Zero-Knowledge Security by Design
We can't read your documents—and that's intentional.
SpeculaFree is built as a zero-knowledge platform. Your files are encrypted on your device before they're uploaded, and only decrypted on your device when you need them. We never see your passphrases, and we never see the plaintext contents of your documents.
Three Zero-Knowledge Surfaces
The same core principles apply everywhere
- PDFs are encrypted in your browser before upload
- Signers decrypt and sign locally; final PDF is re-encrypted
- Our servers only store encrypted blobs and harmless metadata
- Each room can be protected with a passphrase that never leaves the browser
- Files encrypted with per-file keys, wrapped by room key
- Preview and download always decrypt in browser, never on servers
- Your browser generates portal encryption keys; private key stored encrypted
- External users encrypt uploads in their browser before sending
- Only portal owner, with passphrase, can decrypt submissions
On-Device Encryption
All encryption and decryption happen in your browser using the Web Crypto API. Files are never sent to SpeculaFree as plaintext.
Algorithms We Use
AES-GCM-256
For file and document encryption
PBKDF2-SHA256
High iteration counts to derive keys from passphrases
RSA-OAEP-2048
SHA-256 to wrap file keys in portal feature
Fresh, random IVs
Initialization vectors for every encryption operation
What We Store
- Encrypted file content (ciphertext)
- Public crypto parameters: IVs, salts, iteration counts
- Wrapped keys (encrypted forms of the keys)
What We Never Store
- Your passphrases
- Raw AES keys
- Plaintext documents or signatures
Upload
You enter a passphrase locally. Your browser derives an encryption key with PBKDF2 and encrypts the PDF using AES-GCM. Only the encrypted PDF is uploaded and stored.
Sign
The signer's browser decrypts the PDF locally using the passphrase. The signature is applied to the document on the client side. The signed version is then re-encrypted in the browser.
Finalize
The final, signed PDF is uploaded as an encrypted file. The backend records that this encrypted file is the official signed artifact. The server never decrypts or inspects the content.
Download
When you download, your browser fetches the encrypted signed PDF. You enter the passphrase; your browser derives the key and decrypts the file locally. You see or save the plaintext, but we never do.
Room Keys and File Keys
You can protect a VDR with a room passphrase. Your browser turns that passphrase into a room key using PBKDF2. Each file gets its own random AES-GCM key, which is encrypted (wrapped) with the room key.
Uploading to a VDR
Your browser encrypts the file with its file key, wraps the file key with the room key, and uploads only the encrypted file and wrapped key.
Previewing & Downloading
Your browser derives the room key from your passphrase, unwraps the file key, and decrypts the file locally to render it.
Access Roles
Owners and admins manage rooms. Contributors upload. Viewers only view/download. Access control enforced server-side; decryption client-side.
Portal Creation
When you create a portal, your browser generates a portal encryption keypair (public/private). The private key is encrypted with a key derived from your passphrase before being stored. The public key is stored in plaintext and used to encrypt file keys.
Receiving Uploads
External users open your upload link. Their browser encrypts the file with a random AES-GCM key, encrypts the file key with your portal public key (RSA-OAEP), and uploads only ciphertext plus the encrypted file key.
Owner Downloads
To decrypt: You enter your passphrase in your browser. Your browser derives your vault key, decrypts your portal private key, and then decrypts each file key. Finally, it decrypts the file content locally.
Result: Anyone can upload (if you allow it), but only you can decrypt what was uploaded.
We Store
- •Encrypted file and document content
- •Filenames, sizes, timestamps, and other metadata
- •Public crypto parameters: IVs, salts, iteration counts
- •Wrapped keys (encrypted keys), RSA public keys, and encrypted RSA private keys
We Never See
- ✗Your passphrases
- ✗Your raw encryption keys
- ✗The plaintext contents of your documents, VDR files, or portal submissions
Access Control
Document Signing
Only the document owner and invited signers can access an envelope.
VDR
Only room owners and invited participants with roles (admin/contributor/viewer) can access files.
Portals
Uploads can be public by design, but only the portal owner can decrypt submissions.
Logging
We Log
- ✓ When uploads and downloads happen
- ✓ Which portal/room/envelope is involved
- ✓ Success/failure and error messages
We Do Not Log
- ✗ File contents
- ✗ Encryption keys
- ✗ Sensitive cryptographic parameters
If our servers were compromised
Attackers would only see encrypted blobs and metadata—not your actual documents.
Staff operating SpeculaFree
Cannot read your documents in production.
If you lose your passphrase
We cannot recover your data—that's the trade-off of true zero-knowledge.
Your device is the only place
Where your information is decrypted and readable.
