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Current release: v2.20.7.
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New FeatureSecurityOperational
August 27th, 2026New Feature:
  • Validation gate: the signer can call an HTTP endpoint you control before performing a signature or key export, and proceeds only on a 200 OK response. Requests can be authenticated with an HMAC shared secret (32-byte hex) and mTLS using dedicated client certificates, and include the public key, key ID, and external ID of the signing request. Applies to full and partial signing and key export; not compatible with ECDSA pre-signatures, which are rejected when the gate is enabled. See Validation gate.
  • Azure Key Vault: key packs can now be stored in and retrieved from Azure Key Vault; make-pack and get-public-identity support Azure alongside the existing backends.
  • AWS RDS IAM authentication: the signer and its migration tool can authenticate to Postgres with RDS IAM credentials instead of a static password.
Security:
  • Security fix.
  • Core keys are protected against accidental overwrite: bootstrap refuses to run when keys already exist, and regenerating core keys requires an explicit flag.
Operational:
  • Observability overhaul: OTLP log export, a --traces-filter option, JSON log output written to stderr, and log/trace correlation.
  • The signer CLI creates and stores core keys automatically when they are missing, gains a --version flag, and tolerates surrounding whitespace when decoding core keys.
  • Key shares are cached in an LRU cache in the secrets manager.
  • Heavy pool misconfiguration is detected at startup, and a minimum of one thread is enforced.
  • New tunnel supporting vsock and TCP transports for AWS Nitro Enclave deployments.
  • Fixed a TLS initialization issue that could prevent the signer from starting.
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SecurityOperational
January 20th, 2026Security:
  • Updated to the released cggmp24 crate including an upstream security fix.
Operational:
  • IBM Z (s390x) architecture support added for signer builds.
  • Key import/export WASM module updated to the latest revision (remains compatible with the prior format).
  • Removed deprecated MAC options and stray gmp dependency; cggmp backend is now selectable via a build feature.
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New FeatureProtocolSecurity
October 28th, 2025Protocol:
  • Migrated to cggmp24. The signing protocol previously referenced as cggmp21 has been renamed and upgraded to its latest revision. Reference implementations of components used in this upgrade are published through the Hyperledger Lockness project.
  • ECDSA pre-signatures can no longer be used with HD derivation or raw signing.
  • Stark signing is now rejected at signer initialization.
Key import/export:
  • KeyImportResponse now includes the chain code for HD-derived keys.
  • Key import/export remains compatible with the prior WASM module format.
Operational:
  • HD wallet support added to KU23 full signing.
  • Replay protection re-enabled on signing requests.
  • Incoming client certificates are verified to match the server’s organization. Subject CN check is optional and configurable.
  • New CLI option to disable client cert verification.
  • Build base updated to Rust 1.89.
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Bug Fix
August 13th, 2025Protocol:
  • Patched cggmp21 dependency.
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OperationalSecurity
July 25th, 2025Healthcheck:
  • Healthcheck server migrated to HTTP, with shared cert validity and HTTP response helpers.
  • CA cert validity is now also checked.
Operational:
  • Migration scripts added with automatic migration number deduction.
  • Build base updated to Rust 1.88 / Rust 2024 edition.
  • S3 bucket uploads now always compute the checksum.
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New FeatureOperational
May 21st, 2025Storage:
  • Postgres support added with a Postgres fallback.
  • Redis dependency removed.
Signing:
  • HD derivation enabled for EdDSA keys.
  • Key import/export: FrostBitcoin support added.
Operational:
  • New key rotation subcommand.
  • tDH (threshold Diffie–Hellman) implementation added, with a new key share type.
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New FeatureOperational
January 24th, 2025Backup & restore:
  • L4 backup support introduced. L4 backup can be enabled independently of L3.
  • New backup restore CLI tool with batched, multi-phased operations.
  • Backup keys can now be read from OpenSSL PEM-DER files.
  • Backup restore output can be emitted in hex format.
Telemetry:
  • W3 Tracing Context propagation across services.
  • Span instrumentation added to SQL queries, delivery handshake, and secrets manager operations.
  • Resource attributes can be overridden via OTel exporter config.
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New FeatureOperational
September 30th, 2024Signing:
  • Bitcoin Schnorr: HD derivation and taproot support added.
  • KU23 pre-signatures batching introduced for higher throughput.
  • Stark pre-signatures added.
  • KU23 pre-signatures are now insensitive to participant identity ordering.
Cluster operations:
  • Added the ability to copy key shares to a smaller cluster.
  • Cluster info is now required for commands that previously assumed cluster awareness.
  • Removed the standalone generate command — keys are now generated on startup (configurable via feature flags).
  • Added a get-public-identity subcommand.
Reliability:
  • Graceful shutdown on SIGINT/SIGTERM.
  • TLS key handling and dev-cert flows reworked.
Telemetry:
  • New TRACECONTEXT_PROPAGATORS_HEADER setting.
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Initial Release
July 17th, 2024First release of the MPC Clusters signer tracked in this changelog.
Last modified on August 27, 2026