/
naclwrap.go
767 lines (638 loc) · 21 KB
/
naclwrap.go
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// Copyright 2015 Keybase, Inc. All rights reserved. Use of
// this source code is governed by the included BSD license.
package libkb
import (
"bytes"
"crypto/hmac"
"crypto/rand"
"crypto/sha256"
"encoding/base64"
"fmt"
"io"
"github.com/keybase/client/go/kbcrypto"
keybase1 "github.com/keybase/client/go/protocol/keybase1"
"github.com/keybase/go-crypto/ed25519"
"golang.org/x/crypto/nacl/box"
)
type NaclEncryptionInfo struct {
Ciphertext []byte `codec:"ciphertext"`
EncryptionType kbcrypto.AlgoType `codec:"enc_type"`
Nonce []byte `codec:"nonce"`
Receiver []byte `codec:"receiver_key"`
Sender []byte `codec:"sender_key"`
}
const NaclDHKeysize = 32
// TODO: Ideally, ed25519 would expose how many random bytes it needs.
const NaclSigningKeySecretSize = 32
// TODO: Ideally, box would expose how many random bytes it needs.
const NaclDHKeySecretSize = 32
// Todo: Ideally, box would specify nonce size
const NaclDHNonceSize = 24
const NaclSecretBoxKeySize = 32
type NaclSigningKeyPair struct {
Public kbcrypto.NaclSigningKeyPublic
Private *kbcrypto.NaclSigningKeyPrivate
}
var _ GenericKey = NaclSigningKeyPair{}
type NaclDHKeyPublic [NaclDHKeysize]byte
type NaclDHKeyPrivate [NaclDHKeysize]byte
type NaclDHKeyPair struct {
Public NaclDHKeyPublic
Private *NaclDHKeyPrivate
}
func (k NaclDHKeyPair) Clone() (ret NaclDHKeyPair) {
ret.Public = k.Public
if k.Private != nil {
tmp := *k.Private
ret.Private = &tmp
}
return ret
}
var _ GenericKey = NaclDHKeyPair{}
type NaclSecretBoxKey [NaclSecretBoxKeySize]byte
func (k NaclSecretBoxKey) IsZero() bool {
var z NaclSecretBoxKey
return hmac.Equal(k[:], z[:])
}
func importNaclHex(s string, typ byte, bodyLen int) (ret []byte, err error) {
kid := keybase1.KIDFromString(s)
return importNaclKid(kid.ToBytes(), typ, bodyLen)
}
func importNaclKid(bkid []byte, typ byte, bodyLen int) (ret []byte, err error) {
l := len(bkid)
if l != bodyLen+3 {
err = kbcrypto.BadKeyError{Msg: fmt.Sprintf("Wrong length; wanted %d, got %d", bodyLen+3, l)}
return
}
if bkid[0] != byte(kbcrypto.KeybaseKIDV1) || bkid[l-1] != byte(kbcrypto.IDSuffixKID) || bkid[1] != typ {
err = kbcrypto.BadKeyError{Msg: "bad header or trailer bytes"}
return
}
ret = bkid[2:(l - 1)]
return
}
func BinaryKIDToRawNaCl(k keybase1.BinaryKID) (ret []byte, err error) {
return importNaclKid([]byte(k), byte(kbcrypto.KIDNaclDH), NaclDHKeysize)
}
func ImportNaclSigningKeyPairFromBytes(pub []byte, priv []byte) (ret NaclSigningKeyPair, err error) {
var body []byte
if body, err = importNaclKid(pub, byte(kbcrypto.KIDNaclEddsa), ed25519.PublicKeySize); err != nil {
