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RNP 0.12.0 released

Author’s picture Ronald Tse on 14 Jan 2019

RNP 0.12.0 significantly expands cryptographic capabilities with support for additional elliptic curves, introduces AEAD encryption support, and enhances both the FFI and CLI interfaces.

This release also includes important fixes for key handling and signature validation.

Introduction

This release marks a major expansion in RNP’s cryptographic capabilities, particularly in the area of elliptic curve cryptography. The addition of new curves and AEAD support, combined with improved developer interfaces, makes RNP more versatile and secure for a wider range of applications.

Key highlights:

  • Added support for extra ECC curves (Brainpool p256, p384, p512, secp256k1, x25519).

  • CLI functionality extended with -f command, allowing to load keys directly from a file.

  • FFI enhancements for AEAD support.

Other highlights:

  • Dependency upgrade: Botan 2.8+.

  • Enhanced key grip calculations across various key types.

  • Improved handling of SM2 signatures for hashing the message. See comment in issue #436.

  • Added support for G10 ECC keys.

  • Enhanced dumping logic for partial-length packets, ensuring accurate handling.

Cryptographic enhancements

Extended ECC support

The release adds support for several important elliptic curves.

RNP supports the RFC 6637 specification which details the implementation and usage of ECC curves in OpenPGP.

The new implemented curves provide:

  • More flexibility in curve selection

  • Better compliance with various standards

  • Enhanced interoperability

  • Improved performance options

Brainpool curves

The Brainpool curves (p256, p384, p512) are standardized elliptic curves developed by the German Federal Office for Information Security (BSI) as specified in RFC 5639. These curves were designed to provide verifiably pseudo-random parameters, offering an important alternative to the NIST curves.

Key characteristics of Brainpool curves include:

  • Rigorous security verification through public, transparent generation processes

  • Three security levels (256-bit, 384-bit, and 512-bit) matching or exceeding RSA 3072-bit to 15360-bit security

  • Widespread adoption in European cryptographic applications and standards

  • Official approval by BSI for use in high-security applications

In OpenPGP applications, Brainpool curves are particularly valuable when regulatory compliance or specific security requirements mandate the use of BSI-approved algorithms. Their implementation in RNP follows the RFC 5639 and enables both ECDSA (for signatures) and ECDH (for encryption) operations.

The inclusion of Brainpool curves enhances RNP’s ability to serve European markets and organizations requiring BSI-approved cryptographic algorithms while maintaining full interoperability within the OpenPGP ecosystem.

secp256k1

The secp256k1 curve, defined by Standards for Efficient Cryptography (SEC), is a specialized elliptic curve that has gained widespread recognition primarily through its use in Bitcoin’s cryptographic operations. This Koblitz curve over a prime field offers unique mathematical properties that make it particularly efficient for cryptographic operations while maintaining strong security characteristics.

Key characteristics of secp256k1 include:

  • 256-bit security level, comparable to 3072-bit RSA

  • Exceptional performance for ECDSA operations

  • Mathematically elegant structure that enables efficient implementation

  • Strong resistance to known cryptographic attacks

  • Widespread adoption and extensive security analysis

In OpenPGP applications, secp256k1 serves dual purposes - it can be used both for ECDSA digital signatures and ECDH key exchange operations, following the RFC 6637 specifications. Its implementation in RNP enables users to leverage the same high-performance cryptographic primitives used in blockchain applications while maintaining full compatibility with the OpenPGP ecosystem.

The curve’s efficiency comes from its specific parameters that enable particularly fast implementation of scalar multiplication operations, making it ideal for resource-constrained environments. While initially controversial due to its unusual generation process compared to NIST curves, secp256k1 has undergone extensive scrutiny and real-world testing through its use in cryptocurrency systems, establishing itself as a trusted option for high-security applications.

x25519

The x25519 curve, designed by Daniel J. Bernstein, represents a significant advancement in elliptic curve cryptography. It is specifically optimized for the Montgomery ladder implementation of elliptic curve Diffie-Hellman (ECDH) key exchange, as specified in curve 25519.

Key characteristics of x25519 include:

  • Designed for high-speed key exchange operations while maintaining strong security

  • Provides 128 bits of security, comparable to 3072-bit RSA

  • Resistant to various side-channel attacks due to its constant-time implementation

  • Widely adopted in protocols like TLS 1.3, Signal, and Wireguard

In OpenPGP applications, x25519 is particularly valuable for secure key exchange operations, offering an excellent balance of security and performance. Its inclusion in RNP, following OpenPGP specification, enables modern, high-performance encrypted communications while maintaining compatibility with the OpenPGP ecosystem.

Additionally, the x25519 curve strengthens the overall security framework, ensuring efficient and robust encryption methods are employed across various applications. It also positions RNP as a leader in the adoption of contemporary cryptographic practices, facilitating secure communication in today’s digital landscape.

