Questions tagged [pgp]

The OpenPGP encrypted data format (RFC 4880), and its implementations PGP and GnuPG.

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How to implement a Hybrid cryptosystem via GnuPGP?

I would upload some file on the cloud and share to my friends (more than one), securly. Reading on wikipedia I found an explication on how it works, but I have doubs, because I don't understand if I ...
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What is the PGP Web of Trust Strongset?

I understand that it is a system that "establishes the authenticity of the binding between public keys and their owners", but how does one join this web of trust? Do you have to physically meet one of ...
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Why is the key creation date part of the OpenPGP Key Fingerprint?

In Version 3 keys, the Key Fingerprint was defined as follows: The fingerprint of a V3 key is formed by hashing the body (but not the two-octet length) of the MPIs that form the key material (...
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Encrypt text message with Wireguard public key

With its public and private key(s), Wireguard looks a bit like PGP. But it is used for encryption of network packets and not normal text messages. I'm on a system with Wireguard already installed and ...
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What prevents ProtonMail from sending me the wrong public keys?

I've recently been looking at ProtonMail, an email service which provides transparent end to end encryption between users with PGP. In order for the encryption to be transparent, ProtonMail manages ...
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Is it possible to verify a clearsigned message with a short public key (fingerprints)?

For practical reasons, I'd like people to be able to post clearsigned messages with their public key fingerprints (8E570D9F7F70256595769E49F9BC5BCAD7E18635) for the ...
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59 views

What does Modification Detection Code (MDC) in OpenPGP do?

The authentication is often done by an HMAC in modern cryptosystems. What does MDC do exactly in OpenPGP and is it a software hack or an algorithmic authentication? Also, how to force GnuPG to stop ...
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why Efail CFB malleability gadget is different from CFB mode decryption?

Really, I could not understand why the decryption process of CFB malleability gadget takes the next cipher block while PGP uses the previous block as shown in the equations in the attached image, I ...
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Testing speed of symmetric vs asymmetric encryption and decryption using gpg

I'm aware that symmetric is faster than asymmetric. I want to test this, but my (obviously incorrect) tests show the reverse. Symmetric test: ...
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56 views

Encrypt symmetric session key with asymmetric or symmetric master key?

Every day, I must backup my server's files, encrypt the backup, and upload it to untrusted cloud storage (dropbox, s3, etc.) I've spent time on security.stackexchange where I discovered the typical ...
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Creating nested messages in OpenPGP

I need to create a nested message in OpenPGP (my understanding is that the protocol itself should support it). Let's say I have Payload ("Time in Lordran is ...
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Computing PGP ed25519 and curve25519 keygrips?

There are public key algorithmic differences for how PGP computes fingerprints and keygrips. For the v4 protocol, fingerprints are not exclusively computed from public keys while keygrips are. RFC ...
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Assistance with parsing PGP PRIVATE KEY BLOCK's Secret-Key Packet (0x6) and Secret-Subkey Packet (0x7) using command lines and RFC 4880?

The throw away private keys below (master ed25519 & subkey curve 25519) were exported without being password encrypted. % cat skaht_0523F5B4_Secret.asc ...
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Is it possible in PGP to provide verification/verify the ownership of a public key?

I am new to PGP/GPG and I am somewhat confused by the idea of the Web of Trust (WoT). Isn't signing a public key with its private key enough to prove the ownership of it? if it is so, why don't key ...
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Safest method for encrypting a file on a local machine

I am looking for a safe method to encrypt a local file on my machine. Let's say I have a file containing my logins and passwords -- how can I make sure that the encryption is reasonably sufficient in ...
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Asymmetric algorithm with indefinite number of public keys

So RSA algorithm uses pre-generated set of public and private key, and public key is usually included in private key. So public key stays always the same. Is it theoretically possible to have some ...
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PGP double encrypt instead of signing?

So, maybe this is a dumb question, or maybe it's something someone's already done and it's really common, but whatever, here goes: Why do we sign a message with our private key and then encrypt it ...
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Decrypting an already sent encrypted file in PGP

I am a novice in cryptography and need few clarifications. If I am SenderA, sending document to Receiver using PGP encryption. Let's say, SenderA shuts down and SenderC takes on the role of SenderA. ...
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Message types in GPG

I am trying to check the part where messages are both encrypted and signed. But what is the difference between a message which looks like this ...
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What are some examples of out of bound channels that work over the Internet in practice?

If I want to verify a public key (be it RSA, PGP, etc.) with another client over the Internet only, what are some viable out-of-bound channels for verification? Which channels have been used in ...
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Possible to convert PGP ed25519 signature into signify-compatible format?

Both PGP and Signify (or Minisign) are capable of generating ED25519 detached signatures. Is it possible to convert a PGP-generated ED25519 signature into a signify-compatible format?
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Is encrypted e-mail sent over TLS 1.3 a form of “forward secrecy” (similar to something like Signal)?

One common complaint about GPG-encrypted e-mail is that it doesn't provide forward secrecy; however with opportunistic TLS becoming increasingly common in both IMAP and SMTP, it's not unreasonable to ...
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How does gpg know what cipher algorithm is needed for decryption?

I am using gpg to make encrypt a tar.gz. My first try uses --verbose --symmetric and then the decryption is done with ...
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Is this PGP key exchange secure?

I am currently trying to create a secure key exchange between two parties. I have a good implementation of PGP that works well for my app, but my DH is really slow and doesn't work well; so I was ...
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Is there a human readable easier version to represent PGP Private keys?

I'm working on a distributed application, and we need a way to authorize clients. Every client has a PGP keypair associated with them, and we require them to enter their private key (which is not ...
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What is a nested signature in GPG and how to decrypt it in OpenPGP?

