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v/vlib/crypto/ed25519/ed25519.v
2022-04-15 15:35:35 +03:00

182 lines
5.0 KiB
V

module ed25519
import crypto.rand
import crypto.sha512
import crypto.internal.subtle
import crypto.ed25519.internal.edwards25519
// public_key_size is the sizeof public keys in bytes
pub const public_key_size = 32
// private_key_size is the sizeof private keys in bytes
pub const private_key_size = 64
// signature_size is the size of signatures generated and verified by this modules, in bytes.
pub const signature_size = 64
// seed_size is the size of private key seeds in bytes
pub const seed_size = 32
// `PublicKey` is Ed25519 public keys.
pub type PublicKey = []u8
// equal reports whether p and x have the same value.
pub fn (p PublicKey) equal(x []u8) bool {
return subtle.constant_time_compare(p, PublicKey(x)) == 1
}
// PrivateKey is Ed25519 private keys
pub type PrivateKey = []u8
// seed returns the private key seed corresponding to priv.
// RFC 8032's private keys correspond to seeds in this module.
pub fn (priv PrivateKey) seed() []u8 {
mut seed := []u8{len: ed25519.seed_size}
copy(mut seed, priv[..32])
return seed
}
// public_key returns the []u8 corresponding to priv.
pub fn (priv PrivateKey) public_key() PublicKey {
assert priv.len == ed25519.private_key_size
mut publickey := []u8{len: ed25519.public_key_size}
copy(mut publickey, priv[32..])
return PublicKey(publickey)
}
// currentyly x not `crypto.PrivateKey`
pub fn (priv PrivateKey) equal(x []u8) bool {
return subtle.constant_time_compare(priv, PrivateKey(x)) == 1
}
// sign signs the given message with priv.
pub fn (priv PrivateKey) sign(message []u8) ?[]u8 {
/*
if opts.HashFunc() != crypto.Hash(0) {
return nil, errors.New("ed25519: cannot sign hashed message")
}*/
return sign(priv, message)
}
// sign`signs the message with privatekey and returns a signature
pub fn sign(privatekey PrivateKey, message []u8) ?[]u8 {
mut signature := []u8{len: ed25519.signature_size}
sign_generic(mut signature, privatekey, message) ?
return signature
}
fn sign_generic(mut signature []u8, privatekey []u8, message []u8) ? {
if privatekey.len != ed25519.private_key_size {
panic('ed25519: bad private key length: $privatekey.len')
}
seed, publickey := privatekey[..ed25519.seed_size], privatekey[ed25519.seed_size..]
mut h := sha512.sum512(seed)
mut s := edwards25519.new_scalar()
s.set_bytes_with_clamping(h[..32]) ?
mut prefix := h[32..]
mut mh := sha512.new()
mh.write(prefix) ?
mh.write(message) ?
mut msg_digest := []u8{cap: sha512.size}
msg_digest = mh.sum(msg_digest)
mut r := edwards25519.new_scalar()
r.set_uniform_bytes(msg_digest) ?
mut rr := edwards25519.Point{}
rr.scalar_base_mult(mut r)
mut kh := sha512.new()
kh.write(rr.bytes()) ?
kh.write(publickey) ?
kh.write(message) ?
mut hram_digest := []u8{cap: sha512.size}
hram_digest = kh.sum(hram_digest)
mut k := edwards25519.new_scalar()
k.set_uniform_bytes(hram_digest) ?
mut ss := edwards25519.new_scalar()
ss.multiply_add(k, s, r)
copy(mut signature[..32], rr.bytes())
copy(mut signature[32..], ss.bytes())
}
// verify reports whether sig is a valid signature of message by publickey.
pub fn verify(publickey PublicKey, message []u8, sig []u8) ?bool {
if publickey.len != ed25519.public_key_size {
return error('ed25519: bad public key length: $publickey.len')
}
if sig.len != ed25519.signature_size || sig[63] & 224 != 0 {
return false
}
mut aa := edwards25519.Point{}
aa.set_bytes(publickey) ?
mut kh := sha512.new()
kh.write(sig[..32]) ?
kh.write(publickey) ?
kh.write(message) ?
mut hram_digest := []u8{cap: sha512.size}
hram_digest = kh.sum(hram_digest)
mut k := edwards25519.new_scalar()
k.set_uniform_bytes(hram_digest) ?
mut ss := edwards25519.new_scalar()
ss.set_canonical_bytes(sig[32..]) ?
// [S]B = R + [k]A --> [k](-A) + [S]B = R
mut minus_a := edwards25519.Point{}
minus_a.negate(aa)
mut rr := edwards25519.Point{}
rr.vartime_double_scalar_base_mult(k, minus_a, ss)
return subtle.constant_time_compare(sig[..32], rr.bytes()) == 1
}
// generate_key generates a public/private key pair entropy using `crypto.rand`.
pub fn generate_key() ?(PublicKey, PrivateKey) {
mut seed := rand.bytes(ed25519.seed_size) ?
privatekey := new_key_from_seed(seed)
mut publickey := []u8{len: ed25519.public_key_size}
copy(mut publickey, privatekey[32..])
return publickey, privatekey
}
// new_key_from_seed calculates a private key from a seed. private keys of RFC 8032
// correspond to seeds in this module
pub fn new_key_from_seed(seed []u8) PrivateKey {
// Outline the function body so that the returned key can be stack-allocated.
mut privatekey := []u8{len: ed25519.private_key_size}
new_key_from_seed_generic(mut privatekey, seed)
return PrivateKey(privatekey)
}
fn new_key_from_seed_generic(mut privatekey []u8, seed []u8) {
if seed.len != ed25519.seed_size {
panic('ed25519: bad seed length: $seed.len')
}
mut h := sha512.sum512(seed)
mut s := edwards25519.new_scalar()
s.set_bytes_with_clamping(h[..32]) or { panic(err) }
mut aa := edwards25519.Point{}
aa.scalar_base_mult(mut s)
mut publickey := aa.bytes()
copy(mut privatekey, seed)
copy(mut privatekey[32..], publickey)
}