![]() The only problem is end users tend to like to use easy passwords on things and/or stick to only one method of encryption. This uses intense algorithms to encrypt the data in a file and output in into another file. The Purpose for Using UEDSĪs most of us know you can use an open source program called OpenSSL to encrypt files. I will also provide links explaining the concepts and algorithms used in encryption to anyone who wants to see what is going on under the hood. Finally I will talk about the downsides to the method I use. rw-rw-r- 1 sysadm sysadm 102 Jul 30 12:45 my-secrets-theirname.In this tutorial I will be explaining the purpose of unique encryption/decryption scripts ( I will be referring to these at "UEDS" for this tutorial). If it has worked, OpenSSL will not complain, and you will be able to read the decrypted file: $ ls -l my-secrets-theirname.txt What does openssl say if you use the wrong passphrase ?.If not, what happened ? Did you remember '-a' ? Otherwise OpenSSL cannot know that the file is encoded in ASCII!.To decrypt the file, use the following command: $ openssl aes-256-cbc -d -a -in my-secrets-theirname.asc -out my-secrets-theirname.txt Remember to use 'ls -l' to verify that they have copied their file to your server! Someone is probably going to copy a file to YOUR server, and will ask you to do the same (decrypt the file once they have given you the passphrase). It's probably easiest to write it down on a piece of paper. For this, you will need to communicate your passphrase to them. $ scp my-secrets-myname.asc the file is copied, ask a member of the other group to decrypt your file. You get do decide which server - just pick someone! ** Make sure that you have replace 'myname' with your name! ** If you ALL have called your file "myname" then they will overwrite each other's! Copy your encrypted file to someone else's server in the class.$ rm my-secrets-myname.txt 2.1.2 Decrypting files with OpenSSL You can now delete your unencrypted file. You could, for exmaple, now paste this information into an email, a chat session, and only reveal the passphrase to the recipient over the phone - or maybe only after a certain time. You will notice that only printable characters are used. U2FsdGVkX1+QfdOIoM3qsIFRP48NUgbeHekpKPezReKTgTnrl8c/QShOuhym+NMY What happens if you try and view the contents of the. rw-rw-r- 1 sysadm sysadm 80 Jul 30 11:42 my-secrets-myname.txt rw-rw-r- 1 sysadm sysadm 112 Jul 30 11:43 my-secrets-myname.enc rw-rw-r- 1 sysadm sysadm 155 Jul 30 12:08 my-secrets-myname.asc You can use the same as before, or a different one - just don't forget it!Ĭheck the file sizes once again: $ ls -l my-secrets-myname.* You will, once again, be asked to enter a passphrase. Notice how we introduce the '-a' parameter, and we now create an encrypted file ending in. We can ask OpenSSL to "base64" encode the encrypted file: this will convert the binary file into a slightly larger file, using only ASCII characters which are email-friendly (or even ready to paste in a chat window!) We use the '-a' parameter of the openssl command:Įxample: openssl aes-256-cbc -e -a -in my-secrets-myname.txt -out my-secrets-myname.asc What if you wanted to send this file in an email to one of your friends, or a family member for safekeeping ? Notice that you cannot read the contents - it is a pure binary stream. If you want to, you can write whatever you want it in, or use the example below, replacing "myname" with your name (no spaces - for example JohnDoe). 2.1.1 Encrypting files with OpenSSLįirst, let's find file we want to encrypt. In this lab, we will use the OpenSSL command to encrypt files using the AES 256 encryption algorithm, using a symmetric key. OpenSSL, which is present by default in the base system on Ubuntu (and most other Linux distributions, if not all), is a powerful toolkit that includes many useful tools to generate checksums, manage certificates, and perform encryption/decryption. "RTR-GW>" or "mysql>") imply that you are executing commands on remote equipment, or within another program.Ģ Exercises 2.1 Using OpenSSL and symmetric encryption to encrypt files Commands with more specific command lines (e.g.Commands preceded with "#" imply that you should be working as root.Commands preceded with "$" imply that you should execute the command as a general user - not as root.2.1 Using OpenSSL and symmetric encryption to encrypt files. ![]()
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