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

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How to replicate GPA's Sign and Compress option on command line in Windows [migrated]

As the title says, I need to replicate GPA's "Sign and Compress" option on the command line. I'm trying to automate some encryption of files for submission to a bank and the instructions they gave me ...
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1answer
97 views

PGP String to Key specifiers

I've been reading through the PGP Standard and here I'm a little confused. This section is discussing converting string data to a session key. I'm confused about the paragraph in bold. First off, what ...
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22 views

Recipient ID asked whie using Symmetric encryption with GnuPG [migrated]

I'm trying to encrypt a file using AES algo and sign it using my private key in GPG. The command I'm using is gpg --encrypt --symmetric --cipher-algo aes256 --armor --sign input-file It asks me for ...
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1answer
623 views

Is it possible to determine a PGP public key from encrypted data?

Is it possible to find out which public key was used to generate the message? Scenario is like this : I got data which is encrypted with a public key. Now a "bad guy" hast the encrypted data, and ...
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1answer
914 views

How does GPG verify succesful decryption?

How does GPG (or other programs using the OpenPGP file format) verify that it has succeeded with decryption (for symmetrically encrypted data)? Is something appended to the clear text so there exist ...
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Do OpenPGP SmartCards have the same or better security than an air-gapped machine?

Are OpenPGP SmartCards, such as the OpenPGP SmartCard V2, suitable enough to have secure communications? Meaning, if I connect my smart card to my Mac which is connected to the internet and always ...
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1answer
76 views

GPG & Mcrypt - difference?

in short I'm learning GUI programming in python and thought it could be interesting to make a small GUI for symmetric encryption. Not being mad/mathematical/experienced (take your pick) enough to try ...
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2answers
563 views

Can you fake messages from recorded message-history?

Lets assume Eve has a lot of PGP conversation with Alice and records all those messages. Bob is also regularly communicating with PGP with Alice. If Bob doesn't care about not having a signature ...
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250 views

What characters are valid in PGP encrypted and signed messages?

What characters may be present in a PGP encrypted message or a PGP signature? For example, do encrypted messages only use the Roman alphabet + some numbers and symbols? Can the character set be ...
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74 views

PGP message integrity : How can receiver of an email check the integrity using the sender's public key?

PGP message integrity: Basically, only private key can decrypt message encrypted with public key. But in the message integrity service in PGP does the reverse, where the Hash of the message if ...
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2k views

Is a 1024-bit DSA key considered safe?

I created my PGP key in 2000. I’ve revoked the older, weaker sub-keys in favor of a 4096-bit RSA one, but the primary key is 1024-bit DSA. I read on Wikipedia that… NIST 800-57 recommends lengths ...
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1answer
73 views

Familiar key signing over video call

Say that a friend of mine and I have both generated new PGP keys, and we want to use a video call to verify each other's new keys because we live on opposite sides of the planet. While we could both ...
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Want to use ECC but am clueless [closed]

First off, I'm not an experienced cryptography or computer person, please bear with me. I have some basic experiences with PGP software though (not much of a redemption huh?). I have some data that ...
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238 views

Is there a “brainwallet” for GPG keys? [closed]

“Brainwallet” is a program that takes a passphrase (hopefully a good one) and deterministically creates a Bitcoin wallet. This wallet can be used for transactions, then deleted from the computer. To ...
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4answers
697 views

Is there an intuitive explanation as to why only the private key can decrypt a message encrypted with the public key?

I have just learned about using PGP/GPG for email encryption and one thing has always bugged me: How is it possible that a message encrypted with somebody's public key can be decrypted only with that ...
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1answer
130 views

Reusing PGP key when generating SSL Certificate Authority?

Does it make sense to reuse some of the keys from my PGP (gnupg, gpg) keyblock when generating my own SSL Certificate Authority (a toy one for myself and a few web services of mine)? In an ideal ...
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54 views

What vulnerabilities would open up if PGP authentication didn't have integrity checking?

