question: Why does strong encryption matter if passwords can be cracked easily through brute force anyway?
comment: Encryption stores a password in a a secret code. So even if someone can hack a server to find your password, they wouldn’t be able to read it without knowing how to crack the secret code. This is added security. It would be like putting that crappy building lock in a very strong safe/box that can only be opened with a very complex, hidden key. It doesn’t necessarily matter if the password is poor if the security for that password is super strong. However, simple passwords are easier to guess at random. If you can guess a password, there is no need to even hack and translate the secret code. That’s why it’s still important to have a fairly-complicated password, AND use encryption
passages: Demonstrating the resistance of any cryptographic scheme to attack is a complex matter, requiring extensive testing and reviews, preferably in a public forum. Good algorithms and protocols are required, and good system design and implementation is needed as well. For instance, the operating system on which the cryptographic software runs should be as carefully secured as possible. Users may handle passwords insecurely, or trust 'service' personnel overly much, or simply misuse the software. (See social engineering.) "Strong" thus is an imprecise term and may not apply in particular situations.
  
  Section::::Background.
   There will always be uncertainty as advances (e.g., in cryptanalytic theory or merely affordable computer capacity) may reduce the effort needed to successfully use some attack method against an algorithm. 
  
  In addition, actual use of cryptographic algorithms requires their encapsulation in a cryptosystem, and doing so often introduces vulnerabilities which are not due to faults in an algorithm. For example, essentially all algorithms require random choice of keys, and any cryptosystem which does not provide such keys will be subject to attack regardless of any attack resistant qualities of the encryption algorithm(s) used.
  
  Section::::Legal issues.
   "Cryptographically strong" would seem to mean that the described method has some kind of maturity, perhaps even approved for use against different kinds of systematic attacks in theory and/or practice. Indeed, that the method may resist those attacks long enough to protect the information carried (and what stands behind the information) for a useful length of time. But due to the complexity and subtlety of the field, neither is almost ever the case. Since such assurances are not actually available in real practice, sleight of hand in language which implies that they are will generally be misleading. 
   As with any security measure, passwords vary in effectiveness (i.e., strength); some are weaker than others. For example, the difference in weakness between a dictionary word and a word with obfuscation (i.e., letters in the password are substituted by, say, numbers — a common approach) may cost a password cracking device a few more seconds; this adds little strength. The examples below illustrate various ways weak passwords might be constructed, all of which are based on simple patterns which result in extremely low entropy, allowing them to be tested automatically at high speeds.:
   Using strong passwords lowers overall risk of a security breach, but strong passwords do not replace the need for other effective security controls. The effectiveness of a password of a given strength is strongly determined by the design and implementation of the factors (knowledge, ownership, inherence). The first factor is the main focus in this article.
   The design of most asymmetric algorithms (i.e. public-key cryptography) relies on neat mathematical problems that are efficient to compute in one direction, but inefficient to reverse by the attacker. However, attacks against current public-key systems are always faster than brute-force search of the key space. Their security level isn't set at design time, but represents a computational hardness assumption, which is adjusted to match the best currently known attack.
   In academic cryptography, a "weakness" or a "break" in a scheme is usually defined quite conservatively: it might require impractical amounts of time, memory, or known plaintexts. It also might require the attacker be able to do things many real-world attackers can't: for example, the attacker may need to choose particular plaintexts to be encrypted or even to ask for plaintexts to be encrypted using several keys related to the secret key. Furthermore, it might only reveal a small amount of information, enough to prove the cryptosystem imperfect but too little to be useful to real-world attackers. Finally, an attack might only apply to a weakened version of cryptographic tools, like a reduced-round block cipher, as a step towards breaking of the full system.
   It is common for a cryptosystem to leak some information but nevertheless maintain its security properties even against an adversary that has unlimited computational resources. Such a cryptosystem would have information theoretic but not perfect security. The exact definition of security would depend on the cryptosystem in question.
  