return
}
copy(ret.Public[:], body)
if priv == nil {
} else if len(priv) != ed25519.PrivateKeySize {
err = kbcrypto.BadKeyError{Msg: "Secret key was wrong size"}
} else {
ret.Private = &kbcrypto.NaclSigningKeyPrivate{}
copy(ret.Private[:], priv)
}
return
}
func ImportKeypairFromKID(k keybase1.KID) (key GenericKey, err error) {
kid := k.ToBytes()
l := len(kid)
if l < 3 {
err = kbcrypto.BadKeyError{Msg: "KID was way too short"}
return
}
if kid[0] != byte(kbcrypto.KeybaseKIDV1) || kid[l-1] != byte(kbcrypto.IDSuffixKID) {
err = kbcrypto.BadKeyError{Msg: "bad header or trailer found"}
return
}
raw := kid[2:(l - 1)]
switch kid[1] {
case byte(kbcrypto.KIDNaclEddsa):
if len(raw) != ed25519.PublicKeySize {
err = kbcrypto.BadKeyError{Msg: "Bad EdDSA key size"}
} else {
tmp := NaclSigningKeyPair{}
copy(tmp.Public[:], raw)
key = tmp
}
case byte(kbcrypto.KIDNaclDH):
if len(raw) != NaclDHKeysize {
err = kbcrypto.BadKeyError{Msg: "Bad DH key size"}
} else {
tmp := NaclDHKeyPair{}
copy(tmp.Public[:], raw)
key = tmp
}
default:
err = kbcrypto.BadKeyError{Msg: fmt.Sprintf("Bad key prefix: %d", kid[1])}
}
return
}
func ImportDHKeypairFromKID(k keybase1.KID) (*NaclDHKeyPair, error) {
genericKey, err := ImportKeypairFromKID(k)
if err != nil {
return nil, err
}
naclKey, ok := genericKey.(NaclDHKeyPair)
if !ok {
return nil, fmt.Errorf("expected NaclDHKeyPair, got %T", genericKey)
}
return &naclKey, nil
}
func ImportNaclSigningKeyPairFromHex(s string) (ret NaclSigningKeyPair, err error) {
var body []byte
if body, err = importNaclHex(s, byte(kbcrypto.KIDNaclEddsa), ed25519.PublicKeySize); err != nil {
return
}
copy(ret.Public[:], body)
return
}
func ImportNaclDHKeyPairFromBytes(pub []byte, priv []byte) (ret NaclDHKeyPair, err error) {
var body []byte
if body, err = importNaclKid(pub, byte(kbcrypto.KIDNaclDH), NaclDHKeysize); err != nil {
return
}
copy(ret.Public[:], body)
if priv == nil {
} else if len(priv) != NaclDHKeysize {
err = kbcrypto.BadKeyError{Msg: "Secret key was wrong size"}
} else {
ret.Private = &NaclDHKeyPrivate{}
copy(ret.Private[:], priv)
}
return
}
func ImportNaclDHKeyPairFromHex(s string) (ret NaclDHKeyPair, err error) {
var body []byte
if body, err = importNaclHex(s, byte(kbcrypto.KIDNaclDH), NaclDHKeysize); err != nil {
return
}
copy(ret.Public[:], body)
return
}
func (k NaclDHKeyPublic) GetKID() keybase1.KID {
return k.GetBinaryKID().ToKID()
}
func (k NaclDHKeyPublic) GetBinaryKID() keybase1.BinaryKID {
prefix := []byte{
byte(kbcrypto.KeybaseKIDV1),
byte(kbcrypto.KIDNaclDH),
}
suffix := byte(kbcrypto.IDSuffixKID)
out := prefix
out = append(out, k[:]...)
