package chainkd
import (
+ "crypto/hmac"
"crypto/rand"
"crypto/sha512"
- "encoding/binary"
- "hash"
"io"
"github.com/bytom/crypto/ed25519"
- "github.com/bytom/crypto/ed25519/internal/edwards25519"
+ "github.com/bytom/crypto/ed25519/ecmath"
)
type (
- // TODO(bobg): consider making these types opaque. See https://github.com/chain/chain/pull/1875#discussion_r80577736
+ //XPrv external private key
XPrv [64]byte
+ //XPub external public key
XPub [64]byte
)
var one = [32]byte{1}
-// NewXPrv takes a source of random bytes and produces a new XPrv. If
-// r is nil, crypto/rand.Reader is used.
+// NewXPrv takes a source of random bytes and produces a new XPrv.
+// If r is nil, crypto/rand.Reader is used.
func NewXPrv(r io.Reader) (xprv XPrv, err error) {
if r == nil {
r = rand.Reader
if err != nil {
return xprv, err
}
- hasher := sha512.New()
- hasher.Write([]byte("Bytom seed"))
- hasher.Write(entropy[:])
- hasher.Sum(xprv[:0])
- modifyScalar(xprv[:32])
- return xprv, nil
+ return RootXPrv(entropy[:]), nil
}
-func (xprv XPrv) XPub() XPub {
- var buf [32]byte
- copy(buf[:], xprv[:32])
+// RootXPrv takes a seed binary string and produces a new xprv.
+func RootXPrv(seed []byte) (xprv XPrv) {
+ h := hmac.New(sha512.New, []byte{'R', 'o', 'o', 't'})
+ h.Write(seed)
+ h.Sum(xprv[:0])
+ pruneRootScalar(xprv[:32])
+ return
+}
+
+// XPub derives an extended public key from a given xprv.
+func (xprv XPrv) XPub() (xpub XPub) {
+ var scalar ecmath.Scalar
+ copy(scalar[:], xprv[:32])
- var P edwards25519.ExtendedGroupElement
- edwards25519.GeScalarMultBase(&P, &buf)
- P.ToBytes(&buf)
+ var P ecmath.Point
+ P.ScMulBase(&scalar)
+ buf := P.Encode()
- var xpub XPub
copy(xpub[:32], buf[:])
copy(xpub[32:], xprv[32:])
- return xpub
+ return
}
-func (xprv XPrv) Child(sel []byte, hardened bool) (res XPrv) {
+// Child derives a child xprv based on `selector` string and `hardened` flag.
+// If `hardened` is false, child xpub can be derived independently
+// from the parent xpub without using the parent xprv.
+// If `hardened` is true, child key can only be derived from the parent xprv.
+func (xprv XPrv) Child(sel []byte, hardened bool) XPrv {
if hardened {
- hashKeySaltSelector(res[:], 0, xprv[:32], xprv[32:], sel)
- return res
+ return xprv.hardenedChild(sel)
}
+ return xprv.nonhardenedChild(sel)
+}
- var s [32]byte
- copy(s[:], xprv[:32])
- var P edwards25519.ExtendedGroupElement
- edwards25519.GeScalarMultBase(&P, &s)
-
- var pubkey [32]byte
- P.ToBytes(&pubkey)
-
- hashKeySaltSelector(res[:], 1, pubkey[:], xprv[32:], sel)
-
- var (
- f [32]byte
- s2 [32]byte
- )
- copy(f[:], res[:32])
- edwards25519.ScMulAdd(&s2, &one, &f, &s)
- copy(res[:32], s2[:])
+func (xprv XPrv) hardenedChild(sel []byte) (res XPrv) {
+ h := hmac.New(sha512.New, xprv[32:])
+ h.Write([]byte{'H'})
+ h.Write(xprv[:32])
+ h.Write(sel)
+ h.Sum(res[:0])
+ pruneRootScalar(res[:32])
+ return
+}
- return res
+func (xprv XPrv) nonhardenedChild(sel []byte) (res XPrv) {
+ xpub := xprv.XPub()
+
+ h := hmac.New(sha512.New, xpub[32:])
+ h.Write([]byte{'N'})
+ h.Write(xpub[:32])
+ h.Write(sel)
+ h.Sum(res[:0])
+
+ pruneIntermediateScalar(res[:32])
+
+ // Unrolled the following loop:
+ // var carry int
+ // carry = 0
+ // for i := 0; i < 32; i++ {
+ // sum := int(xprv[i]) + int(res[i]) + carry
+ // res[i] = byte(sum & 0xff)
+ // carry = (sum >> 8)
+ // }
+
+ sum := int(0)
+
+ sum = int(xprv[0]) + int(res[0]) + (sum >> 8)
+ res[0] = byte(sum & 0xff)
+ sum = int(xprv[1]) + int(res[1]) + (sum >> 8)
+ res[1] = byte(sum & 0xff)
+ sum = int(xprv[2]) + int(res[2]) + (sum >> 8)
+ res[2] = byte(sum & 0xff)
+ sum = int(xprv[3]) + int(res[3]) + (sum >> 8)
+ res[3] = byte(sum & 0xff)
+ sum = int(xprv[4]) + int(res[4]) + (sum >> 8)
+ res[4] = byte(sum & 0xff)
+ sum = int(xprv[5]) + int(res[5]) + (sum >> 8)
+ res[5] = byte(sum & 0xff)
+ sum = int(xprv[6]) + int(res[6]) + (sum >> 8)
