Imagine you have a special machine called a "Hasher." This machine takes any kind of information you give it, like a sentence or a picture, and turns it into a secret code. The code is like a jumbled-up version of the original information, and it always has the same fixed length, let's say 10 digits.
Now, let's think about some important things this Hasher machine can do:
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It's like a representative: The code it generates represents the original information. Just like if you have a picture of a cat, the code represents that cat. But you can't really tell what the original information was just by looking at the code.
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It's hard to go backwards: If you have the code, it's very difficult to figure out the original information. It's like having a secret language that only the Hasher machine knows how to decode. So even if someone gets hold of the code, they can't easily find out what the original information was.
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No two things are the same: The Hasher machine makes sure that if you give it two different pieces of information, it will always produce different codes for them. It's like having two different pictures of different animals and the Hasher machine always gives you different codes for each animal.
Now, let's apply this to a real-world scenario relating to something you might get. Imagine you have a school with lots of students, like this one, and each student has a locker. The lockers are labeled with unique codes, just like the codes from the Hasher machine.
Teachers want to use the lockers to store something important, like the students' grades. But they want to keep the grades private, so they put the grades in envelopes and lock them in the lockers using the codes. The codes are generated by the Hasher machine.
Here's how the Hasher machine's properties relate to this scenario:
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Representing the message: The code on each locker represents the student's grades. Teachers can tell which locker belongs to which student without actually looking inside the locker.
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Going backwards: Even if someone tries to peek inside the lockers or tries different codes, they can't figure out what the grades are. Only the teachers, who know the original grades, can open the lockers and see the grades.
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No two lockers are the same: Each student has their own locker with a unique code. If you try to open one student's locker using another student's code, you won't find the correct grades. The lockers and their codes ensure that each student's grades are kept separate.
In short, a cryptographic hash function (like the Hasher machine) is a way to transform information into secret codes with specific properties. It helps protect the privacy and integrity of data, just like lockers and codes can keep students' grades secure in a school.
P.S I am working on pictures.
POPULAR_WEBSITE? Now lets say you are registering an account onPOPULAR_WEBSITEand you type in your password you want to use...salt || MD5(grade || salt || secret)as the code on the lockers.saltis just a random value which makes sure that every hash will be different.secretis a secret value which only teachers know. This prevents that students can just try every grade and compare hashes.||I mean concatenation.