add scrypt kdf to keyfile and implement test for it

eth/keyfile/keyfile.nim

@@ -9,7 +9,7 @@
 
 {.push raises: [Defect].}
 
-import nimcrypto/[bcmode, hmac, rijndael, pbkdf2, sha2, sysrand, utils, keccak],
+import nimcrypto/[bcmode, hmac, rijndael, pbkdf2, sha2, sysrand, utils, keccak, scrypt],
        eth/keys, json, uuid, strutils, stew/results
 
 export results
@@ -43,6 +43,8 @@ type
     CipherNotSupported    = "kf: `cipher` parameter is not supported"
     IncorrectMac          = "kf: `mac` verification failed"
     IncorrectPrivateKey   = "kf: incorrect private key"
+    IncorrectN            = "kf: incorrect N value for scrypt"
+    ScryptBadParam        = "kf: bad scrypt's parameters"
     OsError               = "kf: OS specific error"
     JsonError             = "kf: JSON encoder/decoder error"
 
@@ -59,6 +61,32 @@ type
     CipherNoSupport,    ## Cipher not supported
     AES128CTR           ## AES-128-CTR
 
+  CipherParams = object
+    iv: seq[byte]
+
+  Cipher = object
+    kind: CryptKind
+    params: CipherParams
+    text: seq[byte]
+
+  Crypto = object
+    kind: KdfKind
+    cipher: Cipher
+    kdfParams: JsonNode
+    mac: seq[byte]
+
+  ScryptParams* = object
+    dklen: int
+    n, p, r: int
+    salt: string
+
+  Pbkdf2Params* = object
+    dklen: int
+    c: int
+    prf: HashKind
+    salt: string
+
+  DKey = array[DKLen, byte]
   KfResult*[T] = Result[T, KeyFileError]
 
 proc mapErrTo[T, E](r: Result[T, E], v: static KeyFileError): KfResult[T] =
@@ -113,9 +141,9 @@ proc deriveKey(password: string,
                salt: string,
                kdfkind: KdfKind,
                hashkind: HashKind,
-               workfactor: int): KfResult[array[DKLen, byte]] =
+               workfactor: int): KfResult[DKey] =
   if kdfkind == PBKDF2:
-    var output: array[DKLen, byte]
+    var output: DKey
     var c = if workfactor == 0: Pbkdf2WorkFactor else: workfactor
     case hashkind
     of HashSHA2_224:
@@ -171,6 +199,16 @@ proc deriveKey(password: string,
   else:
     err(NotImplemented)
 
+proc deriveKey(password: string, salt: string,
+               workFactor, r, p: int): KfResult[DKey] =
+
+  let wf = if workFactor == 0: ScryptWorkFactor else: workFactor
+  var output: DKey
+  if scrypt(password, salt, wf, r, p, output) == 0:
+    return err(ScryptBadParam)
+
+  result = ok(output)
+
 proc encryptKey(seckey: PrivateKey,
                 cryptkind: CryptKind,
                 key: openarray[byte],
@@ -279,11 +317,11 @@ proc createKeyFileJson*(seckey: PrivateKey,
 
   let u = ? uuidGenerate().mapErrTo(UuidError)
 
-  if kdfkind != PBKDF2:
-    return err(NotImplemented)
-
   let
-    dkey = ? deriveKey(password, saltstr, kdfkind, HashSHA2_256, workfactor)
+    dkey = case kdfkind
+           of PBKDF2: ? deriveKey(password, saltstr, kdfkind, HashSHA2_256, workfactor)
+           of SCRYPT: ? deriveKey(password, saltstr, workfactor, ScryptR, ScryptP)
+
     ciphertext = ? encryptKey(seckey, cryptkind, dkey, iv)
 
   var ctx: keccak256
@@ -313,11 +351,8 @@ proc createKeyFileJson*(seckey: PrivateKey,
     }
   )
 
-proc decodeKeyFileJson*(j: JsonNode,
+proc decodeCrypto(n: JsonNode): KfResult[Crypto] =
-                        password: string): KfResult[PrivateKey] =
+  var crypto = n.getOrDefault("crypto")
-  ## Decode private key into ``seckey`` from keyfile json object ``j`` using
-  ## password string ``password``.
-  var crypto = j.getOrDefault("crypto")
   if isNil(crypto):
     return err(MalformedError)
 
