Signet App is a cryptographic application which enables governmental and business users to communicate privately and securely using Commercial off-the-shelf smart phones and widely available messaging services. Signet App provides a secure and verifiable method of exchanging and saving cryptographic keys in an Android or iOS device for encrypting confidential messages and documents. After encryption any available service can be used for the actual message transport such as email, WhatsApp, Facebook Messenger, WeChat or Slack.