Table of Contents
Generating a new keypair
Exchanging keys
Encrypting and decrypting documents
Making and verifying signatures

GnuPG is a tool for secure communication.This chapter is a quick-start guide that covers the core functionalityof GnuPG.This includes keypair creation, exchanging and verifying keys, encryptingand decrypting documents, and authenticating documents with digitalsignatures.It does not explain in detail the concepts behind public-key cryptography,encryption, and digital signatures.This is covered in Chapter 2.It also does not explain how to use GnuPG wisely.This is covered in Chapters 3 and 4.

Apr 15, 2008  How-To: Import/Export GPG key pair 1 minute read This tutorial will show how you can export and import a set of GPG keys from one computer to another. This way, you can sign/encrypt the same way one different computer. A simple way of doing it would be to: $. I'm trying to generate a new key with: gpg -full-generate-key and it keeps ending with: g. Stack Exchange Network Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to. May 16, 2018  How To Use GPG Private Public Keys To Encrypt And Decrypt Files On Ubuntu Linux GNU Privacy Guard (GnuPG or GPG) is a free software replacement for Symantec's PGP.

Here is a GUI way to generate a new PGP key. Open the Passwords and Keys (Seahorse) application. This screen will appear. Either go to File → New in the global menu or hit Ctrl + N. Generated key slash plus sign. In the Create New. Window select PGP Key and hit Continue. Enter your full name. If you are on version 2.1.17 or greater, paste the text below to generate a GPG key pair. $ gpg -full-generate-key; If you are not on version 2.1.17 or greater, the gpg -full-generate-key command doesn't work. Paste the text below and skip to step 6. $ gpg -default-new-key-algo rsa4096 -gen-key. How to quickly generate (insecure) GPG keys? And I needed to generate multiple GPG keys in a row each test. Copy and paste this URL into your RSS reader.

GnuPG uses public-key cryptography so that users may communicate securely.In a public-key system, each user has a pair of keys consisting ofa private key and a public key.A user's private key is kept secret; it need never be revealed.The public key may be given to anyone with whom the user wants tocommunicate.GnuPG uses a somewhat more sophisticated scheme in which a user hasa primary keypair and then zero or more additional subordinate keypairs.The primary and subordinate keypairs are bundled to facilitate keymanagement and the bundle can often be considered simply as one keypair.

The command-line option --gen-keyis used to create a new primary keypair.GnuPG is able to create several different types of keypairs, but a primarykey must be capable of making signatures.There are therefore only three options.Option 1 actually creates two keypairs.A DSA keypair is the primary keypair usable only for making signatures.An ElGamal subordinate keypair is also created for encryption. Option 2 is similar but creates only a DSA keypair.Option 4[1] creates a single ElGamal keypair usable for both making signatures and performing encryption.In all cases it is possible to later add additional subkeys for encryptionand signing.For most users the default option is fine.

Jul 01, 2019  Once GnuPG is installed, you’ll need to generate your own GPG key pair, consisting of a private and public key. The private key is your master key. It allows you to decrypt/encrypt your files and create signatures which are signed with your private key.

You must also choose a key size.The size of a DSA key must be between 512 and 1024 bits, and an ElGamalkey may be of any size.GnuPG, however, requires that keys be no smaller than 768 bits.Therefore, if Option 1 was chosen and you choose a keysize larger than1024 bits, the ElGamal key will have the requested size, but the DSAkey will be 1024 bits.The longer the key the more secure it is against brute-force attacks,but for almost all purposes the default keysize is adequate sinceit would be cheaper to circumvent the encryption than try to break it.Also, encryption and decryption will be slower as thekey size is increased, and a larger keysize may affect signature length.Once selected, the keysize can never be changed.

Finally, you must choose an expiration date.If Option 1 was chosen, the expiration date will be used for both theElGamal and DSA keypairs.For most users a key that does not expire is adequate.The expiration time should be chosen with care, however,since although it is possible to change the expiration date after the keyis created, it may be difficult to communicate a changeto users who have your public key.

You must provide a user ID in addition to the key parameters.The user ID is used to associate the key being created with a realperson.Only one user ID is created when a key is created, but it is possibleto create additional user IDs if you want to use the key in two ormore contexts, e.g., as an employee at work and a political activiston the side.A user ID should be created carefully since it cannot be edited afterit is created.

GnuPG needs a passphrase to protect the primary and subordinate private keys that you keep in your possession.There is no limit on the length of a passphrase, and it should becarefully chosen.From the perspective of security, the passphrase to unlock the privatekey is one of the weakest points in GnuPG (and other public-key encryption systems as well) since it is the only protection you have if another individual gets your private key.Ideally, the passphrase should not use words from a dictionary andshould mix the case of alphabetic characters as well as use non-alphabetic characters.A good passphrase is crucial to the secure use of GnuPG.

Generating a revocation certificate

After your keypair is created you should immediately generate a revocationcertificate for the primary public key using the option--gen-revoke.If you forget your passphrase or if your private key is compromised or lost, this revocation certificate may be published to notify othersthat the public key should no longer be used.A revoked public key can still be used to verify signatures madeby you in the past, but it cannot be used to encrypt future messagesto you.It also does not affect your ability to decrypt messages sent toyou in the past if you still do have access to the private key.The argument mykey must be a keyspecifier,either the key ID of your primary keypair or any part of a user IDthat identifies your keypair.The generated certificate will be left in the filerevoke.asc.If the --output option is omitted, the result will be placed on standard output.Since the certificate is short, you may wish to print a hardcopy ofthe certificate to store somewhere safe such as your safe deposit box.The certificate should not be stored where others can access it sinceanybody can publish the revocation certificate and render thecorresponding public key useless.

