MD5 vs SHA-1 vs SHA-2 - Which is the Most Secure Encryption Hash and How to Check Them (2024)

Table of Contents
MD5 SHA-1 SHA-2 SHA-3 FAQs References
/ #hash functions, MD5, SHA-1, SHA-2, checksum
MD5 vs SHA-1 vs SHA-2 - Which is the Most Secure Encryption Hash and How to Check Them (1)
Jeff M Lowery
MD5 vs SHA-1 vs SHA-2 - Which is the Most Secure Encryption Hash and How to Check Them (2)

A hash function takes an input value (for instance, a string) and returns a fixed-length value. An ideal hash function has the following properties:

  • it is very fast
  • it can return an enormous range of hash values
  • it generates a unique hash for every unique input (no collisions)
  • it generates dissimilar hash values for similar input values
  • generated hash values have no discernable pattern in their distribution

No ideal hash function exists, of course, but each aims to operate as close to the ideal as possible. Given that (most) hash functions return fixed-length values and the range of values is therefore constrained, that constraint can practically be ignored. The number of possible values that can be returned by a a 256-bit hash function, for instance, is roughly the same as the number of atoms in the universe.

Ideally, a hash function returns practically no collisions – that is to say, no two different inputs generate the same hash value. This is particularly import for cryptographic hash functions: hash collisions are considered a vulnerability.

Finally, a hash function should generate unpredictably different hash values for any input value. For example, take the following two very similar sentences:

1. "The quick brown fox."2. "The quick brown fax."

We can compare the MD5 hash values generated from each of the two sentences:

1. 2e87284d245c2aae1c74fa4c50a74c772. c17b6e9b160cda0cf583e89ec7b7fc22

Two very dissimilar hashes were generated for two similar sentences, which is a property useful both for validation and cryptography. This is a corollary of distribution: the hash values of all inputs should be spread evenly and unpredictably across the whole range of possible hash values.

There are several hash functions that are widely used. All were designed by mathematicians and computer scientists. Over the course of further research, some have been shown to have weaknesses, though all are considered good enough for noncryptographic applications.

MD5

The MD5 hash function produces a 128-bit hash value. It was designed for use in cryptography, but vulnerabilities were discovered over the course of time, so it is no longer recommended for that purpose. However, it is still used for database partitioning and computing checksums to validate files transfers.

SHA-1

SHA stands for Secure Hash Algorithm. The first version of the algorithm was SHA-1, and was later followed by SHA-2 (see below).

Whereas MD5 produces a 128-bit hash, SHA1 generates 160-bit hash (20 bytes). In hexadecimal format, it is an integer 40 digits long. Like MD5, it was designed for cryptology applications, but was soon found to have vulnerabilities also. As of today, it is no longer considered to be any less resistant to attack than MD5.

SHA-2

The second version of SHA, called SHA-2, has many variants. Probably the one most commonly used is SHA-256, which the National Institute of Standards and Technology (NIST) recommends using instead of MD5 or SHA-1.

The SHA-256 algorithm returns hash value of 256-bits, or 64 hexadecimal digits. While not quite perfect, current research indicates it is considerably more secure than either MD5 or SHA-1.

Performance-wise, a SHA-256 hash is about 20-30% slower to calculate than either MD5 or SHA-1 hashes.

SHA-3

This hash method was developed in late 2015, and has not seen widespread use yet. Its algorithm is unrelated to the one used by its predecessor, SHA-2.

The SHA3-256 algorithm is a variant with equivalent applicability to that of the earlier SHA-256, with the former taking slightly longer to calculate than the later.

A typical use of hash functions is to perform validation checks. One frequent usage is the validation of compressed collections of files, such as .zip or .tar archive files.

Given an archive and its expected hash value (commonly referred to as a checksum), you can perform your own hash calculation to validate that the archive you received is complete and uncorrupted.

For instance, I can generate an MD5 checksum for a tar file in Unix using the following piped commands:

tar cf - files | tee tarfile.tar | md5sum -

To get the MD5 hash for a file in Windows, use the Get-FileHash PowerShell command:

Get-FileHash tarfile.tar -Algorithm MD5

The generated checksum can be posted on the download site, next to the archive download link. The receiver, once they have downloaded the archive, can validate that it came across correctly by running the following command:

echo '2e87284d245c2aae1c74fa4c50a74c77 tarfile.tar' | md5sum -c

where 2e87284d245c2aae1c74fa4c50a74c77 is the generated checksum that was posted. Successful execution of the above command will generate an OK status like this:

echo '2e87284d245c2aae1c74fa4c50a74c77 tarfile.tar' | md5sum -ctarfile.tar: OK

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MD5 vs SHA-1 vs SHA-2 - Which is the Most Secure Encryption Hash and How to Check Them (3)
Jeff M Lowery

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MD5 vs SHA-1 vs SHA-2 - Which is the Most Secure Encryption Hash and How to Check Them (2024)

FAQs

Which is more secure, MD5 or SHA-1? ›

MD5 generates the same hash function for different inputs. MD5 provides poor security over SHA1. MD5 is neither a symmetric nor asymmetric algorithm.