@@ -325,57 +360,122 @@ proc decodeKeyFileJson*(j: JsonNode,
   if isNil(kdf):
     return err(MalformedError)
 
+  var c: Crypto
+  case kdf.getStr()
+  of "pbkdf2": c.kind = PBKDF2
+  of "scrypt": c.kind = SCRYPT
+  else: return err(KdfNotSupported)
+
   var cipherparams = crypto.getOrDefault("cipherparams")
   if isNil(cipherparams):
     return err(MalformedError)
 
-  if kdf.getStr() == "pbkdf2":
+  c.cipher.kind = getCipher(crypto.getOrDefault("cipher").getStr())
-    var params = crypto.getOrDefault("kdfparams")
+  c.cipher.params.iv = decodeHex(cipherparams.getOrDefault("iv").getStr())
+  c.cipher.text = decodeHex(crypto.getOrDefault("ciphertext").getStr())
+  c.mac = decodeHex(crypto.getOrDefault("mac").getStr())
+  c.kdfParams = crypto.getOrDefault("kdfparams")
 
-    if isNil(params):
+  if c.cipher.kind == CipherNoSupport:
+    return err(CipherNotSupported)
+  if len(c.cipher.text) == 0:
+    return err(EmptyCiphertext)
+  if len(c.cipher.text) != KeyLength:
+      return err(IncorrectPrivateKey)
+  if len(c.mac) == 0:
+    return err(EmptyMac)
+  if isNil(c.kdfParams):
     return err(MalformedError)
 
-    var salt = decodeSalt(params.getOrDefault("salt").getStr())
+  result = ok(c)
-    var ciphertext = decodeHex(crypto.getOrDefault("ciphertext").getStr())
-    var mactext = decodeHex(crypto.getOrDefault("mac").getStr())
-    var cryptkind = getCipher(crypto.getOrDefault("cipher").getStr())
-    var iv = decodeHex(cipherparams.getOrDefault("iv").getStr())
 
-    if len(salt) == 0:
+proc decodePbkdf2Params(params: JsonNode): KfResult[Pbkdf2Params] =
+  var p: Pbkdf2Params
+  p.salt = decodeSalt(params.getOrDefault("salt").getStr())
+  if len(p.salt) == 0:
     return err(EmptySalt)
-    if len(ciphertext) == 0:
-      return err(EmptyCiphertext)
-    if len(mactext) == 0:
-      return err(EmptyMac)
-    if cryptkind == CipherNoSupport:
-      return err(CipherNotSupported)
 
-    var dklen = params.getOrDefault("dklen").getInt()
+  p.dklen = params.getOrDefault("dklen").getInt()
-    var c = params.getOrDefault("c").getInt()
+  p.c = params.getOrDefault("c").getInt()
-    var hash = getPrfHash(params.getOrDefault("prf").getStr())
+  p.prf = getPrfHash(params.getOrDefault("prf").getStr())
 
-    if hash == HashNoSupport:
+  if p.prf == HashNoSupport:
     return err(PrfNotSupported)
-    if dklen == 0 or dklen > MaxDKLen:
+  if p.dklen == 0 or p.dklen > MaxDKLen:
     return err(IncorrectDKLen)
-    if len(ciphertext) != KeyLength:
+  result = ok(p)
-      return err(IncorrectPrivateKey)
 
-    let dkey = ? deriveKey(password, salt, PBKDF2, hash, c)
+proc decodeScryptParams(params: JsonNode): KfResult[ScryptParams] =
+  var p: ScryptParams
+  p.salt = decodeSalt(params.getOrDefault("salt").getStr())
+  if len(p.salt) == 0:
+    return err(EmptySalt)
 
