---
title: MD2, MD4, and MD5 are weak hash functions
description: Datadog, the leading service for cloud-scale monitoring.
breadcrumbs: >-
  Docs > Datadog Security > Code Security > Static Code Analysis (SAST) > SAST
  Rules > MD2, MD4, and MD5 are weak hash functions
---

# MD2, MD4, and MD5 are weak hash functions

{% callout %}
# Important note for users on the following Datadog sites: app.ddog-gov.com

{% alert level="danger" %}
This product is not supported for your selected [Datadog site](https://docs.datadoghq.com/getting_started/site). ().
{% /alert %}

{% /callout %}

## Metadata{% #metadata %}

**ID:** `java-security/weak-message-digest-md5`

**Language:** Java

**Severity:** Warning

**Category:** Security

**CWE**: [328](https://cwe.mitre.org/data/definitions/328.html)

**Related CWEs**:

- [916](https://cwe.mitre.org/data/definitions/916.html)

## Description{% #description %}

The security of the MD5 hash function is severely compromised. A collision attack exists that can find collisions within seconds on a computer with a 2.6 GHz Pentium 4 processor. Further, there is also a chosen-prefix collision attack that can produce a collision for two inputs with specified prefixes within hours, using off-the-shelf computing hardware.

#### Learn More{% #learn-more %}

- [CWE-328: Use of Weak Hash](https://cwe.mitre.org/data/definitions/328.html)
- [On Collisions for MD5](https://www.win.tue.nl/hashclash/On%20Collisions%20for%20MD5%20-%20M.M.J.%20Stevens.pdf)

## Non-Compliant Code Examples{% #non-compliant-code-examples %}

```java
public class MyClass {
    public void myMethod1() {
        MessageDigest md5Digest = MessageDigest.getInstance("MD5");
        md5Digest.update(password.getBytes());
        byte[] hashValue = md5Digest.digest();
    }
    public void myMethod2() {
        MessageDigest md5Digest = java.security.MessageDigest.getInstance("MD5");
        md5Digest.update(password.getBytes());
        byte[] hashValue = md5Digest.digest();
    }
}
```

## Compliant Code Examples{% #compliant-code-examples %}

```java
public class MyClass {
    public static byte[] getEncryptedPassword(String password, byte[] salt) throws NoSuchAlgorithmException, InvalidKeySpecException {
        PKCS5S2ParametersGenerator gen = new PKCS5S2ParametersGenerator(new SHA256Digest());
        gen.init(password.getBytes("UTF-8"), salt.getBytes(), 4096);
        return ((KeyParameter) gen.generateDerivedParameters(256)).getKey();
    }
}
```
  Seamless integrations. Try Datadog Code SecurityDatadog Code Security 
{% icon name="icon-external-link" /%}