+ res[6] = byte(sum & 0xff)
+ sum = int(xprv[7]) + int(res[7]) + (sum >> 8)
+ res[7] = byte(sum & 0xff)
+ sum = int(xprv[8]) + int(res[8]) + (sum >> 8)
+ res[8] = byte(sum & 0xff)
+ sum = int(xprv[9]) + int(res[9]) + (sum >> 8)
+ res[9] = byte(sum & 0xff)
+ sum = int(xprv[10]) + int(res[10]) + (sum >> 8)
+ res[10] = byte(sum & 0xff)
+ sum = int(xprv[11]) + int(res[11]) + (sum >> 8)
+ res[11] = byte(sum & 0xff)
+ sum = int(xprv[12]) + int(res[12]) + (sum >> 8)
+ res[12] = byte(sum & 0xff)
+ sum = int(xprv[13]) + int(res[13]) + (sum >> 8)
+ res[13] = byte(sum & 0xff)
+ sum = int(xprv[14]) + int(res[14]) + (sum >> 8)
+ res[14] = byte(sum & 0xff)
+ sum = int(xprv[15]) + int(res[15]) + (sum >> 8)
+ res[15] = byte(sum & 0xff)
+ sum = int(xprv[16]) + int(res[16]) + (sum >> 8)
+ res[16] = byte(sum & 0xff)
+ sum = int(xprv[17]) + int(res[17]) + (sum >> 8)
+ res[17] = byte(sum & 0xff)
+ sum = int(xprv[18]) + int(res[18]) + (sum >> 8)
+ res[18] = byte(sum & 0xff)
+ sum = int(xprv[19]) + int(res[19]) + (sum >> 8)
+ res[19] = byte(sum & 0xff)
+ sum = int(xprv[20]) + int(res[20]) + (sum >> 8)
+ res[20] = byte(sum & 0xff)
+ sum = int(xprv[21]) + int(res[21]) + (sum >> 8)
+ res[21] = byte(sum & 0xff)
+ sum = int(xprv[22]) + int(res[22]) + (sum >> 8)
+ res[22] = byte(sum & 0xff)
+ sum = int(xprv[23]) + int(res[23]) + (sum >> 8)
+ res[23] = byte(sum & 0xff)
+ sum = int(xprv[24]) + int(res[24]) + (sum >> 8)
+ res[24] = byte(sum & 0xff)
+ sum = int(xprv[25]) + int(res[25]) + (sum >> 8)
+ res[25] = byte(sum & 0xff)
+ sum = int(xprv[26]) + int(res[26]) + (sum >> 8)
+ res[26] = byte(sum & 0xff)
+ sum = int(xprv[27]) + int(res[27]) + (sum >> 8)
+ res[27] = byte(sum & 0xff)
+ sum = int(xprv[28]) + int(res[28]) + (sum >> 8)
+ res[28] = byte(sum & 0xff)
+ sum = int(xprv[29]) + int(res[29]) + (sum >> 8)
+ res[29] = byte(sum & 0xff)
+ sum = int(xprv[30]) + int(res[30]) + (sum >> 8)
+ res[30] = byte(sum & 0xff)
+ sum = int(xprv[31]) + int(res[31]) + (sum >> 8)
+ res[31] = byte(sum & 0xff)
+
+ if (sum >> 8) != 0 {
+ panic("sum does not fit in 256-bit int")
+ }
+ return
}
+// Child derives a child xpub based on `selector` string.
+// The corresponding child xprv can be derived from the parent xprv
+// using non-hardened derivation: `parentxprv.Child(sel, false)`.
func (xpub XPub) Child(sel []byte) (res XPub) {
- hashKeySaltSelector(res[:], 1, xpub[:32], xpub[32:], sel)
+ h := hmac.New(sha512.New, xpub[32:])
+ h.Write([]byte{'N'})
+ h.Write(xpub[:32])
+ h.Write(sel)
+ h.Sum(res[:0])
+
+ pruneIntermediateScalar(res[:32])
var (
- f [32]byte
- F edwards25519.ExtendedGroupElement
+ f ecmath.Scalar
+ F ecmath.Point
)
copy(f[:], res[:32])
- edwards25519.GeScalarMultBase(&F, &f)
+ F.ScMulBase(&f)
var (
pubkey [32]byte
- P edwards25519.ExtendedGroupElement
+ P ecmath.Point
)
copy(pubkey[:], xpub[:32])
- P.FromBytes(&pubkey)
-
- var (
- P2 edwards25519.ExtendedGroupElement
- R edwards25519.CompletedGroupElement
- Fc edwards25519.CachedGroupElement
- )
- F.ToCached(&Fc)
- edwards25519.GeAdd(&R, &P, &Fc)
- R.ToExtended(&P2)
-
- P2.ToBytes(&pubkey)
+ _, ok := P.Decode(pubkey)
+ if !ok {
+ panic("XPub should have been validated on initialization")
+ }
+ P.Add(&P, &F)
+ pubkey = P.Encode()
copy(res[:32], pubkey[:])
- return res
+ return
}
+// Derive generates a child xprv by recursively deriving
+// non-hardened child xprvs over the list of selectors:
+// `Derive([a,b,c,...]) == Child(a).Child(b).Child(c)...`
func (xprv XPrv) Derive(path [][]byte) XPrv {
res := xprv
for _, p := range path {
return res
}
+// Derive generates a child xpub by recursively deriving
+// non-hardened child xpubs over the list of selectors:
+// `Derive([a,b,c,...]) == Child(a).Child(b).Child(c)...`
func (xpub XPub) Derive(path [][]byte) XPub {
res := xpub
for _, p := range path {
return res
}
+// Sign creates an EdDSA signature using expanded private key
+// derived from the xprv.
