// Map.Lookup require updates to the hasher, so a full Mutex lock (not a
// read-lock) is require around all Map operations if a shared
// hasher is accessed from multiple threads.
//
// If SetHasher is not called, the Map will create a private hasher at
// the first call to Insert.
func (m *Map) SetHasher(hasher Hasher) {
	m.hasher = hasher
}

// Delete removes the entry with the given key, if any.

Der Dieb kann also nicht versuchen, die gleichen Passwörter in einem anderen System zu verwenden (da viele Benutzer überall das gleiche Passwort verwenden, wäre dies gefährlich).

## `passlib` installieren

PassLib ist ein großartiges Python-Package, um Passwort-Hashes zu handhaben.

        val root = this@hashWithoutMessages
        val hasher = Hashing.newHasher()
        for (failure in sequence { visitFailures(root) }) {
            hasher.putString(failure.exceptionType.name)
            for (element in failure.stackTrace) {
                hasher.putString(element.toString())
            }
        }
        return hasher.hash()
    }

    private

	}
	if ctxt != nil {
		ctxts = append(ctxts, ctxt)
	}
	assert(len(ctxts) > 0)

	// Compute all hashes; hashes may differ across contexts due to different
	// unique IDs for Named types within the hasher.
	hashes := make([]string, len(ctxts))
	for i, ctxt := range ctxts {
		hashes[i] = ctxt.instanceHash(orig, targs)
	}

	// Record the result in all contexts.

	}
	if ctxt != nil {
		ctxts = append(ctxts, ctxt)
	}
	assert(len(ctxts) > 0)

	// Compute all hashes; hashes may differ across contexts due to different
	// unique IDs for Named types within the hasher.
	hashes := make([]string, len(ctxts))
	for i, ctxt := range ctxts {
		hashes[i] = ctxt.instanceHash(orig, targs)
	}

	// Record the result in all contexts.

If your database is stolen, the thief won't have your users' plaintext passwords, only the hashes.

So, the thief won't be able to try to use that password in another system (as many users use the same password everywhere, this would be dangerous).

## Install `passlib`

PassLib is a great Python package to handle password hashes.

It supports many secure hashing algorithms and utilities to work with them.

            hasher.putInt(bytes.length);
            hasher.putBytes(bytes);
        }

        @Override
        public void putBytes(byte[] bytes, int off, int len) {
            hasher.putInt(len);
            hasher.putBytes(bytes, off, len);
        }

        @Override
        public void putHash(HashCode hashCode) {
            hasher.putInt(hashCode.length());
            hasher.putHash(hashCode);

    }

    @Override
    public String toString() {
        return primitiveType.toString(array);
    }

    @Override
    public void appendToHasher(Hasher hasher) {
        primitiveType.appendTo(hasher, array);
    }

    @Override
    public ValueSnapshot snapshot(@Nullable Object value, ValueSnapshotter snapshotter) {
        PrimitiveType valueType = PrimitiveType.maybeOfValue(value);

	priv, _ := GenerateKey(c, rand.Reader)

	hashed := []byte("testing")
	r, s, err := Sign(rand.Reader, priv, hashed)
	if err != nil {
		t.Errorf("error signing: %s", err)
		return
	}

	if !Verify(&priv.PublicKey, hashed, r, s) {
		t.Errorf("Verify failed")
	}

	hashed[0] ^= 0xff
	if Verify(&priv.PublicKey, hashed, r, s) {
		t.Errorf("Verify always works!")
	}
}

include::{snippetsPath}/workerApi/md5CustomTask/tests/md5Task1.out[]
----

In the `build/md5` directory, you should now see corresponding files with an `md5` extension containing MD5 hashes of the files from the `src` directory.
Notice that the task takes at least 9 seconds to run because it hashes each file one at a time (i.e., three files at ~3 seconds apiece).

[[converting_to_worker_api]]
=== Step 2. Convert to the Worker API