out = append(out, suffix)
return keybase1.BinaryKID(out)
}
func (k NaclDHKeyPair) GetFingerprintP() *PGPFingerprint {
return nil
}
func (k NaclDHKeyPair) GetAlgoType() kbcrypto.AlgoType {
return kbcrypto.KIDNaclDH
}
func (k NaclSigningKeyPair) GetAlgoType() kbcrypto.AlgoType {
return kbcrypto.KIDNaclEddsa
}
func (k NaclSigningKeyPair) GetKID() (ret keybase1.KID) {
return k.Public.GetKID()
}
func (k NaclSigningKeyPair) GetBinaryKID() (ret keybase1.BinaryKID) {
return k.Public.GetBinaryKID()
}
func (k NaclSigningKeyPair) ToShortIDString() string {
return k.Public.GetKID().ToShortIDString()
}
func (k NaclDHKeyPair) ToShortIDString() string {
return k.Public.GetKID().ToShortIDString()
}
func (k NaclSigningKeyPair) VerboseDescription() string {
return fmt.Sprintf("255-bit EdDSA signing key (%s)", k.ToShortIDString())
}
func (k NaclDHKeyPair) VerboseDescription() string {
return fmt.Sprintf("255-bit Curve25519 DH key (%s)", k.ToShortIDString())
}
func (k NaclSigningKeyPair) GetFingerprintP() *PGPFingerprint {
return nil
}
func (k NaclDHKeyPair) GetKID() keybase1.KID {
return k.Public.GetKID()
}
func (k NaclDHKeyPair) GetBinaryKID() (ret keybase1.BinaryKID) {
return k.Public.GetBinaryKID()
}
func (k NaclSigningKeyPair) CheckSecretKey() error {
if k.Private == nil {
return NoSecretKeyError{}
}
return nil
}
func (k NaclSigningKeyPair) HasSecretKey() bool {
return k.Private != nil
}
func (k NaclSigningKeyPair) Encode() (string, error) {
return k.GetKID().String(), nil
}
func (k NaclDHKeyPair) Encode() (string, error) {
return k.GetKID().String(), nil
}
func (k NaclDHKeyPair) CheckSecretKey() error {
if k.Private == nil {
return NoSecretKeyError{}
}
return nil
}
func (k NaclDHKeyPair) HasSecretKey() bool {
return k.Private != nil
}
func (k NaclSigningKeyPair) CanSign() bool { return k.Private != nil }
func (k NaclDHKeyPair) CanSign() bool { return false }
func (k NaclSigningKeyPair) Sign(msg []byte) (kbcrypto.NaclSigInfo, error) {
if k.Private == nil {
return kbcrypto.NaclSigInfo{}, NoSecretKeyError{}
}
return k.Private.SignInfoV0(msg, k.Public), nil
}
func (k NaclSigningKeyPair) SecretSymmetricKey(reason EncryptionReason) (NaclSecretBoxKey, error) {
return NaclSecretBoxKey{}, KeyCannotEncryptError{}
}
const encryptionReasonMinLength = 8
type EncryptionReason string
func (r EncryptionReason) Bytes() []byte {
return []byte(r)
}
func (k NaclSigningKeyPair) SignV2(msg []byte, prefix kbcrypto.SignaturePrefix) (kbcrypto.NaclSigInfo, error) {
if k.Private == nil {
return kbcrypto.NaclSigInfo{}, NoSecretKeyError{}
}
return k.Private.SignInfoV2(msg, k.Public, prefix)
}
func (k NaclSigningKeyPair) SignToString(msg []byte) (string, keybase1.SigIDBase, error) {
return k.Private.SignToStringV0(msg, k.Public)
}
func (k NaclSigningKeyPair) VerifyStringAndExtract(ctx VerifyContext, sig string) (msg []byte, id keybase1.SigIDBase, err error) {
