codeql/java/ql/test/experimental/query-tests/quantum/examples/WeakOrUnknownHash/WeakHashing.java

package test.cwe327.semmle.tests;

import java.util.Properties;
import java.io.FileInputStream;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class WeakHashing {
    void hashing() throws NoSuchAlgorithmException, IOException {
        java.util.Properties props = new java.util.Properties();
        props.load(new FileInputStream("example.properties"));

        // BAD: Using a weak hashing algorithm even with a secure default
        MessageDigest bad = MessageDigest.getInstance(props.getProperty("hashAlg1")); // $Alert[java/quantum/examples/weak-hash]

        // BAD: Using a weak hashing algorithm even with a secure default
        MessageDigest bad2 = MessageDigest.getInstance(props.getProperty("hashAlg1", "SHA-256")); // $Alert[java/quantum/examples/weak-hash]

        // BAD: Using a strong hashing algorithm but with a weak default
        MessageDigest bad3 = MessageDigest.getInstance(props.getProperty("hashAlg2", "MD5")); // $Alert[java/quantum/examples/weak-hash]

        // BAD: Using a weak hash
        MessageDigest bad4 = MessageDigest.getInstance("SHA-1"); // $Alert[java/quantum/examples/weak-hash]

        // BAD: Property does not exist and default (used value) is unknown
        MessageDigest bad5 = MessageDigest.getInstance(props.getProperty("non-existent_property", "non-existent_default")); // $Alert[java/quantum/examples/unknown-hash]

        java.util.Properties props2 = new java.util.Properties();

        props2.load(new FileInputStream("unobserved-file.properties"));

        // BAD: "hashAlg2" is not visible in the file loaded for props2, should be an unknown 
        // FALSE NEGATIVE for unknown hash
        MessageDigest bad6 = MessageDigest.getInstance(props2.getProperty("hashAlg2", "SHA-256")); // $Alert[java/quantum/examples/unknown-hash]

        // GOOD: Using a strong hashing algorithm
        MessageDigest ok = MessageDigest.getInstance(props.getProperty("hashAlg2"));

        // BAD?: Property does not exist (considered unknown) and but default is secure
        MessageDigest ok2 = MessageDigest.getInstance(props.getProperty("non-existent-property", "SHA-256")); // $Alert[java/quantum/examples/unknown-hash]

        // GOOD: Using a strong hashing algorithm
        MessageDigest ok3 = MessageDigest.getInstance("SHA3-512");

         // GOOD: Using a strong hashing algorithm
        MessageDigest ok4 = MessageDigest.getInstance("SHA384");

    }
}