001/*-
002 * #%L
003 * HAPI FHIR Storage api
004 * %%
005 * Copyright (C) 2014 - 2024 Smile CDR, Inc.
006 * %%
007 * Licensed under the Apache License, Version 2.0 (the "License");
008 * you may not use this file except in compliance with the License.
009 * You may obtain a copy of the License at
010 *
011 *      http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing, software
014 * distributed under the License is distributed on an "AS IS" BASIS,
015 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
016 * See the License for the specific language governing permissions and
017 * limitations under the License.
018 * #L%
019 */
020package ca.uhn.fhir.jpa.util;
021
022import java.security.SecureRandom;
023
024public class RandomTextUtils {
025
026        private static final SecureRandom ourRandom = new SecureRandom();
027        private static final String ALPHANUMERIC_CHARS = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
028
029        /**
030         * Creates a new string using randomly selected characters (using a secure random
031         * PRNG) containing letters (mixed case) and numbers.
032         */
033        public static String newSecureRandomAlphaNumericString(int theLength) {
034                StringBuilder b = new StringBuilder();
035                for (int i = 0; i < theLength; i++) {
036                        int nextInt = Math.abs(ourRandom.nextInt());
037                        b.append(ALPHANUMERIC_CHARS.charAt(nextInt % ALPHANUMERIC_CHARS.length()));
038                }
039                return b.toString();
040        }
041}