Deep cold storage for long-term security

Full network and physical isolation

Sygnum’s deep cold storage is built to protect long-term digital asset holdings today and stay ready for future security needs.

 

Powered by Sygnum Cryo, our deep cold key management technology, private keys are stored in a fully offline, physically isolated environment. The system is designed to evolve with security standards, including post-quantum cryptography. 

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Why Sygnum cold storage

Sygnum’s cold storage builds on traditional cold storage by providing full separation from connected systems while remaining ready for evolving security needs.

 

At Sygnum, cold storage is defined by one principle: full network and physical isolation at all times.

 

Built on Sygnum Cryo, private keys are kept in a physically isolated, fully air-gapped environment, with structured governance and multi-person approval processes.

 

Sygnum Cryo is designed to support evolving security standards, enabling the custody environment to adapt as digital asset infrastructure and blockchains evolve, including considerations around post-quantum cryptography.

What Sygnum cold storage provides

Full offline separation

Assets are held in an environment with no network connectivity, supporting use cases where complete separation from connected systems is required.

Structured and governed access

Asset transfers follow defined approval processes with clear roles and multi-person authorisation, supporting controlled and consistent execution.

Readiness for evolving standards

Sygnum Cryo is designed to adapt as digital asset infrastructure evolves, including post-quantum requirements.

How Sygnum Cryo creates full key isolation

Sygnum Cryo is our proprietary technology for deep cold key management. It reflects an advanced approach to key isolation, combining offline separation, physical protection and governed control into one integrated environment.

Offline key environment

Key material is generated and maintained in a fully air-gapped environment.

Physical isolation

Key material is stored in a dedicated high-security facility with controlled access and layered security controls. 

Structural separation

Digital assets are held independently from trading and liquidity infrastructure.

Governed transaction control

Asset movement follows defined multi-person approval procedures. 

Swiss-regulated framework

Custody operates within Sygnum’s Swiss-regulated banking environment.

Audited and regulated cold storage

Halborn, a recognised blockchain security firm, has independently reviewed Sygnum’s cold storage environment. This is complemented by regular penetration testing, supporting its integrity.

 

Sygnum’s custody platform operates within a Swiss-regulated banking framework and is supported by established control and compliance standards:  


▪️ Custody processes audited under ISAE 3000 and ISAE 3402 by PwC 

▪️ Hardware protection through FIPS 140-2 Level 3 HSMs   

▪️ Digital asset transactions screened using Crypto-AML controls   

▪️ Client assets held off-balance sheet in accordance with Swiss banking law

 

These controls are designed to support secure key management, transaction processing and regulatory compliance. 

Sygnum Cryo

Powered by Sygnum Cryo, our deep cold key management technology, private keys are stored in a fully offline, physically isolated environment.

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Download the factsheet

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