It is my understanding that PGP has both an integrity check and an authentication check. What vulnerabilities would open up if it didn't have that integrity check? It seems like the authentication ...
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encrypted file sharing protocol

I am trying to design a file exchange protocol for learning purposes, inspired by PGP, but fixing some of its shortcomings. Assuming the machine where the creation and decryption of the file happens ...
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156 views

Generate a new public/private key pair for each new message?

When using PGP type public encrypted communication, would it be a good idea to generate a new public for each message and attach that in the new public key in the reply to back to sender mail body? ...
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2answers
361 views

How do I create a short signature? (e.g. less than 100 bytes)

I want to put information into a QR code and have it signed so that the authenticity of the information can be verified. But QR codes have limited storage capacity and when I used e.g. gpg I get ...
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582 views

If PGP and GPG both follow the OpenPGP standard, are they 100% compatible in all use cases?

If someone gives me their PGP key, can I use it with GPG, and vice versa, all the time (100% interchangeable)? Or are there times when they are not compatible, when only PGP can be used with a PGP ...
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2answers
142 views

Can the passphrase of a PGP key be deduced from an old backup?

Let's assume that Bob, at some point in time, has created a PGP (key length and other parameters are not relevant at this point). For some reason, he has chosen a very poor passphrase, for instance ...
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41 views

gnupg: display digest of key [closed]

How can I display what digest algorithm has a key? If I import a public key which has MD5 as digest, I get a warning about this weak algorith. But how can I check, what digest algorithms all my keys ...
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45 views

Would requiring reciprocal signatures create a stronger Web of Trust?

In this post on Cryptome it's noted that a person called Michael Vario is willy-nilly signing people's public key's and uploading those signatures. He is effectively forging a web of trust. I'm sure ...
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114 views

What is the GnuPG process for going from a passphrase to a symmetric key?

Suppose I use GnuPG to symmetrically encrypt a file like so: gpg --no-options -c --cipher-algo AES256 --no-random-seed-file -o my.out my.file I then provide a ...
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1answer
105 views

How is a PRNG used in the PGP?

I'm currently reading up on the components of PGP and I am wondering what exactly the PRNG is used for. PGP uses ANSI X9.17 and entropy from a users keystrokes to generate a temporary key. So, is ...
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471 views

OpenPGP/X.509 bridge: how to verify public key?

I'd like to use OpenPGP authentication over TLS, but lack of implementations made me use a temporary solution: an OpenPGP/X.509 bridge certificate. The approach is very similar to the approach used ...
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1k views

Is compressing data prior to encryption necessary to reduce plaintext redundancy?

As explained in William Stallings' Book, in PGP encryption is done after compression, since it reduces redundancy. I couldn't relate encryption strength with redundancy. Could anyone explain more on ...
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90 views

How do you use the Tiger hash function with GPG?

I've searched Google and the GnuPG documentation and I haven't been able to find an answer. Some pointers in the right direction would be greatly appreciated.
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431 views

two public keys with same passphrase insecure? | can two hashes be compared?

Suppose someone had generated a 2.048-Bit RSA GPG/PGP key pair and published the public key on the usual key servers. Then he withdraws this key and generates a new one in 4.096-Bit RSA using the same ...
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955 views

How can I determine the GPG/PGP key ID from the RSA modulus?

According to http://www.pgp.net/pgpnet/pgp-faq/pgp-faq-keys.html#key-public-key-forgery, key ID is some lower bits sequence from the modulus (i.e. the $n$ variable): A PGP key ID is just the ...
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GPG symmetric encryption and javascript

I have a use case where I need to encrypt some text in the browser using javascript. Only the encrypted text will be stored on the server. The user should then be able to take the encrypted result and ...
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308 views

Why are the first few bytes of a gpg encryption always the same?

If I run the command 'gpg -a -e < input.txt > output.txt' with completely different inputs (e.g. from /dev/urandom), the first 19 characters are always the same. What is this header? Is it ...
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374 views

Why the symmetric key layer in PGP?