Which is more secure SHA-256 or MD5? ›

SHA256 has several advantages over MD5 and SHA-1, such as producing a longer hash (256 bits) that is more resistant to collisions and brute-force attacks. Additionally, there are no known vulnerabilities or weaknesses with SHA256, unlike MD5 and SHA-1 which have been exploited by hackers and researchers.

Which hash function is most secure? ›

Common attacks like brute force attacks can take years or even decades to crack the hash digest, so SHA-2 is considered the most secure hash algorithm.

Should I use SHA-2 or MD5? ›

In terms of speed, the MD5 is slightly faster than SHA-2. Therefore, the MD5 is often used as a checksum for verifying files integrity. To sum up, in most cases, SHA-2 will do better than MD5. It's more secure, reliable, and less likely to be broken.

Is SHA-1 more secure than SHA-2? ›

SHA1 is vulnerable to collision attacks, which undermines its reliability in ensuring data integrity. SHA2 and SHA256 offer a much higher level of security. The increased bit length and complexity of SHA256 make it resistant to collision and preimage attacks and provide you with a more secure hashing solution.

Why is MD5 no longer secure? ›

Weak security: MD5 produces a fixed-sized 128-bit hash value, which is significantly shorter than modern secure hash functions like SHA-256 or SHA-3. A shorter hash length reduces the resistance against brute-force and collision attacks, increasing the risk of an attacker successfully compromising the data.

Is MD5 Secure enough for passwords? ›

MD5 is used to store passwords with a one-way hash of the password, but it is not among the recommended hashes for this purpose. MD5 is common and easy to use, and developers often still choose it for password hashing and storage. MD5 is also still used in cybersecurity to verify and authenticate digital signatures.

Is SHA-1 secure? ›

While SHA-1 was once considered a secure hash algorithm, it is now vulnerable to various attacks. The primary vulnerability of SHA-1 is its collision resistance, which means that it is possible to find two different messages that produce the same hash value.

Why is SHA-256 not good for passwords? ›

SHA-256 is the successor of SHA-1, a widely popular algorithm in the past. However, it has since been deemed insecure due to vulnerabilities discovered in its code.

Is SHA-2 secure? ›

SHA-256, a SHA-2 (Secure Hash Algorithm 2) family member, is a robust and secure hash function compared to SHA-1. It produces a hash value of 256 bits. The double length of the output results in a stronger secure hash function, making it more secure against brute force attacks.

What is the best hash for security? ›

Best Practices for Hashing. Avoiding Weak Algorithms: It's essential to use strong and secure hashing algorithms, such as SHA-256, SHA-3, or bcrypt, rather than weak algorithms like MD5 or SHA-1. Weak algorithms are more susceptible to attacks and can be cracked more easily.

What is the fastest secure hash algorithm? ›

xxHash is an Extremely fast Hash algorithm, running at RAM speed limits. It successfully completes the SMHasher test suite which evaluates collision, dispersion and randomness qualities of hash functions.

What are the disadvantages of SHA-2? ›

The Weaknesses of SHA-2

In theory, SHA-2 is vulnerable to collision attacks, where an attacker tries to find two distinct inputs that hash to the same output. However, it's important to note that such attacks remain theoretical due to the massive amount of computational power required.

What is the difference between SHA-1 SHA-2 and MD5? ›

SHA stands for Secure Hash Algorithm. The first version of the algorithm was SHA-1, and was later followed by SHA-2 (see below). Whereas MD5 produces a 128-bit hash, SHA1 generates 160-bit hash (20 bytes). In hexadecimal format, it is an integer 40 digits long.

What is the drawback of SHA-1? ›

The biggest problem displayed above was that the input was a known length with limited combinations. This allowed for a brute force attack to easily crack the hashes since it was running at 300 MH/s, or 300 million hashes per second for the credit card numbers, and 1200 MH/s, or 1.2 billion hashes per second.

Why is SHA-1 no longer secure? ›

The vulnerability here is that only one hash algorithm output is signed at any given time, and therefore finding an efficient way to find different source data that produces same hash result is direct threat to all signatures.

Is SHA-1 Secure enough? ›

Since 2005, SHA-1 has not been considered secure against well-funded opponents; as of 2010 many organizations have recommended its replacement. NIST formally deprecated use of SHA-1 in 2011 and disallowed its use for digital signatures in 2013, and declared that it should be phased out by 2030.

Which authentication algorithm is most secure? ›

AES (Advanced Encryption Standard) — AES is the strongest encryption algorithm available. Fireware can use AES encryption keys of these lengths: 128, 192, or 256 bits.

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