Reading assignment: Hashing

Blockchain and Bitcoin 101
#1550

  1. SHA-256

  2. It would take way too long to brute force a hashing algorithm.

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#1551

Hash functions, and Cryptography Questions, July 17th 2020

  1. What is the hashing algorithm called, used in Bitcoin?
    Bitcoin transactions run through a hashing algorithm SHA-256.

  2. Why is this hashing algorithm really hard (almost impossible) to brute-force?
    Itā€™s almost impossible to match the output to the original input in a hash function.
    The computational difficulty is high.

-Hector A. Martinez

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#1552
  1. SHA 256
  2. Because its near impossible to do it max (2^128-1) avg (1.7 X 10^38) still a very high number of attempts
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#1553

1. What is the hashing algorithm called used in Bitcoin?
SHA 256 (Secure Hash Algorithm)
2. Why is this hashing algorithm really hard (almost impossible) to brute-force?
because it is a too huge number to simply guess by trail and erro, even an average hit rate would take too long.

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#1554

  1. What is the hashing algorithm called used in Bitcoin?
    SHA-256

  2. Why is this hashing algorithm really hard (almost impossible) to brute-force?
    With 2^256 possibilities, the chance that you match the right Function and Input in random guesses (brute-force) is infeasible.

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#1555

  1. SHA 256

  2. There is too many options and probability of guessing the right one is almost none.

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#1556
  1. SHA-256 (Secure Hashing Algorithm 256)
  2. Computationally, it would take several lifetimes to determine the input data based on the output hash, that is why it is infeasible to brute-force the hashing algorithm.
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#1557
  1. SHA-256
  2. The time required to randomly guess would be ridiculous
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#1558
  1. SHA-256
  2. it use 256 bit hash algorithm and it will take infinite time to succeed.
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#1559

  1. SHA-256

  2. It will take longer then a lifetime to match the correct output to the original input.

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#1560

#1 hashing algorithm used in bitcoin is SHA-256 ā€¦

#2 the hashing algorithm is considered hard because of the large amount of numbers at use at one time 256bit set rate brute-force that many digits over and over takes 5 life times randomly .

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#1561
  1. SHA256
  2. A person could never guess the correct input over a life time, so it does not matterā€¦
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#1562

  1. What is the hashing algorithm called used in Bitcoin?
    SHA256

  2. Why is this hashing algorithm really hard (almost impossible) to brute-force?
    Pre-imaging resistance is a property of a blockchain that makes it infeasible to determine input data from the output hash. Since a blockchain is a sequence of blocks that contain data, a hash pointer not only points to the previous block but also contains the hash of the previous blockā€™s data. Even the smallest change in the input results in drastic changes in the hash output. This means any change made to a specific block will change the hash of the previous block and so on. The math indicates the brute force attempt would take so long that the probability of success can be safely ignored.

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#1563

  1. The algorithm used in Bitcoin is SHA-256

  2. This hashing algorithm is really hard to brute-force because of Pre Image Resistance. It is practically infeasible.

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#1564

[quote=ā€œivan, post:1, topic:8422ā€]

  • What is the hashing algorithm called used in Bitcoin?
    SHA256, Secure Hash Algorithem 256-bit.
  • Why is this hashing algorithm really hard (almost impossible) to brute-force?
    To find the variable needed would require an exorbitant amount of time rendering it useless.
1 Like
#1565
  1. SHA-256
  2. The chances of cracking a hash has an exponential relationship to the length of the hash value itself (number of valid characters raised to the power of the length of the value string)
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#1566

Sha-256

Every specific hash output has a specific input, so itā€™s very difficult to compare all the outputs to all the inputs when there is a larger amount of data being hashedā€¦Allso a small change in the input creates a large difference in the output.

Am I right?
Peace

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#1567

SHA-256

No matter how big or small the input, the output will always be 256 bits in length. To guess the input with a given hash, you can only do this via brute force. In this case with SHA-256, that means there are 2^256 possibilities. Even if you find the answer somewhere in the middle of the data (2^(256/2) , I think) that is such a huge number. The video says that even if you spent your whole life guessing hashes, and your children did, their children did, and then THEIR children did, you wouldnā€™t come close. So while it is theoretically possible it would take so long that it is infeasible.

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#1568
  1. What is the hashing algorithm called used in Bitcoin?

sha-256

  1. Why is this hashing algorithm really hard (almost impossible) to brute-force?

There are way too many possibilities and combinations to randomly guess (brute-force)

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#1569
  1. What does it mean when we say that hash functions need to be collision resistant?

When 2 different inputs result in the same hash output, we have a ā€˜collisionā€™. Collisions result in orphan blocks. While no hash function is collision-free, it is rare enough (like in the case of breaking pre-image resistance) to be safely ignored. However some hash functions like MD5 and SHA1 have proved vulnerable. While a hash function is vulnerable to brute force attack, a provably secure, collision-resistant hash function means itā€™s at least as difficult to find collisions as some hard mathematical problem.

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