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Bitmessage

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Vikram Reddy
Vikram Reddy

This document summarizes Bitmessage, an anonymous and encrypted messaging protocol. Some key points: - Bitmessage is based on the Bitcoin protocol and uses a "Everyone Gets Everything" model where all active users receive and try to decrypt messages. - It aims to anonymize both message content and metadata like sender/receiver addresses. - Issues include a lack of perfect forward secrecy and questions around scalability with high message volumes. - The document proposes a thin client architecture like Bitcoin's Electrum to help address scalability by avoiding downloading the full blockchain locally.

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Bitmessage:An Analysis Vikram Reddy Pareddy CSc 8222 Department of Computer Science, Georgia State University
Email SMTP 1981 Simple Protocol - designed mainly for academic and government use. No data protection strategies included
SMTP
Improvements on SMTP Sender Policy Framework(SPF) It is an email validation system that tries to prevent spam by detecting spoofing, by verifying senders IP address. The domain administrators are expected to designate hosts in that domain that are legitimate hosts. Domain Keys Identified Mail(DKIM) It is a method of associating a domain name to the email message to make someone responsible for the email. This responsibility is set by using digital signatures.
Secure Email PGP 1991 Phil Zimmerman It uses signing, encryption, certificates etc. to create secure environments for email or for encrypted file systems etc. Public key authentication decentralized Web of Trust
Web of Trust
Assumptions in Web of Trust In order to verify the key, the assumption made is that everyone signs the key of others Also everyone submits these signatures to the key servers.
Idea of PGP
Off the record messaging Cryptographic protocol used to provide strong encryption for instant messaging and email It uses a combination of AES symmetric key encryption, Diffie-Hellman key exchange, and SHA1 hash function.
Features of OTR systems Encryption Authentication Deniable Encryption Perfect Forward Secrecy
Invisible Internet Project Provides a layer that serves secure communication/data transfer mechanism Introduced in 2003 as a beta software Not reviewed yet No anonymity guaranteed
Issues with protocols based on SMTP
Bitcoin Open source decentralized Peer to Peer currency No central authority Not designed for anonymity Proof of work Mining
Bitmessage Based on Bitcoin, although it is designed to handle a different application It differs from the protocols based on SMTP as it is based on the concept of EGE or Everyone Gets Everything Using this concept, Bitmessage can not only mask the message body but also the metadata associated with the message i.e. the sender and receiver
EGE No end points to a message Encrypt the message and drop it into the block chain of messages All the active users try to decrypt the message. Only the intended recipient will be able to decrypt the message.
Other services of Bitmessage Broadcasting Since Bitmessage is based on the concept of EGE, broadcasting a message comes naturally The users have to get the password of the channel from some forum or word of mouth and then they will be able to decrypt the messages using the password
Chans Chans or channels are anonymous chat rooms Users can simply encrypt using the public key of the chat room and post it Completely anonymous
Perfect Forward Secrecy An intruder can store all the encrypted conversations and later when he eventually breaks or somehow gets the private key, all the previously encrypted information is lost This is a concern in almost all the PKI systems In Bitmessage this concern is even more pronounced as anyone can store the block chains easily
Bitmessage doesnt provide PFS However, this can be supported in Bitmessage using and implementation of key rotation Every message that is sent has to be sent using a new key. These are called ephemeral keys
Message Retention In Bitmessage, the messages are retained for two days before they are deleted The sender expects an acknowledgement from the receiver which confirms the delivery of the message If the receiver doesnt check his mailbox in two days that the message was sent, the messae is lost and the sender has to send it again This concept is being improved using the Time-to-live concept
Streams According to Prof. Tom Rodden of Univ of Nottingham, 2.8 million mails are being sent per second across the world. If Bitmessage is expected to store all these messages, it has to implement some concept compared to the normal block chain used by bitcoin For this, Bitmessage uses Streams. Streams are a way to self-segregate the messages when the volume of the messages is too high
When the volume of messages become too high, the client can divide the block chain into child streams Problem: Inter stream messaging is not possible in Bitmessage. If the receiver of the message is in a different stream, the sender has to create an address in that other stream in order to send the message.
Conclusion Bitmessage completely redesigns the email system It is completely anonymous There are a few issues that still exist such as Perfect Forward Secrecy and the question of scalability
Future Work An MIT graduate has developed a new protocol based on Bitmessage This message is called Bitmask or Bitmessage 2.0. This protocol uses bandwidth based metrics instead of proof of work A protocol called LibertyMail is being developed which is again based on Bitmessage system
Idea Currently, Bitmessage, like bitcoin in the beginning has only one client, Bitmessage-Qt This is a standalone client in the system which is used independent of any mail client The problem with this kind of client is that it downloads all the block chain into the individual system While this is a hindrance only when downloading the client for the first time, it is still a hindrance
Bitcoin overcomes this hindrance by using a thin client based architecture Electrum is an example Electrum has its multiple servers located across the world. A person who wants to use a bitcoin client can generate the keys on his local machine and send it to the electrum server which posts it onto the block chain
Electrum uses passphrase based electrum client that creates deterministic addresses based on the seed value. The idea of my project is to use a similar architecture in Bitmessage. Using this architecture, we can still mask the metadata
References

