SECURITY · CRYPTOGRAPHY

dsig

GPG message signing for Vencord / Vesktop. Authorship attestation for every message.

Signs Discord messages with your GPG key. Verifies authorship, prevents impersonation. Compact (113-char) and invisible footer formats.

TypeScript GPG / OpenPGP Vencord Discord
Message composition │ ▼ Canonicalize (NFC, CRLF→LF, whitespace) │ ▼ OpenPGP v4 signature (SHA-256/384/512) │ ▼ Encode to invisible characters (U+200B, U+200C, U+2060, U+2062) │ ▼ Append to message footer (compact 113-char or invisible)
GitHub ↗

Problem

Discord has no native message signing. Anyone can impersonate anyone by copying their display name and avatar. There is no cryptographic way to verify that a message was actually written by the claimed author.

Threat model

Invariants
Message tamperingDETECTED
Author impersonationBLOCKED
Replay attacksNONCE
Key compromiseOUT OF SCOPE
gpg-agent isolationTHROWAWAY GNUPGHOME

Key decisions

Invisible encoding

Signatures are encoded as Unicode invisible characters (zero-width spaces, non-joiners) appended to the message. Empirically tested against Discord's actual client behavior to ensure preservation across platforms.

Content canonicalization

NFC normalization, CRLF→LF conversion, whitespace collapsing. Prevents trivial bypasses via Unicode normalization or line-ending differences.

gpg-agent isolation

Verification uses a throwaway GNUPGHOME to prevent verification from accessing the signing key. Each verify operation runs in isolation.

Desktop-only by design

Web browsers cannot access gpg-agent. The plugin is desktop-only (Vencord/Vesktop) because the security model requires local key access.

Results

Test count
142
Test lines
1,817
Source lines
3,782
Footer size
113 chars

Tradeoffs

  • ·Desktop-only (web cannot access gpg-agent)
  • ·Requires GPG key pair setup
  • ·Invisible encoding may be stripped by some clients
  • ·Key compromise is out of scope (standard GPG limitation)