• Gpg Key Generation
• Generate Gpg Key Linux
• Install Gpg Public Keys
• Gpg Gen Key
• Gpg Generate Public Key
• Generate Gpg Key Pair Linux Free

Table of Contents

Generating a new keypair

Exchanging keys

Encrypting and decrypting documents

Making and verifying signatures

Apr 17, 2013 File Encryption using GPG Key Pair in Linux Step 1: Create GPG Key Pair. The very first step is to generate key pair. Step 2: Encrypt/Decrypt File Current User. Encrypt file for single user only. Step 3: Encrypt File for Other User. Use #1 steps to generate encrypted file. Step 4: Decrypt Other. How to Generate the key pair with GPG in Linux The steps for generating the key pairs are as follows: 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. Generate a GPG key pair. Since there are multiple versions of GPG, you may need to consult the relevant man page to find the appropriate key generation command. Your key must use RSA. If you are on version 2.1.17 or greater, paste the text below to generate a GPG key pair. $ gpg -full-generate-key. Apr 04, 2017  1) Instructions to use of gpg. When installing gnupg package, we need to understand the concept to use gpg as well. To encrypt your communication, the first thing to do is to create a new keypair. GPG is able to create several types of keypairs, but a primary key.

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.

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.

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.

Linux comes with the GNU Privacy Guard (GnuPG or GPG) encryption and authentication utility. With GnuPG, you can create your public and private key pair on your Linux system, encrypt files with your key, and digitally sign a message to authenticate that it’s from you. If you send a digitally signed message to someone who has your public key, the recipient can verify that you signed the message.

Understanding public key encryption

Gpg Key Generation

The basic idea behind public key encryption is to use a pair of keys — one private and the other public — that are related but can’t be used to guess one from the other. Anything encrypted with the private key can be decrypted only with the corresponding public key, and vice versa. The public key is for distribution to other people; you keep the private key in a safe place.

You can use public key encryption to communicate securely with others. Let’s try an example. Suppose that Alice wants to send secure messages to Bob. Each person generates public key and private key pairs, after which they exchange their public keys. When Alice wants to send a message to Bob, she encrypts the message by using Bob’s public key and sends the encrypted message to him. Now the message is secure from eavesdropping, because only Bob’s private key can decrypt the message, and only Bob has that key. When Bob receives the message, he uses his private key to decrypt the message and read it.

At this point, you might say, “Wait a minute! How does Bob know that the message really came from Alice? What if someone else uses Bob’s public key and sends a message as though it came from Alice?” This situation is where digital signatures come in.

Aug 16, 2019  The software originally came with a Product Key as part of the retail package. See Product Key Location for locating the Product Key on the original items. If you are missing your key but the program is still installed and unlocked on a different computer, you can try obtaining your key from the menu in the program when it is open. Mac product key finder.

Understanding digital signatures

The purpose of digital (electronic) signatures is the same as that of pen-and-ink signatures, but how you sign digitally is different. Unlike a pen-and-ink signature, your digital signature depends on the message you’re signing. The first step in creating a digital signature is applying a mathematical function to the message and reducing it to a fixed-size message digest (also called a hash or a fingerprint). No matter how big your message is, the message digest is usually 128 or 160 bits, depending on the hashing function.

The next step is applying public key encryption. Simply encrypt the message digest with your private key, and you get the digital signature for the message. Typically, the digital signature is added to the end of the message, and voilà — you get an electronically signed message.

What good does the digital signature do? Well, anyone who wants to verify that the message is indeed signed by you takes your public key and decrypts the digital signature. What that person gets is the message digest (the encrypted hash) of the message. Then he or she applies the same hash function to the message and compares the computed hash with the decrypted value. If the two match, then no one has tampered with the message. Because your public key was used to verify the signature, the message must have been signed with the private key known only to you, so the message must be from you!

In the theoretical scenario in which Alice sends private messages to Bob, Alice can digitally sign her message to make sure that Bob can tell that the message is really from her.

Here’s how Alice sends her private message to Bob with the assurance that Bob can tell it’s from her:

1. Alice uses software to compute the message digest of the message and then encrypts the digest by using her private key — her digital signature for the message.
2. Alice encrypts the message (again, using some convenient software and Bob’s public key).
3. She sends both the encrypted message and the digital signature to Bob.
4. Bob decrypts the message, using his private key.
5. Bob decrypts the digital signature, using Alice’s public key, which gives him the message digest.
6. Bob computes the message digest of the message and compares it with what he got by decrypting the digital signature.
7. If the two message digests match, Bob can be sure that the message really came from Alice.

Using GPG in a Linux system

GPG includes the tools you need to use public key encryption and digital signatures. You can figure out how to use GPG gradually as you begin using encryption. The following information shows some of the typical tasks you can perform with GPG.

Generating the key pair in Linux

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.

Exchanging keys using Linux

Generate Gpg Key Linux

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.

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.

When you import a key from someone, you typically get it in ASCII-armored format as well. If you have a us-cert@us-cert.gov GPG public key in 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:

Key fingerprint = 049F E3BA 240B 4CF1 3A76 06DC 1868 49EC F0E1 87D0

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.

Signing a file 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:

If you indeed signed the message, the last line of the output says that the signature is good.

Encrypting and decrypting documents in Linux

Install Gpg Public Keys

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).

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:

Gpg Gen Key

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 Generate Public Key

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.

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To decrypt a file encrypted with a symmetric key, type

Generate Gpg Key Pair Linux Free

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.