+  p.dklen = params.getOrDefault("dklen").getInt()
+  p.n = params.getOrDefault("n").getInt()
+  p.p = params.getOrDefault("p").getInt()
+  p.r = params.getOrDefault("r").getInt()
+
+  if p.n <= 1 or (p.n and (p.n-1)) != 0:
+    return err(IncorrectN)
+  if p.dklen == 0 or p.dklen > MaxDKLen:
+    return err(IncorrectDKLen)
+
+  const
+    maxInt = high(int64)
+    maxIntd128 = maxInt div 128
+    maxIntd256 = maxInt div 256
+
+  let
+    badParam1 = uint64(p.r)*uint64(p.p) >= 1 shl 30
+    badParam2 = p.r > maxIntd128 div p.p
+    badParam3 = p.r > maxIntd256
+    badParam4 = p.n > maxIntd128 div p.r
+
+  if badParam1 or badParam2 or badParam3 or badParam4:
+    return err(ScryptBadParam)
+
+  result = ok(p)
+
+func decryptPrivateKey(crypto: Crypto, dkey: DKey): KfResult[PrivateKey] =
   var ctx: keccak256
   ctx.init()
   ctx.update(toOpenArray(dkey, 16, 31))
-    ctx.update(ciphertext)
+  ctx.update(crypto.cipher.text)
   var mac = ctx.finish()
-    if not compareMac(mac.data, mactext):
+  if not compareMac(mac.data, crypto.mac):
     return err(IncorrectMac)
 
-    let plaintext = ? decryptKey(ciphertext, cryptkind, dkey, iv)
+  let plaintext = ? decryptKey(crypto.cipher.text, crypto.cipher.kind, dkey, crypto.cipher.params.iv)
-
   PrivateKey.fromRaw(plaintext).mapErrTo(IncorrectPrivateKey)
-  else:
+
-    err(KdfNotSupported)
+proc decodeKeyFileJson*(j: JsonNode,
+                        password: string): KfResult[PrivateKey] =
+  ## Decode private key into ``seckey`` from keyfile json object ``j`` using
+  ## password string ``password``.
+  let res = decodeCrypto(j)
+  if res.isErr:
+    return err(res.error)
+  let crypto = res.get()
+
+  case crypto.kind
+  of PBKDF2:
+    let res = decodePbkdf2Params(crypto.kdfParams)
+    if res.isErr:
+      return err(res.error)
+
+    let params = res.get()
+    let dkey = ? deriveKey(password, params.salt, PBKDF2, params.prf, params.c)
+    result = decryptPrivateKey(crypto, dkey)
+
+  of SCRYPT:
+    let res = decodeScryptParams(crypto.kdfParams)
+    if res.isErr:
+      return err(res.error)
+
+    let params = res.get()
+    let dkey = ? deriveKey(password, params.salt, params.n, params.r, params.p)
+    result = decryptPrivateKey(crypto, dkey)
 
 proc loadKeyFile*(pathname: string,
                   password: string): KfResult[PrivateKey] =

tests/keyfile/test_keyfile.nim

@@ -84,6 +84,83 @@ var TestVectors = [
     "name": "evilnonce",
     "password": "bar",
     "priv": "0202020202020202020202020202020202020202020202020202020202020202"
+  },
+  %*{
+    "keyfile": {
+      "version" : 3,
+      "crypto" : {
+          "cipher" : "aes-128-ctr",
+          "cipherparams" : {
+              "iv" : "83dbcc02d8ccb40e466191a123791e0e"
+          },
+          "ciphertext" : "d172bf743a674da9cdad04534d56926ef8358534d458fffccd4e6ad2fbde479c",
+          "kdf" : "scrypt",
+          "kdfparams" : {
+              "dklen" : 32,
+              "n" : 262144,
+              "r" : 1,
+              "p" : 8,
+              "salt" : "ab0c7876052600dd703518d6fc3fe8984592145b591fc8fb5c6d43190334ba19"
+          },
+          "mac" : "2103ac29920d71da29f15d75b4a16dbe95cfd7ff8faea1056c33131d846e3097"
+      },
+      "id" : "3198bc9c-6672-5ab3-d995-4942343ae5b6"
+    },
+    "name" : "test2",
+    "password": "testpassword",
+    "priv": "7a28b5ba57c53603b0b07b56bba752f7784bf506fa95edc395f5cf6c7514fe9d"
+  },
+  %*{
+    "keyfile": {
+      "version": 3,
+      "address": "460121576cc7df020759730751f92bd62fd78dd6",
+      "crypto": {
+          "ciphertext": "54ae683c6287fa3d58321f09d56e26d94e58a00d4f90bdd95782ae0e4aab618b",
+          "cipherparams": {
+              "iv": "681679cdb125bba9495d068b002816a4"
+          },
+          "cipher": "aes-128-ctr",
+          "kdf": "scrypt",
+          "kdfparams": {
+              "dklen": 32,
+              "salt": "c3407f363fce02a66e3c4bf4a8f6b7da1c1f54266cef66381f0625c251c32785",
+              "n": 8192,
+              "r": 8,
+              "p": 1
+          },
+          "mac": "dea6bdf22a2f522166ed82808c22a6311e84c355f4bbe100d4260483ff675a46"
+      },
+      "id": "0eb785e0-340a-4290-9c42-90a11973ee47"
+    },
+    "name": "mycrypto",
+    "password": "foobartest121",
+    "priv": "05a4d3eb46c742cb8850440145ce70cbc80b59f891cf5f50fd3e9c280b50c4e4"
+  },
+  %*{
+    "keyfile": {
+        "crypto": {
+            "cipher": "aes-128-ctr",
+            "cipherparams": {
+                "iv": "7e7b02d2b4ef45d6c98cb885e75f48d5",
+            },
+            "ciphertext": "a7a5743a6c7eb3fa52396bd3fd94043b79075aac3ccbae8e62d3af94db00397c",
+            "kdf": "scrypt",
+            "kdfparams": {
+                "dklen": 32,
+                "n": 8192,
+                "p": 1,
+                "r": 8,
+                "salt": "247797c7a357b707a3bdbfaa55f4c553756bca09fec20ddc938e7636d21e4a20",
+            },
+            "mac": "5a3ba5bebfda2c384586eda5fcda9c8397d37c9b0cc347fea86525cf2ea3a468",
+        },
+        "address": "0b6f2de3dee015a95d3330dcb7baf8e08aa0112d",
+        "id": "3c8efdd6-d538-47ec-b241-36783d3418b9",
+        "version": 3
+    },
+    "password": "moomoocow",
+    "priv": "21eac69b9a52f466bfe9047f0f21c9caf3a5cdaadf84e2750a9b3265d450d481",
+    "name": "eth-keyfile-conftest"
   }
 ]
 