var keyInSignature *kbcrypto.NaclSigningKeyPublic
var fullSigBody []byte
keyInSignature, msg, fullSigBody, err = kbcrypto.NaclVerifyAndExtract(sig)
if err != nil {
return nil, id, err
}
kidInSig := keyInSignature.GetKID()
kidWanted := k.GetKID()
if kidWanted.NotEqual(kidInSig) {
err = WrongKidError{kidInSig, kidWanted}
return nil, id, err
}
id = kbcrypto.ComputeSigIDFromSigBody(fullSigBody)
return msg, id, nil
}
func (k NaclSigningKeyPair) VerifyString(ctx VerifyContext, sig string, msg []byte) (id keybase1.SigIDBase, err error) {
var keyInSignature *kbcrypto.NaclSigningKeyPublic
var fullSigBody []byte
keyInSignature, fullSigBody, err = kbcrypto.NaclVerifyWithPayload(sig, msg)
if err != nil {
return id, err
}
kidInSig := keyInSignature.GetKID()
kidWanted := k.GetKID()
if kidWanted.NotEqual(kidInSig) {
err = WrongKidError{kidInSig, kidWanted}
return id, err
}
id = kbcrypto.ComputeSigIDFromSigBody(fullSigBody)
return id, nil
}
func (k NaclDHKeyPair) SignToString(msg []byte) (sig string, id keybase1.SigIDBase, err error) {
err = KeyCannotSignError{}
return
}
func (k NaclDHKeyPair) VerifyStringAndExtract(ctx VerifyContext, sig string) (msg []byte, id keybase1.SigIDBase, err error) {
err = KeyCannotVerifyError{}
return
}
func (k NaclDHKeyPair) VerifyString(ctx VerifyContext, sig string, msg []byte) (id keybase1.SigIDBase, err error) {
err = KeyCannotVerifyError{}
return
}
func EncryptionKIDToPublicKeyBytes(bk []byte) ([]byte, error) {
if len(bk) != 3+NaclDHKeysize {
return []byte{}, fmt.Errorf("invalid DH encryption key kbcrypto.KID (wrong length)")
}
if bk[0] != byte(kbcrypto.KeybaseKIDV1) || bk[1] != byte(kbcrypto.KIDNaclDH) || bk[len(bk)-1] != byte(kbcrypto.IDSuffixKID) {
return []byte{}, fmt.Errorf("invalid DH encryption key kbcrypto.KID (wrong type)")
}
return bk[2 : len(bk)-1], nil
}
func (k NaclSigningKeyPair) ExportPublicAndPrivate() (RawPublicKey, RawPrivateKey, error) {
return RawPublicKey(k.GetKID().ToBytes()), RawPrivateKey(k.Private[:]), nil
}
func (k NaclDHKeyPair) ExportPublicAndPrivate() (RawPublicKey, RawPrivateKey, error) {
return RawPublicKey(k.GetKID().ToBytes()), RawPrivateKey(k.Private[:]), nil
}
func makeNaclSigningKeyPair(reader io.Reader) (NaclSigningKeyPair, error) {
publicKey, privateKey, err := ed25519.GenerateKey(reader)
if err != nil {
return NaclSigningKeyPair{}, err
}
var publicArray kbcrypto.NaclSigningKeyPublic
var privateArray kbcrypto.NaclSigningKeyPrivate
copy(publicArray[:], publicKey)
copy(privateArray[:], privateKey)
return NaclSigningKeyPair{
Public: publicArray,
Private: &privateArray,
}, nil
}
// MakeNaclSigningKeyPairFromSecret makes a signing key pair given a
// secret. Of course, the security of depends entirely on the
// randomness of the bytes in the secret.
