ECDP: Elliptic Curve Data Protocol
Internet-Draft draft-ruas-cfrg-ecdp-00
Isak Ruas
Nrolabs
BR
isakruas@nrolabs.com
15 November 2024
IRTF
Crypto Forum
peer-to-peer
encryption
cryptography
data protocol
This document specifies the Elliptic Curve Data Protocol (ECDP), a peer-to-peer (P2P) communication protocol tailored for decentralized networks. ECDP utilizes elliptic curve cryptography (ECC) for encryption, employs the Elliptic Curve Digital Signature Algorithm (ECDSA) for message authentication, and leverages the Diffie-Hellman key exchange using elliptic curves for secure session initialization. The protocol supports a variety of elliptic curves (e.g., secp256k1, secp384r1) with varying key sizes, and is designed to operate over both TCP and UDP. Additionally, it utilizes SHA-256 or SHA-512 for cryptographic hash verification to ensure message integrity.
About This Document
The latest revision of this draft can be found at https://isakruas.github.io/ecdp/draft-ruas-cfrg-ecdp.html. Status information for this document may be found at https://datatracker.ietf.org/doc/draft-ruas-cfrg-ecdp/.
Discussion of this document takes place on the Crypto Forum Research Group mailing list (mailto:cfrg@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/cfrg. Subscribe at https://www.ietf.org/mailman/listinfo/cfrg/.
Source for this draft and an issue tracker can be found at https://github.com/isakruas/ecdp.
Introduction
P2P networks are widely used for data exchange but often face challenges related to security and data integrity. ECDP addresses these issues by implementing strong cryptographic measures and robust authentication mechanisms. ECDP is designed for scalability and security by enabling nodes to communicate indirectly through a network pool.
To enhance the security and integrity of the messages exchanged, the protocol employs elliptic curve cryptography (ECC) with various well-established curves, as well as the SHA-256 and SHA-512 algorithms for cryptographic hash functions.
The protocol dynamically supports different ECC key lengths, ensuring flexibility and forward compatibility with future developments in elliptic curve cryptography.
Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].
Goals of the Protocol
- The protocol MUST facilitate secure communication between nodes through a pool network.
- The protocol MUST ensure data integrity and confidentiality of the messages transmitted.
- The protocol MUST authenticate messages using elliptic curve signature schemes, ensuring their origin and integrity.
- The protocol MUST be extensible and support future advances in cryptographic techniques.
- The protocol SHOULD be scalable, able to operate in decentralized large-scale P2P networks.
- The protocol MUST support multiple key sizes for flexible elliptic curve operations.
Supported Algorithms
ECDP relies on a variety of standardized and widely used algorithms to ensure secure, authenticated, and efficient communication.
4.1 Cryptography
4.1.1 Supported Elliptic Curves
ECDP supports the following elliptic curves for encryption, Diffie-Hellman key exchange, and signing operations (ECDSA):
- secp192k1
- secp192r1
- secp224k1
- secp224r1
- secp256k1
- secp256r1
- secp384r1
- secp521r1
Each curve corresponds to a distinct key size. To accommodate different security levels, the protocol includes a parameter for indicating the key size used in message operations. Implementations MUST support secp256k1, secp256r1, and secp384r1 as a minimum requirement. Support for other curves is RECOMMENDED for greater flexibility and stronger cryptography when necessary.
4.1.2 Supported Cryptographic Hash Algorithms
ECDP uses cryptographic hash functions for various integrity checks, including checksums and digital signatures.
Supported hash functions include:
- SHA-256 (RECOMMENDED)
- SHA-512 (OPTIONAL for longer data integrity verification)
Implementations MUST support SHA-256 as a minimum requirement.
Protocol Operation
Message Types
- 0x01: Handshake
- 0x02: Data Transfer
- 0x03: Acknowledgment (Ack)
- 0x04: Data Request
Message Structure
5.1 Base Message Structure
The base structure contains fields that are common across various message types, with extensions for specific needs. Messages are routed through a pool network to enhance scalability and security.
Field | Description | Size (bytes)
Protocol Version | Identifies the version of the ECDP protocol | 1
Message Type | Indicates the type of message | 1
Key Size | Indicates the ECC key size used (e.g., 192, 224, 256, 384, 521 bits) | 2
Sender ECC Public Key | Public key of the sending node | Variable (based on key size)
Receiver ECC Public Key | Public key of the receiving node (if applicable) | Variable (based on key size)
Nonce | Random number to prevent replay attacks | 8