func (xprv XPrv) Sign(msg []byte) []byte {
- var s [32]byte
- copy(s[:], xprv[:32])
-
- var h [64]byte
- hashKeySalt(h[:], 2, xprv[:32], xprv[32:])
-
- var P edwards25519.ExtendedGroupElement
- edwards25519.GeScalarMultBase(&P, &s)
-
- var pubkey [32]byte
- P.ToBytes(&pubkey)
-
- var r [64]byte
- hasher := sha512.New()
- hasher.Write(h[:32])
- hasher.Write(msg)
- hasher.Sum(r[:0])
-
- var rReduced [32]byte
- edwards25519.ScReduce(&rReduced, &r)
-
- var rPoint edwards25519.ExtendedGroupElement
- edwards25519.GeScalarMultBase(&rPoint, &rReduced)
-
- var R [32]byte
- rPoint.ToBytes(&R)
-
- hasher.Reset()
- hasher.Write(R[:])
- hasher.Write(pubkey[:])
- hasher.Write(msg)
-
- var k [64]byte
- hasher.Sum(k[:0])
-
- var kReduced [32]byte
- edwards25519.ScReduce(&kReduced, &k)
-
- var S [32]byte
- edwards25519.ScMulAdd(&S, &kReduced, &s, &rReduced)
-
- return append(R[:], S[:]...)
+ return Ed25519InnerSign(xprv.ExpandedPrivateKey(), msg)
}
+// Verify checks an EdDSA signature using public key
+// extracted from the first 32 bytes of the xpub.
func (xpub XPub) Verify(msg []byte, sig []byte) bool {
return ed25519.Verify(xpub.PublicKey(), msg, sig)
}
+// ExpandedPrivateKey generates a 64-byte key where
+// the first half is the scalar copied from xprv,
+// and the second half is the `prefix` is generated via PRF
+// from the xprv.
+func (xprv XPrv) ExpandedPrivateKey() ExpandedPrivateKey {
+ var res [64]byte
+ h := hmac.New(sha512.New, []byte{'E', 'x', 'p', 'a', 'n', 'd'})
+ h.Write(xprv[:])
+ h.Sum(res[:0])
+ copy(res[:32], xprv[:32])
+ return res[:]
+}
+
// PublicKey extracts the ed25519 public key from an xpub.
func (xpub XPub) PublicKey() ed25519.PublicKey {
return ed25519.PublicKey(xpub[:32])
}
-func hashKeySaltSelector(out []byte, version byte, key, salt, sel []byte) {
- hasher := hashKeySaltHelper(version, key, salt)
- var l [10]byte
- n := binary.PutUvarint(l[:], uint64(len(sel)))
- hasher.Write(l[:n])
- hasher.Write(sel)
- hasher.Sum(out[:0])
- modifyScalar(out)
-}
-
-func hashKeySalt(out []byte, version byte, key, salt []byte) {
- hasher := hashKeySaltHelper(version, key, salt)
- hasher.Sum(out[:0])
-}
-
-func hashKeySaltHelper(version byte, key, salt []byte) hash.Hash {
- hasher := sha512.New()
- hasher.Write([]byte{version})
- hasher.Write(key)
- hasher.Write(salt)
- return hasher
+// s must be >= 32 bytes long and gets rewritten in place.
+// This is NOT the same pruning as in Ed25519: it additionally clears the third
+// highest bit to ensure subkeys do not overflow the second highest bit.
+func pruneRootScalar(s []byte) {
+ s[0] &= 248
+ s[31] &= 31 // clear top 3 bits
+ s[31] |= 64 // set second highest bit
}
-// s must be >= 32 bytes long and gets rewritten in place
-func modifyScalar(s []byte) {
- s[0] &= 248
- s[31] &= 127
- s[31] |= 64
+// Clears lowest 3 bits and highest 23 bits of `f`.