I've been familiarizing myself with the basics of PGP. If I understand correctly, PGP symmetrically encrypts the data of interest using a random single-use key, then encrypts the encrypted data and ...
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381 views

KDF and number of iterations for GPG

I gather, from reading the GPG manual, that symmetric encryption based on a password uses one of a variety of Key Derivation Functions (KDF). Although not explicitly mentioned I assume that PBKDF2 is ...
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2answers
1k views

How can I remove my personal data from my PGP public key?

According to this Q&A-discussion it is possible to remove all personal data (name and mail address) that is attached to a public key. What steps do I have to follow in order to remove all ...
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152 views

Is my identity exposed when publishing my public key or encrypting with PGP?

Let's say I create my PGP keys with my appropriate name and email address. Will these personal information be exposed if I publish my public key? When I encrypt a message for sending it to my ...
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224 views

Length of data to hash for PGP

I have finally managed to verify some simple PGP signed message blocks. However, I discovered that for some reason, my implementation limits me to verifying data that is 9-16 bytes long. no less. no ...
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OpenPGP tag 18/19 description confusion Continuation [closed]

After coming back to try to finish more of my OpenPGP implementation, I refound one of my questions http://stackoverflow.com/questions/6021360/openpgp-tag-18-19-description-confusion that I am still ...
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346 views

Is OpenPGP vulnerable to the “crypto doom principle”?

From reading RFC 2015 (MIME security with PGP), and from looking at the raw format of (GnuPG) encrypted and digitally signed email messages, it seems that first a signature is calculated from the ...
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1answer
682 views

Is it possible to change PGP / GPG Key Size on an exisiting key?

Is it possible for myself to change the key size (say from 2048 to 4096) on an EXISTING PGP / GPG key, and just republishing that key? Or do I have to generate a new key all together? I want to say ...
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180 views

GPG and PAR2 error correction data from the plain archive, will it compromise security?

I have the following scenario: Archives compressed with 7z, hundreds of MiB in size GPG to encrypt the archives (binary, without ASCII armor) PAR2 to create error correction data Question 1. ...
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301 views

Alice trusts Bob only when Bob trusts Alice

some story first: Alice and Bob both have public/private key pairs. Now Bob wants Alice to sign his public key id. Alice agrees but only when Bob signs the public key id of her. Is this something ...
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1k views

GPG vs PGP vs OpenSSH and management of them [closed]

What is the main difference of the three? Can I use only one of them for everything (e.g. GPG for SSH authentication) If I encrypt my private key with a pass-phrase, is it strong enough so that if ...
2
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1answer
328 views

Generate an insecure public / private key pair

I am looking for a way to generate an "insecure" public key pair. and by insecure I actually mean a pair that is breakable using brute-force (or other encryption) methods. As far as I know PGP ...
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2answers
586 views

Is this a correctly formatted PGP session key packet?

RFC 4880 may be full of information, but it can be incredibly vague at times, so im looking for someone who actually knows the answer to this. Given this public key: ...
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3answers
305 views

Can I use PGP to sign a message without providing cryptographic non-repudation?

The difference between a digital signature and a MAC is non-repudiation. A message with a digital signature proves that only the sender could have signed the message, whereas a message with a MAC ...
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405 views

Does gpg's symmetric encryption keep information about the filename?

If I encrypt a file with gpg -c file.zip, and change the filename. Is there any way I can restore the filename as I used as a password. or the name encrypted to?
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2answers
112 views

When is each key used when encrypting an email using OpenPGP?

When you send an email using PGP to encrypt emails, is the recipients public key used to encrypt the email, or is your private key used? Are they both used? At what points do each of the four keys ...
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787 views

GPG/PGP Verification of Revocation

How does one verify a key revocation? After revoking a key and sending the revocation to MIT's keyserver, I noticed that the key is listed as such: ...