From 1b516682bdef195174e632bc1772a75c97950e2f Mon Sep 17 00:00:00 2001
From: Jacek Sieka <jacek@status.im>
Date: Fri, 17 Jun 2022 22:45:37 +0200
Subject: [PATCH] bearssl: use split api (#510)

---
 eth/keys.nim                                  | 24 +++-----
 eth/p2p.nim                                   |  2 +-
 eth/p2p/auth.nim                              | 58 +++++++++----------
 eth/p2p/discovery.nim                         |  2 +-
 eth/p2p/discoveryv5/encoding.nim              | 50 ++++++++--------
 eth/p2p/discoveryv5/node.nim                  |  7 +--
 eth/p2p/discoveryv5/protocol.nim              |  4 +-
 eth/p2p/discoveryv5/random2.nim               | 17 +++---
 eth/p2p/discoveryv5/routing_table.nim         |  7 ++-
 eth/p2p/ecies.nim                             | 11 ++--
 eth/p2p/kademlia.nim                          | 11 +---
 eth/p2p/private/p2p_types.nim                 |  4 +-
 .../rlpx_protocols/whisper/whisper_types.nim  | 17 +++---
 eth/utp/packets.nim                           |  8 +--
 eth/utp/utp_protocol.nim                      |  2 +-
 eth/utp/utp_router.nim                        |  4 +-
 eth/utp/utp_socket.nim                        |  6 +-
 .../discoveryv5/fuzz_decode_packet.nim        |  6 +-
 tests/keys/test_keys.nim                      |  5 +-
 tests/p2p/discv5_test_helper.nim              | 16 ++---
 tests/p2p/p2p_test_helper.nim                 |  4 +-
 tests/p2p/test_discoveryv5.nim                |  2 +-
 tests/p2p/test_discoveryv5_encoding.nim       | 16 ++---
 tests/p2p/test_routing_table.nim              |  5 +-
 tests/p2p/test_shh_connect.nim                |  2 +-
 tests/utp/test_discv5_protocol.nim            |  9 +--
 tests/utp/test_protocol.nim                   | 26 ++++-----
 tests/utp/test_protocol_integration.nim       | 48 +++++++--------
 tests/utp/test_utils.nim                      | 15 ++---
 tests/utp/test_utp_router.nim                 |  6 +-
 tests/utp/test_utp_socket.nim                 | 28 ++++-----
 tests/utp/test_utp_socket_sack.nim            | 30 +++++-----
 32 files changed, 206 insertions(+), 246 deletions(-)

diff --git a/eth/keys.nim b/eth/keys.nim
index 0c89b4b..cd43a47 100644
--- a/eth/keys.nim
+++ b/eth/keys.nim
@@ -16,12 +16,13 @@
 
 import
   std/strformat,
-  secp256k1, bearssl, stew/[byteutils, objects, results],
+  secp256k1, bearssl/hash as bhash, bearssl/rand,
+  stew/[byteutils, objects, results],
   nimcrypto/[hash, keccak]
 
 from nimcrypto/utils import burnMem
 
-export secp256k1, results, bearssl
+export secp256k1, results, rand
 
 const
   KeyLength* = SkEcdhRawSecretSize - 1
@@ -51,24 +52,15 @@ type
 template pubkey*(v: KeyPair): PublicKey = PublicKey(SkKeyPair(v).pubkey)
 template seckey*(v: KeyPair): PrivateKey = PrivateKey(SkKeyPair(v).seckey)
 
-proc newRng*(): ref BrHmacDrbgContext =
+proc newRng*(): ref HmacDrbgContext =
   # You should only create one instance of the RNG per application / library
   # Ref is used so that it can be shared between components
-  # TODO consider moving to bearssl
-  var seeder = brPrngSeederSystem(nil)
-  if seeder == nil:
-    return nil
+  HmacDrbgContext.new()
 
-  var rng = (ref BrHmacDrbgContext)()
-  brHmacDrbgInit(addr rng[], addr sha256Vtable, nil, 0)
-  if seeder(addr rng.vtable) == 0:
-    return nil
-  rng
-
-proc random*(T: type PrivateKey, rng: var BrHmacDrbgContext): T =
+proc random*(T: type PrivateKey, rng: var HmacDrbgContext): T =
   let rngPtr = unsafeAddr rng # doesn't escape
   proc callRng(data: var openArray[byte]) =
-    brHmacDrbgGenerate(rngPtr[], data)
+    generate(rngPtr[], data)
 
   T(SkSecretKey.random(callRng))
 
@@ -106,7 +98,7 @@ func toRaw*(pubkey: PublicKey): array[RawPublicKeySize, byte] =
 
 func toRawCompressed*(pubkey: PublicKey): array[33, byte] {.borrow.}
 
-proc random*(T: type KeyPair, rng: var BrHmacDrbgContext): T =
+proc random*(T: type KeyPair, rng: var HmacDrbgContext): T =
   let seckey = SkSecretKey(PrivateKey.random(rng))
   KeyPair(SkKeyPair(
     seckey: seckey,
diff --git a/eth/p2p.nim b/eth/p2p.nim
index ea2ea4d..a0b6bcb 100644
--- a/eth/p2p.nim
+++ b/eth/p2p.nim
@@ -9,7 +9,7 @@
 
 import
   std/[tables, algorithm, random],
-  bearssl, chronos, chronos/timer, chronicles,
+  chronos, chronos/timer, chronicles,
   ./keys, ./common/eth_types, ./p2p/private/p2p_types,
   ./p2p/[kademlia, discovery, enode, peer_pool, rlpx]
 
diff --git a/eth/p2p/auth.nim b/eth/p2p/auth.nim
index 0360c35..89a9fd1 100644
--- a/eth/p2p/auth.nim
+++ b/eth/p2p/auth.nim
@@ -13,8 +13,8 @@
 {.push raises: [Defect].}
 
 import
-  nimcrypto/[rijndael, keccak, utils], bearssl,
-  stew/[byteutils, endians2, objects, results],
+  nimcrypto/[rijndael, keccak, utils],
+  stew/[arrayops, byteutils, endians2, objects, results],
   ".."/[keys, rlp],
   ./ecies
 
@@ -88,15 +88,11 @@ type
 template toa(a, b, c: untyped): untyped =
   toOpenArray((a), (b), (b) + (c) - 1)
 
-proc `xor`[N: static int](a, b: array[N, byte]): array[N, byte] =
-  for i in 0 ..< len(a):
-    result[i] = a[i] xor b[i]
-
 proc mapErrTo[T, E](r: Result[T, E], v: static AuthError): AuthResult[T] =
   r.mapErr(proc (e: E): AuthError = v)
 
 proc init*(
-    T: type Handshake, rng: var BrHmacDrbgContext, host: KeyPair,
+    T: type Handshake, rng: var HmacDrbgContext, host: KeyPair,
     flags: set[HandshakeFlag] = {Initiator},
     version: uint8 = SupportedRlpxVersion): T =
   ## Create new `Handshake` object.
@@ -108,10 +104,10 @@ proc init*(
 
   if Initiator in flags:
     expectedLength = AckMessageV4Length
-    brHmacDrbgGenerate(rng, initiatorNonce)
+    rng.generate(initiatorNonce)
   else:
     expectedLength = AuthMessageV4Length
-    brHmacDrbgGenerate(rng, responderNonce)
+    rng.generate(responderNonce)
 
   return T(
     version: version,
@@ -124,7 +120,7 @@ proc init*(
   )
 
 proc authMessagePreEIP8(h: var Handshake,
-                        rng: var BrHmacDrbgContext,
+                        rng: var HmacDrbgContext,
                         pubkey: PublicKey,
                         output: var openArray[byte],
                         outlen: var int,
@@ -163,7 +159,7 @@ proc authMessagePreEIP8(h: var Handshake,
   ok()
 
 proc authMessageEIP8(h: var Handshake,
-                     rng: var BrHmacDrbgContext,
+                     rng: var HmacDrbgContext,
                      pubkey: PublicKey,
                      output: var openArray[byte],
                      outlen: var int,
@@ -172,7 +168,6 @@ proc authMessageEIP8(h: var Handshake,
   ## Create EIP8 authentication message.
   var
     buffer: array[PlainAuthMessageMaxEIP8, byte]
-    padsize: array[1, byte]
 
   doAssert(EIP8 in h.flags)
   outlen = 0
@@ -192,29 +187,33 @@ proc authMessageEIP8(h: var Handshake,
   let
     pencsize = eciesEncryptedLength(len(payload))
 
