Digital signature.
Encryption hides a message; a signature vouches for it. Every CarrierPony envelope carries the sender's signature, so what arrives is provably what was sent, from the key that claims to have sent it.
A digital signature is a value computed from a message and the sender's private key that anyone with the matching public key can verify. A valid signature proves origin and integrity: the right key signed exactly these bytes.
What it is
Before sending, CarrierPony signs the message with your Ed25519 key, then encrypts the result to your contact. Their app decrypts, verifies the signature against your public key, and only then treats the message as genuinely yours.
Why it matters
Without signatures, encryption alone can't stop an active attacker from splicing, replaying, or forging traffic. Sign-then-encrypt closes that gap: any tampering, anywhere along the path, makes verification fail loudly instead of silently succeeding.
Related terms
Common questions.
Does a signature reveal my identity?
It proves a message came from your key. Since CarrierPony identities aren't tied to names, numbers, or emails, what it reveals is continuity — same key, same sender — not personal details.
What happens if verification fails?
The app treats the message as untrusted and tells you, rather than displaying it as if nothing happened. Failure is a signal, not a formality.
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