401 unauthorized from Twitter API with oauth gem in Ruby

Question

This is my first experience working with Twitter API's. I am using the following tools:

ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-linux]
gem 'oauth'
- oauth (0.5.1)
- oauth2 (1.1.0)
- omniauth-oauth2 (1.4.0)

I obtained a key and secret from Twitter.

I copied and pasted from the example on Twitter for Ruby.

=begin
code taken directly from the example at 
https://dev.twitter.com/oauth/overview/single-user
=end

require 'oauth'
consumer_key, \
  consumer_secret = [
    'CONSUMER_KEY', 
    'CONSUMER_SECRET'
].map { |key| ENV[key] }
raise "Some key undefined." unless [consumer_key, consumer_secret].all?

# Exchange your oauth_token and oauth_token_secret for an AccessToken instance.
def prepare_access_token(oauth_token, oauth_token_secret)
    consumer = OAuth::Consumer.new("APIKey", "APISecret", { :site => "https://api.twitter.com", :scheme => :header })

    # now create the access token object from passed values
    token_hash = { :oauth_token => oauth_token, :oauth_token_secret => oauth_token_secret }
    access_token = OAuth::AccessToken.from_hash(consumer, token_hash )

    return access_token
end

# Exchange our oauth_token and oauth_token secret for the AccessToken instance.
access_token = prepare_access_token(consumer_key, consumer_secret)
p access_token

# use the access token as an agent to get the home timeline
response = access_token.request(:get, "https://api.twitter.com/1.1/statuses/home_timeline.json")
p response

=begin   

|| #<OAuth::AccessToken:0x000000021ed938 
@token="redacted", @secret="redacted", 
@consumer=#<OAuth::Consumer:0x000000021edb68 
@key="APIKey", 
@secret="APISecret", @options={:signature_method=>"HMAC-SHA1", 
:request_token_path=>"/oauth/request_token", 
:authorize_path=>"/oauth/authorize", 
:access_token_path=>"/oauth/access_token", 
:proxy=>nil, :scheme=>:header, 
:http_method=>:post, :oauth_version=>"1.0", 
:site=>"https://api.twitter.com"}>, 
@params={:oauth_token=>"redacted", :oauth_token_secret=>"redacted"}>
|| #<Net::HTTPUnauthorized 401 Authorization Required readbody=true>
=end

What I tried:

Getting a new key and secret.

Result:

Net::HTTPUnauthorized 401 Authorization Required readbody=true
Synchronized my server's time because many Stack Overflow posts mentioned that a 401 is returned if the server time varies beyond a certain point. I installed ntp.
suggestions from this list
- set the Callback URL in Twitter settings: http://127.0.0.1:3000/auth/twitter/callback
API Console Tool on Twitter. After authenticating with my Twitter account https://api.twitter.com/1.1/statuses/home_timeline.json returns

HTTP/1.1 200 OK

along with expected data.
checked to see if Twitter API operating normally

Suggestions of where to go from here appreciated.

UPDATE OAuth Tool on Twitter Developer returns the expected result with a curl execution:

curl --get 'https://api.twitter.com/1.1/statuses/home_timeline.json' --header 'Authorization: OAuth oauth_consumer_key="redacted", oauth_nonce="redacted", oauth_signature="redacted", oauth_signature_method="HMAC-SHA1", oauth_timestamp="1463742270", oauth_token="redacted", oauth_version="1.0"' --verbose

Expected data is returned.

[{"created_at":"Fri May 20 11:05:21 +0000 2016","id":733614584754515968,"id_str":
"733614584754515968","text":"Three Skills Every New Programmer Should Learn https://t. co/1p9AxO5JPg via @sitepointdotcom","truncated":false,"entities":{"hashtags":[],"symbols" (truncated)…

Jambalaya Jambalaya · Accepted Answer · 2016-05-20T12:03:03

On this line, you should replace "APIKey" and "APISecret" with what you pulled from the CONSUMER_* environment variables.

consumer = OAuth::Consumer.new("APIKey", "APISecret", { :site => "https://api.twitter.com", :scheme => :header })

The example code from Twitter works fine for me. The wrong consumer keys will give you 401 for sure.

401 unauthorized from Twitter API with oauth gem in Ruby

1 Answers