-  while true:
-    brHmacDrbgGenerate(rng, padsize)
-    if int(padsize[0]) > (AuthMessageV4Length - (pencsize + 2)):
-      break
+  var padsize = int(rng.generate(byte)) # aka rand(max)
+  while padsize <= (AuthMessageV4Length - (pencsize + 2)):
+    padsize = int(rng.generate(byte))
+
   # It is possible to make packet size constant by uncommenting this line
   # padsize = 24
-  let wosize = pencsize + int(padsize[0])
-  let fullsize = wosize + 2
-  brHmacDrbgGenerate(
-    rng, toa(buffer, PlainAuthMessageEIP8Length, int(padsize[0])))
+  let
+    wosize = pencsize + padsize
+    fullsize = wosize + 2
+
+  rng.generate(toa(buffer, PlainAuthMessageEIP8Length, padsize))
+
   if encrypt:
-    copyMem(addr buffer[0], addr payload[0], len(payload))
     if len(output) < fullsize:
       return err(BufferOverrun)
+
+    copyMem(addr buffer[0], addr payload[0], len(payload))
+
     let wosizeBE = uint16(wosize).toBytesBE()
     output[0..<2] = wosizeBE
-    if eciesEncrypt(rng, toa(buffer, 0, len(payload) + int(padsize[0])),
+    if eciesEncrypt(rng, toa(buffer, 0, len(payload) + padsize),
                     toa(output, 2, wosize), pubkey,
                     toa(output, 0, 2)).isErr:
       return err(EciesError)
     outlen = fullsize
   else:
-    let plainsize = len(payload) + int(padsize[0])
+    let plainsize = len(payload) + padsize
     if len(output) < plainsize:
       return err(BufferOverrun)
     copyMem(addr output[0], addr buffer[0], plainsize)
@@ -223,7 +222,7 @@ proc authMessageEIP8(h: var Handshake,
   ok()
 
 proc ackMessagePreEIP8(h: var Handshake,
-                       rng: var BrHmacDrbgContext,
+                       rng: var HmacDrbgContext,
                        output: var openArray[byte],
                        outlen: var int,
                        flag: byte = 0,
@@ -250,7 +249,7 @@ proc ackMessagePreEIP8(h: var Handshake,
   ok()
 
 proc ackMessageEIP8(h: var Handshake,
-                    rng: var BrHmacDrbgContext,
+                    rng: var HmacDrbgContext,
                     output: var openArray[byte],
                     outlen: var int,
                     flag: byte = 0,
@@ -267,7 +266,7 @@ proc ackMessageEIP8(h: var Handshake,
   outlen = 0
   let pencsize = eciesEncryptedLength(len(payload))
   while true:
-    brHmacDrbgGenerate(rng, padsize)
+    generate(rng, padsize)
     if int(padsize[0]) > (AckMessageV4Length - (pencsize + 2)):
       break
   # It is possible to make packet size constant by uncommenting this line
@@ -275,8 +274,7 @@ proc ackMessageEIP8(h: var Handshake,
   let wosize = pencsize + int(padsize[0])
   let fullsize = wosize + 2
   if int(padsize[0]) > 0:
-    brHmacDrbgGenerate(
-      rng, toa(buffer, PlainAckMessageEIP8Length, int(padsize[0])))
+    rng.generate(toa(buffer, PlainAckMessageEIP8Length, int(padsize[0])))
 
   copyMem(addr buffer[0], addr payload[0], len(payload))
   if encrypt:
@@ -311,7 +309,7 @@ template ackSize*(h: Handshake, encrypt: bool = true): int =
   else:
     if encrypt: (AckMessageV4Length) else: (PlainAckMessageV4Length)
 
-proc authMessage*(h: var Handshake, rng: var BrHmacDrbgContext,
+proc authMessage*(h: var Handshake, rng: var HmacDrbgContext,
                   pubkey: PublicKey,
                   output: var openArray[byte],
                   outlen: var int, flag: byte = 0,
@@ -323,7 +321,7 @@ proc authMessage*(h: var Handshake, rng: var BrHmacDrbgContext,
   else:
     authMessagePreEIP8(h, rng, pubkey, output, outlen, flag, encrypt)
 
-proc ackMessage*(h: var Handshake, rng: var BrHmacDrbgContext,
+proc ackMessage*(h: var Handshake, rng: var HmacDrbgContext,
                  output: var openArray[byte],
                  outlen: var int, flag: byte = 0,
                  encrypt: bool = true): AuthResult[void] =
diff --git a/eth/p2p/discovery.nim b/eth/p2p/discovery.nim
index eddb43e..0c0000e 100644
--- a/eth/p2p/discovery.nim
+++ b/eth/p2p/discovery.nim
@@ -9,7 +9,7 @@
 
 import
   std/times,
-  chronos, stint, nimcrypto/keccak, chronicles, bearssl,
+  chronos, stint, nimcrypto/keccak, chronicles,
   stew/[objects, results],
   ".."/[keys, rlp],
   "."/[kademlia, enode]
diff --git a/eth/p2p/discoveryv5/encoding.nim b/eth/p2p/discoveryv5/encoding.nim
index 19e9e0f..b46cd51 100644
--- a/eth/p2p/discoveryv5/encoding.nim
+++ b/eth/p2p/discoveryv5/encoding.nim
@@ -15,7 +15,7 @@
 
 import
   std/[tables, options, hashes, net],
-  nimcrypto, stint, chronicles, bearssl, stew/[results, byteutils], metrics,
+  nimcrypto, stint, chronicles, stew/[results, byteutils], metrics,
   ".."/../[rlp, keys],
   "."/[messages, node, enr, hkdf, sessions]
 
@@ -193,18 +193,19 @@ proc encodeStaticHeader*(flag: Flag, nonce: AESGCMNonce, authSize: int):
   # TODO: assert on authSize of > 2^16?
   result.add((uint16(authSize)).toBytesBE())
 
-proc encodeMessagePacket*(rng: var BrHmacDrbgContext, c: var Codec,
+proc encodeMessagePacket*(rng: var HmacDrbgContext, c: var Codec,
     toId: NodeId, toAddr: Address, message: openArray[byte]):
     (seq[byte], AESGCMNonce) =
-  var nonce: AESGCMNonce
-  brHmacDrbgGenerate(rng, nonce) # Random AESGCM nonce
-  var iv: array[ivSize, byte]
-  brHmacDrbgGenerate(rng, iv) # Random IV
+  let
+    nonce = rng.generate(AESGCMNonce) # Random AESGCM nonce
+    iv = rng.generate(array[ivSize, byte]) # Random IV
 
   # static-header
-  let authdata = c.localNode.id.toByteArrayBE()
-  let staticHeader = encodeStaticHeader(Flag.OrdinaryMessage, nonce,
-    authdata.len())
+  let
+    authdata = c.localNode.id.toByteArrayBE()
+    staticHeader = encodeStaticHeader(Flag.OrdinaryMessage, nonce,
+      authdata.len())
+
   # header = static-header || authdata
   var header: seq[byte]
   header.add(staticHeader)
@@ -224,8 +225,7 @@ proc encodeMessagePacket*(rng: var BrHmacDrbgContext, c: var Codec,
     # message. 16 bytes for the gcm tag and 4 bytes for ping with requestId of
     # 1 byte (e.g "01c20101"). Could increase to 27 for 8 bytes requestId in
     # case this must not look like a random packet.
-    var randomData: array[gcmTagSize + 4, byte]
-    brHmacDrbgGenerate(rng, randomData)
+    let randomData = rng.generate(array[gcmTagSize + 4, byte])
     messageEncrypted.add(randomData)
     discovery_session_lru_cache_misses.inc()
 
@@ -238,11 +238,11 @@ proc encodeMessagePacket*(rng: var BrHmacDrbgContext, c: var Codec,
 
   return (packet, nonce)
 
-proc encodeWhoareyouPacket*(rng: var BrHmacDrbgContext, c: var Codec,
+proc encodeWhoareyouPacket*(rng: var HmacDrbgContext, c: var Codec,
     toId: NodeId, toAddr: Address, requestNonce: AESGCMNonce, recordSeq: uint64,
     pubkey: Option[PublicKey]): seq[byte] =
-  var idNonce: IdNonce
-  brHmacDrbgGenerate(rng, idNonce)
+  let
+    idNonce = rng.generate(IdNonce)
 
   # authdata
   var authdata: seq[byte]
@@ -258,10 +258,9 @@ proc encodeWhoareyouPacket*(rng: var BrHmacDrbgContext, c: var Codec,
   header.add(staticHeader)
   header.add(authdata)
 
-  var iv: array[ivSize, byte]
-  brHmacDrbgGenerate(rng, iv) # Random IV
-
-  let maskedHeader = encryptHeader(toId, iv, header)
+  let
+    iv = rng.generate(array[ivSize, byte]) # Random IV
+    maskedHeader = encryptHeader(toId, iv, header)
 
   var packet: seq[byte]
   packet.add(iv)
@@ -280,14 +279,12 @@ proc encodeWhoareyouPacket*(rng: var BrHmacDrbgContext, c: var Codec,
 
   return packet
 
-proc encodeHandshakePacket*(rng: var BrHmacDrbgContext, c: var Codec,
+proc encodeHandshakePacket*(rng: var HmacDrbgContext, c: var Codec,
     toId: NodeId, toAddr: Address, message: openArray[byte],
     whoareyouData: WhoareyouData, pubkey: PublicKey): seq[byte] =
-  var header: seq[byte]
-  var nonce: AESGCMNonce
-  brHmacDrbgGenerate(rng, nonce)
-  var iv: array[ivSize, byte]
-  brHmacDrbgGenerate(rng, iv) # Random IV
+  let
+    nonce = rng.generate(AESGCMNonce)
+    iv = rng.generate(array[ivSize, byte]) # Random IV
 
   var authdata: seq[byte]
   var authdataHead: seq[byte]
@@ -316,6 +313,7 @@ proc encodeHandshakePacket*(rng: var BrHmacDrbgContext, c: var Codec,
   let staticHeader = encodeStaticHeader(Flag.HandshakeMessage, nonce,
     authdata.len())
 
+  var header: seq[byte]
   header.add(staticHeader)
   header.add(authdata)
 
@@ -611,9 +609,9 @@ proc decodePacket*(c: var Codec, fromAddr: Address, input: openArray[byte]):
       input.toOpenArray(0, ivSize - 1), header,
       input.toOpenArray(ivSize + header.len, input.high))
 