+func pruneIntermediateScalar(f []byte) {
+ f[0] &= 248 // clear bottom 3 bits
+ f[29] &= 1 // clear 7 high bits
+ f[30] = 0 // clear 8 bits
+ f[31] = 0 // clear 8 bits
}
package chainkd
import (
+ "bytes"
+ "encoding/hex"
"fmt"
"reflect"
"testing"
)
+func TestVectors1(t *testing.T) {
+ root := RootXPrv([]byte{0x01, 0x02, 0x03})
+
+ verifyTestVector(t, "Root(010203).xprv", root.hex(),
+ "50f8c532ce6f088de65c2c1fbc27b491509373fab356eba300dfa7cc587b07483bc9e0d93228549c6888d3f68ad664b92c38f5ea8ca07181c1410949c02d3146")
+ verifyTestVector(t, "Root(010203).xpub", root.XPub().hex(),
+ "e11f321ffef364d01c2df2389e61091b15dab2e8eee87cb4c053fa65ed2812993bc9e0d93228549c6888d3f68ad664b92c38f5ea8ca07181c1410949c02d3146")
+
+ verifyTestVector(t, "Root(010203)/010203(H).xprv", root.Child([]byte{0x01, 0x02, 0x03}, true).hex(),
+ "6023c8e7633a9353a59bd930ea6dc397e400b1088b86b4a15d8de8567554df5574274bc1a0bd93b4494cb68e45c5ec5aefc1eed4d0c3bfd53b0b4e679ce52028")
+ verifyTestVector(t, "Root(010203)/010203(H).xpub", root.Child([]byte{0x01, 0x02, 0x03}, true).XPub().hex(),
+ "eabebab4184c63f8df07efe31fb588a0ae222318087458b4936bf0b0feab015074274bc1a0bd93b4494cb68e45c5ec5aefc1eed4d0c3bfd53b0b4e679ce52028")
+
+ verifyTestVector(t, "Root(010203)/010203(N).xprv", root.Child([]byte{0x01, 0x02, 0x03}, false).hex(),
+ "705afd25a0e242b7333105d77cbb0ec15e667154916bbed5084c355dba7b0748b0faca523928f42e685ee6deb0cb3d41a09617783c87e9a161a04f2207ad4d2f")
+ verifyTestVector(t, "Root(010203)/010203(N).xpub", root.Child([]byte{0x01, 0x02, 0x03}, false).XPub().hex(),
+ "c0bbd87142e7bf90abfbb3d0cccc210c6d7eb3f912c35f205302c86ae9ef6eefb0faca523928f42e685ee6deb0cb3d41a09617783c87e9a161a04f2207ad4d2f")
+ verifyTestVector(t, "Root(010203)/010203(N).xpub", root.XPub().Child([]byte{0x01, 0x02, 0x03}).hex(),
+ "c0bbd87142e7bf90abfbb3d0cccc210c6d7eb3f912c35f205302c86ae9ef6eefb0faca523928f42e685ee6deb0cb3d41a09617783c87e9a161a04f2207ad4d2f")
+
+ verifyTestVector(t, "Root(010203)/010203(H)/“”(N).xprv", root.Child([]byte{0x01, 0x02, 0x03}, true).Child([]byte{}, false).hex(),
+ "7023f9877813348ca8e67b29d551baf98a43cfb76cdff538f3ff97074a55df5560e3aa7fb600f61a84317a981dc9d1f7e8df2e8a3f8b544a21d2404e0b4e480a")
+ verifyTestVector(t, "Root(010203)/010203(H)/“”(N).xpub", root.Child([]byte{0x01, 0x02, 0x03}, true).Child([]byte{}, false).XPub().hex(),
+ "4e44c9ab8a45b9d1c3daab5c09d73b01209220ea704808f04feaa3614c7c7ba760e3aa7fb600f61a84317a981dc9d1f7e8df2e8a3f8b544a21d2404e0b4e480a")
+ verifyTestVector(t, "Root(010203)/010203(H)/“”(N).xpub", root.Child([]byte{0x01, 0x02, 0x03}, true).XPub().Child([]byte{}).hex(),
+ "4e44c9ab8a45b9d1c3daab5c09d73b01209220ea704808f04feaa3614c7c7ba760e3aa7fb600f61a84317a981dc9d1f7e8df2e8a3f8b544a21d2404e0b4e480a")
+
+ verifyTestVector(t, "Root(010203)/010203(N)/“”(H).xprv", root.Child([]byte{0x01, 0x02, 0x03}, false).Child([]byte{}, true).hex(),
+ "90b60b007e866dacc4b1f844089a805ffd78a295f5b0544034116ace354c58523410b1e6a3c557ca90c322f6ff4b5e547242965eaed8c34767765f0e05ed0e4f")
+ verifyTestVector(t, "Root(010203)/010203(N)/“”(H).xpub", root.Child([]byte{0x01, 0x02, 0x03}, false).Child([]byte{}, true).XPub().hex(),
+ "ca97ec34ef30aa08ebd19b9848b11ebadf9c0ad3a0be6b11d33d9558573aca633410b1e6a3c557ca90c322f6ff4b5e547242965eaed8c34767765f0e05ed0e4f")
+
+ verifyTestVector(t, "Root(010203)/010203(N)/“”(N).xprv", root.Child([]byte{0x01, 0x02, 0x03}, false).Child([]byte{}, false).hex(),
+ "d81ba3ab554a7d09bfd8bda5089363399b7f4b19d4f1806ca0c35feabf7b074856648f55e21bec3aa5df0bce0236aea88a4cc5c395c896df63676f095154bb7b")
+ verifyTestVector(t, "Root(010203)/010203(N)/“”(N).xpub", root.Child([]byte{0x01, 0x02, 0x03}, false).Child([]byte{}, false).XPub().hex(),
+ "28279bcb06aee9e5c0302f4e1db879ac7f5444ec07266a736dd571c21961427b56648f55e21bec3aa5df0bce0236aea88a4cc5c395c896df63676f095154bb7b")
+ verifyTestVector(t, "Root(010203)/010203(N)/“”(N).xpub", root.XPub().Child([]byte{0x01, 0x02, 0x03}).Child([]byte{}).hex(),
