What does it mean to hash data and do I really care? - Dataspace (2023)

What does it mean to hash data and do I really care? - Dataspace (1)


What is Hashing?

Hashing is simply passing some data through a formula that produces a result, called a hash. That hash is usually a string of characters and the hashes generated by a formula are always the same length, regardless of how much data you feed into it. For example, the MD5 formula always produces 32 character-long hashes. Regardless of whether you feed in the entire text of MOBY DICK or just the letter C, you’ll always get 32 characters back.

Finally (and this is important) each time you run that data through the formula, you get the exact same hash out of it. So, for example, the MD5 formula for the string Dataspace returns the value e2d48e7bc4413d04a4dcb1fe32c877f6. Every time it will return that same value. Here, try it yourself.

Changing even one character will produce an entirely different result. For example, the MD5 for dataspace with a small d yields 8e8ff9250223973ebcd4d74cd7df26a7

Hashing is One-Way

Hashing works in one direction only – for a given piece of data, you’ll always get the same hash BUT you can’t turn a hash back into its original data. If you need to go in two directions, you need encrypting, rather than hashing.

With encrypting you pass some data through an encryption formula and get a result that looks something like a hash, but with the biggest difference being that you can take the encrypted result, run it through a decryption formula and get your original data back.

Remember, hashing is different – you can’t get your original data back simply by running a formula on your hash (a bit about how to hack these, though, in a moment).

What Hash Formulae are Available?

There are a huge number of widely accepted hashing algorithms available for general use. For example, MD5, SHA1, SHA224, SHA256, Snefru… Over time these formulae have become more complex and produce longer hashes which are harder to hack.

Hashing capability is available in standard libraries in common programming languages. Here’s a quick example coded in Python (call me if you’d like to walk through this code – I’d love to chat!):

import hashlib
hash = hashlib.md5(“Dataspace”.encode(‘utf-8’))


The result comes back as: e2d48e7bc4413d04a4dcb1fe32c877f6

Notice that it’s the same as the hash value we created earlier! In the words of Bernadette Peters in THE JERK, “This s__t really works!”

Hashing and Passwords

When an online system stores your credentials, it usually stores both your username and password in a database. There’s a problem here, though: any employee who accesses the database, or any hacker who breaks into the system, can see everyone’s username and password. They can then go out to the logon screen for that system, type in that username and password, and get access to anything that you are allowed to do on that system.

However, if the system stores your password as a hash, then seeing it won’t do a hacker any good. He can see that the hash is, for example, 5f4dcc3b5aa765d61d8327deb882cf99, but he can’t use that to get into the system and look like you. He has no way of knowing that your password (i.e. the value you type into a logon screen) is actually the word password. On the system’s side, whenever you log in, it takes the password you give it, runs it through its hash formula and compares the result to what’s in its database. If they match, you’re in!

Can I Break a Hash? Can I Keep Someone Else From Breaking it?

Can hashes be hacked? Absolutely. One of the easiest ways is to access a list of words and the hash that each results in. For example, there are websites that publish millions of words and their related hash values. Anyone (usually a hacker, actually) can go to these sites, search for a hash value and instantly find what the value was before it was hashed:

What does it mean to hash data and do I really care? - Dataspace (2)

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To protect against this, security professionals use a technique known as salting. To salt a hash, simply append a known value to the string before you hash it. For example, if before it’s stored in a database every password is salted with the string ‘dog’, it will likely not be found in online databases. So, password salted with dog (i.e. passworddog) and then run through the md5 calculator becomes 854007583be4c246efc2ee58bf3060e6.

To use these passwords when you log in, the system takes the password that you enter, appends the word ‘dog’ to it, runs that string through the hashing algorithm, and finally looks up the result in its database to see if you’re really authorized and if you’ve typed in the right password.

Hey Ben, Do You Know of Other Cool Uses for Hashing?