-proc init*(T: type RequestId, rng: var BrHmacDrbgContext): T =
+proc init*(T: type RequestId, rng: var HmacDrbgContext): T =
   var reqId = RequestId(id: newSeq[byte](8)) # RequestId must be <= 8 bytes
-  brHmacDrbgGenerate(rng, reqId.id)
+  rng.generate(reqId.id)
   reqId
 
 proc numFields(T: typedesc): int =
diff --git a/eth/p2p/discoveryv5/node.nim b/eth/p2p/discoveryv5/node.nim
index 3b311b9..12b7cf0 100644
--- a/eth/p2p/discoveryv5/node.nim
+++ b/eth/p2p/discoveryv5/node.nim
@@ -86,11 +86,8 @@ func `==`*(a, b: Node): bool =
 func hash*(id: NodeId): Hash =
   hash(id.toByteArrayBE)
 
-proc random*(T: type NodeId, rng: var BrHmacDrbgContext): T =
-  var id: NodeId
-  brHmacDrbgGenerate(addr rng, addr id, csize_t(sizeof(id)))
-
-  id
+proc random*(T: type NodeId, rng: var HmacDrbgContext): T =
+  rng.generate(T)
 
 func `$`*(id: NodeId): string =
   id.toHex()
diff --git a/eth/p2p/discoveryv5/protocol.nim b/eth/p2p/discoveryv5/protocol.nim
index a3bb3b2..16e405d 100644
--- a/eth/p2p/discoveryv5/protocol.nim
+++ b/eth/p2p/discoveryv5/protocol.nim
@@ -83,7 +83,7 @@
 import
   std/[tables, sets, options, math, sequtils, algorithm],
   stew/shims/net as stewNet, json_serialization/std/net,
-  stew/[endians2, results], chronicles, chronos, stint, bearssl, metrics,
+  stew/[endians2, results], chronicles, chronos, stint, metrics,
   ".."/../[rlp, keys, async_utils],
   "."/[messages, encoding, node, routing_table, enr, random2, sessions, ip_vote,
     nodes_verification]
@@ -147,7 +147,7 @@ type
     enrAutoUpdate: bool
     talkProtocols*: Table[seq[byte], TalkProtocol] # TODO: Table is a bit of
     # overkill here, use sequence
-    rng*: ref BrHmacDrbgContext
+    rng*: ref HmacDrbgContext
 
   PendingRequest = object
     node: Node
diff --git a/eth/p2p/discoveryv5/random2.nim b/eth/p2p/discoveryv5/random2.nim
index 0ec72f0..02d69e4 100644
--- a/eth/p2p/discoveryv5/random2.nim
+++ b/eth/p2p/discoveryv5/random2.nim
@@ -1,22 +1,25 @@
-import bearssl
+import
+  bearssl/rand
 
-## Random helpers: similar as in stdlib, but with BrHmacDrbgContext rng
+export rand
+
+## Random helpers: similar as in stdlib, but with HmacDrbgContext rng
 # TODO: Move these somewhere else?
 const randMax = 18_446_744_073_709_551_615'u64
 
-proc rand*(rng: var BrHmacDrbgContext, max: Natural): int =
+proc rand*(rng: var HmacDrbgContext, max: Natural): int =
   if max == 0: return 0
 
   var x: uint64
   while true:
-    brHmacDrbgGenerate(addr rng, addr x, csize_t(sizeof(x)))
+    rng.generate(x)
     if x < randMax - (randMax mod (uint64(max) + 1'u64)): # against modulo bias
       return int(x mod (uint64(max) + 1'u64))
 
-proc sample*[T](rng: var BrHmacDrbgContext, a: openArray[T]): T =
-  result = a[rng.rand(a.high)]
+proc sample*[T](rng: var HmacDrbgContext, a: openArray[T]): T =
+  a[rng.rand(a.high)]
 
-proc shuffle*[T](rng: var BrHmacDrbgContext, a: var openArray[T]) =
+proc shuffle*[T](rng: var HmacDrbgContext, a: var openArray[T]) =
   for i in countdown(a.high, 1):
     let j = rng.rand(i)
     swap(a[i], a[j])
diff --git a/eth/p2p/discoveryv5/routing_table.nim b/eth/p2p/discoveryv5/routing_table.nim
index 136ad39..00f2965 100644
--- a/eth/p2p/discoveryv5/routing_table.nim
+++ b/eth/p2p/discoveryv5/routing_table.nim
@@ -9,7 +9,8 @@
 
 import
   std/[algorithm, times, sequtils, bitops, sets, options],
-  stint, chronicles, metrics, bearssl, chronos, stew/shims/net as stewNet,
+  bearssl/rand,
+  stint, chronicles, metrics, chronos, stew/shims/net as stewNet,
   ../../net/utils,
   "."/[node, random2, enr]
 
@@ -42,7 +43,7 @@ type
     ipLimits: IpLimits ## IP limits for total routing table: all buckets and
     ## replacement caches.
     distanceCalculator: DistanceCalculator
-    rng: ref BrHmacDrbgContext
+    rng: ref HmacDrbgContext
 
   KBucket = ref object
     istart, iend: NodeId ## Range of NodeIds this KBucket covers. This is not a
@@ -260,7 +261,7 @@ proc computeSharedPrefixBits(nodes: openArray[NodeId]): int =
   doAssert(false, "Unable to calculate number of shared prefix bits")
 
 proc init*(T: type RoutingTable, localNode: Node, bitsPerHop = DefaultBitsPerHop,
-    ipLimits = DefaultTableIpLimits, rng: ref BrHmacDrbgContext,
+    ipLimits = DefaultTableIpLimits, rng: ref HmacDrbgContext,
     distanceCalculator = XorDistanceCalculator): T =
   ## Initialize the routing table for provided `Node` and bitsPerHop value.
   ## `bitsPerHop` is default set to 5 as recommended by original Kademlia paper.
diff --git a/eth/p2p/ecies.nim b/eth/p2p/ecies.nim
index d32167a..164cc3c 100644
--- a/eth/p2p/ecies.nim
+++ b/eth/p2p/ecies.nim
@@ -13,7 +13,7 @@
 {.push raises: [Defect].}
 
 import
-  bearssl, stew/[results, endians2],
+  stew/[results, endians2],
   nimcrypto/[rijndael, bcmode, hash, hmac, sha2, utils],
   ../keys
 
@@ -93,7 +93,7 @@ proc kdf*(data: openArray[byte]): array[KeyLength, byte] {.noinit.} =
   ctx.clear() # clean ctx
   copyMem(addr result[0], addr storage[0], KeyLength)
 
-proc eciesEncrypt*(rng: var BrHmacDrbgContext, input: openArray[byte],
+proc eciesEncrypt*(rng: var HmacDrbgContext, input: openArray[byte],
                    output: var openArray[byte], pubkey: PublicKey,
                    sharedmac: openArray[byte] = emptyMac): EciesResult[void] =
   ## Encrypt data with ECIES method using given public key `pubkey`.
@@ -107,13 +107,10 @@ proc eciesEncrypt*(rng: var BrHmacDrbgContext, input: openArray[byte],
     encKey: array[aes128.sizeKey, byte]
     cipher: CTR[aes128]
     ctx: HMAC[sha256]
-    iv: array[aes128.sizeBlock, byte]
 
   if len(output) < eciesEncryptedLength(len(input)):
     return err(BufferOverrun)
 
-  brHmacDrbgGenerate(rng, iv)
-
   var
     ephemeral = KeyPair.random(rng)
     secret = ecdhRaw(ephemeral.seckey, pubkey)
@@ -130,13 +127,13 @@ proc eciesEncrypt*(rng: var BrHmacDrbgContext, input: openArray[byte],
   var header = cast[ptr EciesHeader](addr output[0])
   header.version = 0x04
   header.pubkey = ephemeral.pubkey.toRaw()
-  header.iv = iv
+  rng.generate(header[].iv)
 
   clear(ephemeral)
 
   var so = eciesDataPos()
   var eo = so + len(input)
-  cipher.init(encKey, iv)
+  cipher.init(encKey, header.iv)
   cipher.encrypt(input, toOpenArray(output, so, eo))
   burnMem(encKey)
   cipher.clear()
diff --git a/eth/p2p/kademlia.nim b/eth/p2p/kademlia.nim
index c904647..c75b502 100644
--- a/eth/p2p/kademlia.nim
+++ b/eth/p2p/kademlia.nim
@@ -9,7 +9,7 @@
 
 import
   std/[tables, hashes, times, algorithm, sets, sequtils, random],
-  chronos, bearssl, chronicles, stint, nimcrypto/keccak,
+  chronos, chronicles, stint, nimcrypto/keccak,
   ../keys,
   ./enode
 
@@ -26,7 +26,7 @@ type
     pongFutures: Table[seq[byte], Future[bool]]
     pingFutures: Table[Node, Future[bool]]
     neighboursCallbacks: Table[Node, proc(n: seq[Node]) {.gcsafe, raises: [Defect].}]
-    rng: ref BrHmacDrbgContext
+    rng: ref HmacDrbgContext
 