Beyond Encryption: Our Zero Trust Security Model
Zero-knowledge protects your data at the cryptography layer. Zero Trust is how we protect everything around that data – identities, devices, sessions, and administrative access. Together, they create a defense-in-depth strategy that keeps you safe even if someone tries to break in.
Two Layers of Protection
Encryption alone isn't enough. Even with the strongest cryptography, you need to ensure that only the right people can access encrypted files, that suspicious behavior is caught early, and that administrative powers can't be abused.
That's where Zero Trust comes in. While zero-knowledge ensures we can't read your content, Zero Trust ensures we rigorously verify who can touch those encrypted files, when they can access them, and under what conditions.
Think of it this way: zero-knowledge is the unbreakable vault protecting your data. Zero Trust is the sophisticated security system guarding every door, window, and hallway leading to that vault.
Our Zero Trust Principles
Never Trust by Default
Every request, even from a logged-in user, is checked and validated. We don't assume anyone is safe just because they're "inside" the system.
Least-Privilege Access
Users, administrators, and internal services only get the minimum access they need. No one has blanket permissions to view or modify everything.
Assume Breach
We design the system as if an attacker could already be on the network. That's why we rely on strong identity verification, contextual checks, and continuous monitoring instead of "trusted zones."
Strong Identity & Step-Up Verification
For sensitive actions, we require stronger proof that you are who you claim to be. Modern authentication methods ensure that even if credentials leak, attackers still can't cause damage.
How Zero Trust Works Inside SpeculaFree
Strong Authentication & Additional Verification
Normal access to your files uses secure login credentials. But for high-risk actions – like permanently deleting important documents, or administrators downloading files that belong to someone else – the platform requires an extra verification step.
When available, we use modern passkey technology (also called WebAuthn), which uses biometric verification or security keys to prove it's really you. This "step-up" verification only appears when the action is sensitive, so normal usage stays smooth while dangerous operations are heavily protected.
Per-User, Per-Tenant Access Controls
Every document, file, secure portal, and virtual data room is tied to specific owners and participants. Only the owner and explicitly invited participants can see or act on those encrypted items.
There is no global "super user" who can casually browse customer content. Even administrators are constrained by the same access rules, and any sensitive administrative operations are heavily logged and monitored.
Rate Limiting and Account Lockouts
The platform automatically detects and blocks suspicious activity. If someone tries to guess passwords, spam recovery codes, or rapidly access files in an unusual pattern, the system will:
- Slow down or block repeated failed login attempts
- Temporarily lock accounts after too many failures
- Add cooldown periods to recovery flows to prevent brute force attacks
- Flag unusually high volumes of file access in short time windows
These protections work automatically in the background, keeping your account safe without requiring any action from you.
Short-Lived Access Links to Encrypted Data
When you access an encrypted file, SpeculaFree doesn't download it through our servers. Instead, we generate a short-lived, digitally signed link that points directly to your encrypted data in secure cloud storage.
These links:
- Expire within minutes (typically 1-5 minutes)
- Are tied to a specific user and action
- Don't expose long-term credentials or allow reuse
The platform acts as a secure gatekeeper to encrypted blobs – verifying your identity and authorization – but never decrypts them. You download the encrypted file directly from storage, then your browser decrypts it locally.
Admin Access Protected by IP Controls
Sensitive internal tools – like security diagnostics, anomaly monitoring, and system configuration – are locked behind IP allowlists. Only trusted networks and IP ranges can reach those administrative endpoints.
If those IP rules aren't properly configured, the admin tooling simply won't respond – the system fails closed, not open. This prevents accidental exposure of administrative capabilities even if credentials are compromised.
Structured Logging and Anomaly Detection
Every important security event – logins, lockouts, file access, administrative actions – is logged in a structured, queryable format. These logs focus on "who did what, and when," not on the actual encrypted data being accessed.
Critically, these logs never contain:
- Plaintext document content
- Encryption keys or decryption secrets
- Raw file data or personal information
The platform continuously runs anomaly detection, looking for suspicious patterns like bursts of failed authentication attempts, unusual download spikes, or access from multiple locations that could indicate a compromised account. When something looks wrong, security teams are alerted immediately.
Two Layers, One Goal: Protecting Your Data
Zero-knowledge means SpeculaFree cannot read your content, even from the inside.
Zero Trust means SpeculaFree aggressively limits, verifies, and monitors any attempt to touch that encrypted content.
Even if the worst happens – a password is stolen, someone gains unauthorized access to an account, or an attacker reaches part of the infrastructure – they still face tight permissions, additional verification steps, short-lived access credentials, and continuous anomaly monitoring.
We build every layer of the system with the assumption that someone is always trying to break in. By combining unbreakable encryption with relentless access verification, we protect you even in that worst-case scenario. Your data stays yours, and yours alone.