1package xsecretbox 2 3import ( 4 crypto_rand "crypto/rand" 5 6 "golang.org/x/crypto/chacha20" 7 "golang.org/x/crypto/curve25519" 8) 9 10// SharedKey computes a shared secret compatible with the one used by `crypto_box_xchacha20poly1305`` 11func SharedKey(secretKey [32]byte, publicKey [32]byte) ([32]byte, error) { 12 dhKey, err := curve25519.X25519(secretKey[:], publicKey[:]) 13 var subKey []byte 14 if err == nil { 15 var nonce [16]byte 16 subKey, err = chacha20.HChaCha20(dhKey[:], nonce[:]) 17 } 18 var key [32]byte 19 if err != nil { 20 if _, err2 := crypto_rand.Read(key[:]); err != nil { 21 return key, err2 22 } 23 return key, err 24 } 25 copy(key[:], subKey) 26 return key, nil 27} 28