   NodeId* = UInt256
 
@@ -452,12 +452,7 @@ proc lookup*(k: KademliaProtocol, nodeId: NodeId): Future[seq[Node]] {.async.} =
   result = closest
 
 proc lookupRandom*(k: KademliaProtocol): Future[seq[Node]] =
-  var id: NodeId
-  var buf: array[sizeof(id), byte]
-  brHmacDrbgGenerate(k.rng[], buf)
-  copyMem(addr id, addr buf[0], sizeof(id))
-
-  k.lookup(id)
+  k.lookup(k.rng[].generate(NodeId))
 
 proc resolve*(k: KademliaProtocol, id: NodeId): Future[Node] {.async.} =
   let closest = await k.lookup(id)
diff --git a/eth/p2p/private/p2p_types.nim b/eth/p2p/private/p2p_types.nim
index e9a2042..24d81d0 100644
--- a/eth/p2p/private/p2p_types.nim
+++ b/eth/p2p/private/p2p_types.nim
@@ -8,7 +8,7 @@
 
 import
   std/[deques, tables],
-  bearssl, chronos,
+  chronos,
   stew/results,
   ".."/../[rlp, keys], ".."/../common/eth_types,
   ".."/[enode, kademlia, discovery, rlpxcrypt]
@@ -38,7 +38,7 @@ type
     discovery*: DiscoveryProtocol
     when useSnappy:
       protocolVersion*: uint
-    rng*: ref BrHmacDrbgContext
+    rng*: ref HmacDrbgContext
 
   Peer* = ref object
     remote*: Node
diff --git a/eth/p2p/rlpx_protocols/whisper/whisper_types.nim b/eth/p2p/rlpx_protocols/whisper/whisper_types.nim
index b14fadb..2c5dec1 100644
--- a/eth/p2p/rlpx_protocols/whisper/whisper_types.nim
+++ b/eth/p2p/rlpx_protocols/whisper/whisper_types.nim
@@ -9,7 +9,7 @@
 
 import
   std/[algorithm, bitops, math, options, tables, times, hashes],
-  chronicles, stew/[byteutils, endians2], metrics, bearssl,
+  chronicles, stew/[byteutils, endians2], metrics,
   nimcrypto/[bcmode, hash, keccak, rijndael],
   ".."/../../[keys, rlp, p2p], ../../ecies
 
@@ -160,10 +160,8 @@ proc topicBloom*(topic: Topic): Bloom =
     doAssert idx <= 511
     result[idx div 8] = result[idx div 8] or byte(1 shl (idx and 7'u16))
 
-proc generateRandomID*(rng: var BrHmacDrbgContext): string =
-  var bytes: array[256 div 8, byte]
-  brHmacDrbgGenerate(rng, bytes)
-  toHex(bytes)
+proc generateRandomID*(rng: var HmacDrbgContext): string =
+  toHex(rng.generate(array[256 div 8, byte]))
 
 proc `or`(a, b: Bloom): Bloom =
   for i in 0..<a.len:
@@ -231,7 +229,7 @@ proc decryptAesGcm(cipher: openArray[byte], key: SymKey): Option[seq[byte]] =
 # simply because that makes it closer to EIP 627 - see also:
 # https://github.com/paritytech/parity-ethereum/issues/9652
 
-proc encode*(rng: var BrHmacDrbgContext, self: Payload): Option[seq[byte]] =
+proc encode*(rng: var HmacDrbgContext, self: Payload): Option[seq[byte]] =
   ## Encode a payload according so as to make it suitable to put in an Envelope
   ## The format follows EIP 627 - https://eips.ethereum.org/EIPS/eip-627
 
@@ -284,7 +282,7 @@ proc encode*(rng: var BrHmacDrbgContext, self: Payload): Option[seq[byte]] =
     plain.add self.padding.get()
   else:
     var padding = newSeq[byte](padLen)
-    brHmacDrbgGenerate(rng, padding)
+    rng.generate(padding)
 
     plain.add padding
 
@@ -302,8 +300,7 @@ proc encode*(rng: var BrHmacDrbgContext, self: Payload): Option[seq[byte]] =
     return some(res)
 
   if self.symKey.isSome(): # Symmetric key present - encryption requested
-    var iv: array[gcmIVLen, byte]
-    brHmacDrbgGenerate(rng, iv)
+    let iv = rng.generate(array[gcmIVLen, byte])
 
     return some(encryptAesGcm(plain, self.symKey.get(), iv))
 
@@ -579,7 +576,7 @@ proc initFilter*(src = none[PublicKey](), privateKey = none[PrivateKey](),
          powReq: powReq, allowP2P: allowP2P, bloom: toBloom(topics))
 
 proc subscribeFilter*(
-    rng: var BrHmacDrbgContext, filters: var Filters, filter: Filter,
+    rng: var HmacDrbgContext, filters: var Filters, filter: Filter,
     handler: FilterMsgHandler = nil): string =
   # NOTE: Should we allow a filter without a key? Encryption is mandatory in v6?
   # Check if asymmetric _and_ symmetric key? Now asymmetric just has precedence.
diff --git a/eth/utp/packets.nim b/eth/utp/packets.nim
index 79031af..905154d 100644
--- a/eth/utp/packets.nim
+++ b/eth/utp/packets.nim
@@ -10,10 +10,10 @@ import
   std/[monotimes],
   faststreams,
   chronos,
-  stew/[endians2, results, objects, arrayops], bearssl,
+  stew/[endians2, results, objects, arrayops],
   ../p2p/discoveryv5/random2
 
-export results
+export results, random2
 
 const
   minimalHeaderSize = 20
@@ -80,11 +80,11 @@ proc getMonoTimestamp*(): TimeStampInfo =
   TimeStampInfo(moment: currentMoment, timestamp: timestamp)
 
 # Simple generator, not useful for cryptography
-proc randUint16*(rng: var BrHmacDrbgContext): uint16 =
+proc randUint16*(rng: var HmacDrbgContext): uint16 =
   uint16(rand(rng, int(high(uint16))))
 
 # Simple generator, not useful for cryptography
-proc randUint32*(rng: var BrHmacDrbgContext): uint32 =
+proc randUint32*(rng: var HmacDrbgContext): uint32 =
   uint32(rand(rng, int(high(uint32))))
 
 proc encodeTypeVer(h: PacketHeaderV1): uint8 =
diff --git a/eth/utp/utp_protocol.nim b/eth/utp/utp_protocol.nim
index ab85841..59819b2 100644
--- a/eth/utp/utp_protocol.nim
+++ b/eth/utp/utp_protocol.nim
@@ -8,7 +8,7 @@
 
 import
   std/[tables, options, hashes, sugar, math],
-  chronos, chronicles, bearssl,
+  chronos, chronicles,
   ./utp_router,
   ../keys
 
diff --git a/eth/utp/utp_router.nim b/eth/utp/utp_router.nim
index 0c486cf..4c106e5 100644
--- a/eth/utp/utp_router.nim
+++ b/eth/utp/utp_router.nim
@@ -8,7 +8,7 @@
 
 import
   std/[tables, options, sugar],
-  chronos, bearssl, chronicles, metrics,
+  chronos, chronicles, metrics,
   ../keys,
   ./utp_socket,
   ./packets
@@ -56,7 +56,7 @@ type
    closed: bool
    sendCb*: SendCallback[A]
    allowConnection*: AllowConnectionCallback[A]
-   rng*: ref BrHmacDrbgContext
+   rng*: ref HmacDrbgContext
 
 const
   # Maximal number of tries to generate unique socket while establishing
diff --git a/eth/utp/utp_socket.nim b/eth/utp/utp_socket.nim
index 7b24fcf..da09e14 100644
--- a/eth/utp/utp_socket.nim
+++ b/eth/utp/utp_socket.nim
@@ -8,7 +8,7 @@
 
 import
   std/[sugar, deques],
-  chronos, chronicles, bearssl,
+  chronos, chronicles,
   stew/[results, bitops2],
   ./growable_buffer,
   ./packets,
@@ -1880,7 +1880,7 @@ proc newOutgoingSocket*[A](
   snd: SendCallback[A],
   cfg: SocketConfig,
   rcvConnectionId: uint16,
-  rng: var BrHmacDrbgContext
+  rng: var HmacDrbgContext
 ): UtpSocket[A] =
   let sndConnectionId = rcvConnectionId + 1
   let initialSeqNr = randUint16(rng)
@@ -1905,7 +1905,7 @@ proc newIncomingSocket*[A](
   cfg: SocketConfig,
   connectionId: uint16,
   ackNr: uint16,
-  rng: var BrHmacDrbgContext
+  rng: var HmacDrbgContext
 ): UtpSocket[A] =
   let initialSeqNr = randUint16(rng)
 
diff --git a/tests/fuzzing/discoveryv5/fuzz_decode_packet.nim b/tests/fuzzing/discoveryv5/fuzz_decode_packet.nim
index c320f4c..1583bf4 100644
--- a/tests/fuzzing/discoveryv5/fuzz_decode_packet.nim
+++ b/tests/fuzzing/discoveryv5/fuzz_decode_packet.nim
@@ -28,9 +28,9 @@ test:
   # It is not the best idea to generate extra data and encrypt data but we do
   # it like this as the decodeHeader proc does decrypt + decode + decrypt.
   # There is no separate decrypt step that can be skipped because of this.
-  var iv: array[ivSize, byte]
-  brHmacDrbgGenerate(rng[], iv)
-  let maskedHeader = encryptHeader(nodeB.id, iv, payload)
+  let
+    iv = rng[].generate(array[ivSize, byte])
+    maskedHeader = encryptHeader(nodeB.id, iv, payload)
 
   let decoded = decodePacket(codecB, nodeA.address.get(), @iv & maskedHeader)
   if decoded.isErr():
diff --git a/tests/keys/test_keys.nim b/tests/keys/test_keys.nim
index 600170d..df46bb4 100644
--- a/tests/keys/test_keys.nim
+++ b/tests/keys/test_keys.nim
@@ -11,7 +11,7 @@
 
