Ed25519 Class Reference

Digital signatures based on the elliptic curve modulo 2^255 - 19. More...

#include <Ed25519.h>

Static Public Member Functions
static void	sign (uint8_t signature[64], const uint8_t privateKey[32], const uint8_t publicKey[32], const void *message, size_t len)
	Signs a message using a specific Ed25519 private key. More...
static bool	verify (const uint8_t signature[64], const uint8_t publicKey[32], const void *message, size_t len)
	Verifies a signature using a specific Ed25519 public key. More...
static void	generatePrivateKey (uint8_t privateKey[32])
	Generates a private key for Ed25519 signing operations. More...
static void	derivePublicKey (uint8_t publicKey[32], const uint8_t privateKey[32])
	Derives the public key from a private key. More...

Detailed Description

Digital signatures based on the elliptic curve modulo 2^255 - 19.

The first step in creating a digital signature with Ed25519 is to generate a key pair:

uint8_t privateKey[32];
uint8_t publicKey[32];
 
Ed25519::generatePrivateKey(privateKey);
Ed25519::derivePublicKey(publicKey, privateKey);

The application can store both the private and public key for later signing operations. Or it can store just the private key and then derive the public key at the point where signing is to occur.

Message signing produces a 64-byte signature as follows:

uint8_t message[N];
uint8_t signature[64];
 
Ed25519::sign(signature, privateKey, publicKey, message, N);

And then to verify the signature:

if (!Ed25519::verify(signature, publicKey, message, N)) {
    // The signature is invalid.
    ...
}

Note

The public functions in this class need a substantial amount of stack space to store intermediate results while the curve function is being evaluated. About 1.5k of free stack space is recommended for safety.

References: https://tools.ietf.org/html/draft-irtf-cfrg-eddsa-05

See also

Curve25519

Definition at line 29 of file Ed25519.h.

Member Function Documentation

derivePublicKey()

void Ed25519::derivePublicKey ( uint8_t  publicKey[32], const uint8_t  privateKey[32]  )

static

Derives the public key from a private key.

Parameters

publicKey	The public key.
privateKey	The private key.

See also

generatePrivateKey()

Definition at line 256 of file Ed25519.cpp.

generatePrivateKey()

void Ed25519::generatePrivateKey ( uint8_t  privateKey[32] )

static

Generates a private key for Ed25519 signing operations.

Parameters

privateKey

The resulting private key.

The private key is generated with RNG.rand(). It is the caller's responsibility to ensure that the global random number pool has sufficient entropy to generate the 32 bytes of the key safely before calling this function.

See also

derivePublicKey()

Definition at line 243 of file Ed25519.cpp.

sign()

void Ed25519::sign ( uint8_t  signature[64], const uint8_t  privateKey[32], const uint8_t  publicKey[32], const void *  message, size_t  len  )

static

Signs a message using a specific Ed25519 private key.

Parameters

signature	The signature value.
privateKey	The private key to use to sign the message.
publicKey	The public key corresponding to privateKey.
message	Points to the message to be signed.
len	The length of the message to be signed.

See also

verify(), derivePublicKey()

Definition at line 127 of file Ed25519.cpp.

verify()

bool Ed25519::verify ( const uint8_t  signature[64], const uint8_t  publicKey[32], const void *  message, size_t  len  )

static

Verifies a signature using a specific Ed25519 public key.

Parameters

signature	The signature value to be verified.
publicKey	The public key to use to verify the signature.
message	The message whose signature is to be verified.
len	The length of the message to be verified.

Returns

Returns true if the signature is valid for message; or false if the signature is not valid.

See also

sign()

Definition at line 189 of file Ed25519.cpp.

---

The documentation for this class was generated from the following files:

• Ed25519.h
• Ed25519.cpp