use script for key derivation (#17594)

Use scrypt when creating keys for AES encrypted invitations for shared channels.
2021-05-20 13:43:34 -04:00
--- a/model/remote_cluster.go
+++ b/model/remote_cluster.go
@@ -7,12 +7,14 @@ import (
 	"crypto/aes"
 	"crypto/cipher"
 	"crypto/rand"
-	"crypto/sha512"
 	"encoding/json"
+	"errors"
 	"io"
 	"net/http"
 	"regexp"
 	"strings"
+
+	"golang.org/x/crypto/scrypt"
 )

 const (
@@ -272,8 +274,17 @@ func (rci *RemoteClusterInvite) Encrypt(password string) ([]byte, error) {
 		return nil, err
 	}

-	// hash the pasword to 32 bytes for AES256
-	key := sha512.Sum512_256([]byte(password))
+	// create random salt to be prepended to the blob.
+	salt := make([]byte, 16)
+	if _, err = io.ReadFull(rand.Reader, salt); err != nil {
+		return nil, err
+	}
+
+	key, err := scrypt.Key([]byte(password), salt, 32768, 8, 1, 32)
+	if err != nil {
+		return nil, err
+	}
+
 	block, err := aes.NewCipher(key[:])
 	if err != nil {
 		return nil, err
@@ -291,12 +302,25 @@ func (rci *RemoteClusterInvite) Encrypt(password string) ([]byte, error) {
 	}

 	// prefix the nonce to the cyphertext so we don't need to keep track of it.
-	return gcm.Seal(nonce, nonce, raw, nil), nil
+	sealed := gcm.Seal(nonce, nonce, raw, nil)
+
+	return append(salt, sealed...), nil
 }

 func (rci *RemoteClusterInvite) Decrypt(encrypted []byte, password string) error {
-	// hash the pasword to 32 bytes for AES256
-	key := sha512.Sum512_256([]byte(password))
+	if len(encrypted) <= 16 {
+		return errors.New("invalid length")
+	}
+
+	// first 16 bytes is the salt that was used to derive a key
+	salt := encrypted[:16]
+	encrypted = encrypted[16:]
+
+	key, err := scrypt.Key([]byte(password), salt, 32768, 8, 1, 32)
+	if err != nil {
+		return err
+	}
+
 	block, err := aes.NewCipher(key[:])
 	if err != nil {
 		return err
--- a/model/remote_cluster_test.go
+++ b/model/remote_cluster_test.go
@@ -132,9 +132,9 @@ func TestRemoteClusterInviteEncryption(t *testing.T) {
 		password   string
 		invite     RemoteClusterInvite
 	}{
-		{name: "empty password", badDecrypt: false, password: "", invite: RemoteClusterInvite{RemoteId: NewId(), SiteURL: "https://example.com:8065", Token: NewId()}},
-		{name: "good password", badDecrypt: false, password: "Ultra secret password!", invite: RemoteClusterInvite{RemoteId: NewId(), SiteURL: "https://example.com:8065", Token: NewId()}},
-		{name: "bad decrypt", badDecrypt: true, password: "correct horse battery staple", invite: RemoteClusterInvite{RemoteId: NewId(), SiteURL: "https://example.com:8065", Token: NewId()}},
+		{name: "empty password", badDecrypt: false, password: "", invite: makeInvite("https://example.com:8065")},
+		{name: "good password", badDecrypt: false, password: "Ultra secret password!", invite: makeInvite("https://example.com:8065")},
+		{name: "bad decrypt", badDecrypt: true, password: "correct horse battery staple", invite: makeInvite("https://example.com:8065")},
 	}

 	for _, tt := range testData {
@@ -156,3 +156,12 @@ func TestRemoteClusterInviteEncryption(t *testing.T) {
 		}
 	}
 }
+
+func makeInvite(url string) RemoteClusterInvite {
+	return RemoteClusterInvite{
+		RemoteId:     NewId(),
+		RemoteTeamId: NewId(),
+		SiteURL:      url,
+		Token:        NewId(),
+	}
+}
--- a/vendor/golang.org/x/crypto/pbkdf2/pbkdf2.go
+++ b/vendor/golang.org/x/crypto/pbkdf2/pbkdf2.go
@@ -0,0 +1,77 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+Package pbkdf2 implements the key derivation function PBKDF2 as defined in RFC
+2898 / PKCS #5 v2.0.
+
+A key derivation function is useful when encrypting data based on a password
+or any other not-fully-random data. It uses a pseudorandom function to derive
+a secure encryption key based on the password.