 import
   unittest2,
-  nimcrypto/hash, nimcrypto/keccak, nimcrypto/utils, bearssl, stew/byteutils,
+  nimcrypto/hash, nimcrypto/keccak, nimcrypto/utils, stew/byteutils,
   ../../eth/keys
 
 from strutils import toLowerAscii
@@ -218,8 +218,7 @@ suite "ECC/ECDSA/ECDHE tests suite":
   test "ECDSA/100 signatures":
     # signature test
     for i in 1..100:
-      var m: array[32, byte]
-      brHmacDrbgGenerate(rng[], m)
+      let m = rng[].generate(array[32, byte])
       var s = PrivateKey.random(rng[])
       var key = s.toPublicKey()
       let sig = sign(s, SkMessage(m))
diff --git a/tests/p2p/discv5_test_helper.nim b/tests/p2p/discv5_test_helper.nim
index 397bed5..3034a25 100644
--- a/tests/p2p/discv5_test_helper.nim
+++ b/tests/p2p/discv5_test_helper.nim
@@ -1,5 +1,5 @@
 import
-  stew/shims/net, bearssl, chronos,
+  stew/shims/net, chronos,
   ../../eth/keys,
   ../../eth/p2p/discoveryv5/[enr, node, routing_table],
   ../../eth/p2p/discoveryv5/protocol as discv5_protocol
@@ -10,7 +10,7 @@ proc localAddress*(port: int): Address =
   Address(ip: ValidIpAddress.init("127.0.0.1"), port: Port(port))
 
 proc initDiscoveryNode*(
-    rng: ref BrHmacDrbgContext,
+    rng: ref HmacDrbgContext,
     privKey: PrivateKey,
     address: Address,
     bootstrapRecords: openArray[Record] = [],
@@ -47,14 +47,14 @@ proc generateNode*(privKey: PrivateKey, port: int = 20302,
     some(port), some(port), localEnrFields).expect("Properly intialized private key")
   result = newNode(enr).expect("Properly initialized node")
 
-proc generateNRandomNodes*(rng: ref BrHmacDrbgContext, n: int): seq[Node] =
+proc generateNRandomNodes*(rng: var HmacDrbgContext, n: int): seq[Node] =
   var res = newSeq[Node]()
   for i in 1..n:
-    let node = generateNode(PrivateKey.random(rng[]))
+    let node = generateNode(PrivateKey.random(rng))
     res.add(node)
   res
 
-proc nodeAndPrivKeyAtDistance*(n: Node, rng: var BrHmacDrbgContext, d: uint32,
+proc nodeAndPrivKeyAtDistance*(n: Node, rng: var HmacDrbgContext, d: uint32,
     ip: ValidIpAddress = ValidIpAddress.init("127.0.0.1")): (Node, PrivateKey) =
   while true:
     let pk = PrivateKey.random(rng)
@@ -62,19 +62,19 @@ proc nodeAndPrivKeyAtDistance*(n: Node, rng: var BrHmacDrbgContext, d: uint32,
     if logDistance(n.id, node.id) == d:
       return (node, pk)
 
-proc nodeAtDistance*(n: Node, rng: var BrHmacDrbgContext, d: uint32,
+proc nodeAtDistance*(n: Node, rng: var HmacDrbgContext, d: uint32,
     ip: ValidIpAddress = ValidIpAddress.init("127.0.0.1")): Node =
   let (node, _) = n.nodeAndPrivKeyAtDistance(rng, d, ip)
   node
 
 proc nodesAtDistance*(
-    n: Node, rng: var BrHmacDrbgContext, d: uint32, amount: int,
+    n: Node, rng: var HmacDrbgContext, d: uint32, amount: int,
     ip: ValidIpAddress = ValidIpAddress.init("127.0.0.1")): seq[Node] =
   for i in 0..<amount:
     result.add(nodeAtDistance(n, rng, d, ip))
 
 proc nodesAtDistanceUniqueIp*(
-    n: Node, rng: var BrHmacDrbgContext, d: uint32, amount: int,
+    n: Node, rng: var HmacDrbgContext, d: uint32, amount: int,
     ip: ValidIpAddress = ValidIpAddress.init("127.0.0.1")): seq[Node] =
   var ta = initTAddress(ip, Port(0))
   for i in 0..<amount:
diff --git a/tests/p2p/p2p_test_helper.nim b/tests/p2p/p2p_test_helper.nim
index ca46fd3..b6c04ef 100644
--- a/tests/p2p/p2p_test_helper.nim
+++ b/tests/p2p/p2p_test_helper.nim
@@ -1,6 +1,6 @@
 import
   std/strutils,
-  chronos, bearssl,
+  chronos,
   ../../eth/[keys, p2p], ../../eth/p2p/[discovery, enode]
 
 var nextPort = 30303
@@ -11,7 +11,7 @@ proc localAddress*(port: int): Address =
                    ip: parseIpAddress("127.0.0.1"))
 
 proc setupTestNode*(
-    rng: ref BrHmacDrbgContext,
+    rng: ref HmacDrbgContext,
     capabilities: varargs[ProtocolInfo, `protocolInfo`]): EthereumNode {.gcsafe.} =
   # Don't create new RNG every time in production code!
   let keys1 = KeyPair.random(rng[])
diff --git a/tests/p2p/test_discoveryv5.nim b/tests/p2p/test_discoveryv5.nim
index d97e684..078fda3 100644
--- a/tests/p2p/test_discoveryv5.nim
+++ b/tests/p2p/test_discoveryv5.nim
@@ -3,7 +3,7 @@
 import
   std/[tables, sequtils],
   chronos, chronicles, stint, testutils/unittests, stew/shims/net,
-  stew/byteutils, bearssl,
+  stew/byteutils,
   ../../eth/keys,
   ../../eth/p2p/discoveryv5/[enr, node, routing_table, encoding, sessions,
     messages, nodes_verification],
diff --git a/tests/p2p/test_discoveryv5_encoding.nim b/tests/p2p/test_discoveryv5_encoding.nim
index 4ab089e..8991a45 100644
--- a/tests/p2p/test_discoveryv5_encoding.nim
+++ b/tests/p2p/test_discoveryv5_encoding.nim
@@ -456,18 +456,15 @@ suite "Discovery v5.1 Additional Encode/Decode":
     check decryptGCM(encryptionKey, nonce, invalidCipher, ad).isNone()
 
   test "Encrypt / Decrypt header":
-    var nonce: AESGCMNonce
-    brHmacDrbgGenerate(rng[], nonce)
     let
+      nonce = rng[].generate(AESGCMNonce)
       privKey = PrivateKey.random(rng[])
       nodeId = privKey.toPublicKey().toNodeId()
       authdata = newSeq[byte](32)
       staticHeader = encodeStaticHeader(Flag.OrdinaryMessage, nonce,
         authdata.len())
       header = staticHeader & authdata
-
-    var iv: array[128 div 8, byte]
-    brHmacDrbgGenerate(rng[], iv)
+      iv = rng[].generate(array[128 div 8, byte])
 
     let
       encrypted = encryptHeader(nodeId, iv, header)
@@ -511,8 +508,7 @@ suite "Discovery v5.1 Additional Encode/Decode":
       decoded[].requestNonce == nonce
 
   test "Encode / Decode Whoareyou Packet":
-    var requestNonce: AESGCMNonce
-    brHmacDrbgGenerate(rng[], requestNonce)
+    let requestNonce = rng[].generate(AESGCMNonce)
     let recordSeq = 0'u64
 
     let data = encodeWhoareyouPacket(rng[], codecA, nodeB.id,
@@ -532,9 +528,8 @@ suite "Discovery v5.1 Additional Encode/Decode":
       decoded[].whoareyou.recordSeq == recordSeq
 
   test "Encode / Decode Handshake Message Packet":
-    var requestNonce: AESGCMNonce
-    brHmacDrbgGenerate(rng[], requestNonce)
     let
+      requestNonce = rng[].generate(AESGCMNonce)
       recordSeq = 1'u64
       m = PingMessage(enrSeq: 0)
       reqId = RequestId.init(rng[])
@@ -563,9 +558,8 @@ suite "Discovery v5.1 Additional Encode/Decode":
       decoded.get().node.isNone()
 
   test "Encode / Decode Handshake Message Packet with ENR":
-    var requestNonce: AESGCMNonce
-    brHmacDrbgGenerate(rng[], requestNonce)
     let
+      requestNonce = rng[].generate(AESGCMNonce)
       recordSeq = 0'u64
       m = PingMessage(enrSeq: 0)
       reqId = RequestId.init(rng[])
diff --git a/tests/p2p/test_routing_table.nim b/tests/p2p/test_routing_table.nim
index da35e74..da2d5f0 100644
--- a/tests/p2p/test_routing_table.nim
+++ b/tests/p2p/test_routing_table.nim
@@ -2,7 +2,6 @@
 
 import
   unittest2,
-  bearssl,
   ../../eth/keys, ../../eth/p2p/discoveryv5/[routing_table, node, enr],
   ./discv5_test_helper
 
@@ -528,7 +527,7 @@ suite "Routing Table Tests":
     var table = RoutingTable.init(local, 1, ipLimits, rng = rng,
       distanceCalculator = customDistanceCalculator)
 
-    let nodes = generateNRandomNodes(rng, numNodes)
+    let nodes = generateNRandomNodes(rng[], numNodes)
 
     for n in nodes:
       check table.addNode(n) == Added
@@ -548,7 +547,7 @@ suite "Routing Table Tests":
     var table = RoutingTable.init(local, 1, ipLimits, rng = rng,
       distanceCalculator = customDistanceCalculator)
 
