(DataFlex) Example: Hash Text in Chunks

Shows how to generate a final hash, like SHA-256, for a large text by processing it in chunks.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

Use ChilkatAx-win32.pkg

Procedure Test
    Handle hoCrypt
    Variant vBd
    Handle hoBd
    String s
    Boolean iSuccess
    Boolean iSuccess
    Integer i
    String sEncodedHash

    Get Create (RefClass(cComChilkatCrypt2)) To hoCrypt
    If (Not(IsComObjectCreated(hoCrypt))) Begin
        Send CreateComObject of hoCrypt
    End
    Set ComHashAlgorithm Of hoCrypt To "sha256"
    Set ComCharset Of hoCrypt To "utf-8"

    Get Create (RefClass(cComChilkatBinData)) To hoBd
    If (Not(IsComObjectCreated(hoBd))) Begin
        Send CreateComObject of hoBd
    End

    Move "The quick brown fox jumped over the lazy dog." + (character(13)) + (character(10)) To s

    // Accumulate the text in a StringBuilder.  We'll demonstrate hashing the text in chunks,
    // and then also hashing the entire text at once to show the results are the same.

    Get ComAppendString Of hoBd s "utf-8" To iSuccess
    Get ComHashBeginString Of hoCrypt s To iSuccess

    Move 0 To i
    While (i < 200)
        Get ComAppendString Of hoBd s "utf-8" To iSuccess
        Get ComHashMoreString Of hoCrypt s To iSuccess
        Move (i + 1) To i
    Loop

    // Get the hash in base64 format.
    Set ComEncodingMode Of hoCrypt To "base64"

    Get ComHashFinalENC Of hoCrypt To sEncodedHash
    Showln "Hash computed in chunks: " sEncodedHash

    // Let's alternatively compute the hash of the entire amount of data at once,
    // to show the hash computation is the same:
    Get pvComObject of hoBd to vBd
    Get ComHashBdENC Of hoCrypt vBd To sEncodedHash
    Showln "Hash computed in 1 step: " sEncodedHash

    // Output:

    // Hash computed in chunks: unwkVff61k40roRIJizaknreScHaL6frWe37kydXbZQ=
    // Hash computed in 1 step: unwkVff61k40roRIJizaknreScHaL6frWe37kydXbZQ=


End_Procedure