generate Strong Password - Java Security

Java examples for Security:Password

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Description

generate Strong Password

Demo Code


//package com.java2s;

public class Main {
    private static char[] pwdChars = "abcdefghijklmnopqrstuvqxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890"
            .toCharArray();/*from ww  w. j  ava2 s.c o  m*/

    public static char[] generateStrongPassword(int length) {
        char[] pwd = new char[length];
        try {
            java.security.SecureRandom random = java.security.SecureRandom
                    .getInstance("SHA1PRNG");

            byte[] intbytes = new byte[4];

            for (int i = 0; i < length; i++) {
                random.nextBytes(intbytes);
                pwd[i] = pwdChars[Math.abs(getIntFromByte(intbytes)
                        % pwdChars.length)];
            }
        } catch (Exception ex) {
            // Don't really worry, we won't be using this if we can't use securerandom anyway
        }
        return pwd;
    }

    private static int getIntFromByte(byte[] bytes) {
        int returnNumber = 0;
        int pos = 0;
        returnNumber += byteToInt(bytes[pos++]) << 24;
        returnNumber += byteToInt(bytes[pos++]) << 16;
        returnNumber += byteToInt(bytes[pos++]) << 8;
        returnNumber += byteToInt(bytes[pos++]) << 0;
        return returnNumber;
    }

    private static int byteToInt(byte b) {
        return (int) b & 0xFF;
    }
}

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