Why, yes, there are some other great uses for hashing beyond storing passwords. Here are two:

  • Fighting computer viruses: When a computer virus ‘infects’ a program it does so by changing some of the code in that program, making it do something malicious. One way to protect against viruses, therefore, is to create a hash value for a program when it’s distributed to users (i.e. run the computer code through a hashing algorithm and get a hash). Then, whenever that program is run, create a new hash value for the file you’re about to run. Compare the new hash to the original hash. If the two values match then you’re fine. If they don’t match, someone has fiddled with your copy of the program.
  • Change data capture: When reading data into a data warehouse we frequently want to know if any records in our source system changed. To do this we sometimes read every field in every source record and compare it to every field in the related record in our data warehouse – a complex process that requires a lot of computer cycles. However, we can speed it up as follows:
    • Read all the fields in the source record, concatenate them together, and create a hash of the result
    • Compare that hash to a hash value that was stored on the related record in the data warehouse when it was last updated
    • If the two don’t match, you know that the source record has changed and the changes should be migrated to the warehouse
  • Creating smart keys: Dataspace recently released a software as a service (SaaS) product called Golden Record. Golden Record helps data professionals identify and link records together across databases. For example, it can tell you when the same person appears in a database and in a separate spreadsheet. Internally, the product uses hashes extensively. For example, each match is assigned a ‘key’. That key is actually a hash! This is different than traditional mechanisms where records, in this case matches, are assigned the next available sequential number as a key. Here’s why this is useful: because Golden Record knows the formula it used to create that hash, it can easily find any record / match because it also knows the data that was used to create that key. If, instead, the traditional, sequential number were used, the software would have to read through every record in its list of matches until it came to the one it needs.


OK, this one got a little out of hand. I was asked to write a short paragraph for our monthly email and ended up with four pages of text. Thanks for hearing me out. I just think the concept of and uses for hashes are way cooler than most people realize.

If you’d like to talk about hashes, Python, data science, big data, or World War II aviation, please get in touch – I’d love to chat!


8 replies

  1. What does it mean to hash data and do I really care? - Dataspace (3)

    Steve says:

    October 16, 2020 at 2:00 am

    Hi Ben,

    So, not being very savvy about these things my question is. Suppose one has a 15 character password. But 3 of the characters are the same, e.g. 3 “e”s in the password. Does that reduce it to only a 12 character password and hence easier to hack?


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    • What does it mean to hash data and do I really care? - Dataspace (4)

      Benjamin Taub says:

      October 16, 2020 at 1:38 pm

      Hi, Steve!
      No, each additional character makes the password harder to hack so, all things being equal, longer passwords are always better than shorter ones. Of course, if you go from a password of five random characters to one that’s an English word that’s six characters long, longer isn’t better. But, if you go from five random characters to six random characters, your password will be tighter.

      In the end, most passwords are stored as hash values. So, to get a sense of how they work, you might want to play with a simple hashing tool. I use this one and it’s free: http://www.miraclesalad.com/webtools/md5.php. With every character you add, the hash changes. And, if you change one of your e’s to an uppercase E, the hash will change.

      Hope that helps. Thanks for the question!


  2. What does it mean to hash data and do I really care? - Dataspace (6)

    Anthony Volini says:

    August 27, 2021 at 7:53 pm

    Wonderfully clear explanation of concepts!


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  3. What does it mean to hash data and do I really care? - Dataspace (7)

    Dan Eshet says:

    September 4, 2021 at 4:22 pm

    Wonderful explanation that even a non-techie can get. If you wrote about hashes and crypto mining, I would love to read it.


  4. What does it mean to hash data and do I really care? - Dataspace (9)

    GreyWolf says:

    September 30, 2022 at 9:13 am

    Ben, thank you for this comprehensive explanation. I do have another question: I did a little testing and found that generating the HASH for a file (I used a text file with one word in it “test”) then adding a space at the end “test “, expectedly resulted in two different HASH values. When I changed the file back by deleting the space (going back to “test”), I got the (not unexpected) same HASH value. However, when using this concept for your virus example, could a bad actor not insert malicious code, execute said code, then as part of the execution delete that code to return to the “original” version, thereby defeating the HASH verification? If what I’m asking doesn’t make sense, please let me know.


    • What does it mean to hash data and do I really care? - Dataspace (10)

      Benjamin Taub says:

      October 1, 2022 at 4:18 pm

      Hi, Greywolf!
      Thanks for the question. I’m glad the hashing worked, you had me worried there for a second :)

      The answer to your question is that the hash must be checked before the code is run, not after. In practice, you usually do this when you download the software to your hard drive. After that, most people assume that it hasn’t changed and run it without checking. I suspect, though, that certain virus scanning programs do periodically validate hash totals, maybe even every time you run a program.

