Question 333 of 530 from exam 400-251: CCIE Security written exam

# Question 333 of 530 from exam 400-251: CCIE Security written exam

### Question

Which two statements about the SHA-1 algorithm are true? (Choose two)

### Explanations

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A. B. C. D. E.

BE.

SHA-1 (Secure Hash Algorithm 1) is a cryptographic hash function that is widely used for data integrity and digital signature applications. It takes an input message of any length and produces a fixed-size output of 160 bits.

The two statements that are true about the SHA-1 algorithm are:

B. The SHA-1 algorithm takes input message of any length and produces 160-bit hash output. This statement is true. The SHA-1 algorithm is designed to accept input messages of any length and produce a fixed-size output of 160 bits. This makes it useful for verifying the integrity of data by comparing the hash of the original data to the hash of the received data. If the hashes match, the data is considered to be intact.

E. The purpose of the SHA-1 algorithm is to provide data authenticity. This statement is also true. The primary purpose of the SHA-1 algorithm is to provide data authenticity. In other words, it is used to verify that a message or data has not been altered or tampered with during transmission. A hash function like SHA-1 can provide this assurance because it produces a fixed-size output that is unique to the input message. Any alteration to the original message will result in a different hash value.

A, C, and D are not true:

A. The SHA-1 algorithm is considered secure because it always produces a unique hash for the same message. This statement is false. While it is true that the SHA-1 algorithm always produces a unique hash for a given input message, this does not mean that it is secure. In fact, SHA-1 has been proven to be vulnerable to attacks, and is no longer considered to be a secure cryptographic hash function.

C. The SHA-1 algorithm is considered secure because it is possible to find a message from its hash. This statement is false. In fact, one of the properties of a good cryptographic hash function is that it should be computationally infeasible to find a message that corresponds to a given hash value. If it were easy to find a message from its hash value, the hash function would be useless for providing data integrity and authenticity.

D. The purpose of the SHA-1 algorithm is to provide data confidentiality. This statement is false. The SHA-1 algorithm is not designed to provide data confidentiality, which is the protection of data from unauthorized access or disclosure. Rather, it is designed to provide data integrity and authenticity, which ensure that the data has not been altered or tampered with during transmission.