Dependency updates

Botan upgrade requirement

Starting with this release, RNP requires Botan 2.8 or higher as its cryptographic backend. This upgrade represents a significant step forward in RNP’s cryptographic capabilities and performance.

Botan 2.8+ brings several crucial improvements:

  • Modern cryptographic implementations, including optimized ECC operations and AEAD support

  • Enhanced security features and fixes for known vulnerabilities

  • Improved performance through optimized algorithms and better hardware acceleration

  • More comprehensive API support, enabling better integration and feature expansion

For users, this upgrade means:

  • Stronger security guarantees through up-to-date cryptographic implementations

  • Better performance in key operations, especially with modern CPU features

  • Access to newer cryptographic algorithms and modes

  • Improved stability and reliability

While this change requires updating existing Botan installations, the benefits in security and performance make this upgrade essential for modern cryptographic applications. For installation instructions, see the Botan installation guide.

Foreign Function Interface (FFI) enhancements

AEAD

Authenticated Encryption with Associated Data (AEAD) is now fully supported through FFI, having been available through the CLI. This expansion brings modern encryption capabilities to developers integrating RNP into their applications.

AEAD provides both confidentiality and authenticity of encrypted data, making it a crucial feature for secure communications. The implementation follows RFC 4880bis, ensuring interoperability while providing strong security guarantees.

The FFI enhancements in this release include:

  • Comprehensive AEAD support for programmatic encryption operations

  • New example code demonstrating common usage patterns

  • Fixed regression issues with direct subkey loading

  • Implementation of per-signature hash and timing controls

  • Extended API documentation and usage examples

These improvements particularly benefit:

  • Developers integrating RNP into their applications

  • Systems requiring high-performance authenticated encryption

  • Applications needing fine-grained control over cryptographic operations

  • Projects requiring modern encryption standards compliance

The expanded FFI capabilities make RNP more accessible as a cryptographic library while maintaining its security standards and OpenPGP compliance.

Extensive FFI-AEAD examples are provided to help developers quickly integrate AEAD encryption into their applications.

Other improvements

  • Fixed regression with loading subkeys directly.

Implemented support for per-signature hash and creation/expiration time

This release implements support for per-signature hash and creation/expiration time.

Specifically, the FFI provides fine-grained control over signature creation, allowing developers to specify:

  • Custom hash algorithms for individual signatures

  • Creation time for signatures

  • Expiration time for signatures

This enhancement follows RFC 4880 specifications for signature creation timestamps and provides greater flexibility in signature generation.

Key benefits include:

  • Better control over signature properties

  • Support for specific compliance requirements

  • Enhanced timestamp accuracy

  • Improved signature verification capabilities

The implementation is particularly valuable for:

  • Applications requiring precise signature timing

  • Systems with specific hash algorithm requirements

  • Compliance-focused implementations

  • Long-term document signing solutions

This feature enables developers to create more precise and compliant signature implementations while maintaining full OpenPGP compatibility. Example code demonstrating these capabilities is available in the FFI documentation.

Key handling improvements

Support for G10 ECC keys

This release adds support for G10 format ECC keys, expanding RNP’s compatibility with various OpenPGP implementations. G10 is the native key format used by GnuPG 2.x, making this addition particularly important for interoperability.

Key features of G10 ECC key support:

  • Full compatibility with GnuPG 2.x key storage

  • Support for all implemented ECC curves

  • Seamless import and export capabilities

  • Proper handling of secret key material

This enhancement is particularly beneficial for:

  • Systems migrating from GnuPG

  • Multi-implementation environments

  • Key management systems

  • Cross-platform applications

The implementation follows the GnuPG key storage specification, ensuring reliable key handling across different OpenPGP implementations while maintaining security standards.

Other improvements

  • Better key grip calculations

  • Improved subkey handling

  • More accurate key identification

Command-line interface enhancements

rnp

  • Direct key file loading with -f/--keyfile

  • Fixed issue with selecting G10 secret keys via userid.

rnpkeys

  • rnpkeys now supports SM2 with arbitrary hashes.

  • Improved key information display

redumper

  • Added -g option to dump fingerprints and grips.

  • Display key id/fingerprint/grip in packet listings.

Debugging tools

Enhanced debugging capabilities in redumper:

  • Fingerprint and grip dumping

  • Better packet listings

  • More detailed key information

  • Improved diagnostic output

Technical improvements

Significant codebase improvements:

  • Removed legacy code

  • Better packet handling

  • Improved error handling

  • Enhanced maintainability

Looking ahead

RNP 0.12.0 establishes a stronger foundation for modern cryptographic operations through:

  • Expanded curve support

  • Modern encryption modes

  • Better developer tools

  • Enhanced usability

These improvements demonstrate RNP’s commitment to providing a comprehensive and secure OpenPGP implementation.

For detailed technical information and the complete list of changes, please visit the release page.