user.rb

class User
  def github_student_url
    # The School ID GitHub gave you
    school_id = "your-school-id"
    
    # The secret key GitHub gave you
    secret_key = "secret-key"
    
    # The ID of the student in your database
    student_id = id.to_s
    
    # Generate the signature
    signature = OpenSSL::HMAC.hexdigest(OpenSSL::Digest.new('sha256'), secret_key, school_id + student_id)
    
    "https://education.github.com/student/verify?school_id=#{school_id}&student_id=#{student_id}&signature=#{signature}"
  end
end

view.html.erb

<%= link_to "GitHub Student", @user.github_student_url %>