Notes

[1]

Option 3 is to generate an ElGamal keypair that isnot usable for making signatures.

PrevHomeNextThe GNU Privacy HandbookExchanging keys

GPG includes the tools you need to use public key encryption and digital signatures on your Linux system. You can figure out how to use GPG gradually as you begin using encryption in Linux. The information you find here shows some of the typical tasks you can perform with GPG to protect your Linux system.

How to Generate the key pair with GPG in Linux

Gpg Generate Public Key

The steps for generating the key pairs are as follows:

  1. Type gpg –gen-key.

    If you’re using GPG for the first time, it creates a .gnupg directory in your home directory and a file named gpg.conf in that directory. Then it asks what kind of keys you want:

  2. Press Enter for the default choice, which is good enough.

    GPG prompts you for the key size (the number of bits).

  3. Press Enter again to accept the default value of 2,048 bits.

    GPG asks you when the keys expire. The default is to never expire.

  4. If the default is what you want (and why not?), press Enter.
  5. When GPG asks whether you really want the keys to never expire, press the Y key to confirm.

    GPG prompts you for your name, your email address, and a comment to make it easier to associate the key pair with your name.

  6. Type each piece of requested information, and press Enter.
  7. When GPG gives you a chance to change the information or confirm it, confirm by typing o and pressing Enter.

    GPG prompts you for a passphrase that protects your private key.

  8. Type a long phrase that includes lowercase and uppercase letters, numbers, and punctuation marks — the longer the better — and then press Enter.

    Be careful to choose a passphrase that you can remember easily.

    GPG generates the keys. It may ask you to perform some work on the PC so that the random-number generator can generate enough random numbers for the key-generation process.

How to exchange keys using GPG in Linux

If you’re an administrator, protecting your Linux system should always be at the top of your mind. To communicate with others, you have to give them your public key. You also have to get public keys from those who may send you a message (or when someone who might sign a file and you want to verify the signature). GPG keeps the public keys in your key ring. (The key ring is simply the public keys stored in a file, but the name sounds nice because everyone has a key ring in the real world, and these keys are keys of a sort.) To list the keys in your key ring, type

To send your public key to someone or to place it on a website, you have to export the key to a file. The best way is to put the key in what GPG documentation calls ASCII-armored format, with a command like this:

This command saves the public key in ASCII-armored format (which looks like garbled text) in the file named kdulaneykey.asc. You replace the email address with your email address (the one you used when you created the key) and replace the output filename with something different.

Where To Paste Ubuntu Generate Gpg Keys For Mac

After you export the public key to a file, you can mail that file to others or place it on a website for use by others. Black ops 2 steam product key generator.

When you import a key from someone, you typically get it in ASCII-armored format as well. If you have a us-http://www.us-cert.gov/pgp/email.htmlin a file named uscertkey.asc, you import it into the key ring with the following command:

Use the gpg --list-keys command to verify that the key is in your key ring. Here’s what you might see when typing gpg –list-keys on the system:

The next step is checking the fingerprint of the new key. Type the following command to get the fingerprint of the US-CERT key:

GPG prints the fingerprint, as follows:

At this point, you need to verify the key fingerprint with someone at the US-CERT organization.

If you think that the key fingerprint is good, you can sign the key and validate it. Here’s the command you use to sign the key:

GPG asks for confirmation and then prompts you for your passphrase. After that, GPG signs the key.

Because key verification and signing are potential weak links in GPG, be careful about what keys you sign. By signing a key, you say that you trust the key to be from that person or organization.

How to sign a file with GPG in Linux

You may find signing files to be useful if you send a file to someone and want to assure the recipient that no one tampered with the file and that you did in fact send the file. GPG makes signing a file easy. You can compress and sign a file named message with the following command:

To verify the signature, type

To get back the original document, type

Sometimes, you don’t care about keeping a message secret, but you want to sign it to indicate that the message is from you. In such a case, you can generate and append a clear-text signature with the following command:

This command appends a clear-text signature to the text message. Here’s a typical clear-text signature block:

When a message has a clear-text signature appended, you can use GPG to verify the signature with the following command:

Encrypting and decrypting documents with GPG in Linux

To encrypt a message meant for a recipient, you can use the --encrypt (or -e) GPG command. Here’s how you might encrypt a message for US-CERT by using its GPG key:

The message is encrypted with the US-CERT public key (without a signature, but you can add the signature with the -s command).

Where To Paste Ubuntu Generate Gpg Keys Free

When US-CERT receives the message.gpg file, the recipient must decrypt it by using US-CERT’s private key. Here’s the command that someone at US-CERT can use:

Then GPG prompts for the passphrase to unlock the US-CERT private key, decrypts the message, and saves the output in the file named message.

If you want to encrypt a file that no one else has to decrypt, you can use GPG to perform symmetric encryption. In this case, you provide a passphrase to encrypt the file with the following GPG command:

GPG prompts you for the passphrase and asks you to repeat the passphrase (to make sure that you didn’t mistype anything). Then GPG encrypts the file, using a key generated from the passphrase.

To decrypt a file encrypted with a symmetric key, type

GPG prompts you for the passphrase. If you enter the correct passphrase, GPG decrypts the file and saves the output (in this example) in the file named myfile.

Check here to discover ten security terms you should know for Linux systems.

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