ExcelでSHA256ハッシュ関数を使用する

Public Function GetSHA256(ハッシュ値算出範囲 As Range) As String

    Const LENGTH_OF_HASH = 32
    Const LENGTH_OF_HASH_AS_STRING = 64
    Set objUTF8 = CreateObject("System.Text.UTF8Encoding")
    Set objSHA256 = CreateObject("System.Security.Cryptography.SHA256Managed")

    Dim str As String

    'Rangeの文字列結合（ワークシート関数のConcatを流用）
    str = Application.WorksheetFunction.Concat(ハッシュ値算出範囲)

    'バイト読み込み
    Dim code() As Byte
    code = objUTF8.GetBytes_4(str)

    'ハッシュ値計算
    Dim hashValue() As Byte
    hashValue = objSHA256.ComputeHash_2(code)

    '16進数へ変換
    Dim description As String * LENGTH_OF_HASH_AS_STRING
    Dim i&
    For i = 0 To LENGTH_OF_HASH - 1
        Mid(description, i * 2 + 1) = Right("0" & Hex(hashValue(i)), 2)
    Next i

    'return
    GetSHA256 = LCase(description)
    
End Function