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## Which of the following is defined by the NIST in the FIPS 180-4 standard?

- SHA-1
- MD5
- SHA-256
- SHA-512

**Explanation**:

The SHA-256 hashing algorithm is defined in the FIPS 180-4 standard by the NIST. It is part of the SHA-2 family. The purpose of Secure Hash Algorithm (SHA) is to protect message integrity.

SHA-256, also referred to as SHA-2, is a newer version of SHA and uses 256-bit checksums. SHA-256 should be used with a disk image to protect the image’s integrity so that image can be retained for forensic purposes.

MD5 is hashing algorithm but it is not defined in the FIPS 180-4 standard by the NIST. MD5 is the least secure of the listed hashing algorithms. MD5 is a one-way hashing algorithm. One-way hashing refers to inserting a string of variable length into a hashing algorithm and producing a hash value of fixed length. This hash is appended to the end of the message being sent. This hash value is recomputed at the receivers end in the same fashion in which it was created by using the same computational logic. If the recomputed hash value is the same as the generated hash value, the message was not altered during the course of transmission.

Secure hash algorithm (SHA)-1 is the first version of SHA, and is the least secure version of SHA hashing algorithm. SHA-1 is a hashing algorithm that creates a message digest, which can be used to determine whether a file has been changed since the message digest was created. An unchanged message should create the same message digest on multiple passes through a hashing algorithm. it is not defined in the FIPS 180-4 standard by the NIST.

SHA-512 is a more secure version of SHA-256 and differs only in the number of rounds of computation. It is not defined in the FIPS 180-4 standard by the NIST.

**Objective**: Cryptography

**Sub-Objective**: Describe the uses of a hash algorithm

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