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PGP / GPG Armored Decoder

De-armor PGP keys and messages and inspect their OpenPGP packet structure.

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The pgp-decoder decoder is on the roadmap. The heavier binary and cryptographic parsers ship after the core text and token decoders — all of which are already live and working.

Browse the live decoders

Input is processed on your device. Nothing you paste is sent anywhere.

What is the PGP / GPG Armored Decoder?

A PGP decoder removes the ASCII armor wrapper from an OpenPGP block and parses the binary packets beneath it, showing packet types, key IDs, algorithms and timestamps without decrypting any content.

OpenPGP (RFC 4880) is a packet format. A public key block is a sequence of packets — a primary key, user IDs, signatures, subkeys — and a message is another sequence: encrypted session keys, then the encrypted data, or a literal packet with a signature. ASCII armor is just Base64 over those bytes plus a CRC-24 checksum, added so keys and messages survive email.

Parsing the packets tells you a lot without any secret material: which key ID a message was encrypted to, which algorithms are in play, when a key was created, which subkeys exist and what each is for. That is usually enough to answer the practical question — 'why can't my recipient decrypt this' — which is nearly always the wrong subkey or an expired key rather than a broken cipher.

Decoding structure is not decryption. Reading the ciphertext still requires the private key, which should never be pasted into a web page.

PGP / GPG Armored Decoder at a glance

Standard
OpenPGP · RFC 4880 (RFC 9580 update)
Armor
Base64 + CRC-24 between BEGIN/END PGP lines
Key ID
Low 64 bits of the key fingerprint
Structure
Packet stream: keys, user IDs, signatures, data

How to use the PGP / GPG Armored Decoder

  1. 1Paste the armored block, including the BEGIN PGP and END PGP lines.
  2. 2Read the packet list: types, key IDs, algorithms and creation times.
  3. 3Use the key IDs to work out which key a message was actually encrypted to.

When you would reach for it

  • Finding out which key a PGP message was encrypted for when decryption fails.
  • Inspecting a public key block's subkeys, expiry and algorithms before importing it.
  • Verifying that an armored file is what it claims to be during incident response.

PGP / GPG Armored Decoder — frequently asked questions

Last reviewed · questions or corrections: contact@decoder.tools