Questions tagged [gnupg]

GNU Privacy Guard (GnuPG or GPG) is an open source implementation of PGP, a file encryption and signature tool widely used for emails

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GnuPG verify signature *after/while* decrypting does not fail when it should

I'm encrypting and signing data with the PHP function gnupg_encryptsign() (docs) which has the strange behaviour of signing first and encrypting afterwards. I'm aware of this thread saying this is ...
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How to view gpg default key in windows [migrated]

I have multiple windows servers in my production. Only one of them is active at a time. The encryption command worked perfectly on one server, but has failing on another with the following message: &...
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What use does verifying a file with a signature downloaded from the same server have? [duplicate]

Now, I understand how PGP signatures work and why they can be useful to check if a file has been manipulated but this has always bugged me, if I download a file from a site/server, and read: "...
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GPG unattended ECC key and subkey generation

I wanna generate a ECC key which primary key is just for cert and has 3 subkeys for auth, sign, encrypt. I've found 2 methods to generate it. But I wanna unattended key generation via gpg —-batch —...
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Can a deleted PGP secret key be recovered from private-keys-v1.d directory?

Executing gpg -K --with-keygrip returns one key entry. However the private-keys-v1.d directory has two entries. I assume that one of them belongs to a secret key that has been deleted/removed. Is ...
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create gpg public key from subkey

I have a communication partner that is using some script that does not work well with subkeys. Now, my gpg key is a normal key [SC] with three subkeys for E,S and A specifically. For my communication ...
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Difference between OpenPGP symmetric encryption and AES-256?

I would like to understand the difference between: OpenPGP symmetric encryption and AES-256 using Winzip/7-zip? I mean if you encrypt a file with an OpenPGP program like GnuPG, using AES-256 ...
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How is private key encrypted after export?

For migration I exported private/public key pair from OSX to whonix. I exported the file to my filesystem and opened the asc file with textedit. The private key to my surprise was in plaintext! I ...
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How can one read the time in GPG's Literal Data Packet?

RFC 4880 says that the Literal Data Packet's time stamp is four octets long. Listing packets shows that it is five octets long, at least in GnuPG 2.2.6. The time stamp comes after the word "created", ...
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gpg: Every private key export (of the same key-pair) is different

gpg version: 2.2.16 (as part of Gpg4win 3.1.9). Is this supposed to happen: Every export of my private key partially differs from every other export as follows: 2 middle chunks of the main block, and ...
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73 views

Can a new signature be added to an already signed message?

Suppose Bob receives a clear-signed message from Alice. Bob wants to add his own signature to this signed message, because he has verified the message contents and wants his friends (network of trust) ...
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How to verify a binary correctly even if my github account is hacked by someone

I have a binary file and saved it on github release page. https://github.com/zono/bolt8/releases To allow users to verify it, I saved sha256sum and signature(.asc). However I have a concern that if ...
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How can I get rid of the MDC packet in OpenPGP?

I want to get rid of the MDC packet in OpenPGP because I view SHA1 as a catastrophic threat. If one can invert SHA1, then all plaintext in OpenGPG is ... open. If one tries to go back to RFC 2440 ...
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How can I input a raw session key into GnuPG?

How can I input a raw session key into GnuPG? I presume that I will have to use --sk2-cipher-algo and --sk2-digest-algo at the same time so as to accommodate the length of my chosen session key. ...
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Superceding a passphrased key with a token-based key

I've been using a GPG key for awhile (mostly with the pass password manager but also some with mail). Since it's now in use, a few years old, and entering the passphrase is getting tiresome, I ...
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--s2k-mode 0 session key from equal-length passphrase

In gpg2, how exactly does --s2k-mode 0 go from the passphrase to the session key in this example: gpg2 --armor --s2k-mode 0 --s2k-digest SHA256 --s2k-cipher-algo CAMELLIA256 --symmetric [file path] ...
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Should I delete lost GPG key from GitHub?

