diff --git a/.gitignore b/.gitignore
index d1f2bed..c40a619 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
 .crystal
+.tool-versions
diff --git a/spec/ssh2_spec.cr b/spec/ssh2_spec.cr
index b01f1a8..4699550 100644
--- a/spec/ssh2_spec.cr
+++ b/spec/ssh2_spec.cr
@@ -3,7 +3,7 @@ require "spec"
 
 def connect_ssh
   SSH2::Session.open("localhost", 2222) do |session|
-    session.login_with_pubkey("root", "./spec/keys/id_rsa")
+    session.login_with_pubkey("root", "./spec/keys/id_rsa", "./spec/keys/id_rsa.pub")
     session.authenticated?.should be_true
     yield session
   end
@@ -22,7 +22,7 @@ describe SSH2 do
   end
 
   it "should be able to scp transfer file" do
-    fn = "#{Time.now.epoch}.txt"
+    fn = "#{Time.utc.to_unix}.txt"
     connect_ssh do |session|
       session.scp_send(fn, 0o0644, 12) do |ch|
         ch.puts "hello world"
@@ -59,7 +59,7 @@ describe SSH2::KnownHosts do
       known_hosts.size.should eq(2)
       known_hosts.map(&.name).includes?("localhost").should be_true
       known_hosts.write_file("known_hosts")
-      known_hosts.delete_if {|h| h.name == "localhost"}
+      known_hosts.delete_if { |h| h.name == "localhost" }
       known_hosts.size.should eq(1)
     end
 
@@ -101,7 +101,7 @@ describe SSH2::SFTP do
   it "should be able to upload a file" do
     connect_ssh do |ssh|
       ssh.sftp_session do |sftp|
-        fn = "#{Time.now.epoch}_upload.txt"
+        fn = "#{Time.utc.to_unix}_upload.txt"
         file = sftp.open(fn, "wc", 0o644)
         file.puts "hello world!"
         attrs = file.fstat
diff --git a/src/channel.cr b/src/channel.cr
index b1eab2a..be39bec 100644
--- a/src/channel.cr
+++ b/src/channel.cr
@@ -1,9 +1,8 @@
 require "./session"
 
 class SSH2::Channel < IO
-
-  PROCESS_SHELL = "shell"
-  PROCESS_EXEC = "exec"
+  PROCESS_SHELL     = "shell"
+  PROCESS_EXEC      = "exec"
   PROCESS_SUBSYSTEM = "subsystem"
 
   getter session : Session
@@ -63,7 +62,7 @@ class SSH2::Channel < IO
 
   def process_startup(request, message)
     ret = LibSSH2.channel_process_startup(self, request, request.bytesize.to_u32,
-                                          message, message ? message.bytesize.to_u32 : 0_u32)
+      message, message ? message.bytesize.to_u32 : 0_u32)
     check_error(ret)
   end
 
@@ -71,7 +70,7 @@ class SSH2::Channel < IO
   # leading "SIG"), and the second field populated with the error message.
   def exit_signal
     ret = LibSSH2.channel_get_exit_signal(self, out exitsignal, out exitsignal_len,
-                                          out errmsg, out errmsg_len, nil, nil)
+      out errmsg, out errmsg_len, nil, nil)
     check_error(ret)
     exitsignal_str = String.new(exitsignal, exitsignal_len) if exitsignal
     errmsg_str = String.new(errmsg, errmsg_len) if errmsg
@@ -110,6 +109,16 @@ class SSH2::Channel < IO
     read(0, slice)
   end
 
+  def read(slice : Slice(UInt32))
+    return 0 if eof?
+    read(0, slice)
+  end
+
+  def read(slice : Slice(UInt64))
+    return 0 if eof?
+    read(0, slice)
+  end
+
   def write(slice : Slice(UInt8))
     write(0, slice)
   end
@@ -167,8 +176,8 @@ class SSH2::Channel < IO
   def request_pty(term, modes = nil, width = LibSSH2::TERM_WIDTH, height = LibSSH2::TERM_HEIGHT,
                   width_px = LibSSH2::TERM_WIDTH_PX, height_px = LibSSH2::TERM_HEIGHT_PX)
     ret = LibSSH2.channel_request_pty(self, term, term.bytesize.to_u32,
-                                      modes, modes ? modes.bytesize.to_u32 : 0_u32,
-                                      width, height, width_px, height_px)
+      modes, modes ? modes.bytesize.to_u32 : 0_u32,
+      width, height, width_px, height_px)
     check_error(ret)
   end
 
@@ -219,7 +228,6 @@ class SSH2::Channel < IO
   end
 
   class StreamIO < IO
-
     getter channel : Channel
     getter stream_id : Int32
 
diff --git a/src/lib_ssh2.cr b/src/lib_ssh2.cr
index 5f0c0f4..2433a62 100644
--- a/src/lib_ssh2.cr
+++ b/src/lib_ssh2.cr
@@ -10,7 +10,7 @@ lib LibSSH2
 
   @[Flags]
   enum BlockDirections
-    Inbound,
+    Inbound
     Outbound
   end
 
diff --git a/src/session.cr b/src/session.cr
index 3f0d64e..4e991e1 100644
--- a/src/session.cr
+++ b/src/session.cr
@@ -35,23 +35,23 @@ class SSH2::Session
   # Login with username and password
   def login(username, password)
     ret = LibSSH2.userauth_password(self, username, username.bytesize.to_u32,
-                                    password, password.bytesize.to_u32, nil)
+      password, password.bytesize.to_u32, nil)
     check_error(ret)
   end
 
