Public key encryption (asymmetric encryption)

Generating RSA public/private key pairs with `gpg`

The gpg program is the OpenPGP encryption and signing tool. PGP stands for "pretty good protection".

Step 1. Generate a public private key pair.

First ssh to the Kali Linux machine.
Run the following gpg command:
```
  $ gpg --full-generate-key
```
Follow the prompts to answer the questions.

Below is how I answered these questions to generate my keys:

  gpg (GnuPG) 2.2.40; Copyright (C) 2022 g10 Code GmbH
  This is free software: you are free to change and redistribute it.
  There is NO WARRANTY, to the extent permitted by law.

  gpg: directory '/home/kali/.gnupg' created
  gpg: keybox '/home/kali/.gnupg/pubring.kbx' created
  Please select what kind of key you want:
  (1) RSA and RSA (default)
  (2) DSA and Elgamal
  (3) DSA (sign only)
  (4) RSA (sign only)
  (14) Existing key from card
  Your selection? 1
  RSA keys may be between 1024 and 4096 bits long.
  What keysize do you want? (3072)
  Requested keysize is 3072 bits
  Please specify how long the key should be valid.
          0 = key does not expire
      <n>  = key expires in n days
      <n>w = key expires in n weeks
      <n>m = key expires in n months
      <n>y = key expires in n years
  Key is valid for? (0)
  Key does not expire at all
  Is this correct? (y/N) y

  GnuPG needs to construct a user ID to identify your key.

  Real name: Dr. David Balash
  Email address: david.balash@richmond.edu
  Comment: RSA keys for CMSC 240
  You selected this USER-ID:
      "Dr. David Balash (RSA keys for CMSC 240) <david.balash@richmond.edu>"

  Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? O
  We need to generate a lot of random bytes. It is a good idea to perform
  some other action (type on the keyboard, move the mouse, utilize the
  disks) during the prime generation; this gives the random number
  generator a better chance to gain enough entropy.
  We need to generate a lot of random bytes. It is a good idea to perform
  some other action (type on the keyboard, move the mouse, utilize the
  disks) during the prime generation; this gives the random number
  generator a better chance to gain enough entropy.
  gpg: /home/kali/.gnupg/trustdb.gpg: trustdb created
  gpg: directory '/home/kali/.gnupg/openpgp-revocs.d' created
  gpg: revocation certificate stored as '/home/kali/.gnupg/openpgp-revocs.d/3EE0A0EFB95B62BECAE0F893059FA9C60FCE1D9B.rev'
  public and secret key created and signed.

  pub   rsa3072 2024-01-31 [SC]
      3EE0A0EFB95B62BECAE0F893059FA9C60FCE1D9B
  uid                      Dr. David Balash (RSA keys for CMSC 240) <david.balash@richmond.edu>
  sub   rsa3072 2024-01-31 [E]
  

Step 2. Verify that your keys where created.

Run the following gpg command:
```
  $ gpg --list-public-keys
```

Mine looks like this:

  gpg: checking the trustdb
  gpg: marginals needed: 3  completes needed: 1  trust model: pgp
  gpg: depth: 0  valid:   1  signed:   0  trust: 0-, 0q, 0n, 0m, 0f, 1u
  /home/kali/.gnupg/pubring.kbx
  -----------------------------
  pub   rsa3072 2024-01-31 [SC]
      3EE0A0EFB95B62BECAE0F893059FA9C60FCE1D9B
  uid           [ultimate] Dr. David Balash (RSA keys for CMSC 240) <david.balash@richmond.edu>
  sub   rsa3072 2024-01-31 [E]
  

Step 3. Output your public key to a file.

Run this gpg command to output your public key to a file (but change the email address to your email address and change the name of your key to your firstname.key):
```
  $ gpg --output ~/firstname.key --armor --export your.email@richmond.edu
```

Step 4. Take a look at your key.

View the file.
```
  $ cat firstname.key
```

Here is what mine looks like:

Step 5. Copy your key to the directory /opt/publickeys/.

Copy the file.
```
  $ cp firstname.key /opt/publickeys/
```

CMSC 334

Computer Security

David G. Balash

david.balash@richmond.edu

Slack for Q&A

Public key encryption (asymmetric encryption)

Generating RSA public/private key pairs with `gpg`

CMSC 334

Computer Security

David G. Balash

david.balash@richmond.edu

Slack for Q&A

Public key encryption (asymmetric encryption)

Generating RSA public/private key pairs with gpg

Generating RSA public/private key pairs with `gpg`