+ "28279bcb06aee9e5c0302f4e1db879ac7f5444ec07266a736dd571c21961427b56648f55e21bec3aa5df0bce0236aea88a4cc5c395c896df63676f095154bb7b")
+
+ verifyTestVector(t, "Root(010203)/010203(N)/“”(N).xprv", root.Derive([][]byte{[]byte{0x01, 0x02, 0x03}, []byte{}}).hex(),
+ "d81ba3ab554a7d09bfd8bda5089363399b7f4b19d4f1806ca0c35feabf7b074856648f55e21bec3aa5df0bce0236aea88a4cc5c395c896df63676f095154bb7b")
+ verifyTestVector(t, "Root(010203)/010203(N)/“”(N).xprv", root.Derive([][]byte{[]byte{0x01, 0x02, 0x03}, []byte{}}).XPub().hex(),
+ "28279bcb06aee9e5c0302f4e1db879ac7f5444ec07266a736dd571c21961427b56648f55e21bec3aa5df0bce0236aea88a4cc5c395c896df63676f095154bb7b")
+ verifyTestVector(t, "Root(010203)/010203(N)/“”(N).xpub", root.XPub().Derive([][]byte{[]byte{0x01, 0x02, 0x03}, []byte{}}).hex(),
+ "28279bcb06aee9e5c0302f4e1db879ac7f5444ec07266a736dd571c21961427b56648f55e21bec3aa5df0bce0236aea88a4cc5c395c896df63676f095154bb7b")
+}
+
+func TestVectors2(t *testing.T) {
+ seed, _ := hex.DecodeString("fffcf9f6f3f0edeae7e4e1dedbd8d5d2cfccc9c6c3c0bdbab7b4b1aeaba8a5a29f9c999693908d8a8784817e7b7875726f6c696663605d5a5754514e4b484542")
+ root := RootXPrv(seed)
+
+ verifyTestVector(t, "Root(fffcf9...).xprv", root.hex(),
+ "0031615bdf7906a19360f08029354d12eaaedc9046806aefd672e3b93b024e495a95ba63cf47903eb742cd1843a5252118f24c0c496e9213bd42de70f649a798")
+ verifyTestVector(t, "Root(fffcf9...).xpub", root.XPub().hex(),
+ "f153ef65bbfaec3c8fd4fceb0510529048094093cf7c14970013282973e117545a95ba63cf47903eb742cd1843a5252118f24c0c496e9213bd42de70f649a798")
+
+ verifyTestVector(t, "Root(fffcf9...)/0(N).xprv", root.Child([]byte{0x00}, false).hex(),
+ "883e65e6e86499bdd170c14d67e62359dd020dd63056a75ff75983a682024e49e8cc52d8e74c5dfd75b0b326c8c97ca7397b7f954ad0b655b8848bfac666f09f")
+ verifyTestVector(t, "Root(fffcf9...)/0(N).xpub", root.Child([]byte{0x00}, false).XPub().hex(),
+ "f48b7e641d119b8ddeaf97aca104ee6e6a780ab550d40534005443550ef7e7d8e8cc52d8e74c5dfd75b0b326c8c97ca7397b7f954ad0b655b8848bfac666f09f")
+ verifyTestVector(t, "Root(fffcf9...)/0(N).xpub", root.XPub().Child([]byte{0x00}).hex(),
+ "f48b7e641d119b8ddeaf97aca104ee6e6a780ab550d40534005443550ef7e7d8e8cc52d8e74c5dfd75b0b326c8c97ca7397b7f954ad0b655b8848bfac666f09f")
+
+ verifyTestVector(t, "Root(fffcf9...)/0(N)/2147483647(H).xprv", root.Child([]byte{0x00}, false).Child([]byte{0xff, 0xff, 0xff, 0x7f}, true).hex(),
+ "5048fa4498bf65e2b10d26e6c99cc43556ecfebf8b9fddf8bd2150ba29d63154044ef557a3aa4cb6ae8b61e87cb977a929bc4a170e4faafc2661231f5f3f78e8")
+ verifyTestVector(t, "Root(fffcf9...)/0(N)/2147483647(H).xpub", root.Child([]byte{0x00}, false).Child([]byte{0xff, 0xff, 0xff, 0x7f}, true).XPub().hex(),
+ "a8555c5ee5054ad03c6c6661968d66768fa081103bf576ea63a26c00ca7eab69044ef557a3aa4cb6ae8b61e87cb977a929bc4a170e4faafc2661231f5f3f78e8")
+
+ verifyTestVector(t, "Root(fffcf9...)/0(N)/2147483647(H)/1(N).xprv", root.Child([]byte{0x00}, false).Child([]byte{0xff, 0xff, 0xff, 0x7f}, true).Child([]byte{0x01}, false).hex(),
+ "480f6aa25f7c9f4a569896f06614303a697f00ee8d240c6277605d44e0d63154174c386ad6ae01e54acd7bb422243c6055058f4231e250050134283a76de8eff")
+ verifyTestVector(t, "Root(fffcf9...)/0(N)/2147483647(H)/1(N).xpub", root.Child([]byte{0x00}, false).Child([]byte{0xff, 0xff, 0xff, 0x7f}, true).Child([]byte{0x01}, false).XPub().hex(),
+ "7385ab0b06eacc226c8035bab1ff9bc6972c7700d1caede26fe2b4d57b208bd0174c386ad6ae01e54acd7bb422243c6055058f4231e250050134283a76de8eff")
+ verifyTestVector(t, "Root(fffcf9...)/0(N)/2147483647(H)/1(N).xpub", root.Child([]byte{0x00}, false).Child([]byte{0xff, 0xff, 0xff, 0x7f}, true).XPub().Child([]byte{0x01}).hex(),
+ "7385ab0b06eacc226c8035bab1ff9bc6972c7700d1caede26fe2b4d57b208bd0174c386ad6ae01e54acd7bb422243c6055058f4231e250050134283a76de8eff")
+
+ verifyTestVector(t, "Root(fffcf9...)/0(N)/2147483647(H)/1(N)/2147483646(H).xprv", root.Child([]byte{0x00}, false).Child([]byte{0xff, 0xff, 0xff, 0x7f}, true).Child([]byte{0x01}, false).Child([]byte{0xfe, 0xff, 0xff, 0x7f}, true).hex(),