   # Login with username using pub/priv key values
   def login_with_data(username, privkey, pubkey, passphrase = nil)
     ret = LibSSH2.userauth_publickey_frommemory(self, username, username.bytesize.to_u32,
-                                                pubkey, LibC::SizeT.new(pubkey.bytesize),
-                                                privkey, LibC::SizeT.new(privkey.bytesize),
-                                                passphrase)
+      pubkey, LibC::SizeT.new(pubkey.bytesize),
+      privkey, LibC::SizeT.new(privkey.bytesize),
+      passphrase)
     check_error(ret)
   end
 
   # Login with username using pub/priv key files
   def login_with_pubkey(username, privkey, pubkey = nil, passphrase = nil)
     ret = LibSSH2.userauth_publickey_fromfile(self, username, username.bytesize.to_u32,
-                                              pubkey, privkey, passphrase)
+      pubkey, privkey, passphrase)
     check_error(ret)
   end
 
@@ -242,8 +242,8 @@ class SSH2::Session
   # Allocate a new channel for exchanging data with the server.
   def open_channel(channel_type, window_size, packet_size, message)
     handle = LibSSH2.channel_open(self, channel_type, channel_type.bytesize.to_u32,
-                                  window_size.to_u32, packet_size.to_u32,
-                                  message, message ? message.bytesize.to_u32 : 0_u32)
+      window_size.to_u32, packet_size.to_u32,
+      message, message ? message.bytesize.to_u32 : 0_u32)
     Channel.new self, handle
   end
 
@@ -280,16 +280,16 @@ class SSH2::Session
   end
 
   # Send a file to the remote host via SCP.
+  # LibC::TimeT.new(mtime), LibC::TimeT.new(atime))
   def scp_send(path, mode, size, mtime, atime)
-    handle = LibSSH2.scp_send(self, path, mode.to_i32, size.to_u64,
-                              LibC::TimeT.new(mtime), LibC::TimeT.new(atime))
+    handle = LibSSH2.scp_send(self, path, mode.to_i32, size.to_u64, mtime, atime)
     check_error(LibSSH2.session_last_errno(self))
     Channel.new self, handle
   end
 
   # Send a file to the remote host via SCP.
   # A new channel is passed to the block and closed afterwards.
-  def scp_send(path, mode, size, mtime = Time.now.epoch, atime = Time.now.epoch)
+  def scp_send(path, mode, size, mtime = Time.utc.to_unix, atime = Time.utc.to_unix)
     channel = scp_send(path, mode, size, mtime, atime)
     begin
       yield channel
@@ -304,13 +304,25 @@ class SSH2::Session
       raise Errno.new("Unable to get stat for '#{path}'")
     end
     scp_send(path, (stat.st_mode & 0x3ff).to_i32, stat.st_size.to_u64,
-             stat.st_mtimespec.tv_sec, stat.st_atimespec.tv_sec) do |ch|
+      stat.st_mtimespec.tv_sec, stat.st_atimespec.tv_sec) do |ch|
       File.open(path, "r") do |f|
         IO.copy(f, ch)
       end
     end
   end
 
+  # Send a file from a local filesystem to the remote host via SCP.
+  def scp_send_file(path, localpath)
+    if LibC.stat(localpath, out stat) != 0
+      raise Errno.new("Unable to get stat for '#{path}'")
+    end
+    scp_send(path, (stat.st_mode & 0x3ff).to_i32, stat.st_size.to_u64) do |ch|
+      File.open(localpath, "r") do |f|
+        IO.copy(f, ch)
+      end
+    end
+  end
+
   # Request a file from the remote host via SCP.
   def scp_recv(path)
     handle = LibSSH2.scp_recv(self, path, out stat)
@@ -331,7 +343,7 @@ class SSH2::Session
 
   # Download a file from the remote host via SCP to the local filesystem.
   def scp_recv_file(path, local_path = path)
-    min = -> (x : Int32|Int64, y : Int32|Int64) { x < y ? x : y}
+    min = ->(x : Int64 | Int32, y : Int64 | Int32) { x < y ? x : y }
 
     # libssh2 scp_recv method has a bug where its channel's read method doesn't
     # return 0 value to indicate the end of file(EOF). The only way to find EOF
@@ -341,15 +353,17 @@ class SSH2::Session
       file_size = stat.st_size
       read_bytes = 0
       File.open(local_path, "w") do |f|
-        buf = uninitialized UInt8[1024]
+        buf = StaticArray(UInt8, 1024).new(0) # => 42#uninitialized UInt8[1024]
         while read_bytes < file_size
-          bytes_to_read = min.call(buf.length, file_size - read_bytes)
-          len = ch.read(buf.to_slice, bytes_to_read).to_i32
-          f.write(buf.to_slice, len)
+          bytes_to_read = min.call(buf.size, file_size - read_bytes).to_i32
+          buf2 = Slice(UInt8).new(bytes_to_read)
+          len = ch.read(buf2).to_i32
           break if len <= 0
+          f.write buf2.to_slice
           read_bytes += len
         end
       end
+
       if file_size != read_bytes
         File.delete(local_path)
         raise SSH2Error.new "Premature end of file"
diff --git a/src/sftp/attributes.cr b/src/sftp/attributes.cr
index 3cd128f..133e923 100644
--- a/src/sftp/attributes.cr
+++ b/src/sftp/attributes.cr
@@ -52,7 +52,7 @@ class SSH2::SFTP::Attributes
   end
 
   def atime
-    Time.epoch(@stat.atime.to_i32)
+    Time.unix_ms(@stat.atime.to_i32)
   end
 
   def atime=(v : Time)
@@ -60,7 +60,7 @@ class SSH2::SFTP::Attributes
   end
 
   def mtime
-    Time.epoch(@stat.mtime.to_i32)
+    Time.unix_ms(@stat.mtime.to_i32)
   end
 
   def mtime=(v : Time)