Encrypted Data | Content of the message encrypted using ECC | Variable
Signature | Digital signature of the sender (ECDSA) | Variable (based on key size)
In this structure: - Key Size is a 2-byte field that indicates the key size in bits (e.g., 192, 224, 256, 384, 521). This allows both endpoints to use flexible key sizes as per their security requirements.
5.2 Handshake (0x01)
Field | Description | Size (bytes)
Protocol Version | Identifies the version of the ECDP protocol | 1
Message Type | Set to Handshake (0x01) | 1
Key Size | Indicates the ECC key size used | 2
Sender ECC Public Key | Public key of the sending node | Variable
Receiver ECC Public Key | Public key of the receiving node | Variable
Nonce | Random number to prevent session replay | 8
Node Identifier | Unique ID of the node (e.g., hash of the public key) | 32
Node Capability | Information about bandwidth and supported data types | 4
Signature | Digital signature of the sender (ECDSA) | Variable
5.3 Data Transfer (0x02)
Field | Description | Size (bytes)
Protocol Version | Identifies the version of the ECDP protocol | 1
Message Type | Set to Data Transfer (0x02) | 1
Key Size | Indicates the ECC key size used | 2
Sender ECC Public Key | Public key of the sending node | Variable
Receiver ECC Public Key | Public key of the receiving node | Variable
Nonce | Exclusive random number for the session | 8
Encrypted Data | Message content encrypted using ECC | Variable
Checksum | Cryptographic hash (SHA-256 or SHA-512) for data integrity verification | 32 or 64
Signature | Digital signature of the sender (ECDSA) | Variable
5.4 Acknowledgment (Ack) (0x03)
Field | Description | Size (bytes)
Protocol Version | Identifies the version of the ECDP protocol | 1
Message Type | Set to Acknowledgment (0x03) | 1
Nonce | Random number corresponding to the session | 8
Message Hash | Hash of the received data message (SHA-256 or SHA-512) | 32 or 64
Status | Indicates Success (0x00) or Error (0x01) | 1
5.5 Data Request (0x04)
Field | Description | Size (bytes)
Protocol Version | Identifies the version of the ECDP protocol | 1
Message Type | Set to Data Request (0x04) | 1
Key Size | Indicates the ECC key size used | 2
Sender ECC Public Key | Public key of the requesting node | Variable
Receiver ECC Public Key | Public key of the data-holding node | Variable
Nonce | Random number for the session | 8
Data Identifier | Unique hash or ID of the requested data (using SHA-256, SHA-512) | 32 or 64
Signature | Digital signature of the sender (ECDSA) | Variable
Security Considerations
ECDP employs ECC for secure communication between nodes, with messages authenticated through ECDSA. The inclusion of a Key Size field allows nodes to negotiate and use varying key lengths based on the curve chosen, ensuring flexibility in security levels.
Nonces are used to prevent replay attacks. The protocol uses the Diffie-Hellman key exchange over elliptic curves for secure session initialization. The following elliptic curves are supported, with corresponding key sizes:
- secp192k1 (192-bit)
- secp192r1 (192-bit)
- secp224k1 (224-bit)
- secp224r1 (224-bit)
- secp256k1 (256-bit) (RECOMMENDED)
- secp256r1 (256-bit) (RECOMMENDED)
- secp384r1 (384-bit) (RECOMMENDED)
- secp521r1 (521-bit)
Additional Recommendations
- Implementations SHOULD regularly update their cryptographic libraries to maintain security against evolving threats.
- Nodes MUST verify the signatures of incoming messages to ensure authenticity.
- Nonce sizes MUST be sufficient (8 bytes at minimum) to prevent replay attacks.
- It is RECOMMENDED that nodes securely store their private keys using encryption and protected hardware when possible to prevent unauthorized access.
IANA Considerations
This document has no actions directed at IANA at this time. However, if future protocol updates require additional message types, code points, or other attributes, a registration with IANA MAY be required.
Normative References
[RFC2119]

Key words for use in RFCs to Indicate Requirement Levels
S. Bradner
March 1997
BCP 14
RFC 2119
DOI 10.17487/RFC2119
[RFC5639]

Elliptic Curve Cryptography (ECC) Brainpool Standard Curves and Curve Generation
M. Lochter
J. Merkle
March 2010
RFC 5639
DOI 10.17487/RFC5639
[RFC4492]

Elliptic Curve Cryptography (ECC) Cipher Suites for Transport Layer Security (TLS)
S. Blake-Wilson
N. Bolyard
V. Gupta
C. Hawk
B. Moeller
May 2006
RFC 4492
DOI 10.17487/RFC4492
[RFC6979]

Deterministic Usage of the Digital Signature Algorithm (DSA) and Elliptic Curve Digital Signature Algorithm (ECDSA)
T. Pornin
August 2013
RFC 6979
DOI 10.17487/RFC6979
Acknowledgments
The authors acknowledge the valuable contributions of cryptographic and P2P networking experts. Special thanks to those who provided feedback on elliptic curve performance and secure key storage recommendations.