+ "386014c6dfeb8dadf62f0e5acacfbf7965d5746c8b9011df155a31df7be0fb59986c923d979d89310acd82171dbaa7b73b20b2033ac6819d7f309212ff3fbabd")
+ verifyTestVector(t, "Root(fffcf9...)/0(N)/2147483647(H)/1(N)/2147483646(H).xpub", root.Child([]byte{0x00}, false).Child([]byte{0xff, 0xff, 0xff, 0x7f}, true).Child([]byte{0x01}, false).Child([]byte{0xfe, 0xff, 0xff, 0x7f}, true).XPub().hex(),
+ "9f66aa8019427a825dd72a13ce982454d99f221c8d4874db59f52c2945cbcabd986c923d979d89310acd82171dbaa7b73b20b2033ac6819d7f309212ff3fbabd")
+
+ verifyTestVector(t, "Root(fffcf9...)/0(N)/2147483647(H)/1(N)/2147483646(H)/2(N).xprv", root.Child([]byte{0x00}, false).Child([]byte{0xff, 0xff, 0xff, 0x7f}, true).Child([]byte{0x01}, false).Child([]byte{0xfe, 0xff, 0xff, 0x7f}, true).Child([]byte{0x02}, false).hex(),
+ "08c3772f5c0eee42f40d00f4faff9e4c84e5db3c4e7f28ecb446945a1de1fb59ef9d0a352f3252ea673e8b6bd31ac97218e019e845bdc545c268cd52f7af3f5d")
+ verifyTestVector(t, "Root(fffcf9...)/0(N)/2147483647(H)/1(N)/2147483646(H)/2(N).xpub", root.Child([]byte{0x00}, false).Child([]byte{0xff, 0xff, 0xff, 0x7f}, true).Child([]byte{0x01}, false).Child([]byte{0xfe, 0xff, 0xff, 0x7f}, true).Child([]byte{0x02}, false).XPub().hex(),
+ "67388f59a7b62644c3c6148575770e56969d77244530263bc9659b8563d7ff81ef9d0a352f3252ea673e8b6bd31ac97218e019e845bdc545c268cd52f7af3f5d")
+ verifyTestVector(t, "Root(fffcf9...)/0(N)/2147483647(H)/1(N)/2147483646(H)/2(N).xpub", root.Child([]byte{0x00}, false).Child([]byte{0xff, 0xff, 0xff, 0x7f}, true).Child([]byte{0x01}, false).Child([]byte{0xfe, 0xff, 0xff, 0x7f}, true).XPub().Child([]byte{0x02}).hex(),
+ "67388f59a7b62644c3c6148575770e56969d77244530263bc9659b8563d7ff81ef9d0a352f3252ea673e8b6bd31ac97218e019e845bdc545c268cd52f7af3f5d")
+}
+
+func TestExpandedPrivateKey(t *testing.T) {
+ root := RootXPrv([]byte{0xca, 0xfe})
+ verifyTestVector(t, "Root(cafe).xprv", root.hex(),
+ "a0cde08fd2ea06e16dd5d21e64ca0609fa1d719b79fed4245a5b8ada0242464cebbc2b9e1e989aca72d9766efd9b63ebcfc968027ef27cb786babb7897f9248a")
+ verifyTestVector(t, "Root(cafe).xprv.expandedkey", root.ExpandedPrivateKey().hex(),
+ "a0cde08fd2ea06e16dd5d21e64ca0609fa1d719b79fed4245a5b8ada0242464c1437c8234e21e43eb9c79df0ce370dc82d4c7a952ef317e716b0762146bb61a0")
+
+ child := root.Child([]byte{0xbe, 0xef}, false)
+ verifyTestVector(t, "Root(cafe)/beef.xprv", child.hex(),
+ "684df1aa25e0425c48c76392f42abc87a359ef2a2328ad31e53318128242464cf85916f4261b03f71afa64ad4bc2be4f335f15e433e815b45bbd15fcc7d1a864")
+ verifyTestVector(t, "Root(cafe)/beef.xprv.expandedkey", child.ExpandedPrivateKey().hex(),
+ "684df1aa25e0425c48c76392f42abc87a359ef2a2328ad31e53318128242464c0abdda57709eff7e9c60e0d4199065a6941122566c0a30ffa3ce0449d0582278")
+}
+
func TestChildKeys(t *testing.T) {
rootXPrv, err := NewXPrv(nil)
if err != nil {
}
for i := 0; i < 32; i++ {
- xpub[i] ^= 0xff
- if xpub.Verify(msg, sig) {
- t.Fatalf("altered %s should not verify signature from %s", xpubdesc, xprvdesc)
+ for mask := byte(1); mask != 0; mask <<= 1 {
+ xpub[i] ^= mask
+ if xpub.Verify(msg, sig) {
+ t.Fatalf("altered %s should not verify signature from %s", xpubdesc, xprvdesc)
+ }
+ xpub[i] ^= mask
}
- xpub[i] ^= 0xff
}
- for i := 0; i < len(msg); i++ {
- msg[i] ^= 0xff
- if xpub.Verify(msg, sig) {
- t.Fatalf("%s should not verify signature from %s against altered message", xpubdesc, xprvdesc)
+ // permute only 1/7th of the bits to make tests run faster
+ for i := 0; i < len(msg); i += 7 {
+ for mask := byte(1); mask != 0; mask <<= 1 {
+ msg[i] ^= mask
+ if xpub.Verify(msg, sig) {
+ t.Fatalf("%s should not verify signature from %s against altered message", xpubdesc, xprvdesc)
+ }
+ msg[i] ^= mask
}
- msg[i] ^= 0xff
}
for i := 0; i < len(sig); i++ {
- sig[i] ^= 0xff
- if xpub.Verify(msg, sig) {
- t.Fatalf("%s should not verify altered signature from %s", xpubdesc, xprvdesc)
