class ActiveSupport::MessageVerifier

@verifier = ActiveSupport::MessageVerifier.new(‘s3Krit’, digest: ‘SHA256’)
‘:digest` key as an option while initializing the verifier:
If you want to use a different hash algorithm, you can change it by providing
MessageVerifier creates HMAC signatures using SHA1 hash algorithm by default.
@verifier = ActiveSupport::MessageVerifier.new(’s3Krit’, serializer: YAML)
hash upon initialization:
another serialization method, you can set the serializer in the options
By default it uses Marshal to serialize the message. If you want to use
end
self.current_user = User.find(id)
if Time.now < time
id, time = @verifier.verify(cookies)
In the authentication filter:<br><br>cookies = @verifier.generate([@user.id, 2.weeks.from_now])
Remember Me:
where the session store isn’t suitable or available.
This is useful for cases like remember-me tokens and auto-unsubscribe links
signed to prevent tampering.
MessageVerifier makes it easy to generate and verify messages which are

def decode(data) 

def decode(data)
  ::Base64.strict_decode64(data)
end

def encode(data) 

def encode(data)
  ::Base64.strict_encode64(data)
end

def generate(value)

verifier.generate 'a private message' # => "BAhJIhRwcml2YXRlLW1lc3NhZ2UGOgZFVA==--e2d724331ebdee96a10fb99b089508d1c72bd772"
verifier = ActiveSupport::MessageVerifier.new 's3Krit'

the secret, the original value cannot be extracted from the message.
The message is signed with the +MessageVerifier+'s secret. Without knowing

Generates a signed message for the provided value. 
def generate(value)
  data = encode(@serializer.dump(value))
  "#{data}--#{generate_digest(data)}"
end

def generate_digest(data) 

def generate_digest(data)
  require 'openssl' unless defined?(OpenSSL)
  OpenSSL::HMAC.hexdigest(OpenSSL::Digest.const_get(@digest).new, @secret, data)
end

def initialize(secret, options = {}) 

def initialize(secret, options = {})
  raise ArgumentError, 'Secret should not be nil.' unless secret
  @secret = secret
  @digest = options[:digest] || 'SHA1'
  @serializer = options[:serializer] || Marshal
end

def valid_message?(signed_message)

verifier.valid_message?(tampered_message) # => false
tampered_message = signed_message.chop # editing the message invalidates the signature

verifier.valid_message?(signed_message) # => true
signed_message = verifier.generate 'a private message'
verifier = ActiveSupport::MessageVerifier.new 's3Krit'

with the +MessageVerifier+'s secret.
Checks if a signed message could have been generated by signing an object 
def valid_message?(signed_message)
  return if signed_message.nil? || !signed_message.valid_encoding? || signed_message.blank?
  data, digest = signed_message.split("--".freeze)
  data.present? && digest.present? && ActiveSupport::SecurityUtils.secure_compare(digest, generate_digest(data))
end

def verified(signed_message)

verifier.verified(incompatible_message) # => TypeError: incompatible marshal file format
incompatible_message = "test--dad7b06c94abba8d46a15fafaef56c327665d5ff"

Raises any error raised while decoding the signed message.

verifier.verified(invalid_message) # => nil
invalid_message = "f--46a0120593880c733a53b6dad75b42ddc1c8996d"

Returns +nil+ if the message is not Base64-encoded.

other_verifier.verified(signed_message) # => nil
other_verifier = ActiveSupport::MessageVerifier.new 'd1ff3r3nt-s3Krit'

Returns +nil+ if the message was not signed with the same secret.

verifier.verified(signed_message) # => 'a private message'
signed_message = verifier.generate 'a private message'

verifier = ActiveSupport::MessageVerifier.new 's3Krit'

Decodes the signed message using the +MessageVerifier+'s secret. 
def verified(signed_message)
  if valid_message?(signed_message)
    begin
      data = signed_message.split("--".freeze)[0]
      @serializer.load(decode(data))
    rescue ArgumentError => argument_error
      return if argument_error.message =~ %r{invalid base64}
      raise
    end
  end
end

def verify(signed_message)

other_verifier.verify(signed_message) # => ActiveSupport::MessageVerifier::InvalidSignature
other_verifier = ActiveSupport::MessageVerifier.new 'd1ff3r3nt-s3Krit'

secret or was not Base64-encoded.
Raises +InvalidSignature+ if the message was not signed with the same

verifier.verify(signed_message) # => 'a private message'

signed_message = verifier.generate 'a private message'
verifier = ActiveSupport::MessageVerifier.new 's3Krit'

Decodes the signed message using the +MessageVerifier+'s secret. 
def verify(signed_message)
  verified(signed_message) || raise(InvalidSignature)
end