Provide steps in creating hashes with openSSL.

Question

OpenSSL can be used as a standalone tool for hashing. To create a hash of a text file, follow the steps
below:

Answer 1

Step 1. Hashing a text file
a. In the CyberOps Workstation virtual machine, open a terminal window.
b. Because the text file to hash is in the /home/analyst/lab.support.files/ directory, change

to that directory:
```
[analyst@secOps ~]$ cd /home/analyst/lab.support.files/
```
c. Type the command below to list the contents of the letter_to_grandma.txt text file on

the screen:
```
[analyst@secOps lab.support.files]$ cat letter_to_grandma.txt
Hi Grandma,
I am writing this letter to thank you for the chocolate chip cookies you sent
me. I got them this morning and I have already eaten half of the box! They are
absolutely delicious!
I wish you all the best. Love,
Your cookie-eater grandchild.
```
d. Still from the terminal window, issue the command below to hash the text file. The
command will use MD5 as a hashing algorithm to generate a hash of the text file. The
hash will be displayed on the screen after OpenSSL has computed it.
```
[analyst@secOps lab.support.files]$ openssl md5 letter_to_grandma.txt
MD5(letter_to_grandma.txt)= 8a82289f681041f5e44fa8fbeeb3afb6
```
Notice the format of the output. OpenSSL displays the hashing algorithm used, MD5,
followed by the name of the file used as input data. The MD5 hash itself is displayed
after the equal (‘=’) sign.
e. Hash functions are useful for verifying the integrity of the data regardless of whether it

is an image, a song, or a simple text file. The smallest change results in a completely dif-
ferent hash. Hashes can be calculated before and after transmission, and then compared.

If the hashes do not match, then data was modified during transmission.
Let’s modify the letter_to_grandma.txt text file and recalculate the MD5 hash. Issue the
command below to open nano, a command-line text editor.
```
[analyst@secOps lab.support.files]$ nano letter_to_grandma.txt
```
Using nano, change the first sentence from ‘Hi Grandma’ to ‘Hi Grandpa’. Notice we
are changing only one character, ‘m’ to ‘p’. After the change has been made, press the
keys to save the modified file. Press ‘Y’ to confirm the name and save
the file.

f. Now that the file has been modified and saved, run the same command again to gener-
ate an MD5 hash of the file.
```
[analyst@secOps lab.support.files]$ openssl md5 letter_to_grandma.txt
MD5(letter_to_grandma.txt)= dca1cf6470f0363afb7a65a4148fb442
```
Is the new hash different than the hash calculated in item (d)? How different?
g. MD5 hashes are considered weak and susceptible to attacks. More robust hashing algo-
rithms include SHA-1 and SHA-2. To generate an SHA-1 hash of the letter_to_grandma.

txt file, use the command below:
```
[analyst@secOps lab.support.files]$ openssl sha1 letter_to_grandma.txt
SHA1(letter_to_grandma.txt)= 08a835c7bcd21ff57d1236726510c79a0867e861
[analyst@secOps lab.support.files]$
```
Note: Other tools exist to generate hashes. Namely, md5sum, sha1sum, and sha256sum can be used to
generate MD5, SHA-1 and SHA-2-256 hashes, respectively.
h. Use md5sum and sha1sum to generate MD5 and SHA-1 hash of the letter_to_grandma.

txt file:
```
[analyst@secOps lab.support.files]$ md5sum letter_to_grandma.txt
dca1cf6470f0363afb7a65a4148fb442 letter_to_grandma.txt
[analyst@secOps lab.support.files]$ sha1sum letter_to_grandma.txt
08a835c7bcd21ff57d1236726510c79a0867e861 letter_to_grandma.txt
[analyst@secOps lab.support.files]$
```
Do the hashes generated with md5sum and sha1sum match the images generated in
items (g) and (h), respectively? Explain.
Yes. While different tools are used, they use the same hashing algorithm and input data.
Note: While SHA-1 has not yet been effectively compromised, computers are becoming more and
more powerful. It is expected that this natural evolution will soon make it possible for attackers to
break SHA-1. In a proactive move, SHA-2 is now the recommended standard for hashing. It is also
worth noting that SHA-2 is in fact, a family of hashing algorithms. The SHA-2 family is comprised of
six hash functions, namely SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, SHA-512/256.
These functions generate hash values that are 224, 256, 384 or 512 bits long, respectively.
Note: The CyberOps VM only includes support for SHA-2-224 and SHA-2-256 (sha224sum and sha-
256sum, respectively).