func MakeNaclSigningKeyPairFromSecret(secret [NaclSigningKeySecretSize]byte) (NaclSigningKeyPair, error) {
r := bytes.NewReader(secret[:])
kp, err := makeNaclSigningKeyPair(r)
if err != nil {
return NaclSigningKeyPair{}, err
}
if r.Len() > 0 {
return NaclSigningKeyPair{}, fmt.Errorf("Did not use %d secret byte(s)", r.Len())
}
return kp, err
}
func MakeNaclSigningKeyPairFromSecretBytes(secret []byte) (NaclSigningKeyPair, error) {
if len(secret) != NaclSigningKeySecretSize {
return NaclSigningKeyPair{}, fmt.Errorf("Bad NaCl signing key size: %d", len(secret))
}
var fixed [NaclSigningKeySecretSize]byte
copy(fixed[:], secret)
return MakeNaclSigningKeyPairFromSecret(fixed)
}
func GenerateNaclSigningKeyPair() (NaclSigningKeyPair, error) {
return makeNaclSigningKeyPair(rand.Reader)
}
func makeNaclDHKeyPair(reader io.Reader) (NaclDHKeyPair, error) {
pub, priv, err := box.GenerateKey(reader)
if err != nil {
return NaclDHKeyPair{}, err
}
return NaclDHKeyPair{
Public: *pub,
Private: (*NaclDHKeyPrivate)(priv),
}, nil
}
func MakeNaclDHKeyPairFromSecretBytes(secret []byte) (NaclDHKeyPair, error) {
if len(secret) != NaclDHKeySecretSize {
return NaclDHKeyPair{}, fmt.Errorf("Bad NaCl DH key size: %d", len(secret))
}
var fixed [NaclDHKeySecretSize]byte
copy(fixed[:], secret)
return MakeNaclDHKeyPairFromSecret(fixed)
}
// MakeNaclDHKeyPairFromSecret makes a DH key pair given a secret. Of
// course, the security of depends entirely on the randomness of the
// bytes in the secret.
func MakeNaclDHKeyPairFromSecret(secret [NaclDHKeySecretSize]byte) (NaclDHKeyPair, error) {
r := bytes.NewReader(secret[:])
kp, err := makeNaclDHKeyPair(r)
if err != nil {
return NaclDHKeyPair{}, err
}
if r.Len() > 0 {
return NaclDHKeyPair{}, fmt.Errorf("Did not use %d secret byte(s)", r.Len())
}
return kp, err
}
func GenerateNaclDHKeyPair() (NaclDHKeyPair, error) {
return makeNaclDHKeyPair(rand.Reader)
}
func GenerateNaclSigningKeyPairFromSeed(seed [ed25519.SeedSize]byte) (NaclSigningKeyPair, error) {
return makeNaclSigningKeyPair(bytes.NewReader(seed[:]))
}
func KbOpenSig(armored string) ([]byte, error) {
return base64.StdEncoding.DecodeString(armored)
}
func SigExtractKbPayloadAndKID(armored string) (payload []byte, kid keybase1.KID, sigID keybase1.SigIDBase, err error) {
var byt []byte
var sig kbcrypto.NaclSigInfo
if byt, err = KbOpenSig(armored); err != nil {
return nil, kid, sigID, err
}
if sig, err = kbcrypto.DecodeNaclSigInfoPacket(byt); err != nil {
return nil, kid, sigID, err
}
sigID = kbcrypto.ComputeSigIDFromSigBody(byt)
kid = sig.Kid.ToKID()
payload = sig.Payload
return payload, kid, sigID, nil
}
func SigAssertKbPayload(armored string, expected []byte) (sigID keybase1.SigIDBase, err error) {
var payload []byte
nilSigID := keybase1.SigIDBase("")
payload, _, sigID, err = SigExtractKbPayloadAndKID(armored)
if err != nil {
return nilSigID, err
}
if !FastByteArrayEq(expected, payload) {
return nilSigID, BadSigError{"wrong payload"}
}
return sigID, nil
}
// EncryptToString fails for this type of key.
func (k NaclSigningKeyPair) EncryptToString(plaintext []byte, sender GenericKey) (ciphertext string, err error) {
err = KeyCannotEncryptError{}
return
}
// DecryptFromString fails for this type of key.
func (k NaclSigningKeyPair) DecryptFromString(ciphertext string) (msg []byte, sender keybase1.KID, err error) {
err = KeyCannotDecryptError{}
return
}
// CanEncrypt always returns false for a signing key pair.
func (k NaclSigningKeyPair) CanEncrypt() bool { return false }
// CanDecrypt always returns false for a signing key pair.
func (k NaclSigningKeyPair) CanDecrypt() bool { return false }
// CanEncrypt always returns true for an encryption key pair.
