(Java) Example: Hash Text in Chunks

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

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import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    CkCrypt2 crypt = new CkCrypt2();
    crypt.put_HashAlgorithm("sha256");
    crypt.put_Charset("utf-8");

    CkBinData bd = new CkBinData();

    String s = "The quick brown fox jumped over the lazy dog.\r\n";

    // 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.

    bd.AppendString(s,"utf-8");
    boolean success = crypt.HashBeginString(s);

    int i = 0;
    while (i < 200) {
        bd.AppendString(s,"utf-8");
        crypt.HashMoreString(s);
        i = i+1;
        }

    // Get the hash in base64 format.
    crypt.put_EncodingMode("base64");

    String encodedHash = crypt.hashFinalENC();
    System.out.println("Hash computed in chunks: " + encodedHash);

    // Let's alternatively compute the hash of the entire amount of data at once,
    // to show the hash computation is the same:
    encodedHash = crypt.hashBdENC(bd);
    System.out.println("Hash computed in 1 step: " + encodedHash);

    // Output:

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