ssh_ed25519.h File Reference

Ed25519 signatures (RFC 8032) for ssh-ed25519 host keys + client auth. More...

#include <stddef.h>
#include <stdint.h>

Go to the source code of this file.

Macros
#define	SSH_ED25519_SEED_LEN   32
	Ed25519 seed (private key) length.
#define	SSH_ED25519_PUBKEY_LEN   32
	Ed25519 public key length.
#define	SSH_ED25519_SIG_LEN   64
	Ed25519 signature length (R || S).

Functions
void	ssh_ed25519_pubkey (uint8_t pub[SSH_ED25519_PUBKEY_LEN], const uint8_t seed[SSH_ED25519_SEED_LEN])
	Derive the 32-byte public key A from a 32-byte seed.
void	ssh_ed25519_sign (uint8_t sig[SSH_ED25519_SIG_LEN], const uint8_t *msg, size_t mlen, const uint8_t seed[SSH_ED25519_SEED_LEN])
	Deterministically sign mlen bytes of msg with seed (RFC 8032 §5.1.6).
bool	ssh_ed25519_verify (const uint8_t pub[SSH_ED25519_PUBKEY_LEN], const uint8_t *msg, size_t mlen, const uint8_t sig[SSH_ED25519_SIG_LEN])
	Verify an Ed25519 signature (RFC 8032 §5.1.7).

Detailed Description

Ed25519 signatures (RFC 8032) for ssh-ed25519 host keys + client auth.

PureEdDSA over edwards25519. Deterministic signing (RFC 8032 §5.1.6) - no RNG - and verification, built on the shared Curve25519 field arithmetic (ssh_curve25519) and SHA-512 (ssh_sha512). No heap; state is on the stack. Correctness is pinned to the RFC 8032 §7.1 vectors and to a reference implementation (test_ssh_ed25519).

The server signs the KEX exchange hash with its ssh-ed25519 host key, and verifies a client's ed25519 public-key authentication signature.

Author

Douglas Quigg (dstroy0)

Date

2026

Definition in file ssh_ed25519.h.

Macro Definition Documentation

SSH_ED25519_SEED_LEN

#define SSH_ED25519_SEED_LEN   32

Ed25519 seed (private key) length.

Definition at line 27 of file ssh_ed25519.h.

SSH_ED25519_PUBKEY_LEN

#define SSH_ED25519_PUBKEY_LEN   32

Ed25519 public key length.

Definition at line 29 of file ssh_ed25519.h.

SSH_ED25519_SIG_LEN

#define SSH_ED25519_SIG_LEN   64

Ed25519 signature length (R || S).

Definition at line 31 of file ssh_ed25519.h.

Function Documentation

ssh_ed25519_pubkey()

void ssh_ed25519_pubkey	(	uint8_t	pub[SSH_ED25519_PUBKEY_LEN],
		const uint8_t	seed[SSH_ED25519_SEED_LEN]
	)

Derive the 32-byte public key A from a 32-byte seed.

ssh_ed25519_sign()

void ssh_ed25519_sign	(	uint8_t	sig[SSH_ED25519_SIG_LEN],
		const uint8_t *	msg,
		size_t	mlen,
		const uint8_t	seed[SSH_ED25519_SEED_LEN]
	)

Deterministically sign mlen bytes of msg with seed (RFC 8032 §5.1.6).

Parameters

sig	Output R || S, SSH_ED25519_SIG_LEN bytes.

ssh_ed25519_verify()

bool ssh_ed25519_verify	(	const uint8_t	pub[SSH_ED25519_PUBKEY_LEN],
		const uint8_t *	msg,
		size_t	mlen,
		const uint8_t	sig[SSH_ED25519_SIG_LEN]
	)

Verify an Ed25519 signature (RFC 8032 §5.1.7).

Returns

true if sig is a valid signature of msg under public key pub.