I've been using GPG key for a while to sign commits on GitHub. However, I recently lost it by accident when moving data around. It haven't leaked anywhere and signed commits can be trusted, I just don'...
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Import/Register GPG keys from a SmartCard/Yubi

I used my desktop to setup my GPG keys, added them to my Yubikey, and then removed them from my desktop so that when I am prompted for the key it asks me to use my Yubikey --instead of asking for a ...
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1answer
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Is GPG symmetric (decryption) vulnerable?

Suppose a file (say, a text file source.txt) was encrypted into danger.gpg using GPG symmetric encryption on a compromised device. Since the device is compromised, danger.gpg could have been created ...
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445 views

How do I delete secret subkeys correctly?

I tried to use gpg --delete-secret-keys to delete some revoked subkeys but ended up accidentally deleting my primary key instead. I was able to reproduce my mistake with the following commands: $ ...
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1answer
162 views

GnuPG can see a card under root user, but not under normal user

When under an unprivileged user: $ gpg --card-status gpg: selecting openpgp failed: No such device gpg: OpenPGP card not available: No such device With sudo or under a root user: $ sudo gpg --card-...
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Is it permissible to use GPG without an encryption key?

Will I be disapproved of or get frowned upon a lot if I choose to deploy and use GnuPG without an encryption key? E.g. I generate keys manually and skip the encryption key entirely. The reason is ...
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Import ssh keys into gpg (openpgp) as mutliple authentication subkeys?

I have successfully converted ssh keys to gpg primary keys and then converted them to authentication subkeys using pem2openpgp. Unfortunately there is only one primary key and only one authentication ...
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154 views

How do I create a detached plain text signature?

If I use gpg --detach-sig file, then I get a small file.sig, but it is not plain text, so this is not useful if you wish to send the signature in a plain text format. If I use gpg --clearsign file, ...
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Is gnupg2 --refresh-keys susceptible to any attacks based on fingerprint collisions?

Alice updates her OpenPGP key yearly. Bob updates his copy using: gpg2 --refresh-keys Mallory ensures that Bob uses her keyserver, which offers her own key, which is sharing the 32-bit "short" Key ...
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Can I decrypt a .gpg file by using Windows CNG store/ProtectedData?

I'm creating this tool in C# that would take a .gpg file and decrypt it using Windows CNG. I get a .gpg file as my input parameter and it is encrypted with my key using WinPT. Decrypting it works with ...
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1answer
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How do I interpret output that produces gpg listing keys?

Correct me where I'm wrong. There are public and private (or secret) keys. A public and a private key make up a keypair. Some keypairs are bound to the other ones. The former are called subkeys, the ...
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1answer
85 views

Length of a stretched gnupg passphrase that is comparable in strength to an unstretched string of 256 random bits

Assume that we want to encrypt a file with gnupg using AES-256 as the encryption algorithm. (Hence, symmetric encryption.) In this mode, gnupg requires a passphrase from the user. I understand that ...
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How can I trust a GPG key when I download it based on the fingerprint contained in the file I want to verify?

The instructions at https://tutorials.ubuntu.com/tutorial/tutorial-how-to-verify-ubuntu#3 suggest that you can download an ISO for installing an OS, along with the checksums and a signature. You then ...
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Is that a good idea? - Firefox/Chrome in-content encryption

I'm currently thinking about writing a Firefox/Chrome and Python/PHP/JS plugin to accomplish the following: Assuming you are on a non-SSL secured site or you simply don't trust any CA like Let's ...
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586 views

RSA 4096 vs. ECC Curve 25519

I want to use GPG to encrypt files before storing them as backup in the cloud. I don't care about interoperability or performance/resource consumption during encryption/decription. I only care about ...
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Which encryption algorithm for cloud backup?

I want to backup my data to the cloud. Before that, I want to encrypt it using GPG (gpg (GnuPG) 2.2.11 and libgcrypt 1.8.4). The backup is just for me, so I don't care about interoperability I only ...
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165 views

Is there a security difference between GPG signing a file directly or its SHA512SUM file?