+
+While v2.0 of the standard defines only one pseudorandom function to use,
+HMAC-SHA1, the drafted v2.1 specification allows use of all five FIPS Approved
+Hash Functions SHA-1, SHA-224, SHA-256, SHA-384 and SHA-512 for HMAC. To
+choose, you can pass the `New` functions from the different SHA packages to
+pbkdf2.Key.
+*/
+package pbkdf2 // import "golang.org/x/crypto/pbkdf2"
+
+import (
+	"crypto/hmac"
+	"hash"
+)
+
+// Key derives a key from the password, salt and iteration count, returning a
+// []byte of length keylen that can be used as cryptographic key. The key is
+// derived based on the method described as PBKDF2 with the HMAC variant using
+// the supplied hash function.
+//
+// For example, to use a HMAC-SHA-1 based PBKDF2 key derivation function, you
+// can get a derived key for e.g. AES-256 (which needs a 32-byte key) by
+// doing:
+//
+// 	dk := pbkdf2.Key([]byte("some password"), salt, 4096, 32, sha1.New)
+//
+// Remember to get a good random salt. At least 8 bytes is recommended by the
+// RFC.
+//
+// Using a higher iteration count will increase the cost of an exhaustive
+// search but will also make derivation proportionally slower.
+func Key(password, salt []byte, iter, keyLen int, h func() hash.Hash) []byte {
+	prf := hmac.New(h, password)
+	hashLen := prf.Size()
+	numBlocks := (keyLen + hashLen - 1) / hashLen
+
+	var buf [4]byte
+	dk := make([]byte, 0, numBlocks*hashLen)
+	U := make([]byte, hashLen)
+	for block := 1; block <= numBlocks; block++ {
+		// N.B.: || means concatenation, ^ means XOR
+		// for each block T_i = U_1 ^ U_2 ^ ... ^ U_iter
+		// U_1 = PRF(password, salt || uint(i))
+		prf.Reset()
+		prf.Write(salt)
+		buf[0] = byte(block >> 24)
+		buf[1] = byte(block >> 16)
+		buf[2] = byte(block >> 8)
+		buf[3] = byte(block)
+		prf.Write(buf[:4])
+		dk = prf.Sum(dk)
+		T := dk[len(dk)-hashLen:]
+		copy(U, T)
+
+		// U_n = PRF(password, U_(n-1))
+		for n := 2; n <= iter; n++ {
+			prf.Reset()
+			prf.Write(U)
+			U = U[:0]
+			U = prf.Sum(U)
+			for x := range U {
+				T[x] ^= U[x]
+			}
+		}
+	}
+	return dk[:keyLen]
+}
--- a/vendor/golang.org/x/crypto/scrypt/scrypt.go
+++ b/vendor/golang.org/x/crypto/scrypt/scrypt.go
@@ -0,0 +1,212 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package scrypt implements the scrypt key derivation function as defined in
+// Colin Percival's paper "Stronger Key Derivation via Sequential Memory-Hard
+// Functions" (https://www.tarsnap.com/scrypt/scrypt.pdf).
+package scrypt // import "golang.org/x/crypto/scrypt"
+
+import (
+	"crypto/sha256"
+	"encoding/binary"
+	"errors"
+	"math/bits"
+
+	"golang.org/x/crypto/pbkdf2"
+)
+
+const maxInt = int(^uint(0) >> 1)
+
+// blockCopy copies n numbers from src into dst.
+func blockCopy(dst, src []uint32, n int) {
+	copy(dst, src[:n])
+}
+
+// blockXOR XORs numbers from dst with n numbers from src.
+func blockXOR(dst, src []uint32, n int) {
+	for i, v := range src[:n] {
+		dst[i] ^= v
+	}
+}
+
+// salsaXOR applies Salsa20/8 to the XOR of 16 numbers from tmp and in,
+// and puts the result into both tmp and out.