func (k NaclDHKeyPair) CanEncrypt() bool { return true }
// CanDecrypt returns true if there's a private key available
func (k NaclDHKeyPair) CanDecrypt() bool { return k.Private != nil }
func (k NaclDHKeyPair) IsNil() bool {
var empty NaclDHKeyPublic
return bytes.Equal(k.Public[:], empty[:])
}
func (k NaclSigningKeyPair) IsNil() bool {
var empty kbcrypto.NaclSigningKeyPublic
return bytes.Equal(k.Public[:], empty[:])
}
// Encrypt a message to the key `k` from the given `sender`. If sender is nil, an ephemeral
// keypair will be invented
func (k NaclDHKeyPair) Encrypt(msg []byte, sender *NaclDHKeyPair) (*NaclEncryptionInfo, error) {
if sender == nil {
if tmp, err := GenerateNaclDHKeyPair(); err == nil {
sender = &tmp
} else {
return nil, err
}
} else if sender.Private == nil {
return nil, NoSecretKeyError{}
}
var nonce [NaclDHNonceSize]byte
if nRead, err := rand.Read(nonce[:]); err != nil {
return nil, err
} else if nRead != NaclDHNonceSize {
return nil, fmt.Errorf("Short random read: %d", nRead)
}
var ctext []byte
ctext = box.Seal(ctext, msg, &nonce, ((*[32]byte)(&k.Public)), ((*[32]byte)(sender.Private)))
ret := &NaclEncryptionInfo{
Ciphertext: ctext,
EncryptionType: kbcrypto.KIDNaclDH,
Nonce: nonce[:],
Receiver: k.GetKID().ToBytes(),
Sender: sender.GetKID().ToBytes(),
}
return ret, nil
}
// EncryptToString encrypts the plaintext using DiffieHelman; the this object is
// the receiver, and the passed sender is optional. If not provided, we'll make
// up an ephemeral key.
func (k NaclDHKeyPair) EncryptToString(plaintext []byte, sender GenericKey) (string, error) {
var senderDh *NaclDHKeyPair
if sender != nil {
var ok bool
if senderDh, ok = sender.(*NaclDHKeyPair); !ok {
return "", NoSecretKeyError{}
}
}
info, err := k.Encrypt(plaintext, senderDh)
if err != nil {
return "", err
}
return kbcrypto.EncodePacketToArmoredString(info)
}
func (k NaclDHKeyPair) SecretSymmetricKey(reason EncryptionReason) (NaclSecretBoxKey, error) {
if !k.CanDecrypt() {
return NaclSecretBoxKey{}, NoSecretKeyError{}
}
return deriveSymmetricKeyFromAsymmetric(*k.Private, reason)
}
// Derive a symmetric key using HMAC(k, reason).
// Suitable for deriving from an asymmetric encryption key.
// For deriving from a shared encryption key, this output is too close
// to something that might be used as a public authenticator.
func deriveSymmetricKeyFromAsymmetric(inKey NaclDHKeyPrivate, reason EncryptionReason) (NaclSecretBoxKey, error) {
var outKey = [32]byte{}
if len(reason) < encryptionReasonMinLength {
return outKey, KeyGenError{Msg: "reason must be at least 8 bytes"}
}
mac := hmac.New(sha256.New, inKey[:])
_, err := mac.Write(reason.Bytes())
if err != nil {
return outKey, err
}
out := mac.Sum(nil)
if copy(outKey[:], out) != len(outKey) {
return outKey, KeyGenError{Msg: "derived key of wrong size"}
}
return outKey, nil
}
// Derive a symmetric key.
