AWS Nitro API Co-signer Version History

Fireblocks updates the API Co-signer software to include stability enhancements and new features. This article details the most recent AWS Nitro Co-signer versions. Always use the latest version listed here for optimal performance.

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Latest version

Version 2026.03.02 (March 2026)

Version hash: 95a317d3c7

• Added support for POLICY_CHANGE approval request type (the customer co-signer can now approve policy changes via Policy Service v2)
• Performance improvements and bug fixes

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Version history

Version 2026.01.29 (January 2026)

Version hash: 340d9f6057

• Bug fixes and performance improvements

Version 2025.12.30 (December 2025)

Version hash: a294449c1b

• Added support for “Protected Tags” approval requests

Version 2025.12.11 (December 2025)

Version hash: c44604398e

• The callback can now return a “retry” response in an exchange withdraw operation

Version 2025.11.20 (November 2025)

Version hash: 82a5cc0078

• Fixed a bug that may cause the Co-signer not to load correctly after a graceful shutdown

Version 2025.10.09 (October 2025)

Version hash: 4e34888c01

• Fixed bug parsing messages after websocket reconnect
• Fixed bug sending messages on half closed websocket connections

Version 2025.08.12 (August 2025; US environments only)

Version hash: 19c07421dc

• Fixed WebSocket bug causing performance issues

Version 2025.07.16 (July 2025)

Version hash: bb61e507

• Fixed bugs and increased performance
• Better support for web sockets

Version 2.1.1 (April 2025)

Version hash: 7160d7b833

• Bug fixes and performance improvements

Version 2.0.5 (September 2024)

Version hash: d177e696c3

• Decreased signing latency along with general performance increases
• Extended filtering of environment variables
• Improvements to key handling within the enclave
• Bug fixes

Version 2.0.4 (August 2024)

Version hash: 41d1888dc8

• Fixed the issue when setting AWS region using environment variables
• Removed unnecessary testing artifacts

Version 2.0.2 (August 2024)

• Modified KMS CMK ARN prompt
• Added start, stop and restart commands
• Added echo to show where logs are saved to
• Fixed AWS NTP sync issue
• Fixed Callback Handler public key issue on install
• Removed unnecessary testing artifacts

Version 2.0.1 (July 2024)

• Added check for force flag and existence of destination before the user is prompted for details
• Added route DNS queries to the DNS server defined on the host EC2 instance

Version 2.0.0 (June 2024)

• Initial release