+func salsaXOR(tmp *[16]uint32, in, out []uint32) {
+	w0 := tmp[0] ^ in[0]
+	w1 := tmp[1] ^ in[1]
+	w2 := tmp[2] ^ in[2]
+	w3 := tmp[3] ^ in[3]
+	w4 := tmp[4] ^ in[4]
+	w5 := tmp[5] ^ in[5]
+	w6 := tmp[6] ^ in[6]
+	w7 := tmp[7] ^ in[7]
+	w8 := tmp[8] ^ in[8]
+	w9 := tmp[9] ^ in[9]
+	w10 := tmp[10] ^ in[10]
+	w11 := tmp[11] ^ in[11]
+	w12 := tmp[12] ^ in[12]
+	w13 := tmp[13] ^ in[13]
+	w14 := tmp[14] ^ in[14]
+	w15 := tmp[15] ^ in[15]
+
+	x0, x1, x2, x3, x4, x5, x6, x7, x8 := w0, w1, w2, w3, w4, w5, w6, w7, w8
+	x9, x10, x11, x12, x13, x14, x15 := w9, w10, w11, w12, w13, w14, w15
+
+	for i := 0; i < 8; i += 2 {
+		x4 ^= bits.RotateLeft32(x0+x12, 7)
+		x8 ^= bits.RotateLeft32(x4+x0, 9)
+		x12 ^= bits.RotateLeft32(x8+x4, 13)
+		x0 ^= bits.RotateLeft32(x12+x8, 18)
+
+		x9 ^= bits.RotateLeft32(x5+x1, 7)
+		x13 ^= bits.RotateLeft32(x9+x5, 9)
+		x1 ^= bits.RotateLeft32(x13+x9, 13)
+		x5 ^= bits.RotateLeft32(x1+x13, 18)
+
+		x14 ^= bits.RotateLeft32(x10+x6, 7)
+		x2 ^= bits.RotateLeft32(x14+x10, 9)
+		x6 ^= bits.RotateLeft32(x2+x14, 13)
+		x10 ^= bits.RotateLeft32(x6+x2, 18)
+
+		x3 ^= bits.RotateLeft32(x15+x11, 7)
+		x7 ^= bits.RotateLeft32(x3+x15, 9)
+		x11 ^= bits.RotateLeft32(x7+x3, 13)
+		x15 ^= bits.RotateLeft32(x11+x7, 18)
+
+		x1 ^= bits.RotateLeft32(x0+x3, 7)
+		x2 ^= bits.RotateLeft32(x1+x0, 9)
+		x3 ^= bits.RotateLeft32(x2+x1, 13)
+		x0 ^= bits.RotateLeft32(x3+x2, 18)
+
+		x6 ^= bits.RotateLeft32(x5+x4, 7)
+		x7 ^= bits.RotateLeft32(x6+x5, 9)
+		x4 ^= bits.RotateLeft32(x7+x6, 13)
+		x5 ^= bits.RotateLeft32(x4+x7, 18)
+
+		x11 ^= bits.RotateLeft32(x10+x9, 7)
+		x8 ^= bits.RotateLeft32(x11+x10, 9)
+		x9 ^= bits.RotateLeft32(x8+x11, 13)
+		x10 ^= bits.RotateLeft32(x9+x8, 18)
+
+		x12 ^= bits.RotateLeft32(x15+x14, 7)
+		x13 ^= bits.RotateLeft32(x12+x15, 9)
+		x14 ^= bits.RotateLeft32(x13+x12, 13)
+		x15 ^= bits.RotateLeft32(x14+x13, 18)
+	}
+	x0 += w0
+	x1 += w1
+	x2 += w2
+	x3 += w3
+	x4 += w4
+	x5 += w5
+	x6 += w6
+	x7 += w7
+	x8 += w8
+	x9 += w9
+	x10 += w10
+	x11 += w11
+	x12 += w12
+	x13 += w13
+	x14 += w14
+	x15 += w15
+
+	out[0], tmp[0] = x0, x0
+	out[1], tmp[1] = x1, x1
+	out[2], tmp[2] = x2, x2
+	out[3], tmp[3] = x3, x3
+	out[4], tmp[4] = x4, x4
+	out[5], tmp[5] = x5, x5
+	out[6], tmp[6] = x6, x6
+	out[7], tmp[7] = x7, x7
+	out[8], tmp[8] = x8, x8
+	out[9], tmp[9] = x9, x9
+	out[10], tmp[10] = x10, x10
+	out[11], tmp[11] = x11, x11
+	out[12], tmp[12] = x12, x12
+	out[13], tmp[13] = x13, x13
+	out[14], tmp[14] = x14, x14
+	out[15], tmp[15] = x15, x15
+}
+
+func blockMix(tmp *[16]uint32, in, out []uint32, r int) {
+	blockCopy(tmp[:], in[(2*r-1)*16:], 16)
+	for i := 0; i < 2*r; i += 2 {
+		salsaXOR(tmp, in[i*16:], out[i*8:])
+		salsaXOR(tmp, in[i*16+16:], out[i*8+r*16:])
+	}
+}
+
+func integer(b []uint32, r int) uint64 {
+	j := (2*r - 1) * 16
+	return uint64(b[j]) | uint64(b[j+1])<<32
+}
+
+func smix(b []byte, r, N int, v, xy []uint32) {
+	var tmp [16]uint32
+	R := 32 * r
+	x := xy
+	y := xy[R:]
+
+	j := 0
+	for i := 0; i < R; i++ {
