P_SHA1 for Ruby

psha1.rb

#Testing function PHA1:
require 'base64'
require 'openssl'

#Sample Data:
secret      = Base64.decode64("kAIthWJeZ3UoS4k6qLIbfA==")
label       = "WS-SecureConversationWS-SecureConversation"
seed        = Base64.decode64("yP9lu4OUF1ah534Re/ZfcQ==")
new_seed    = label + seed

#puts Base64.encode64(new_seed)
length      = 24


def p_sha1(client_secret, server_secret, size_bytes = 32)
    digest = OpenSSL::Digest.new('sha1')
    hmac_key = client_secret
    i = 0
    b1 = server_secret
    psha = []

    while i < size_bytes do        
        b1      = OpenSSL::HMAC.digest(digest,hmac_key, b1)
        b2      = b1+ server_secret
        temp    = OpenSSL::HMAC.digest(digest,hmac_key,b2 )
        j = 0
        while j < temp.length do
            if i < size_bytes
                psha[i] = temp[j]
                i+=1
            else
                break
            end
            j+=1
        end

    end
    return psha.join('')
end    

psha1 = p_sha1(secret, new_seed, length)

puts Base64.encode64(psha1)