+ for mask := byte(1); mask != 0; mask <<= 1 {
+ sig[i] ^= mask
+ if xpub.Verify(msg, sig) {
+ t.Fatalf("%s should not verify altered signature from %s", xpubdesc, xprvdesc)
+ }
+ sig[i] ^= mask
+ }
+ }
+}
+
+func verifyTestVector(t *testing.T, message string, got []byte, want string) {
+ if !bytes.Equal(got, []byte(want)) {
+ t.Errorf("ChainKD Test Vector: %s:\n got = %s\n want = %s", message, got, want)
+ }
+}
+
+func (xpub XPub) hex() []byte {
+ s, _ := xpub.MarshalText()
+ return s
+}
+
+func (xprv XPrv) hex() []byte {
+ s, _ := xprv.MarshalText()
+ return s
+}
+
+func (key ExpandedPrivateKey) hex() []byte {
+ hexBytes := make([]byte, hex.EncodedLen(len(key[:])))
+ hex.Encode(hexBytes, key[:])
+ return hexBytes
+}
+
+func TestBits(t *testing.T) {
+ for i := 0; i < 256; i++ {
+ root := RootXPrv([]byte{byte(i)})
+
+ rootbytes := root.Bytes()
+ if rootbytes[0]&7 != 0 {
+ t.Errorf("ChainKD root key must have low 3 bits set to '000'")
+ }
+ if (rootbytes[31] >> 5) != 2 {
+ t.Errorf("ChainKD root key must have high 3 bits set to '010'")
+ }
+
+ xprv := root
+ for d := 0; d < 1000; d++ { // at least after 1000 levels necessary bits are survived
+ xprv = xprv.Child([]byte("child"), false)
+ xprvbytes := xprv.Bytes()
+
+ if xprvbytes[0]&7 != 0 {
+ t.Errorf("ChainKD non-hardened child key must have low 3 bits set to '000'")
+ }
+ if xprvbytes[31]>>6 != 1 {
+ t.Errorf("ChainKD non-hardened child key must have high 2 bits set to '10' (LE)")
+ }
+
+ hchild := xprv.Child([]byte("hardened child"), true)
+ hchildbytes := hchild.Bytes()
+ if hchildbytes[0]&7 != 0 {
+ t.Errorf("ChainKD hardened key must have low 3 bits set to '000'")
+ }
+ if (hchildbytes[31] >> 5) != 2 {
+ t.Errorf("ChainKD hardened key must have high 3 bits set to '010'")
+ }
}
- sig[i] ^= 0xff
}
}
--- /dev/null
+// Package chainkd This is an extension to ed25519.Sign that is compatible with NaCl `crypto_sign`
+// function taking 64-byte expanded private key (where the left part is a pre-multiplied
+// scalar and the right part is "prefix" used for generating a nonce).
+//
+// Invariants:
+// 1) Expanded(PrivateKey).Sign() == PrivateKey.Sign()
+// 2) InnerSign(Expanded(PrivateKey)) == Sign(PrivateKey)
+package chainkd
+
+import (
+ "crypto"
+ "crypto/sha512"
+ "errors"
+ "io"
+ "strconv"
+
+ "github.com/bytom/crypto/ed25519"
+ "github.com/bytom/crypto/ed25519/internal/edwards25519"
+)
+
+const (
+ // ExpandedPrivateKeySize is the size, in bytes, of a "secret key" as defined in NaCl.
+ ExpandedPrivateKeySize = 64
+)
+
+// ExpandedPrivateKey is the type of NaCl secret keys. It implements crypto.Signer.
+type ExpandedPrivateKey []byte
+
+// Public returns the PublicKey corresponding to secret key.
+func (priv ExpandedPrivateKey) Public() crypto.PublicKey {
+ var A edwards25519.ExtendedGroupElement
+ var scalar [32]byte
+ copy(scalar[:], priv[:32])
+ edwards25519.GeScalarMultBase(&A, &scalar)
+ var publicKeyBytes [32]byte
+ A.ToBytes(&publicKeyBytes)
+ return ed25519.PublicKey(publicKeyBytes[:])
+}
+
+func expandEd25519PrivateKey(priv ed25519.PrivateKey) ExpandedPrivateKey {
+ digest := sha512.Sum512(priv[:32])
+ digest[0] &= 248
+ digest[31] &= 127
+ digest[31] |= 64
+ return ExpandedPrivateKey(digest[:])
+}
+
+// Sign signs the given message with expanded private key.
+// Ed25519 performs two passes over messages to be signed and therefore cannot
+// handle pre-hashed messages. Thus opts.HashFunc() must return zero to
+// indicate the message hasn't been hashed. This can be achieved by passing
+// crypto.Hash(0) as the value for opts.
+func (priv ExpandedPrivateKey) Sign(rand io.Reader, message []byte, opts crypto.SignerOpts) (signature []byte, err error) {
+ if opts.HashFunc() != crypto.Hash(0) {
+ return nil, errors.New("ed25519: cannot sign hashed message")
+ }
+
+ return Ed25519InnerSign(priv, message), nil
+}
+
+// Ed25519InnerSign signs the message with expanded private key and returns a signature.