@@ -115,6 +192,39 @@ suite "KeyFile test suite":
                         "wrongpassword")
     check:
       seckey.error == KeyFileError.IncorrectMac
+
+
+  test "KeyStoreTests/basic_tests.json test2":
+    var expectkey = PrivateKey.fromHex(TestVectors[3].getOrDefault("priv").getStr())[]
+    let seckey =
+      decodeKeyFileJson(TestVectors[3].getOrDefault("keyfile"),
+                        TestVectors[3].getOrDefault("password").getStr())[]
+    check:
+      seckey.toRaw == expectkey.toRaw
+
+  test "KeyStoreTests/basic_tests.json mycrypto":
+    var expectkey = PrivateKey.fromHex(TestVectors[4].getOrDefault("priv").getStr())[]
+    let seckey =
+      decodeKeyFileJson(TestVectors[4].getOrDefault("keyfile"),
+                        TestVectors[4].getOrDefault("password").getStr())[]
+    check:
+      seckey.toRaw == expectkey.toRaw
+
+  test "eth-key/conftest.py":
+    var expectkey = PrivateKey.fromHex(TestVectors[5].getOrDefault("priv").getStr())[]
+    let seckey =
+      decodeKeyFileJson(TestVectors[5].getOrDefault("keyfile"),
+                        TestVectors[5].getOrDefault("password").getStr())[]
+    check:
+      seckey.toRaw == expectkey.toRaw
+
+  test "eth-key/conftest.py with wrong password":
+    let seckey =
+      decodeKeyFileJson(TestVectors[5].getOrDefault("keyfile"),
+                        "wrongpassword")
+    check:
+      seckey.error == KeyFileError.IncorrectMac
+
   test "Create/Save/Load test":
     var seckey0 = PrivateKey.random(rng[])
     let jobject = createKeyFileJson(seckey0, "randompassword")[]
@@ -125,6 +235,15 @@ suite "KeyFile test suite":
     check:
       seckey0.toRaw == seckey1.toRaw
     removeFile("test.keyfile")
+
+  test "Scrypt roundtrip":
+    let
+      seckey1 = PrivateKey.random(rng[])
+      jobject = createKeyFileJson(seckey1, "miawmiawcat", 3, AES128CTR, SCRYPT)[]
+      privKey = decodeKeyFileJson(jobject, "miawmiawcat")[]
+
+    check privKey.toRaw == secKey1.toRaw
+
   test "Load non-existent pathname test":
     check:
       loadKeyFile("nonexistant.keyfile", "password").error ==