-    let nodes = generateNRandomNodes(rng, numNodes)
+    let nodes = generateNRandomNodes(rng[], numNodes)
 
     for n in nodes:
       check table.addNode(n) == Added
diff --git a/tests/p2p/test_shh_connect.nim b/tests/p2p/test_shh_connect.nim
index 3964a44..c4913dc 100644
--- a/tests/p2p/test_shh_connect.nim
+++ b/tests/p2p/test_shh_connect.nim
@@ -11,7 +11,7 @@
 
 import
   std/[sequtils, options, tables],
-  chronos, testutils/unittests, bearssl,
+  chronos, testutils/unittests,
   ../../eth/[keys, p2p], ../../eth/p2p/peer_pool,
   ../../eth/p2p/rlpx_protocols/whisper_protocol,
   ./p2p_test_helper
diff --git a/tests/utp/test_discv5_protocol.nim b/tests/utp/test_discv5_protocol.nim
index 3c238e3..d4e4545 100644
--- a/tests/utp/test_discv5_protocol.nim
+++ b/tests/utp/test_discv5_protocol.nim
@@ -8,7 +8,7 @@
 
 import
   std/options,
-  chronos, bearssl,
+  chronos,
   stew/shims/net, stew/byteutils,
   testutils/unittests,
   ../../eth/p2p/discoveryv5/[enr, node, routing_table],
@@ -17,11 +17,6 @@ import
   ../../eth/keys,
   ../p2p/discv5_test_helper
 
-proc generateByteArray(rng: var BrHmacDrbgContext, length: int): seq[byte] =
-  var bytes = newSeq[byte](length)
-  brHmacDrbgGenerate(rng, bytes)
-  return bytes
-
 procSuite "Utp protocol over discovery v5 tests":
   let rng = newRng()
   let utpProtId = "test-utp".toBytes()
@@ -91,7 +86,7 @@ procSuite "Utp protocol over discovery v5 tests":
 
     let serverSocket = await queue.get()
 
-    let bytesToTransfer = generateByteArray(rng[], numOfBytes)
+    let bytesToTransfer = rng[].generateBytes(numOfBytes)
     let written = await clientSocket.write(bytesToTransfer)
 
     let received = await serverSocket.read(numOfBytes)
diff --git a/tests/utp/test_protocol.nim b/tests/utp/test_protocol.nim
index a262d01..f24790d 100644
--- a/tests/utp/test_protocol.nim
+++ b/tests/utp/test_protocol.nim
@@ -8,7 +8,7 @@
 
 import
   sequtils,
-  chronos, bearssl,
+  chronos,
   testutils/unittests,
   ./test_utils,
   ../../eth/utp/utp_router,
@@ -210,7 +210,7 @@ procSuite "Utp protocol over udp tests":
       # Server socket is not in connected state, until first data transfer
       (not s.serverSocket.isConnected())
 
-    let bytesToTransfer = generateByteArray(rng[], 100)
+    let bytesToTransfer = rng[].generateBytes(100)
 
     let bytesReceivedFromClient = await transferData(s.clientSocket, s.serverSocket, bytesToTransfer)
 
@@ -237,7 +237,7 @@ procSuite "Utp protocol over udp tests":
       (not s.serverSocket.isConnected())
 
     # 5000 bytes is over maximal packet size
-    let bytesToTransfer = generateByteArray(rng[], 5000)
+    let bytesToTransfer = rng[].generateBytes(5000)
 
     let bytesReceivedFromClient = await transferData(s.clientSocket, s.serverSocket, bytesToTransfer)
     let bytesReceivedFromServer = await transferData(s.serverSocket, s.clientSocket, bytesToTransfer)
@@ -266,14 +266,14 @@ procSuite "Utp protocol over udp tests":
 
 
     # 5000 bytes is over maximal packet size
-    let bytesToTransfer = generateByteArray(rng[], 5000)
+    let bytesToTransfer = rng[].generateBytes(5000)
 
     let written = await s.clientSocket.write(bytesToTransfer)
 
     check:
       written.get() == len(bytesToTransfer)
 
-    let bytesToTransfer1 = generateByteArray(rng[], 5000)
+    let bytesToTransfer1 = rng[].generateBytes(5000)
 
     let written1 = await s.clientSocket.write(bytesToTransfer1)
 
@@ -301,8 +301,8 @@ procSuite "Utp protocol over udp tests":
       s.clientSocket2.numPacketsInOutGoingBuffer() == 0
 
     let numBytesToTransfer = 5000
-    let client1Data = generateByteArray(rng[], numBytesToTransfer)
-    let client2Data = generateByteArray(rng[], numBytesToTransfer)
+    let client1Data = rng[].generateBytes(numBytesToTransfer)
+    let client2Data = rng[].generateBytes(numBytesToTransfer)
 
     discard s.clientSocket1.write(client1Data)
     discard s.clientSocket2.write(client2Data)
@@ -327,7 +327,7 @@ procSuite "Utp protocol over udp tests":
       # Server socket is not in connected state, until first data transfer
       (not s.serverSocket.isConnected())
 
-    let bytesToTransfer = generateByteArray(rng[], 100)
+    let bytesToTransfer = rng[].generateBytes(100)
 
     let bytesReceivedFromClient = await transferData(s.clientSocket, s.serverSocket, bytesToTransfer)
 
@@ -362,9 +362,9 @@ procSuite "Utp protocol over udp tests":
       # Server socket is not in connected state, until first data transfer
       (not s.serverSocket.isConnected())
 
-    let bytesToTransfer1 = generateByteArray(rng[], 1000)
-    let bytesToTransfer2 = generateByteArray(rng[], 1000)
-    let bytesToTransfer3 = generateByteArray(rng[], 1000)
+    let bytesToTransfer1 = rng[].generateBytes(1000)
+    let bytesToTransfer2 = rng[].generateBytes(1000)
+    let bytesToTransfer3 = rng[].generateBytes(1000)
 
     let w1 = await s.clientSocket.write(bytesToTransfer1)
     let w2 = await s.clientSocket.write(bytesToTransfer2)
@@ -436,7 +436,7 @@ procSuite "Utp protocol over udp tests":
       (not s.serverSocket.isConnected())
 
     # big transfer of 50kb
-    let bytesToTransfer = generateByteArray(rng[], 50000)
+    let bytesToTransfer = rng[].generateBytes(50000)
 
     let bytesReceivedFromClient = await transferData(s.clientSocket, s.serverSocket, bytesToTransfer)
 
@@ -468,7 +468,7 @@ procSuite "Utp protocol over udp tests":
       (not s.serverSocket.isConnected())
 
     # big transfer of 50kb
-    let bytesToTransfer = generateByteArray(rng[], 50000)
+    let bytesToTransfer = rng[].generateBytes(50000)
 
     let bytesReceivedFromClient = await transferData(s.clientSocket, s.serverSocket, bytesToTransfer)
 
diff --git a/tests/utp/test_protocol_integration.nim b/tests/utp/test_protocol_integration.nim
index 63fad08..553ccbf 100644
--- a/tests/utp/test_protocol_integration.nim
+++ b/tests/utp/test_protocol_integration.nim
@@ -8,7 +8,7 @@
 
 import
   std/[sequtils, tables, options, sugar],
-  chronos, bearssl,
+  chronos,
   testutils/unittests,
   ./test_utils,
   ../../eth/utp/utp_router,
@@ -17,7 +17,7 @@ import
   ../../eth/p2p/discoveryv5/random2
 
 
-proc connectTillSuccess(p: UtpProtocol, to: TransportAddress, maxTries: int = 20): Future[UtpSocket[TransportAddress]] {.async.} = 
+proc connectTillSuccess(p: UtpProtocol, to: TransportAddress, maxTries: int = 20): Future[UtpSocket[TransportAddress]] {.async.} =
   var i = 0
   while true:
     let res = await p.connectTo(to)
@@ -31,7 +31,7 @@ proc connectTillSuccess(p: UtpProtocol, to: TransportAddress, maxTries: int = 20
 
 proc buildAcceptConnection(
     t: ref Table[UtpSocketKey[TransportAddress], UtpSocket[TransportAddress]]
-  ): AcceptConnectionCallback[TransportAddress] = 
+  ): AcceptConnectionCallback[TransportAddress] =
   return (
     proc (server: UtpRouter[TransportAddress], client: UtpSocket[TransportAddress]): Future[void] =
       let fut = newFuture[void]()
@@ -42,7 +42,7 @@ proc buildAcceptConnection(
   )
 
 proc getServerSocket(
-  t: ref Table[UtpSocketKey[TransportAddress], UtpSocket[TransportAddress]], 
+  t: ref Table[UtpSocketKey[TransportAddress], UtpSocket[TransportAddress]],
   clientAddress: TransportAddress,
   clientConnectionId: uint16): Option[UtpSocket[TransportAddress]] =
   let serverSocketKey = UtpSocketKey[TransportAddress](remoteAddress: clientAddress, rcvId: clientConnectionId + 1)
@@ -68,27 +68,27 @@ procSuite "Utp protocol over udp tests with loss and delays":
         )
     )
 