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Bitmessage

  • 1. Bitmessage:An Analysis Vikram Reddy Pareddy CSc 8222 Department of Computer Science, Georgia State University
  • 2. Email SMTP 1981 Simple Protocol - designed mainly for academic and government use. No data protection strategies included
  • 4. Improvements on SMTP Sender Policy Framework(SPF) It is an email validation system that tries to prevent spam by detecting spoofing, by verifying senders IP address. The domain administrators are expected to designate hosts in that domain that are legitimate hosts. Domain Keys Identified Mail(DKIM) It is a method of associating a domain name to the email message to make someone responsible for the email. This responsibility is set by using digital signatures.
  • 5. Secure Email PGP 1991 Phil Zimmerman It uses signing, encryption, certificates etc. to create secure environments for email or for encrypted file systems etc. Public key authentication decentralized Web of Trust
  • 7. Assumptions in Web of Trust In order to verify the key, the assumption made is that everyone signs the key of others Also everyone submits these signatures to the key servers.
  • 9. Off the record messaging Cryptographic protocol used to provide strong encryption for instant messaging and email It uses a combination of AES symmetric key encryption, Diffie-Hellman key exchange, and SHA1 hash function.
  • 10. Features of OTR systems Encryption Authentication Deniable Encryption Perfect Forward Secrecy
  • 11. Invisible Internet Project Provides a layer that serves secure communication/data transfer mechanism Introduced in 2003 as a beta software Not reviewed yet No anonymity guaranteed
  • 12. Issues with protocols based on SMTP
  • 13. Bitcoin Open source decentralized Peer to Peer currency No central authority Not designed for anonymity Proof of work Mining
  • 14. Bitmessage Based on Bitcoin, although it is designed to handle a different application It differs from the protocols based on SMTP as it is based on the concept of EGE or Everyone Gets Everything Using this concept, Bitmessage can not only mask the message body but also the metadata associated with the message i.e. the sender and receiver
  • 15. EGE No end points to a message Encrypt the message and drop it into the block chain of messages All the active users try to decrypt the message. Only the intended recipient will be able to decrypt the message.
  • 16. Other services of Bitmessage Broadcasting Since Bitmessage is based on the concept of EGE, broadcasting a message comes naturally The users have to get the password of the channel from some forum or word of mouth and then they will be able to decrypt the messages using the password
  • 17. Chans Chans or channels are anonymous chat rooms Users can simply encrypt using the public key of the chat room and post it Completely anonymous
  • 18. Perfect Forward Secrecy An intruder can store all the encrypted conversations and later when he eventually breaks or somehow gets the private key, all the previously encrypted information is lost This is a concern in almost all the PKI systems In Bitmessage this concern is even more pronounced as anyone can store the block chains easily
  • 19. Bitmessage doesnt provide PFS However, this can be supported in Bitmessage using and implementation of key rotation Every message that is sent has to be sent using a new key. These are called ephemeral keys
  • 20. Message Retention In Bitmessage, the messages are retained for two days before they are deleted The sender expects an acknowledgement from the receiver which confirms the delivery of the message If the receiver doesnt check his mailbox in two days that the message was sent, the messae is lost and the sender has to send it again This concept is being improved using the Time-to-live concept
  • 21. Streams According to Prof. Tom Rodden of Univ of Nottingham, 2.8 million mails are being sent per second across the world. If Bitmessage is expected to store all these messages, it has to implement some concept compared to the normal block chain used by bitcoin For this, Bitmessage uses Streams. Streams are a way to self-segregate the messages when the volume of the messages is too high
  • 22. When the volume of messages become too high, the client can divide the block chain into child streams Problem: Inter stream messaging is not possible in Bitmessage. If the receiver of the message is in a different stream, the sender has to create an address in that other stream in order to send the message.
  • 23. Conclusion Bitmessage completely redesigns the email system It is completely anonymous There are a few issues that still exist such as Perfect Forward Secrecy and the question of scalability
  • 24. Future Work An MIT graduate has developed a new protocol based on Bitmessage This message is called Bitmask or Bitmessage 2.0. This protocol uses bandwidth based metrics instead of proof of work A protocol called LibertyMail is being developed which is again based on Bitmessage system
  • 25. Idea Currently, Bitmessage, like bitcoin in the beginning has only one client, Bitmessage-Qt This is a standalone client in the system which is used independent of any mail client The problem with this kind of client is that it downloads all the block chain into the individual system While this is a hindrance only when downloading the client for the first time, it is still a hindrance
  • 26. Bitcoin overcomes this hindrance by using a thin client based architecture Electrum is an example Electrum has its multiple servers located across the world. A person who wants to use a bitcoin client can generate the keys on his local machine and send it to the electrum server which posts it onto the block chain
  • 27. Electrum uses passphrase based electrum client that creates deterministic addresses based on the seed value. The idea of my project is to use a similar architecture in Bitmessage. Using this architecture, we can still mask the metadata