Hidden Bitcoin Custody Dependencies

Hidden Dependencies on Email, Phone, and Accounts

This memo is published by CustodyStress, an independent Bitcoin custody stress test that produces reference documents for individuals, families, and professionals.

Email Account Dependencies

Bitcoin custody depends on more than keys and backups. Hidden bitcoin custody dependencies include email accounts, phone numbers, physical locations, relationships, and services that custody relies on without explicit acknowledgment. When these dependencies fail, custody can fail—even when the obvious components remain intact.

Dependencies become hidden through familiarity. The holder uses them so routinely that their existence as dependencies goes unnoticed. Only when a dependency fails does its role become apparent. By then, the failure may already have caused damage.

---

Email Account Dependencies

Email accounts serve functions in custody that often go unrecognized. Password recovery, service communications, and verification processes may route through email. The holder's primary email account may be a hidden foundation that multiple custody elements rest on.

Account recovery for wallets and services often depends on email access. If the holder forgets a password, the recovery link goes to their email. Without access to that email account, recovery becomes impossible—even when the holder controls everything else.

Two-factor authentication sometimes uses email as a factor. Losing email access can lock the holder out of accounts they would otherwise control. The email dependency was invisible until it became the blocking factor.

After death, email accounts become particularly problematic. Heirs may not know the password. The email provider may not grant access without the holder's credentials. A dependency that worked fine during life becomes an insurmountable barrier after death.

---

Phone Number Dependencies

Phone numbers anchor many security and verification systems. SMS codes, authenticator apps, and recovery procedures often depend on having a specific phone number. When that number changes or becomes inaccessible, the dependency reveals itself.

SIM cards tie phone numbers to physical possession. Losing a phone, having it stolen, or simply upgrading to a new device can disrupt the phone number dependency. What seemed like reliable access becomes suddenly unavailable.

After death, phone numbers present special challenges. The number may be deactivated by the carrier. The heir may not have the PIN to access voicemail or transfer the number. A dependency the holder never thought about becomes an obstacle heirs cannot overcome.

International numbers add complexity. Maintaining a foreign phone number while living in another country, keeping roaming active, or ensuring the number remains valid—these logistics can fail in ways that cascade to custody access.

---

Physical Location Dependencies

Custody often depends on physical access to specific places. A home, a safe deposit box, a relative's house, a storage unit—materials stored in these locations require the ability to reach them. Location access is rarely absolute.

Homes change. People move. Properties are sold. What was stored at one address may become inaccessible when that address is no longer the holder's residence. The backup that was secure at home becomes unreachable when home changes.

Institutional locations have access rules that can shift. Safe deposit box access requires the bank's cooperation. Storage unit access requires the facility to exist and recognize the accessor's authority. These system dependencies operate on the institution's terms, not the holder's.

Geographic distance creates access friction. A backup stored in another city requires travel to retrieve. A backup in another country requires international travel, customs, and potentially different legal frameworks. Distance that seemed like security through distribution becomes barrier through inaccessibility.

---

Relationship Dependencies

People play roles in custody that create dependencies. A family member who knows a passphrase. A friend who holds a key. An advisor who understands the setup. These relationships are dependencies that can fail when relationships fail.

Death removes people from the dependency chain. The uncle who held a backup key passes away. His role in custody disappears with him. Unless his role was documented and his materials transferred, the dependency becomes a gap.

Relationships deteriorate for many reasons. Divorce, family conflict, business disputes, or simple drifting apart can transform a trusted person into someone unavailable or uncooperative. The dependency that rested on trust fails when trust evaporates.

People move and lose touch. A friend who relocated to another country becomes harder to reach. Contact information goes stale. The person still exists but cannot be found. The dependency on that person becomes a dependency on locating them.

---

Service Provider Dependencies

External services embed themselves in custody without explicit acknowledgment. A wallet software provider, a hardware manufacturer, a coordination service, a cloud storage provider—these companies become dependencies even in "self-custody" arrangements.

Software providers can disappear. A wallet application the holder relies on may be discontinued, acquired and changed, or simply abandoned. The interface the holder knows how to use becomes unavailable. Alternative software may exist but requires learning and may behave differently.