-  proc testScenario(maxDelay: int, dropRate: int, cfg: SocketConfig = SocketConfig.init()): 
+  proc testScenario(maxDelay: int, dropRate: int, cfg: SocketConfig = SocketConfig.init()):
     Future[(
-      UtpProtocol, 
-      UtpSocket[TransportAddress], 
-      UtpProtocol, 
+      UtpProtocol,
+      UtpSocket[TransportAddress],
+      UtpProtocol,
       UtpSocket[TransportAddress])
     ] {.async.} =
 
     var connections1 = newTable[UtpSocketKey[TransportAddress], UtpSocket[TransportAddress]]()
     let address1 = initTAddress("127.0.0.1", 9080)
-    let utpProt1 = 
+    let utpProt1 =
       UtpProtocol.new(
-        buildAcceptConnection(connections1), 
+        buildAcceptConnection(connections1),
         address1,
         socketConfig = cfg,
-        sendCallbackBuilder = sendBuilder(maxDelay, dropRate), 
+        sendCallbackBuilder = sendBuilder(maxDelay, dropRate),
         rng = rng)
 
     var connections2 = newTable[UtpSocketKey[TransportAddress], UtpSocket[TransportAddress]]()
     let address2 = initTAddress("127.0.0.1", 9081)
-    let utpProt2 = 
+    let utpProt2 =
       UtpProtocol.new(
         buildAcceptConnection(connections2),
         address2,
@@ -112,9 +112,9 @@ procSuite "Utp protocol over udp tests with loss and delays":
     cfg: SocketConfig
 
   proc init(
-    T: type TestCase, 
-    maxDelay: int, 
-    dropRate: int, 
+    T: type TestCase,
+    maxDelay: int,
+    dropRate: int,
     bytesToTransfer: int,
     cfg: SocketConfig = SocketConfig.init(),
     bytesPerRead: int = 0): TestCase =
@@ -138,7 +138,7 @@ procSuite "Utp protocol over udp tests with loss and delays":
         serverSocket) = await testScenario(testCase.maxDelay, testCase.dropRate, testcase.cfg)
 
       let smallBytes = 10
-      let smallBytesToTransfer = generateByteArray(rng[], smallBytes)
+      let smallBytesToTransfer = rng[].generateBytes(smallBytes)
       # first transfer and read to make server socket connecteced
       let write1 = await clientSocket.write(smallBytesToTransfer)
       let read1 = await serverSocket.read(smallBytes)
@@ -148,11 +148,11 @@ procSuite "Utp protocol over udp tests with loss and delays":
         read1 == smallBytesToTransfer
 
       let numBytes = testCase.bytesToTransfer
-      let bytesToTransfer = generateByteArray(rng[], numBytes)
+      let bytesToTransfer = rng[].generateBytes(numBytes)
 
       discard clientSocket.write(bytesToTransfer)
       discard serverSocket.write(bytesToTransfer)
-      
+
       let serverReadFut = serverSocket.read(numBytes)
       let clientReadFut = clientSocket.read(numBytes)
 
@@ -165,7 +165,7 @@ procSuite "Utp protocol over udp tests with loss and delays":
       check:
         clientRead == bytesToTransfer
         serverRead == bytesToTransfer
-      
+
       await clientProtocol.shutdownWait()
       await serverProtocol.shutdownWait()
 
@@ -184,7 +184,7 @@ procSuite "Utp protocol over udp tests with loss and delays":
       res.add(bytes)
       inc i
     return res
-    
+
   asyncTest "Write and Read large data in different network conditions split over several reads":
     for testCase in testCases1:
 
@@ -195,7 +195,7 @@ procSuite "Utp protocol over udp tests with loss and delays":
         serverSocket) = await testScenario(testCase.maxDelay, testCase.dropRate, testcase.cfg)
 
       let smallBytes = 10
-      let smallBytesToTransfer = generateByteArray(rng[], smallBytes)
+      let smallBytesToTransfer = rng[].generateBytes(smallBytes)
       # first transfer and read to make server socket connecteced
       let write1 = await clientSocket.write(smallBytesToTransfer)
       let read1 = await serverSocket.read(smallBytes)
@@ -204,11 +204,11 @@ procSuite "Utp protocol over udp tests with loss and delays":
         read1 == smallBytesToTransfer
 
       let numBytes = testCase.bytesToTransfer
-      let bytesToTransfer = generateByteArray(rng[], numBytes)
+      let bytesToTransfer = rng[].generateBytes(numBytes)
 
       discard clientSocket.write(bytesToTransfer)
       discard serverSocket.write(bytesToTransfer)
-      
+
       let numOfReads = int(testCase.bytesToTransfer / testCase.bytesPerRead)
       let serverReadFut = serverSocket.readWithMultipleReads(numOfReads, testCase.bytesPerRead)
       let clientReadFut = clientSocket.readWithMultipleReads(numOfReads, testCase.bytesPerRead)
@@ -244,7 +244,7 @@ procSuite "Utp protocol over udp tests with loss and delays":
 
 
       let numBytes = testCase.bytesToTransfer
-      let bytesToTransfer = generateByteArray(rng[], numBytes)
+      let bytesToTransfer = rng[].generateBytes(numBytes)
 
       discard await clientSocket.write(bytesToTransfer)
       clientSocket.close()
diff --git a/tests/utp/test_utils.nim b/tests/utp/test_utils.nim
index 556b558..962a31a 100644
--- a/tests/utp/test_utils.nim
+++ b/tests/utp/test_utils.nim
@@ -9,11 +9,6 @@ type AssertionCallback = proc(): bool {.gcsafe, raises: [Defect].}
 let testBufferSize = 1024'u32
 let defaultRcvOutgoingId = 314'u16
 
-proc generateByteArray*(rng: var BrHmacDrbgContext, length: int): seq[byte] =
-  var bytes = newSeq[byte](length)
-  brHmacDrbgGenerate(rng, bytes)
-  return bytes
-
 proc waitUntil*(f: AssertionCallback): Future[void] {.async.} =
   while true:
     let res = f()
@@ -65,7 +60,7 @@ template connectOutGoingSocketWithIncoming*(
 
   let incomingSocket = newIncomingSocket[TransportAddress](
     testAddress,
-    initTestSnd(incomingQueue), 
+    initTestSnd(incomingQueue),
     cfg,
     initialPacket.header.connectionId,
     initialPacket.header.seqNr,
@@ -77,9 +72,9 @@ template connectOutGoingSocketWithIncoming*(
   let responseAck = await incomingQueue.get()
 
   await outgoingSocket.processPacket(responseAck)
-  
+
   await waitUntil(proc (): bool = outgoingSocket.isConnected())
-  
+
   check:
     outgoingSocket.isConnected()
 
@@ -91,7 +86,7 @@ proc generateDataPackets*(
   initialSeqNr: uint16,
   connectionId: uint16,
   ackNr: uint16,
-  rng: var BrHmacDrbgContext): seq[Packet] =
+  rng: var HmacDrbgContext): seq[Packet] =
   let packetSize = 100
   var packets = newSeq[Packet]()
   var i = 0'u16
@@ -101,7 +96,7 @@ proc generateDataPackets*(
       connectionId,
       ackNr,
       testBufferSize,
-      generateByteArray(rng, packetSize),
+      rng.generateBytes(packetSize),
       0
     )
     packets.add(packet)
diff --git a/tests/utp/test_utp_router.nim b/tests/utp/test_utp_router.nim
index cb198cb..a72a22c 100644
--- a/tests/utp/test_utp_router.nim
+++ b/tests/utp/test_utp_router.nim
@@ -8,7 +8,7 @@
 
 import
   std/[hashes, options],
-  chronos, bearssl, chronicles,
+  chronos, chronicles,
   testutils/unittests,
   ./test_utils,
   ../../eth/utp/utp_router,
@@ -313,7 +313,7 @@ procSuite "Utp router unit tests":
     let connectResult = await connectFuture
 
     await waitUntil(proc (): bool = router.len() == 0)
-    
+
     check:
       connectResult.isErr()
       connectResult.error().kind == ConnectionTimedOut
@@ -356,7 +356,7 @@ procSuite "Utp router unit tests":
 
     check:
       connectResult.isErr()
-      # even though send is failing we will just finish with timeout, 
+      # even though send is failing we will just finish with timeout,
       connectResult.error().kind == ConnectionTimedOut
       router.len() == 0
 
diff --git a/tests/utp/test_utp_socket.nim b/tests/utp/test_utp_socket.nim
index 8d3cf60..7b7586f 100644
--- a/tests/utp/test_utp_socket.nim
+++ b/tests/utp/test_utp_socket.nim
@@ -8,7 +8,7 @@
 
 import
   std/[algorithm, random, sequtils, options],
-  chronos, bearssl, chronicles,
+  chronos, chronicles,
   testutils/unittests,
   ./test_utils,
   ../../eth/utp/utp_router,
@@ -186,7 +186,7 @@ procSuite "Utp socket unit test":
       await outgoingSocket.processPacket(p)
 
     var sentAcks: seq[Packet] = @[]
-    
+
     for i in 0'u16..<numOfPackets:
       let ack = await q.get()
       sentAcks.add(ack)
@@ -238,7 +238,7 @@ procSuite "Utp socket unit test":
       await outgoingSocket.processPacket(p)
 
     var sentAcks: seq[Packet] = @[]
-    
+
     for i in 0'u16..<numOfPackets:
       let ack = await q.get()
       sentAcks.add(ack)
@@ -378,7 +378,7 @@ procSuite "Utp socket unit test":
     let initialRemoteSeq = 10'u16
 
     # lot of data which will generate at least 5 packets
-    let bigDataTowWrite = generateByteArray(rng[], 10000)
+    let bigDataTowWrite = rng[].generateBytes(10000)
     let (outgoingSocket, initialPacket) = connectOutGoingSocket(initialRemoteSeq, q)
 
     let acker = outgoingSocket.ackAllPacket(q, initialRemoteSeq)
@@ -389,7 +389,7 @@ procSuite "Utp socket unit test":
 
     await waitUntil(proc (): bool = outgoingSocket.numPacketsInOutGoingBuffer() == 0)
 
