mirror of
https://github.com/henrydcase/nobs.git
synced 2024-11-22 23:28:57 +00:00
109 lines
2.0 KiB
Go
109 lines
2.0 KiB
Go
package mkem
|
|
|
|
import (
|
|
"github.com/henrydcase/nobs/dh/csidh"
|
|
"github.com/henrydcase/nobs/drbg"
|
|
"github.com/henrydcase/nobs/hash/sha3"
|
|
)
|
|
|
|
const (
|
|
SharedSecretSz = 64
|
|
PublicKeySz = 64
|
|
)
|
|
|
|
// Used for storing cipertext
|
|
type ciphertext struct {
|
|
// public key
|
|
U [64]byte
|
|
// private key
|
|
V [64]byte
|
|
}
|
|
|
|
type PKE struct {
|
|
Rng *drbg.CtrDrbg
|
|
H sha3.ShakeHash
|
|
}
|
|
|
|
type MultiPKE struct {
|
|
PKE
|
|
// stores ephemeral/internal public key
|
|
Ct0 [PublicKeySz]byte
|
|
// stores list of ciphertexts ct[i]
|
|
Cts [][SharedSecretSz]byte
|
|
}
|
|
|
|
// Allocates PKE
|
|
func (c *PKE) Allocate(rng *drbg.CtrDrbg) {
|
|
c.Rng = rng
|
|
|
|
// Function H used in Algorithm 16 and 18
|
|
c.H = sha3.NewShake128()
|
|
}
|
|
|
|
// Allocates MultiPKE
|
|
func (c *MultiPKE) Allocate(recipients_nb uint, rng *drbg.CtrDrbg) {
|
|
c.PKE.Allocate(rng)
|
|
c.Cts = make([][SharedSecretSz]byte, recipients_nb)
|
|
}
|
|
|
|
// PKE encryption
|
|
func (c *PKE) Enc(pk *csidh.PublicKey, pt *[16]byte) (ct ciphertext) {
|
|
var ss [64]byte
|
|
var pkA csidh.PublicKey
|
|
var skA csidh.PrivateKey
|
|
|
|
csidh.GeneratePrivateKey(&skA, c.Rng)
|
|
csidh.DeriveSecret(&ss, pk, &skA, c.Rng)
|
|
|
|
c.H.Reset()
|
|
c.H.Write(ss[:])
|
|
c.H.Read(ss[:16])
|
|
for i := 0; i < 16; i++ {
|
|
ct.V[i] = pt[i] ^ ss[i]
|
|
}
|
|
|
|
csidh.GeneratePublicKey(&pkA, &skA, c.Rng)
|
|
pkA.Export(ct.U[:])
|
|
return
|
|
}
|
|
|
|
// PKE decryption
|
|
func (c *PKE) Dec(sk *csidh.PrivateKey, ct *ciphertext) (pt [16]byte) {
|
|
var ss [64]byte
|
|
var pk csidh.PublicKey
|
|
|
|
pk.Import(ct.U[:])
|
|
csidh.DeriveSecret(&ss, &pk, sk, c.Rng)
|
|
|
|
c.H.Reset()
|
|
c.H.Write(ss[:])
|
|
c.H.Read(ss[:16])
|
|
for i := 0; i < 16; i++ {
|
|
pt[i] = ct.V[i] ^ ss[i]
|
|
}
|
|
return
|
|
}
|
|
|
|
// mPKE encryption
|
|
func (c *MultiPKE) Encrypt(keys []csidh.PublicKey, pt *[16]byte) {
|
|
var ss [64]byte
|
|
var pkA csidh.PublicKey
|
|
var skA csidh.PrivateKey
|
|
|
|
csidh.GeneratePrivateKey(&skA, c.Rng)
|
|
for i, pk := range keys {
|
|
csidh.DeriveSecret(&ss, &pk, &skA, c.Rng)
|
|
|
|
c.H.Write(ss[:])
|
|
c.H.Read(ss[:16])
|
|
c.H.Reset()
|
|
for j := 0; j < 16; j++ {
|
|
c.Cts[i][j] = pt[j] ^ ss[j]
|
|
}
|
|
}
|
|
|
|
csidh.GeneratePublicKey(&pkA, &skA, c.Rng)
|
|
pkA.Export(c.Ct0[:])
|
|
return
|
|
}
|