HMAC Methods Reference

📋 Method List

Traditional Methods

Method	Description
SetKey	Set key from string
SetKeyBytes	Set key from byte array
Compute	Compute string HMAC (returns Hex)
ComputeBytes	Compute byte array HMAC (returns byte array)
ComputeBytesToHex	Compute byte array HMAC (returns Hex)

Chainable Methods

Method	Description
Mode	Set HMAC algorithm
Secret	Set key from string/Hex/Base64
SecretBytes	Set key from byte array
DataString	Input string data
DataBytes	Input byte array data
ReturnHex	Return Hex format result
ReturnBase64	Return Base64 format result
ReturnBytes	Return byte array result

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🔑 SetKey / SetKeyBytes Methods

Description

Sets the HMAC key (traditional way).

Syntax

' Set from string
Public Sub SetKey(ByVal KeyString As String, _
                  Optional ByVal Encoding As HMACStringEncoding = HMAC_ENCODING_UTF8)

' Set from byte array
Public Sub SetKeyBytes(ByRef KeyBytes() As Byte)

Example

Dim Hmac As New cCryptoHMAC

' Set UTF-8 key
Hmac.SetKey "my-secret-key"

' Set ANSI key
Hmac.SetKey "my-secret-key", HMAC_ENCODING_ANSI

' Set byte array key
Dim keyBytes() As Byte
keyBytes = StrConv("my-key", vbFromUnicode)
Hmac.SetKeyBytes keyBytes

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🔐 Compute Method

Description

Computes HMAC of string data, returning a hexadecimal string.

Syntax

Public Function Compute(ByVal Data As String, _
                        ByVal KeyString As String, _
                        Optional ByVal Algorithm As HMACAlgorithm, _
                        Optional ByVal Encoding As HMACStringEncoding = HMAC_ENCODING_UTF8) As String

Parameters

Parameter	Type	Description
Data	String	Data to sign
KeyString	String	Key string
Algorithm	HMACAlgorithm	Optional, algorithm (defaults to class property)
Encoding	HMACStringEncoding	Optional, encoding (default UTF8)

Example

Dim Hmac As New cCryptoHMAC
Dim result As String

' Simple computation
result = Hmac.Compute("data to sign", "secret-key")

' Specify algorithm
result = Hmac.Compute("data to sign", "secret-key", HMAC_ALG_SHA256)

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⛓️ Chainable Methods

Mode Method

Sets the HMAC algorithm.

Public Function Mode(ByVal Algorithm As HMACAlgorithm) As cCryptoHMAC

Secret Method

Sets the key, supports string, Hex, Base64 formats.

Public Function Secret(ByVal KeyString As String, _
                    Optional ByVal KeyType As SecretKeyType = SECRET_KEY_STRING, _
                    Optional ByVal Encoding As HMACStringEncoding = HMAC_ENCODING_UTF8) As cCryptoHMAC

Key Types:

• SECRET_KEY_STRING - Plain string (default)
• SECRET_KEY_HEX - Hex-encoded key
• SECRET_KEY_BASE64 - Base64-encoded key

SecretBytes Method

Sets the key from byte array.

Public Function SecretBytes(ByRef KeyBytes() As Byte) As cCryptoHMAC

DataString Method

Inputs string data.

Public Function DataString(ByVal Text As String, _
                           Optional ByVal Encoding As HMACStringEncoding = HMAC_ENCODING_UTF8) As cCryptoHMAC

DataBytes Method

Inputs byte array data.

Public Function DataBytes(ByRef Data() As Byte) As cCryptoHMAC

ReturnHex Method

Returns HMAC in hexadecimal format.

Public Function ReturnHex(Optional ByVal UpperCase As Boolean = False) As String

ReturnBase64 Method

Returns HMAC in Base64 format.

Public Function ReturnBase64() As String

ReturnBytes Method

Returns HMAC as byte array.

Public Function ReturnBytes() As Byte()

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📌 Chainable Call Examples

Basic Chainable Call

Dim Hmac As New cCryptoHMAC
Dim result As String

' Complete chainable call
result = Hmac.Mode(HMAC_ALG_SHA256) _
            .Secret("secret-key") _
            .DataString("data to sign") _
            .ReturnHex()

Using Hex Key

' Use Hex-formatted key
result = Hmac.Mode(HMAC_ALG_SHA256) _
            .Secret("deadbeef123456", SECRET_KEY_HEX) _
            .DataString("data") _
            .ReturnHex()

Multiple Output Formats

' Set key and data
Hmac.Mode(HMAC_ALG_SHA256) _
      .Secret("secret") _
      .DataString("data")

' Get different formats
Debug.Print "Hex: " & Hmac.ReturnHex()
Debug.Print "Hex(Upper): " & Hmac.ReturnHex(True)
Debug.Print "Base64: " & Hmac.ReturnBase64()

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📌 Usage Scenarios Summary

API Request Signing

Private Function SignApiRequest(ByVal method As String, _
                                ByVal path As String, _
                                ByVal timestamp As String, _
                                ByVal apiSecret As String) As String
    Dim Hmac As New cCryptoHMAC
    Dim dataToSign As String
    
    ' Build signature string
    dataToSign = method & "|" & path & "|" & timestamp
    
    ' Compute HMAC
    SignApiRequest = Hmac.Mode(HMAC_ALG_SHA256) _
                          .Secret(apiSecret) _
                          .DataString(dataToSign) _
                          .ReturnHex()
End Function

Message Authentication

Private Function CreateMessageAuth(ByVal message As String, _
                                   ByVal sharedSecret As String) As String
    Dim Hmac As New cCryptoHMAC
    
    ' Create message authentication code
    CreateMessageAuth = Hmac.Compute(message, sharedSecret, HMAC_ALG_SHA256)
End Function

Private Function VerifyMessageAuth(ByVal message As String, _
                                   ByVal mac As String, _
                                   ByVal sharedSecret As String) As Boolean
    Dim Hmac As New cCryptoHMAC
    Dim expectedMac As String
    
    ' Recompute MAC
    expectedMac = Hmac.Compute(message, sharedSecret, HMAC_ALG_SHA256)
    
    ' Compare (case-insensitive)
    VerifyMessageAuth = (LCase(mac) = LCase(expectedMac))
End Function

JWT Signing

Private Function CreateJwtSignature(ByVal headerBase64 As String, _
                                    ByVal payloadBase64 As String, _
                                    ByVal secret As String) As String
    Dim Hmac As New cCryptoHMAC
    Dim signingInput As String
    
    ' JWT signing input
    signingInput = headerBase64 & "." & payloadBase64
    
    ' HS256 signature
    CreateJwtSignature = Hmac.Mode(HMAC_ALG_SHA256) _
                              .Secret(secret) _
                              .DataString(signingInput) _
                              .ReturnBase64()
End Function

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Last Updated: 2026-05-17