package yggdrasil /* This part of the package wraps crypto operations needed elsewhere In particular, it exposes key generation for ed25519 and nacl box It also defines NodeID and TreeID as hashes of keys, and wraps hash functions */ import "crypto/rand" import "crypto/sha512" import "golang.org/x/crypto/ed25519" import "golang.org/x/crypto/nacl/box" //////////////////////////////////////////////////////////////////////////////// // NodeID and TreeID const NodeIDLen = sha512.Size const TreeIDLen = sha512.Size const handleLen = 8 type NodeID [NodeIDLen]byte type TreeID [TreeIDLen]byte type handle [handleLen]byte func getNodeID(pub *boxPubKey) *NodeID { h := sha512.Sum512(pub[:]) return (*NodeID)(&h) } func getTreeID(pub *sigPubKey) *TreeID { h := sha512.Sum512(pub[:]) return (*TreeID)(&h) } func newHandle() *handle { var h handle _, err := rand.Read(h[:]) if err != nil { panic(err) } return &h } //////////////////////////////////////////////////////////////////////////////// // Signatures const sigPubKeyLen = ed25519.PublicKeySize const sigPrivKeyLen = ed25519.PrivateKeySize const sigLen = ed25519.SignatureSize type sigPubKey [sigPubKeyLen]byte type sigPrivKey [sigPrivKeyLen]byte type sigBytes [sigLen]byte func newSigKeys() (*sigPubKey, *sigPrivKey) { var pub sigPubKey var priv sigPrivKey pubSlice, privSlice, err := ed25519.GenerateKey(rand.Reader) if err != nil { panic(err) } copy(pub[:], pubSlice) copy(priv[:], privSlice) return &pub, &priv } func sign(priv *sigPrivKey, msg []byte) *sigBytes { var sig sigBytes sigSlice := ed25519.Sign(priv[:], msg) copy(sig[:], sigSlice) return &sig } func verify(pub *sigPubKey, msg []byte, sig *sigBytes) bool { // Should sig be an array instead of a slice?... // It's fixed size, but return ed25519.Verify(pub[:], msg, sig[:]) } //////////////////////////////////////////////////////////////////////////////// // NaCl-like crypto "box" (curve25519+xsalsa20+poly1305) const boxPubKeyLen = 32 const boxPrivKeyLen = 32 const boxSharedKeyLen = 32 const boxNonceLen = 24 type boxPubKey [boxPubKeyLen]byte type boxPrivKey [boxPrivKeyLen]byte type boxSharedKey [boxSharedKeyLen]byte type boxNonce [boxNonceLen]byte func newBoxKeys() (*boxPubKey, *boxPrivKey) { pubBytes, privBytes, err := box.GenerateKey(rand.Reader) if err != nil { panic(err) } pub := (*boxPubKey)(pubBytes) priv := (*boxPrivKey)(privBytes) return pub, priv } func getSharedKey(myPrivKey *boxPrivKey, othersPubKey *boxPubKey) *boxSharedKey { var shared [boxSharedKeyLen]byte priv := (*[boxPrivKeyLen]byte)(myPrivKey) pub := (*[boxPubKeyLen]byte)(othersPubKey) box.Precompute(&shared, pub, priv) return (*boxSharedKey)(&shared) } func boxOpen(shared *boxSharedKey, boxed []byte, nonce *boxNonce) ([]byte, bool) { out := util_getBytes() //return append(out, boxed...), true // XXX HACK to test without encryption s := (*[boxSharedKeyLen]byte)(shared) n := (*[boxNonceLen]byte)(nonce) unboxed, success := box.OpenAfterPrecomputation(out, boxed, n, s) return unboxed, success } func boxSeal(shared *boxSharedKey, unboxed []byte, nonce *boxNonce) ([]byte, *boxNonce) { if nonce == nil { nonce = newBoxNonce() } nonce.update() out := util_getBytes() //return append(out, unboxed...), nonce // XXX HACK to test without encryption s := (*[boxSharedKeyLen]byte)(shared) n := (*[boxNonceLen]byte)(nonce) boxed := box.SealAfterPrecomputation(out, unboxed, n, s) return boxed, nonce } func newBoxNonce() *boxNonce { var nonce boxNonce _, err := rand.Read(nonce[:]) for ; err == nil && nonce[0] == 0xff ; _, err = rand.Read(nonce[:]){ // Make sure nonce isn't too high // This is just to make rollover unlikely to happen // Rollover is fine, but it may kill the session and force it to reopen } if err != nil { panic(err) } return &nonce } func (n *boxNonce) update() { oldNonce := *n n[len(n)-1] += 2 for i := len(n)-2 ; i >= 0 ; i-- { if n[i+1] < oldNonce[i+1] { n[i] += 1 } } }