-    let maxWindowAfterSuccesfulSends = outgoingSocket.currentMaxWindowSize() 
+    let maxWindowAfterSuccesfulSends = outgoingSocket.currentMaxWindowSize()
 
     check:
       # after processing a lot of data, our window size should be a lot bigger than our packet size
@@ -397,9 +397,9 @@ procSuite "Utp socket unit test":
 
     # cancel acking process, next writes will for sure timeout
     await acker.cancelAndWait()
-    
+
     # data which fits one packet and will timeout
-    let smallerData = generateByteArray(rng[], 100)
+    let smallerData = rng[].generateBytes(100)
 
     let bytesWritten1 = await outgoingSocket.write(smallerData)
 
@@ -411,7 +411,7 @@ procSuite "Utp socket unit test":
 
     # ignore also first re-send
     discard await q.get()
-    
+
     let maxWindowAfterTimeout = outgoingSocket.currentMaxWindowSize()
 
     check:
@@ -1059,7 +1059,7 @@ procSuite "Utp socket unit test":
     let q = newAsyncQueue[Packet]()
     let initialRemoteSeq = 10'u16
 
-    let dataToWrite = generateByteArray(rng[], 1001)
+    let dataToWrite = rng[].generateBytes(1001)
 
     # remote is initialized with buffer to small to handle whole payload
     let (outgoingSocket, initialPacket) = connectOutGoingSocket(initialRemoteSeq, q, cfg = SocketConfig.init(optSndBuffer = 1000))
@@ -1101,7 +1101,7 @@ procSuite "Utp socket unit test":
     # remote is initialized with buffer to small to handle whole payload
     let (outgoingSocket, initialPacket) = connectOutGoingSocket(initialRemoteSeq, q, cfg = SocketConfig.init(optSndBuffer = 1160))
 
-    let twoPacketData = generateByteArray(rng[], int(dataToWirte))
+    let twoPacketData = rng[].generateBytes(int(dataToWirte))
 
     let writeResult = await outgoingSocket.write(twoPacketData)
 
@@ -1140,7 +1140,7 @@ procSuite "Utp socket unit test":
     # we are using ack from remote to setup our snd window size to one packet size on one packet
     await outgoingSocket.processPacket(someAckFromRemote)
 
-    let twoPacketData = generateByteArray(rng[], int(2 * remoteRcvWindowSize))
+    let twoPacketData = rng[].generateBytes(int(2 * remoteRcvWindowSize))
 
     let writeFut = outgoingSocket.write(twoPacketData)
 
@@ -1197,7 +1197,7 @@ procSuite "Utp socket unit test":
 
     # write result will be successfull as send buffer has space
     let writeResult = await outgoingSocket.write(someData)
-    
+
     # this will finish in seconds(3) as only after this time window will be set to min value
     let p = await q.get()
 
@@ -1356,7 +1356,7 @@ procSuite "Utp socket unit test":
 
     let writeRes1 = await outgoingSocket.write(dataToWrite1)
     let writeRes2 = await outgoingSocket.write(dataToWrite2)
-    let writeRes3 = await outgoingSocket.write(dataToWrite3)  
+    let writeRes3 = await outgoingSocket.write(dataToWrite3)
 
     check:
       writeRes1.isOk()
@@ -1529,7 +1529,7 @@ procSuite "Utp socket unit test":
   asyncTest "Maximum payload size should be configurable":
     let q = newAsyncQueue[Packet]()
     let initalRemoteSeqNr = 10'u16
-    let d = generateByteArray(rng[], 5000)
+    let d = rng[].generateBytes(5000)
     let maxPayloadSize = 800'u32
     let config = SocketConfig.init(payloadSize = maxPayloadSize)
 
diff --git a/tests/utp/test_utp_socket_sack.nim b/tests/utp/test_utp_socket_sack.nim
index 567d7e7..e27e119 100644
--- a/tests/utp/test_utp_socket_sack.nim
+++ b/tests/utp/test_utp_socket_sack.nim
@@ -8,7 +8,7 @@
 
 import
   std/[options, sequtils],
-  chronos, bearssl, chronicles,
+  chronos, chronicles,
   stew/bitops2,
   testutils/unittests,
   ./test_utils,
@@ -62,7 +62,7 @@ procSuite "Utp socket selective acks unit test":
       numOfSetBits = numOfSetBits + countOnes(b)
     return numOfSetBits
 
-  proc hasOnlyOneBitSet(arr: openArray[byte]): bool = 
+  proc hasOnlyOneBitSet(arr: openArray[byte]): bool =
     return numOfSetBits(arr) == 1
 
   asyncTest "Socket with empty buffer should generate array with only zeros":
@@ -75,7 +75,7 @@ procSuite "Utp socket selective acks unit test":
 
     check:
       extArray == [0'u8, 0, 0, 0]
-  
+
   asyncTest "Socket should generate correct bit mask for each missing packet":
     # 1 means that received packet is packet just after expected packet i.e
     # packet.seqNr - receivingSocket.ackNr = 2
@@ -113,7 +113,7 @@ procSuite "Utp socket selective acks unit test":
       let bitMask = await connectAndProcessMissingPacketWithIndexes(missingIndexes)
       check:
         numOfSetBits(bitMask) == len(missingIndexes)
-      
+
       for idx in missingIndexes:
         check:
           getBit(bitMask, idx - 1)
@@ -128,7 +128,7 @@ procSuite "Utp socket selective acks unit test":
       check:
         numOfSetBits(bitMask) == 32
         len(bitMask) == 4
-      
+
   type TestCase = object
     # number of packet to generate by writitng side
     numOfPackets: int
@@ -155,7 +155,7 @@ procSuite "Utp socket selective acks unit test":
     outgoingQueue: AsyncQueue[Packet],
     incomingQueue: AsyncQueue[Packet],
     testCase: TestCase): Future[(UtpSocket[TransportAddress], UtpSocket[TransportAddress], seq[Packet])] {.async.} =
-    let (outgoingSocket, incomingSocket) = 
+    let (outgoingSocket, incomingSocket) =
       connectOutGoingSocketWithIncoming(
         initialRemoteSeq,
         outgoingQueue,
@@ -168,7 +168,7 @@ procSuite "Utp socket selective acks unit test":
       discard await outgoingSocket.write(dataToWrite)
       let packet = await outgoingQueue.get()
       packets.add(packet)
-    
+
     for toDeliver in testCase.packetsDelivered:
       await incomingSocket.processPacket(packets[toDeliver])
 
@@ -179,7 +179,7 @@ procSuite "Utp socket selective acks unit test":
   asyncTest "Socket should calculate number of bytes acked by selective acks":
     let dataSize = 10
     let initialRemoteSeq = 10'u16
-    let smallData = generateByteArray(rng[], 10)
+    let smallData = rng[].generateBytes(10)
 
     for testCase in selectiveAckTestCases:
       let outgoingQueue = newAsyncQueue[Packet]()
@@ -209,7 +209,7 @@ procSuite "Utp socket selective acks unit test":
 
       let ackedBytes = outgoingSocket.calculateSelectiveAckBytes(finalAck.header.ackNr, finalAck.eack.unsafeGet())
 
-      check: 
+      check:
         int(ackedBytes) == len(testCase.packetsDelivered) * dataSize
 
       await outgoingSocket.destroyWait()
@@ -218,12 +218,12 @@ procSuite "Utp socket selective acks unit test":
   asyncTest "Socket should ack packets based on selective ack packet":
     let dataSize = 10
     let initialRemoteSeq = 10'u16
-    let smallData = generateByteArray(rng[], 10)
+    let smallData = rng[].generateBytes(10)
 
     for testCase in selectiveAckTestCases:
       let outgoingQueue = newAsyncQueue[Packet]()
       let incomingQueue = newAsyncQueue[Packet]()
-    
+
       let (outgoingSocket, incomingSocket, _) = await setupTestCase(
         smallData,
         initialRemoteSeq,
@@ -252,8 +252,8 @@ procSuite "Utp socket selective acks unit test":
       await outgoingSocket.processPacket(finalAck)
 
       let expectedPackets = testCase.numOfPackets - len(testCase.packetsDelivered)
-      
-      await waitUntil(proc (): bool =  outgoingSocket.numPacketsInOutGoingBuffer() == expectedPackets) 
+
+      await waitUntil(proc (): bool =  outgoingSocket.numPacketsInOutGoingBuffer() == expectedPackets)
 
       check:
         outgoingSocket.numPacketsInOutGoingBuffer() == expectedPackets
@@ -276,7 +276,7 @@ procSuite "Utp socket selective acks unit test":
   asyncTest "Socket should re-send packets when there are at least 3 packets acked ahead":
     let dataSize = 10
     let initialRemoteSeq = 10'u16
-    let smallData = generateByteArray(rng[], 10)
+    let smallData = rng[].generateBytes(10)
 
     for testCase in packetResendTestCases:
       let outgoingQueue = newAsyncQueue[Packet]()
@@ -314,7 +314,7 @@ procSuite "Utp socket selective acks unit test":
           resentPacket.header.seqNr == initialPackets[idx].header.seqNr
 
       let endBufferSize = outgoingSocket.currentMaxWindowSize()
-      
+
       if len(testCase.packetsResent) == 0:
         check:
           # when there is no packet loss (no resent packets), buffer size increases