Hardware manufacturers face the same mortality. The company that made the hardware wallet may not exist in ten years. Without the company, support ends, firmware updates stop, and replacement devices become unavailable. The hardware dependency extends to the company's survival.

Cloud services that seem peripheral may be central. Where was that configuration file saved? Which cloud account holds the backup document? These services can change terms, lock accounts, or cease operation. Dependencies on free services are particularly fragile.

---

Password and Credential Dependencies

Access to other accounts creates hidden chains. The password to one account may be stored in another account. The credential for a backup may require accessing a password manager. Each link in the chain represents a dependency.

Password managers are powerful but create concentration risk. All passwords in one place means one master password unlocks everything—and losing that master password locks everything. The convenience that made the password manager appealing becomes the single point of failure.

Recovery credentials for password managers present their own challenge. The emergency kit, the recovery key, the master seed—wherever these are stored, that storage location becomes a dependency. Dependencies nest inside dependencies.

Biometric access adds complexity. Fingerprints and face recognition cannot be transferred to heirs. Devices that unlock only with the holder's biometrics remain locked when the holder is gone. The security feature becomes the access barrier.

---

Documentation Location Dependencies

Instructions and documentation must be findable to be useful. Where documentation is stored creates dependencies on accessing that location. Heirs who cannot find documentation cannot follow it, regardless of how well it was written.

Physical documentation has physical location dependencies. A letter in a filing cabinet requires access to that cabinet, which requires access to that home, which requires knowing which home and which cabinet. The chain of physical access dependencies can be long.

Digital documentation has platform dependencies. A document in cloud storage requires the account credentials. A file on a specific computer requires access to that computer. The digital location creates digital access requirements.

Pointer documents that reference other locations create chains. The document that says "the backup is in the safe deposit box" depends on the heir finding that document, accessing that safe deposit box, and understanding how these connect. Each step is a dependency.

---

Memory Dependencies

Despite efforts to document everything, some information lives only in the holder's memory. These memory dependencies are hidden because the holder does not realize they have not externalized certain knowledge. Only attempted recovery reveals what was never recorded.

Passphrases trusted to memory represent obvious memory dependencies. Less obvious are procedural memories—the sequence of steps the holder performs automatically, the tricks that make things work, the workarounds discovered through experience.

Context and meaning live in memory. Documentation may say "use the secondary backup" but only the holder knows which backup is secondary, why it is secondary, and in what circumstances to use it. The meaning that makes documentation actionable lives in the holder's mind.

Memory changes over time without the holder noticing. Information that was sharp at fifty may be fuzzy at seventy. The holder relies on memory without noticing that the memory has degraded. A dependency assumed to be solid proves unreliable.

---

Discovering Hidden Dependencies

Finding hidden dependencies requires actively looking for them. Normal operation does not surface dependencies that are working. Only analysis, testing, or failure reveals what custody actually depends on.

Mapping the access chain helps identify dependencies. Starting from the bitcoin, trace backward through every step needed to access it. Each step that requires something—an account, a location, a person, a credential—represents a dependency.

Asking "what if" questions surfaces assumptions. What if this email account were inaccessible? What if this phone number were lost? What if this person could not be reached? Each "what if" tests whether a dependency exists.

Testing recovery under realistic constraints reveals dependencies that analysis misses. Attempt recovery using only what heirs would have. Every obstacle encountered is a dependency that was hidden until tested against.

---

Conclusion

Hidden bitcoin custody dependencies include email accounts, phone numbers, physical locations, relationships, service providers, credentials, documentation storage, and memory. These dependencies are not obvious because they work seamlessly—until they fail. Their hidden nature means they receive less attention than visible components like keys and backups.

Dependencies can fail through loss of access, relationship deterioration, service discontinuation, or simply forgetting. Each hidden dependency represents a potential failure point that the holder may not recognize as part of their custody architecture.

Discovering hidden dependencies requires active investigation through access chain mapping, "what if" questioning, and recovery testing. The holder who identifies their hidden dependencies can assess their reliability. Those who never look for hidden dependencies remain exposed to risks they do not know they carry.

---

System Context

Examining Bitcoin Custody Under Stress

Bitcoin Dementia Progression

Bitcoin Mediation Custody Division

← Return to CustodyStress