slackhq_nebula/noise.go

76 lines
2.0 KiB
Go

package nebula
import (
"crypto/cipher"
"encoding/binary"
"errors"
"github.com/flynn/noise"
)
type endianness interface {
PutUint64(b []byte, v uint64)
}
var noiseEndianness endianness = binary.BigEndian
type NebulaCipherState struct {
c noise.Cipher
//k [32]byte
//n uint64
}
func NewNebulaCipherState(s *noise.CipherState) *NebulaCipherState {
return &NebulaCipherState{c: s.Cipher()}
}
// EncryptDanger encrypts and authenticates a given payload.
//
// out is a destination slice to hold the output of the EncryptDanger operation.
// - ad is additional data, which will be authenticated and appended to out, but not encrypted.
// - plaintext is encrypted, authenticated and appended to out.
// - n is a nonce value which must never be re-used with this key.
// - nb is a buffer used for temporary storage in the implementation of this call, which should
// be re-used by callers to minimize garbage collection.
func (s *NebulaCipherState) EncryptDanger(out, ad, plaintext []byte, n uint64, nb []byte) ([]byte, error) {
if s != nil {
// TODO: Is this okay now that we have made messageCounter atomic?
// Alternative may be to split the counter space into ranges
//if n <= s.n {
// return nil, errors.New("CRITICAL: a duplicate counter value was used")
//}
//s.n = n
nb[0] = 0
nb[1] = 0
nb[2] = 0
nb[3] = 0
noiseEndianness.PutUint64(nb[4:], n)
out = s.c.(cipher.AEAD).Seal(out, nb, plaintext, ad)
//l.Debugf("Encryption: outlen: %d, nonce: %d, ad: %s, plainlen %d", len(out), n, ad, len(plaintext))
return out, nil
} else {
return nil, errors.New("no cipher state available to encrypt")
}
}
func (s *NebulaCipherState) DecryptDanger(out, ad, ciphertext []byte, n uint64, nb []byte) ([]byte, error) {
if s != nil {
nb[0] = 0
nb[1] = 0
nb[2] = 0
nb[3] = 0
noiseEndianness.PutUint64(nb[4:], n)
return s.c.(cipher.AEAD).Open(out, nb, ciphertext, ad)
} else {
return []byte{}, nil
}
}
func (s *NebulaCipherState) Overhead() int {
if s != nil {
return s.c.(cipher.AEAD).Overhead()
}
return 0
}