  There are a variety of cryptographic tasks for which information-theoretic security is a meaningful and useful requirement. A few of these are:
   More secure systems store each password in a cryptographically protected form, so access to the actual password will still be difficult for a snooper who gains internal access to the system, while validation of user access attempts remains possible. The most secure don't store passwords at all, but a one-way derivation, such as a polynomial, modulus, or an advanced hash function.
   Brute-force attacks can be made less effective by obfuscating the data to be encoded making it more difficult for an attacker to recognize when the code has been cracked or by making the attacker do more work to test each guess. One of the measures of the strength of an encryption system is how long it would theoretically take an attacker to mount a successful brute-force attack against it.
  
  Brute-force attacks are an application of brute-force search, the general problem-solving technique of enumerating all candidates and checking each one.
  
  Section::::Basic concept.
   There are three attacks known that can break the full 16 rounds of DES with less complexity than a brute-force search: differential cryptanalysis (DC), linear cryptanalysis (LC), and Davies' attack. However, the attacks are theoretical and are generally considered infeasible to mount in practice; these types of attack are sometimes termed certificational weaknesses.
   This article discusses physical security in the context of information cycle security; see Physical security for a more general view of the topic. Protection of both sensitive information in human-readable form, as well as of cryptographic equipment and keys, is the complement of communications security. The strongest cryptography in the world cannot protect information that, when not being sent through strong cryptographic channels, is left in an area where it can be copied or stolen.
   Information theory leads us to believe it is much more difficult to keep secrets than it might first appear. A brute force attack can break systems based on asymmetric key algorithms or on most commonly used methods of symmetric key algorithms (sometimes called secret key algorithms), such as block ciphers. The security of all such methods currently comes from the assumption that no known attack can break them in a practical amount of time.
   Section::::Required bits of entropy.
   The upper end is related to the stringent requirements of choosing keys used in encryption. In 1999, an Electronic Frontier Foundation project broke 56-bit DES encryption in less than a day using specially designed hardware. In 2002, "distributed.net" cracked a 64-bit key in 4 years, 9 months, and 23 days. As of October 12, 2011, "distributed.net" estimates that cracking a 72-bit key using current hardware will take about 45,579 days or 124.8 years. Due to currently understood limitations from fundamental physics, there is no expectation that any digital computer (or combination) will be capable of breaking 256-bit encryption via a brute-force attack. Whether or not quantum computers will be able to do so in practice is still unknown, though theoretical analysis suggests such possibilities.
   NIST requires at least 128 bits of random salt and a NIST-approved cryptographic function, such as the SHA series or AES (MD5 is not approved). Although high throughput is a desirable property in general-purpose hash functions, the opposite is true in password security applications in which defending against brute-force cracking is a primary concern. The growing use of massively-parallel hardware such as GPUs, FPGAs, and even ASICs for brute-force cracking has made the selection of a suitable algorithms even more critical because the good algorithm should not only enforce a certain amount of computational cost not only on CPUs, but also resist the cost/performance advantages of modern massively-parallel platforms for such tasks. Various algorithms have been designed specifically for this purpose, including bcrypt, scrypt and, more recently, Argon2 (the winner of the Password Hashing Competition). The large-scale Ashley Madison data breach in which roughly 36 million passwords hashes were stolen by attackers illustrated the importance of algorithm selection in securing passwords. Although bcrypt was employed to protect the hashes (making large scale brute-force cracking expensive and time-consuming), a significant portion of the accounts in the compromised data also contained a password hash based on the general-purpose MD5 algorithm which made it possible for over 11 million of the passwords to be cracked in a matter of weeks.
   Unfortunately, many common Network Protocols transmit passwords in cleartext or use weak challenge/response schemes.
   A poorly designed hash function can make attacks feasible even if a strong password is chosen. See LM hash for a widely deployed, and insecure, example.
  
  Section::::Factors in the security of a password system.:Methods of verifying a password over a network.
  