// Uses HMAC(key=reason, data=key)
// Note the message and data are swapped as inputs to HMAC because that is less
// likely to be accidentally used for another purpose such as authentication.
func DeriveSymmetricKey(inKey NaclSecretBoxKey, reason EncryptionReason) (NaclSecretBoxKey, error) {
var outKey = [32]byte{}
if len(reason) < encryptionReasonMinLength {
return outKey, KeyGenError{Msg: "reason must be at least 8 bytes"}
}
mac := hmac.New(sha256.New, []byte(reason))
_, err := mac.Write(inKey[:])
if err != nil {
return outKey, err
}
out := mac.Sum(nil)
if copy(outKey[:], out) != len(outKey) {
return outKey, KeyGenError{Msg: "derived key of wrong size"}
}
return outKey, nil
}
// Derive a key from another.
// Uses HMAC(key=key, data=reason)
// Not to be confused with DeriveSymmetricKey which has hmac inputs swapped.
// This one makes sense for derivation from secrets used only to derive from.
func DeriveFromSecret(inKey [32]byte, reason DeriveReason) (outKey [32]byte, err error) {
if len(reason) < 8 {
return outKey, KeyGenError{Msg: "reason must be at least 8 bytes"}
}
mac := hmac.New(sha256.New, inKey[:])
_, err = mac.Write([]byte(reason))
if err != nil {
return outKey, err
}
out := mac.Sum(nil)
if copy(outKey[:], out) != len(outKey) {
return outKey, KeyGenError{Msg: "derived key of wrong size"}
}
return outKey, nil
}
func (k *NaclEncryptionInfo) GetTagAndVersion() (kbcrypto.PacketTag, kbcrypto.PacketVersion) {
return kbcrypto.TagEncryption, kbcrypto.KeybasePacketV1
}
// DecryptFromString decrypts the output of EncryptToString above,
// and returns the kbcrypto.KID of the other end.
func (k NaclDHKeyPair) DecryptFromString(ciphertext string) (msg []byte, sender keybase1.KID, err error) {
var nei NaclEncryptionInfo
if nei, err = DecodeArmoredNaclEncryptionInfoPacket(ciphertext); err != nil {
return
}
return k.Decrypt(&nei)
}
// Decrypt a NaclEncryptionInfo packet, and on success return the plaintext
// and the kbcrypto.KID of the sender (which might be an ephemeral key).
func (k NaclDHKeyPair) Decrypt(nei *NaclEncryptionInfo) (plaintext []byte, sender keybase1.KID, err error) {
if k.Private == nil {
err = NoSecretKeyError{}
return
}
if nei.EncryptionType != kbcrypto.KIDNaclDH {
err = DecryptBadPacketTypeError{}
return
}
var nonce [NaclDHNonceSize]byte
if len(nei.Nonce) != NaclDHNonceSize {
err = DecryptBadNonceError{}
return
}
copy(nonce[:], nei.Nonce)
var gk GenericKey
if gk, err = ImportKeypairFromKID(keybase1.KIDFromSlice(nei.Sender)); err != nil {
return
}
var senderDH NaclDHKeyPair
var ok bool
if senderDH, ok = gk.(NaclDHKeyPair); !ok {
err = DecryptBadSenderError{}
return
}
rkid := keybase1.KIDFromSlice(nei.Receiver)
if k.GetKID().NotEqual(rkid) {
err = DecryptWrongReceiverError{}
return
}
if plaintext, ok = box.Open(plaintext, nei.Ciphertext, &nonce,
((*[32]byte)(&senderDH.Public)), ((*[32]byte)(k.Private))); !ok {
err = DecryptOpenError{}
return
}
sender = senderDH.GetKID()
return
}
func GeneratePerUserKeySeed() (res PerUserKeySeed, err error) {
bs, err := RandBytes(32)
if err != nil {
return res, err
}
seed := PerUserKeySeed(MakeByte32(bs))
return seed, nil
}
func RandomNaclDHNonce() (nonce [NaclDHNonceSize]byte, err error) {
nRead, err := rand.Read(nonce[:])
if err != nil {
return nonce, err
}
if nRead != NaclDHNonceSize {
return nonce, fmt.Errorf("Short random read: %d", nRead)
}
return nonce, nil
}