SFTP file transfer — security documentation

This page describes the security measures around Revizo’s SFTP integration for automatic file import. The document is intended for IT managers, security teams, and compliance staff who are considering connecting SAP, banking systems, or other file sources to Revizo via SFTP.

Overview

Revizo supports automatic file retrieval via SFTP (SSH File Transfer Protocol). The integration is used to retrieve bank files (CAMT.053) and trial-balance files (CSV/Excel) from external SFTP servers.

Property	Description
Protocol	SFTP over SSH (port 22)
Direction	Revizo retrieves files (pull model)
Encryption in transit	SSH-encrypted channel (standard SSH encryption algorithms)
Encryption of credentials	AES-256-GCM (application level)
Encryption at rest	AES-256 at database level (Supabase/AWS)
Authentication	Username/password or SSH key pair
Access control	Only Revizo administrators can create/change connections

Connection model

Revizo operates as an SFTP client — we connect to your server and retrieve files. We do not run a publicly available SFTP server.

┌──────────────────────┐          ┌──────────────────────┐
│ Your SFTP server      │◄─SSH────│ Revizo               │
│ (bank, SAP, ERP)      │  port 22│ (SFTP client)        │
│                        │         │                      │
│ /outgoing/             │         │ Polling (interval)   │
│   ├── file1.xml        │         │ Retry with backoff   │
│   └── file2.csv        │         │ Dedup via SHA-256    │
└──────────────────────┘          └──────────────────────┘

IP addresses

Revizo runs on Vercel (frontend/API) and Railway (background worker). Outbound SFTP connections are initiated from the Railway worker. If the firewall requires IP allowlisting, contact us for updated IP addresses.

Credential handling

Storage

All SFTP credentials (username, password, SSH keys) are encrypted before they are stored in the database:

Field	Encryption method	Details
Username	AES-256-GCM	Application-level encryption
Password	AES-256-GCM	Application-level encryption
SSH keys	AES-256-GCM	Application-level encryption

The encryption key is a server-side environment variable that is never exposed to clients
Encrypted values are stored as iv:tag:ciphertext (initialisation vector, authentication tag, encrypted data)
Each field uses a unique initialisation vector (IV) per encryption operation

Access

Credentials are never shown in API responses — GET requests never return passwords or keys
Only administrators can create or change SFTP connections
All changes are logged with user ID and timestamp

Rotation

We recommend rotating SFTP credentials periodically (at least annually). Updating is done in Revizo under Settings → File transfer → SFTP → edit connection.

Data processing

File handling

Step	Description
Download	Files are downloaded to memory (buffer), never to disk
Deduplication	SHA-256 hash is calculated — identical files are never imported twice
Processing	The file is parsed in memory and the result is stored in the database
After import	Configurable: the file can remain, be moved, or be deleted from the SFTP server

Revizo never stores raw files permanently. Only the parsed data (transactions or account balances) is stored in the database.

What is stored

File type	Data stored
Bank files (CAMT)	Individual transactions: date, amount, reference, account number
Trial balance	Account balances: account number, balance, company code, import time

Metadata about the import (filename, hash, timestamp, status) is stored for traceability and deduplication.

Tenant isolation

All data in Revizo is isolated per organisation (tenant_id):

SFTP connections are scoped to the organisation that created them
Imported data is only available to authorised users in the same organisation
The database enforces Row Level Security (RLS) for additional isolation
All API requests validate organisation membership via the Clerk session

Network security

Protocol

SFTP uses SSH (Secure Shell) to establish an encrypted channel. All communication — including authentication, file transfer, and commands — is encrypted.

Connection handling

Property	Value
Timeout	30 seconds per connection attempt
Retry	3 attempts with exponential backoff
Concurrent connections	Max 1 per sync config (sequential polling)
Interval	Configurable (15 min – 24 hours)

Firewall recommendations

If the SFTP server is behind a firewall, we recommend:

Allow only port 22 (or the configured SFTP port) from Revizo’s IP addresses
Block incoming connections — Revizo initiates all connections (pull model)
Enable logging of all SFTP logins for tracing

Logging and tracing

What is logged

Event	Data logged	Purpose
Connection attempt	Timestamp, connection ID, result	Troubleshooting
File retrieved	Filename, SHA-256 hash, size	Traceability
Import completed	Number of rows/transactions, duration	Audit
Import failed	Error message, filename, timestamp	Troubleshooting
Configuration changed	User ID, timestamp, change	Audit trail

What is NOT logged

Passwords and SSH keys
File contents (metadata only)
Personally identifying information beyond user ID

Compliance

Trial-balance files typically contain only account numbers and amounts — no personal data. Bank files (CAMT.053) may contain payment references with personal names. This data:

Is stored encrypted (AES-256) in Revizo’s database
Is subject to tenant isolation and access control
Can be exported and deleted in accordance with GDPR (Articles 15 and 17)
Is processed in the EU (Frankfurt, Germany)

For complete GDPR documentation, see Privacy and GDPR.

SOC 2 and certifications

Revizo’s infrastructure providers:

Component	Provider	Certification
Hosting	Vercel	SOC 2 Type II
Database	Supabase (AWS)	SOC 2, ISO 27001
DNS/CDN	Cloudflare	ISO 27001
Authentication	Clerk	SOC 2 Type II

Recommendations for IT departments

Before setup

Create a dedicated SFTP user for Revizo with read access to the file directory
Restrict access — the user should only have access to the folder with export files
Configure chroot — lock the SFTP user to a specific folder
Enable logging — log all SFTP logins and file transfers
Consider SSH key authentication rather than passwords for stronger security

After setup

Verify that files transfer correctly by checking import status in Revizo
Monitor SFTP logs for unexpected connection attempts
Rotate credentials periodically (recommended: annually)
Document the SFTP access internally (who administers it, which files are shared)

SAP-specific

For SAP customers setting up automatic export of trial balance:

Configure an SAP job that exports the trial balance to the SFTP server (see SAP SFTP documentation)
Set up file format: CSV with semicolon separator, 3 columns (company code, account number, balance)
Configure export frequency — Revizo supports polling from every 15 minutes to daily
Use a consistent filename or a naming pattern that file retrieval can match (e.g. saldobalanse_*.csv)

Contact

For questions about security around the SFTP integration, contact:

Email: karl@savesolutions.no
Subject: SFTP security / IT Due Diligence

We normally reply within 1–2 business days.

Last updated: April 2026

Overview​

Connection model​

IP addresses​

Credential handling​

Storage​

Access​

Rotation​

Data processing​

File handling​

What is stored​

Tenant isolation​

Network security​

Protocol​

Connection handling​

Firewall recommendations​

Logging and tracing​

What is logged​

What is NOT logged​

Compliance​

GDPR​

SOC 2 and certifications​

Recommendations for IT departments​

Before setup​

After setup​

SAP-specific​

Contact​