      It might help to quickly check out this link: https://dev.mysql.com/downloads/connector/python/ This is the download site for the MySQL Python connector. You’ll see that, for each download, they publish an MD5 checksum and specifically suggest that you check this signature after you download. They also provide an even more reliable protocol called GnuPG (they provide a link for more info on that).

      I hope this helps. Thanks for the question!


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What does it mean to hash the data? ›

Hashing is the process of transforming any given key or a string of characters into another value. This is usually represented by a shorter, fixed-length value or key that represents and makes it easier to find or employ the original string. The most popular use for hashing is the implementation of hash tables.

What does the hash function do to data? ›

A hash function is a unique identifier for any given piece of content. It's also a process that takes plaintext data of any size and converts it into a unique ciphertext of a specific length.

What is hashing and when to use it? ›

Hashing is a cryptographic process that can be used to validate the authenticity and integrity of various types of input. It is widely used in authentication systems to avoid storing plaintext passwords in databases, but is also used to validate files, documents and other types of data.

What data do you need to verify a hash? ›

Verifying a Hash

Data can be compared to a hash value to determine its integrity. Usually, data is hashed at a certain time and the hash value is protected in some way. At a later time, the data can be hashed again and compared to the protected value. If the hash values match, the data has not been altered.

What is an example of hashing? ›

Hashing is an important data structure designed to solve the problem of efficiently finding and storing data in an array. For example, if you have a list of 20000 numbers, and you have given a number to search in that list- you will scan each number in the list until you find a match.

What are the 3 types of hashing? ›

This article focuses on discussing different hash functions: Division Method. Mid Square Method. Folding Method.

What is hash function in simple words? ›

Definition: A hash function is a function that takes a set of inputs of any arbitrary size and fits them into a table or other data structure that contains fixed-size elements.

How do you hash something? ›

Hashing is simply passing some data through a formula that produces a result, called a hash. That hash is usually a string of characters and the hashes generated by a formula are always the same length, regardless of how much data you feed into it. For example, the MD5 formula always produces 32 character-long hashes.

How is hashing done? ›

Hashing is implemented in two steps: An element is converted into an integer by using a hash function. This element can be used as an index to store the original element, which falls into the hash table. The element is stored in the hash table where it can be quickly retrieved using hashed key.

Where hashing is used in real life? ›

One of the most famous applications of hashing is the Rabin-Karp algorithm. This is basically a string-searching algorithm which uses hashing to find any one set of patterns in a string. A practical application of this algorithm is detecting plagiarism.

What are the two types of hashing? ›

There are multiple types of hashing algorithms, but the most common are Message Digest 5 (MD5) and Secure Hashing Algorithm (SHA) 1 and 2. The slightest change in the data will result in a dramatic difference in the resulting hash values.

Which hashing is best? ›

SHA-256: This hashing algorithm is a variant of the SHA2 hashing algorithm, recommended and approved by the National Institute of Standards and Technology (NIST). It generates a 256-bit hash value. Even if it's 30% slower than the previous algorithms, it's more complicated, thus, it's more secure.

What is a hash verification? ›

The answer is hash validation. A hash value is a digital fingerprint (a checksum) created by performing a mathematical operation (a hash function) on the data comprising a computer program or other digital file.

How do you make a hash value? ›

Hashing involves applying a hashing algorithm to a data item, known as the hashing key, to create a hash value. Hashing algorithms take a large range of values (such as all possible strings or all possible files) and map them onto a smaller set of values (such as a 128 bit number). Hashing has two main applications.

How do I find the hash value of an application? ›

Here are seven tools you can use to verify the file you're downloading is safe.
  1. Check File Hash Using PowerShell. Handily, Windows comes with an integrated file hash checker. ...
  2. Hash Generator. ...
  3. HashMyFiles. ...
  4. OpenHashTab. ...
  5. QuickHash. ...
  6. MultiHasher. ...
  7. 7-Zip.

Why is it called a hashing? ›

The verb to hash has the same meaning in English. So as other have pointed out it is called hash, because you chop your input that you put in pieces in different places (your table entries).