+// It will panic if len(privateKey) is not ExpandedPrivateKeySize.
+func Ed25519InnerSign(privateKey ExpandedPrivateKey, message []byte) []byte {
+ if l := len(privateKey); l != ExpandedPrivateKeySize {
+ panic("ed25519: bad private key length: " + strconv.Itoa(l))
+ }
+
+ var messageDigest, hramDigest [64]byte
+
+ h := sha512.New()
+ h.Write(privateKey[32:])
+ h.Write(message)
+ h.Sum(messageDigest[:0])
+
+ var messageDigestReduced [32]byte
+ edwards25519.ScReduce(&messageDigestReduced, &messageDigest)
+ var R edwards25519.ExtendedGroupElement
+ edwards25519.GeScalarMultBase(&R, &messageDigestReduced)
+
+ var encodedR [32]byte
+ R.ToBytes(&encodedR)
+
+ publicKey := privateKey.Public().(ed25519.PublicKey)
+ h.Reset()
+ h.Write(encodedR[:])
+ h.Write(publicKey[:])
+ h.Write(message)
+ h.Sum(hramDigest[:0])
+ var hramDigestReduced [32]byte
+ edwards25519.ScReduce(&hramDigestReduced, &hramDigest)
+
+ var sk [32]byte
+ copy(sk[:], privateKey[:32])
+ var s [32]byte
+ edwards25519.ScMulAdd(&s, &hramDigestReduced, &sk, &messageDigestReduced)
+
+ signature := make([]byte, ed25519.SignatureSize)
+ copy(signature[:], encodedR[:])
+ copy(signature[32:], s[:])
+
+ return signature
+}
--- /dev/null
+package chainkd
+
+import (
+ "bytes"
+ "crypto"
+ "testing"
+
+ "github.com/bytom/crypto/ed25519"
+)
+
+// Testing basic InnerSign+Verify and the invariants:
+// 1) Expand(PrivateKey).Sign() == PrivateKey.Sign()
+// 2) InnerSign(Expand(PrivateKey)) == Sign(PrivateKey)
+
+type zeroReader struct{}
+
+func (zeroReader) Read(buf []byte) (int, error) {
+ for i := range buf {
+ buf[i] = 0
+ }
+ return len(buf), nil
+}
+
+func TestInnerSignVerify(t *testing.T) {
+ var zero zeroReader
+ public, private, _ := ed25519.GenerateKey(zero)
+ expprivate := expandEd25519PrivateKey(private)
+
+ message := []byte("test message")
+ sig := Ed25519InnerSign(expprivate, message)
+ if !ed25519.Verify(public, message, sig) {
+ t.Errorf("valid signature rejected")
+ }
+
+ wrongMessage := []byte("wrong message")
+ if ed25519.Verify(public, wrongMessage, sig) {
+ t.Errorf("signature of different message accepted")
+ }
+}
+
+func TestExpandedKeySignerInterfaceInvariant(t *testing.T) {
+ var zero zeroReader
+ public, private, _ := ed25519.GenerateKey(zero)
+ expprivate := expandEd25519PrivateKey(private)
+
+ signer1 := crypto.Signer(private)
+ signer2 := crypto.Signer(expprivate)
+
+ publicInterface1 := signer1.Public()
+ publicInterface2 := signer2.Public()
+ public1, ok := publicInterface1.(ed25519.PublicKey)
+ if !ok {
+ t.Fatalf("expected PublicKey from Public() but got %T", publicInterface1)
+ }
+ public2, ok := publicInterface2.(ed25519.PublicKey)
+ if !ok {
+ t.Fatalf("expected PublicKey from Public() but got %T", publicInterface2)
+ }
+
+ if !bytes.Equal(public, public1) {
+ t.Errorf("public keys do not match: original:%x vs Public():%x", public, public1)
+ }
+ if !bytes.Equal(public, public2) {
+ t.Errorf("public keys do not match: original:%x vs Public():%x", public, public2)
+ }
+
+ message := []byte("message")
+ var noHash crypto.Hash
+ signature1, err := signer1.Sign(zero, message, noHash)
+ if err != nil {
+ t.Fatalf("error from Sign(): %s", err)
+ }
+ signature2, err := signer2.Sign(zero, message, noHash)
+ if err != nil {
+ t.Fatalf("error from Sign(): %s", err)
+ }
+ if !bytes.Equal(signature1[:], signature2[:]) {
+ t.Errorf(".Sign() should return identical signatures for Signer(privkey) and Signer(Expand(privkey))")
+ }
+ if !ed25519.Verify(public, message, signature1) {
+ t.Errorf("Verify failed on signature from Sign()")
+ }
+}
+
+func TestInnerSignInvariant(t *testing.T) {
+ var zero zeroReader
+ _, private, _ := ed25519.GenerateKey(zero)
+ expprivate := expandEd25519PrivateKey(private)
+
+ message := []byte("test message")
+ sig1 := ed25519.Sign(private, message)
+ sig2 := Ed25519InnerSign(expprivate, message)
+
+ if !bytes.Equal(sig1[:], sig2[:]) {
+ t.Errorf("InnerSign(Expand(privkey)) must return the same as Sign(privkey)")
+ }
+}
import (
"bytes"
- "reflect"
- "testing"
-
"encoding/hex"
"encoding/json"
+ "reflect"
+ "testing"
)
func TestMarshalingFuncs(t *testing.T) {
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