+		x[i] = binary.LittleEndian.Uint32(b[j:])
+		j += 4
+	}
+	for i := 0; i < N; i += 2 {
+		blockCopy(v[i*R:], x, R)
+		blockMix(&tmp, x, y, r)
+
+		blockCopy(v[(i+1)*R:], y, R)
+		blockMix(&tmp, y, x, r)
+	}
+	for i := 0; i < N; i += 2 {
+		j := int(integer(x, r) & uint64(N-1))
+		blockXOR(x, v[j*R:], R)
+		blockMix(&tmp, x, y, r)
+
+		j = int(integer(y, r) & uint64(N-1))
+		blockXOR(y, v[j*R:], R)
+		blockMix(&tmp, y, x, r)
+	}
+	j = 0
+	for _, v := range x[:R] {
+		binary.LittleEndian.PutUint32(b[j:], v)
+		j += 4
+	}
+}
+
+// Key derives a key from the password, salt, and cost parameters, returning
+// a byte slice of length keyLen that can be used as cryptographic key.
+//
+// N is a CPU/memory cost parameter, which must be a power of two greater than 1.
+// r and p must satisfy r * p < 2³⁰. If the parameters do not satisfy the
+// limits, the function returns a nil byte slice and an error.
+//
+// For example, you can get a derived key for e.g. AES-256 (which needs a
+// 32-byte key) by doing:
+//
+//      dk, err := scrypt.Key([]byte("some password"), salt, 32768, 8, 1, 32)
+//
+// The recommended parameters for interactive logins as of 2017 are N=32768, r=8
+// and p=1. The parameters N, r, and p should be increased as memory latency and
+// CPU parallelism increases; consider setting N to the highest power of 2 you
+// can derive within 100 milliseconds. Remember to get a good random salt.
+func Key(password, salt []byte, N, r, p, keyLen int) ([]byte, error) {
+	if N <= 1 || N&(N-1) != 0 {
+		return nil, errors.New("scrypt: N must be > 1 and a power of 2")
+	}
+	if uint64(r)*uint64(p) >= 1<<30 || r > maxInt/128/p || r > maxInt/256 || N > maxInt/128/r {
+		return nil, errors.New("scrypt: parameters are too large")
+	}
+
+	xy := make([]uint32, 64*r)
+	v := make([]uint32, 32*N*r)
+	b := pbkdf2.Key(password, salt, 1, p*128*r, sha256.New)
+
+	for i := 0; i < p; i++ {
+		smix(b[i*128*r:], r, N, v, xy)
+	}
+
+	return pbkdf2.Key(password, b, 1, keyLen, sha256.New), nil
+}
--- a/vendor/modules.txt
+++ b/vendor/modules.txt
@@ -197,8 +197,6 @@ github.com/francoispqt/gojay
 # github.com/fsnotify/fsnotify v1.4.9
 ## explicit
 github.com/fsnotify/fsnotify
-# github.com/getkin/kin-openapi v0.49.0
-## explicit
 # github.com/getsentry/sentry-go v0.10.0
 ## explicit
 github.com/getsentry/sentry-go
@@ -401,8 +399,6 @@ github.com/mattermost/ldap
 github.com/mattermost/logr
 github.com/mattermost/logr/format
 github.com/mattermost/logr/target
-# github.com/mattermost/mattermost-govet v0.0.0-20210226164958-a9556728767b
-## explicit
 # github.com/mattermost/rsc v0.0.0-20160330161541-bbaefb05eaa0
 ## explicit
 github.com/mattermost/rsc/gf256
@@ -746,6 +742,8 @@ golang.org/x/crypto/openpgp/elgamal
 golang.org/x/crypto/openpgp/errors
 golang.org/x/crypto/openpgp/packet
 golang.org/x/crypto/openpgp/s2k
+golang.org/x/crypto/pbkdf2
+golang.org/x/crypto/scrypt
 # golang.org/x/image v0.0.0-20210220032944-ac19c3e999fb
 ## explicit
 golang.org/x/image/bmp