What are the types of hashing? ›

Types of Hashing

There are many different types of hash algorithms such as RipeMD, Tiger, xxhash and more, but the most common type of hashing used for file integrity checks are MD5, SHA-2 and CRC32. MD5 - An MD5 hash function encodes a string of information and encodes it into a 128-bit fingerprint.

What data type is hash? ›

It is an abstract data type that maps keys to values. A hash table uses a hash function to compute an index, also called a hash code, into an array of buckets or slots, from which the desired value can be found. During lookup, the key is hashed and the resulting hash indicates where the corresponding value is stored.

What is hash format? ›

The one-way hashing formats include crypt, MD5, SHA, Salted SHA (SSHA), SHA-2, and Salted SHA-2. The SHA-2 and Salted SHA-2 hashing algorithms consist of the following methods: SHA224, SSHA224 (Salted SHA224), SHA256, SSHA256 (Salted SHA256), SHA384, SSHA384(Salted SHA384), SHA512, and SSHA512 (Salted SHA512).

What is a hash key in database? ›

A hash key is a small value that is used to represent a large piece of data in a hash system. A hash function is a mathematical equation that simplifies large amounts of data into small values. This process saves space in a database and makes retrieving information faster and easier for the programs.

What does it mean to go hashing? ›

Hashing is an exhilaratingly fun. combination of running, orienteering, and malt beverages, where bands. of harriers and harriettes chase hares on four to six mile-long.

How is hashing used to store data? ›

Hash is the keyed storage structure that calculates a placement number or address by applying a hashing algorithm to the key data value. A hashing algorithm is a function that does mathematical computations to a piece of data to produce a number. It always produces the same number for the same piece of data.

What are two most popular hashing algorithms? ›

Common hashing algorithms include:
  • MD-5. This is one of the first algorithms to gain widespread approval. ...
  • RIPEMD-160. The RACE Integrity Primitives Evaluation Message Digest (or RIPEMD-160) was developed in Belgium in the mid-1990s. ...
  • SHA. Algorithms in the SHA family are considered slightly more secure. ...
  • Whirlpool.

What type of hashing is good in databases? ›

Two types of hashing methods are 1) static hashing 2) dynamic hashing. In the static hashing, the resultant data bucket address will always remain the same. Dynamic hashing offers a mechanism in which data buckets are added and removed dynamically and on demand.

What is the difference between hashing and encryption? ›

Since encryption is two-way, the data can be decrypted so it is readable again. Hashing, on the other hand, is one-way, meaning the plaintext is scrambled into a unique digest, through the use of a salt, that cannot be decrypted.

What is the latest hashing algorithm? ›

SHA-3 (Secure Hash Algorithm 3) is the latest member of the Secure Hash Algorithm family of standards, released by NIST on August 5, 2015.
DesignersGuido Bertoni, Joan Daemen, Michaël Peeters, and Gilles van Assche.
First published2016
Series(SHA-0), SHA-1, SHA-2, SHA-3
CertificationFIPS PUB 202
6 more rows

What is my password hash? ›

Hashing turns your password (or any other piece of data) into a short string of letters and/or numbers using an encryption algorithm. If a website is hacked, cyber criminals don't get access to your password. Instead, they just get access to the encrypted “hash” created by your password.

How do I find info on hash? ›

How to hash check
  1. Make a note of the hash number published by the developer.
  2. Generate the hash value of the file you have.
  3. Compare the two hash values.
3 Feb 2020

How do hackers get your password hash? ›

The problem is that the hashes still have to be stored, and anything that is stored can be stolen. Hackers could get the password hashes from the server they are stored on in a number of ways. These include through disgruntled employees, SQL injections and a range of other attacks.

How do you write a hash? ›

With modular hashing, the hash function is simply h(k) = k mod m for some m (usually, the number of buckets). The value k is an integer hash code generated from the key. If m is a power of two (i.e., m=2p), then h(k) is just the p lowest-order bits of k.

How many characters is a hash? ›

Each MD5 hash looks like 32 numbers and letters, but each digit is in hexadecimal and represents four bits. Since a single character represents eight bits (to form a byte), the total bit count of an MD5 hash is 128 bits. Two hexadecimal characters form a byte, so 32 hexadecimal characters equal 16 bytes.