I am about to decide what SHA-512 hash sum and / or GPG verification scheme I will choose. Let me present you with two options: Signing the 25 GB ~ 23 GiB (one file fit to a Blu-Ray) directly with: ...
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Decrypting gpg2-symmetrically-encrypted files using non-gpg2 tools

If I encrypt a file using gpg2 and specifying AES256 as my encryption algorithm, can I decrypt it with tools other than gpg2? More generally, does the fact that one tool used AES256 for encrypting a ...
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Is GPG a kind of digital signature?

So I've been using GPG since I've touched Linux&LibreOffice, but I only knew that's its a signature, for identifying the work is created by me. But soon I've been touching some law questions and ...
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GPG: Change expected card number

I have switched from a YubiKey 4 to a YubiKey 5. Both have the same GPG keys stored. After storing the key on the first YubiKey, I fetched my public key so GPG knows where to look for the private key. ...
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I use full-disk encryption. Should I passphrase-encrypt my private key(s) anyway?

Suppose I want to use GnuPG on a GNU/Linux laptop where I've encrypted all filesystems (except /boot) with LUKS/dm-crypt. Backups are encrypted client-side and stored on a physically secure server. ...
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Preparing to change over to new GPG-key - what to do with my old ones?

I've just created a new off-line GPG-key with a sign/certify master-key and two sub-keys - one for signing and one for encrypting. 5 yr expiration for the master, 2 yr for the subs. My master-key got ...
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Know the setting used in creating key pair in GNUPG4Win version 3.15

I am using GNUpg4Win version 3.15. For the last few hours I am trying to figure out what default settings are used for Cipher and Hash during key generation. Basically I want to use AES-128, 3DES ...
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Is layered encryption more secure than long passwords?

The comments in this question debate about the added security of multi-layered encryption. There seems to be some disagreement, and I thought a proper question would be helpful here. So, to provide ...
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Is there a limit on the layers of encryption a file can have?

Consider symmetric GPG encryption of a given file my_file.txt. Something like (in command line) gpg --symmetric --cipher-algo AES256 my_file.txt After suppying the prompt with the new password, the ...
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gpg2 --full-generate-key generated 2 keys with different expiry dates

I was trying to generate a new gpg keypair earlier, so ran: gpg2 --full-gen-key. I selected the default key type (RSA & RSA), keysize (2048) and specified that the key should expire in 2 years (2y)...
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gpg ignores passphrase on my key stored on yubikey 5 nfc

I just set-up my yubikey 5 nfc with 3 seperate subkeys (S, E, A). While encrypting and decrypting works fine (self-tested), I'm questioning the fact that gpg only ever asks me for the yubikey's pgp ...
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Is GPG's AES encryption that much stronger than its RSA headers? [duplicate]

Correct me if I'm wrong at any point of this questino. I understand that AES is a lot cheaper to compute than RSA (or any form of asymmetric encryption) and that that is why GPG and similar programs (...
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How to display the SHA256 hash while signing or in signature

I realize (using --clearsign) that GnuPG is using SHA256 as the hashing algorithm for signing, but I would like to be able to see the actual SHA256 hash in the signature somewhere. Is there a way ...
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1answer
81 views

What are a keypair and a public key ring?

The GNU Privacy Handbook says: The command-line option -gen-key is used to create a new primary keypair. gpg --gen-key Does a keypair mean a pair of private key and public key? The book also ...
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Why is GPG-agent still caching my passphrase?

I can not get gpg to prompt me for my passphrase when I want to decrypt a file. I tried including: default-cache-ttl 0 max-cache-ttl 0 (also flipped the bit to 1) within ~/.gnupg/gpg-agent.conf ...
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1answer
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Leaking `.gnupg` directory when private keys are stored on a smart card

What security risks can be caused by leaking .gnupg directory (for example, accidentally committing it to GitHub) when private keys are stored on a smart card?
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OpenPGP SmartCard: generate revocation certificate on-card?

As far as I can tell: It is possible to generate a private keyring (i.e. signing private key, plus associated encryption private key and authentication private key) entirely on an OpenPGP Smartcard (...
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Use GPG smartcard and gpg-agent to protect multiple SSH keys

I have a Yubikey acting as a GPG smartcard. SSH is configured to use the smart card socket for authentication, and authenticating with the GPG key with Authentication capabilities work fine. ssh-add -...