HASH_AddBytes

Adds an array of bytes to be digested in the HASH context.

VBA/VB6 Syntax

nRet = HASH_AddBytes(hContext, abData(0), nDataLen)

C/C++ Syntax

Parameters

hContext

[in] Handle to the HASH context.

lpData

[in] Byte array containing the next part of the message.

nDataLen

[in] Number of bytes in the array

Returns (VBA/C)

If successful, the return value is 0; otherwise it returns a non-zero error code.

VBA Wrapper Syntax

.NET Equivalent

Hash.AddData Method (Byte[])
Hash.AddData Method (String)

C++ (STL) Equivalent

Remarks

The handle hContext to the context must have been set up with a prior call to HASH_Init. The HASH_AddBytes function may be called many times before creating the final message digest with HASH_Final.

VBA users can use the more convenient wrapper functions hashAddBytes and hashAddString.

Example (VBA core function)

Dim hContext As Long
Dim r As Long
Dim nBytes As Long
Dim lpMessage1() As Byte
Dim lpMessage2() As Byte
Dim lpDigest() As Byte

hContext = HASH_Init(API_HASH_SHA1)
Debug.Print "HASH_Init returns 0x" & Hex(hContext)
' Check for an invalid handle
If hContext = 0 Then
  MsgBox "Failed to set context"
  Exit Sub
End If

' Create two arrays of bytes to digest (long way!)
ReDim lpMessage1(0) ' 1 bytes long
lpMessage1(0) = &H61     ' ASCII 'a'
ReDim lpMessage2(1) ' 2 bytes long
lpMessage2(0) = &H62     ' ASCII 'b'
lpMessage2(1) = &H63     ' ASCII 'c'

' Add data in parts (the string "abc")
r = HASH_AddBytes(hContext, lpMessage1(0), 1)
r = HASH_AddBytes(hContext, lpMessage2(0), 2)
nBytes = HASH_DigestLength(hContext)
Debug.Print "HASH_DigestLength=" & nBytes
ReDim lpDigest(nBytes - 1)
nBytes = HASH_Final(lpDigest(0), nBytes, hContext)
Debug.Print "DIG=" & cnvHexStrFromBytes(lpDigest)
Debug.Print "OK= " & "A9993E364706816ABA3E25717850C26C9CD0D89D"

Example (VBA wrapper function)

Dim hContext As Long
Dim lpDigest() As Byte
' Initialize context to use SHA-3-256 (NB HASH_ func)
hContext = hashInit(API_HASH_SHA3_256)
Debug.Print "hashInit returns 0x" & Hex(hContext)
' Check for an invalid handle
If hContext = 0 Then
  MsgBox "Failed to set context"
  Exit Sub
End If
' Add "abc" in parts
Call hashAddBytes(hContext, cnvBytesFromHexStr("61"))   ' ASCII "a"
Call hashAddString(hContext, "")    ' Empty string => No effect
Call hashAddBytes(hContext, cnvBytesFromHexStr(""))    ' Empty byte array => No effect
Call hashAddString(hContext, "bc")  ' Add a string directly
' Get final digest value
lpDigest = hashFinal(hContext)
Debug.Print "DIG=" & cnvHexStrFromBytes(lpDigest)
Debug.Print "OK= " & "3a985da74fe225b2045c172d6bd390bd855f086e3e9d525b46bfe24511431532"

See Also

HASH_Init HASH_Final

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