What hash has $1$? ›

Passwords starting with "$1$" are interpreted as hashed with Linux MD5 password hashing. Linux SHA256 and SHA512 crypt. Passwords starting with “$5$” or “$6$” are interpreted as hashed with Linux SHA256 or SHA512 password hashing, respectively. Linux Blowfish crypt.

Does every file have a hash? ›

As every file on a computer is, ultimately, just data that can be represented in binary form, a hashing algorithm can take that data and run a complex calculation on it and output a fixed-length string as the result of the calculation. The result is the file's hash value or message digest.

What happens when you hash a file? ›

A message digest, or hash, is a signature that identifies some amount of data, usually a file or message. Cryptographic hashing algorithms are one-directional mathematical formulae designed to generate a unique value for every possible input-in this case, the data.

Is hashing the same as encryption? ›

Since encryption is two-way, the data can be decrypted so it is readable again. Hashing, on the other hand, is one-way, meaning the plaintext is scrambled into a unique digest, through the use of a salt, that cannot be decrypted.

What does hashing mean in Crypto? ›

Hashing is a fundamental part of cryptography.

And plays a huge role behind the “crypto” in cryptocurrencies. In simple terms, hashing means inputting text of ANY length through a hash function which produces an output of a FIXED length. Any piece of data can be “hashed”, no matter its size, type, or length.

Do all files have hash? ›

Yes, you're right. Every file, no file inclusive, has a checksum. SHA1 of the empty string ("") is da39a3ee 5e6b4b0d 3255bfef 95601890 afd80709 . If you submit a file for hashing (checksumming), it will produce a valid output.

How do I view a hash file? ›

  1. Open the Windows command line. Press Windows + R, type cmd and press Enter. ...
  2. Go to the folder that contains the file whose MD5 checksum you want to check and verify. Command: Type cd followed by the path to the folder. ...
  3. Type the command below. certutil -hashfile <file> MD5. ...
  4. Press Enter.
12 Oct 2022

Why do we need hash files? ›

Hashing is also used to verify the integrity of a file after it has been transferred from one place to another, typically in a file backup program like SyncBack. To ensure the transferred file is not corrupted, a user can compare the hash value of both files.

What does a hash means? ›

: a restatement of something that is already known. the same old hash. 3. : hodgepodge, jumble. : a confused muddle.

What does hash stands for? ›

A hash is a mathematical function that converts an input of arbitrary length into an encrypted output of a fixed length. Thus regardless of the original amount of data or file size involved, its unique hash will always be the same size.

What does making hash mean? ›

informal. : to ruin (something) by making many mistakes. He made a hash of the whole project!

Is hashed data secure? ›

Hashing is one of the best and most secure ways to identify and compare databases and files. It transforms data to a fixed size without considering the initial data input. The received output is known as hash value or code. Moreover, the term “hash” can be used to describe both the value and hash function.

Is it better to encrypt data or to hash data? ›

Hashing vs Encryption – Hashing refers to permanent data conversion into message digest while encryption works in two ways, which can encode and decode the data. Hashing helps protect the integrity of the information and Encryption is used to secure the data from the reach of third parties.

How secure is hashing? ›

Hashing and encryption both provide ways to keep sensitive data safe. However, in almost all circumstances, passwords should be hashed, NOT encrypted. Hashing is a one-way function (i.e., it is impossible to "decrypt" a hash and obtain the original plaintext value). Hashing is appropriate for password validation.

Is High Hashrate good for Bitcoin? ›

So, Is a high hash rate a good measure of a network's security? Similar to the majority of PoW crypto, a more significant hash rate is thought to be better for the overall security and stability of the blockchain network as it means more energy costs, more miners and more time is needed to take over the network.

How many Bitcoins are in a hash? ›

Today the block reward is only 6.25 BTC and hashrate is measured in trillions, quadrillions and even quintillions of hashes per second.
Hash Rate Units.
KilohashKH/s (thousands of Hashes/second)
TerahashTH/s (trillions of Hashes/second)
PetahashPH/s (quadrillions of Hashes/second)
2 more rows

What hash is Bitcoin? ›

Bitcoin uses the SHA-256 hash algorithm. This algorithm generates verifiably random numbers in a way that requires a predictable amount of computer processing power.


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