Using HMAC SHA256 in Ruby - ruby-on-rails

Question

I'm trying to apply HMAC-SHA256 for generate a key for an Rest API.
I'm doing something like this:
def generateTransactionHash(stringToHash)
key = '123'
data = 'stringToHash'
digest = OpenSSL::Digest.new('sha256')
hmac = OpenSSL::HMAC.digest(digest, key, data)
puts hmac
end
The output of this is always this: (if I put '12345' as parameter or 'HUSYED815X', I do get the same)
ۯw/{o���p�T����:��a�h��E|q
The API is not working because of this... Can some one help me with that?

Answer 1

According to the documentation OpenSSL::HMAC.digest
Returns the authentication code an instance represents as a binary string.
If you have a problem using that maybe you need a hex encoded form provided by OpenSSL::HMAC.hexdigest
Example
key = 'key'
data = 'The quick brown fox jumps over the lazy dog'
digest = OpenSSL::Digest.new('sha256')
OpenSSL::HMAC.digest(digest, key, data)
#=> "\xF7\xBC\x83\xF40S\x84$\xB12\x98\xE6\xAAo\xB1C\xEFMY\xA1IF\x17Y\x97G\x9D\xBC-\x1A<\xD8"
OpenSSL::HMAC.hexdigest(digest, key, data)
#=> "f7bc83f430538424b13298e6aa6fb143ef4d59a14946175997479dbc2d1a3cd8"

Answer 2

Try This:
hmac = OpenSSL::HMAC.hexdigest(OpenSSL::Digest.new('sha256'), key, data)

Answer 3

def make_payment(user)
#key= SecureRandom.hex(10)
#puts #key
#secret_key = #key
puts " this is the public key #{#secret_key}"
#access_key= generate_key
puts " this is the access key #{#access_key}"
#name= #user.name
puts "#{#name}"
#time= Time.now.in_time_zone("Nairobi")
puts "This is the time request sent #{#time}"
#server_key = SecureRandom.base64
puts "This is the server key #{#server_key}"
#data = 'This request is being made from Learnida for users to make a payment'
#digest = OpenSSL::Digest.new('sha256')
uri = URI.parse("https://learnida.com")
#hmac = OpenSSL::HMAC.hexdigest(OpenSSL::Digest.new('sha256'), #secret_key, #access_key)
puts "This is the HMAC #{#hmac}"
req = Net::HTTP::Get.new(uri)
req['Authorization'] = "TM-HMAC-SHA256 key=#{#access_key} ts=#{#time} sign=#{#hmac}"
res = Net::HTTP.start(uri.hostname, uri.port, use_ssl: true) { |http| http.request(req) }
#hmacdigest= OpenSSL::HMAC.digest(#digest, #server_key, #data)
puts" This is the HMAC:SHA-256: #{#hmacdigest}"
#puts res.body
#=> "\xF7\xBC\x83\xF40S\x84$\xB12\x98\xE6\xAAo\xB1C\xEFMY\xA1IF\x17Y\x97G\x9D\xBC-\x1A<\xD8"
#sslkey= OpenSSL::HMAC.hexdigest(#digest, #server_key, #data)
puts #sslkey

Answer 4

In my case (Ticketmatic) I had to create the HMAC like above and add an Authorization header to the request with the HMAC in it.
hmac = OpenSSL::HMAC.hexdigest(OpenSSL::Digest.new('sha256'), secret_key, access_key + name + time)
req = Net::HTTP::Get.new(uri)
req['Authorization'] = "TM-HMAC-SHA256 key=#{access_key} ts=#{time} sign=#{hmac}"
res = Net::HTTP.start(uri.hostname, uri.port, use_ssl: true) { |http| http.request(req) }
You can find a full gist here
And a blogpost with more explantion here