  Section::::Factors in the security of a password system.:Methods of verifying a password over a network.:Simple transmission of the password.
   Although more information has been published on the cryptanalysis of DES than any other block cipher, the most practical attack to date is still a brute-force approach. Various minor cryptanalytic properties are known, and three theoretical attacks are possible which, while having a theoretical complexity less than a brute-force attack, require an unrealistic number of known or chosen plaintexts to carry out, and are not a concern in practice.
  
  Section::::Security and cryptanalysis.:Brute-force attack.
   The term information-theoretic security is often used interchangeably with the term unconditional security. The latter term can also refer to systems that do not rely on unproven computational hardness assumptions. Today, such systems are essentially the same as those that are information-theoretically secure. Nevertheless, it does not always have to be that way. One day, RSA might be proved secure, as it relies on the assertion that factoring large numbers is hard, thus becoming unconditionally secure, but it will never be information-theoretically secure because even if no efficient algorithms for factoring large primes exist, it could still be done in principle with unlimited computational power.
   There are many other ways a password can be weak, corresponding to the strengths of various attack schemes; the core principle is that a password should have high entropy (usually taken to be equivalent to randomness) and "not" be readily derivable by any "clever" pattern, nor should passwords be mixed with information identifying the user. On-line services often provide a restore password function that a hacker can figure out and by doing so bypass a password. Choosing hard-to-guess restore password questions can further secure the password.
  
  Section::::Guidelines for strong passwords.:Rethinking password change guidelines.
   The rate at which an attacker can submit guessed passwords to the system is a key factor in determining system security. Some systems impose a time-out of several seconds after a small number (e.g. three) of failed password entry attempts. In the absence of other vulnerabilities, such systems can be effectively secured with relatively simple passwords. However the system must store information about the user passwords in some form and if that information is stolen, say by breaching system security, the user passwords can be at risk.
   Software is available for popular hand-held computers that can store passwords for numerous accounts in encrypted form. Passwords can be encrypted by hand on paper and remember the encryption method and key. And another approach is to use a single password or slightly varying passwords for low-security accounts and select distinctly separate strong passwords for a smaller number of high-value applications such as for online banking.
   Modern Unix Systems have replaced traditional DES-based password hashing function crypt() with stronger methods such as bcrypt and scrypt. Other systems have also begun to adopt these methods. For instance, the Cisco IOS originally used a reversible Vigenère cipher to encrypt passwords, but now uses md5-crypt with a 24-bit salt when the "enable secret" command is used. These newer methods use large salt values which prevent attackers from efficiently mounting offline attacks against multiple user accounts simultaneously. The algorithms are also much slower to execute which drastically increases the time required to mount a successful offline attack.
   While pure cryptanalysis uses weaknesses in the algorithms themselves, other attacks on cryptosystems are based on actual use of the algorithms in real devices, and are called "side-channel attacks". If a cryptanalyst has access to, for example, the amount of time the device took to encrypt a number of plaintexts or report an error in a password or PIN character, he may be able to use a timing attack to break a cipher that is otherwise resistant to analysis. An attacker might also study the pattern and length of messages to derive valuable information; this is known as traffic analysis and can be quite useful to an alert adversary. Poor administration of a cryptosystem, such as permitting too short keys, will make any system vulnerable, regardless of other virtues. Social engineering and other attacks against humans (e.g., bribery, extortion, blackmail, espionage, torture, ...) are usually employed due to being more cost-effective and feasible to perform in a reasonable amount of time compared to pure cryptanalysis by a high margin.
  
presuppositions: If passwords can be brute forced then encryption is pointless. Strong encryption doesn't do anything to secure a password that's cracked.
corrections: Encryption makes it hard for someone to crack your password even if they found it. Strong encryption is an added layer of security for a password even after it's cracked.
raw_presuppositions: If passwords can be brute forced then encryption is pointless. Strong encryption doesn't do anything to secure a password that's cracked.
raw_corrections: Encryption makes it hard for someone to crack your password even if they found it. Strong encryption is an added layer of security for a password even after it's cracked.