When I decrypt a file in OpenPGP (in Golang), I receive this error message: unsupported feature: nested signatures There is very little clear information about ...
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Do people sign my subkey?

So, I've generated my GPG key pair. Created a subkey for signing and a subkey for encryption. Exported the whole thing, removed my master key pair to a secure place, re-imported only the subkeys. Now, ...
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Why do I want to use PGP subkeys?

I understand the general notion in play: if my laptop/computer is stolen or compromised I can revoke that particular subkey so (as long as people have updated their keys) they can't impersonate me. ...
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GPG implementation of ECC “Encryption” (ECDH) vs RSA

My understanding of GPG with traditional RSA keys, is that RSA is by definition can be used to both sign and encrypt. This is because RSA can be directly applied to plaintext in the following form: <...
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How to let CA signed x509 key work in OpenPGP mailing system?

So let's say we have a OpenPGP mailing system which all mails are signed and encrypted with OpenPGP keys. And now you bought a CA signed x509 certificate and you want to imement into the mailing ...
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232 views

Should I PGP encrypt using a publickey intended only for Certify?

I'm working with a publickey that does not include EncryptStorage or EncryptCommunication flags (see RFC4880 for flag reference). My question is, is it safe/appropriate to encrypt using this key? <...
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In GnuPG, what's the difference between --s2k-cipher-algo and --cipher-algo? [duplicate]

I want to change some encryption options while using GnuPG to encrypt a file symmetrically. 1) However, for choosing the cipher algorithm, GnuPG has two commands and I don't know which one to use. ...
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About the security of GnuPG private key on-disk storage

GnuPG on-disk storage of secret key material is encrypted with AES-128, with an encryption key generated via an iterated and salted SHA-1 hash of the given passphrase. Is this usage of the SHA-1 hash ...
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Converting a message from one PGP key to another PGP key

I have a message $M$ that is encrypted using a public key $P_1$. I lost the associated private key $p_1$. I have another public/private key pair $(P_2, p_2)$. Is it possible to "translate" the ...
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Book request about elliptic curves, RSA and DSA

I understand that this question can be hardly downvoted, but so be it if someone gives me really useful references :) I wanna learn difference (deeply) between RSA, DSA, and ECC, especially I am ...
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Mathematical explaination of file encryption for multiple persons with multiple keys

Let's say I want to encrypt a document which only can be read by John, Mike, and Dave. This can easily done with PGP/GPG: Import John‘s, Mike‘s, and Dave's public key Encrypt the document using those ...
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Where can I find the standard definition for GPG ECDSA signature?

I am playing around with GPG which I'd like to use to sign an integer and use the resulting signature binary in another piece of code. So far I have created a simple PGP packet parser with which I ...
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Generate PGP keys very very fast

Is there a way to generate thousands of PGP keys at a very very fast rate? I am generating thousands of 3072-bit PGP keys looking like part of a personal research project. Obviously, this is a very ...
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Is there any point to encrypting a file if it's transferred via ssh?

Suppose I have two machines which can ssh into each other. Is there very little point in using gpg with a password protected symmetric cipher to transfer a ...
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Do PGP keys with expiration date set expiration date in Encrypted messages too?

So I am little confused about a type of encryption I read about. You can encrypt your E-mails and pretty much all kind of information using PGP key pairs. However, I am confused if an encrypted ...
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252 views

libsodium vs gnupg curve25519 compatibility

I am trying to create deterministic GPG keys based on cryptosteel. I have implemented a library for (de)serializing PGP packets and am now trying to use keys generated in libsodium for import in GPG. ...
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How Secure is gpg Command Using Symmetric AES-256 From Being Cracked

How secure is any data encrypted using the following command: gpg -o *encrypted_output_file_name* --symmetric --cipher-algo AES256 *file_to_be_encrypted* Can ...
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Concept for a RSA “repeater”. Is it sensible?

I have been using RSA signed/encrypted mailing a lot recently. Naturally, I wanted to use RSA mailing also on my phone, not only on my computer. However, I feel uneasy having my private key on my ...
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Pseudonymous publication of a series of texts online when a bad guy is expected to join in with fakes: will this approach to PGP verifiability work?

Alice wishes to publish under a pseudonym a series of texts online. She expects the texts to circulate, and she will not include any way of contacting her. Bob will not know the identity of the ...
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Format of hybrid crypto envelope structure?

From posts including the accepted answer to How to encrypt file with RSA and AES that anyone with RSA key can decrypt them? hybrid crypto (AKA envelope encryption) a GPG-encrypted file has an ...
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Send content to owner of gpg public key, nested content symmetric encryption

If I want to encrypt a text content file using a symmetric algorithm like AES, is there a standard format gpg will expect, where it can detect a symmetric key (encrypted with recipient gpg public key ...
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Why did TLS 1.3 prohibit PGP authentication?

There is a specification, in Informational(!) RFC 6091, for using PGP keys in TLS authentication, although I don’t think it has ever been implemented outside of GnuTLS (it’s certainly not in OpenSSL). ...
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Is it safe to publicly expose PBE-protected PGP secret keys?

I am working on a PGP scheme where a private key is created offline (and in volatile memory) and must be reused on very rare occasions to sign a piece of exportable data. The private key is locked ...
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Why does gnupg create 4 separate keys and what does sub and ssb mean?

When using gpg to create a single key, I get: ...
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GPG Sub Key Renewal Questions

Last year, I followed this guide to create two GnuPG Smart Cards; one card with the Primary Key and the other card with the Sub-keys. I noticed that the sub keys were close to expiring so I renewed ...

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