256 message digest in Byte array format
from a message in Byte array format.
Public Declare Function SHA2_BytesHash Lib "diCryptoSys.dll"
(ByRef abDigest As Byte, ByRef abData As Byte, ByVal nDataLen As Long) As Long
nRet = SHA2_BytesHash(abDigest(0), abData(0), nDataLen)
Byte array to receive message digest.Byte array containing the message to be hashed.Long containing number of bytes in the array.
long _stdcall SHA2_BytesHash(unsigned char *digest, const unsigned char *bytes, long len);
Long: If successful, the return value is 0;
otherwise it returns a non-zero error code.
This function differs from other SHA2 functions in that it creates a digest in Byte array
format. This is particularly useful when you need to carry out repeated hash operations.
abDigest must be at least 32 (API_MAX_SHA2_BYTES) bytes long.
VB6/VBA users: Note the '(0)' in abDigest(0) and abData(0).
Dim nRet As Long
Dim abData(2) As Byte ' Create 3-byte array (NB zero-based)
Dim abDigest(31) As Byte ' Create 32-byte array to receive digest
' Setup byte array with "abc"
abData(0) = Asc("a")
abData(1) = Asc("b")
abData(2) = Asc("c")
' Compute SHA-256 hash digest
nRet = SHA2_BytesHash(abDigest(0), abData(0), 3)
' Print resulting bytes in hex format
Debug.Print nRet; cnvHexStrFromBytes(abDigest)
This should result in output as follows:
0 BA7816BF8F01CFEA414140DE5DAE2223B00361A396177A9CB410FF61F20015AD
This second example shows how to carry out repeated hashes of the digest.
Dim nRet As Long
Dim abData(2) As Byte ' Create 3-byte array (NB zero-based)
Dim abDigest(31) As Byte ' Create 32-byte array to receive digest
Dim i As Integer
' Setup byte array with "abc"
abData(0) = Asc("a")
abData(1) = Asc("b")
abData(2) = Asc("c")
' Compute SHA-256 hash digest of input
nRet = SHA2_BytesHash(abDigest(0), abData(0), 3)
' Now carry out repeated hashes of the digest
For i = 2 To 1000
nRet = SHA2_BytesHash(abDigest(0), abDigest(0), 32)
Next
' Print H(1000) in hex format
Debug.Print cnvHexStrFromBytes(abDigest)
This should result in output as follows:
FC8A6B86A13F71CD9A67F558AB6FD82A3DD89186163A017ED8051ACF6D3F8F99