Are there any secure file sharing tools that enforce encryption at rest and in transit for export-controlled files?

Yes. There are secure file sharing platforms designed to support export-controlled or otherwise sensitive files, and many enforce encryption:

• Encryption in transit: typically via TLS 1.2+ / 1.3
• Encryption at rest: typically AES-256 or equivalent
• Access controls: MFA, role-based access, audit logs, link expiration, watermarking, etc.

Examples often used in regulated environments include:

• Microsoft OneDrive / SharePoint / Teams (with Microsoft 365 compliance features)
• Box Enterprise / Box Shield
• Google Drive / Google Workspace Enterprise
• Citrix ShareFile
• Egnyte
• M-Files
• Tresorit (strong zero-knowledge / end-to-end encryption focus)
• Virtru (especially for email and file protection)
• Nextcloud Enterprise (self-hosted options, depending on configuration)

For export-controlled files, the key is not just encryption, but also:

• whether the vendor supports U.S. export control compliance workflows
• data residency options
• access logging and retention
• customer-managed encryption keys or end-to-end encryption
• whether the service is acceptable under your organization’s ITAR/EAR/DFARS policies

If you want, I can also help you narrow this down to:

1. cloud services,
2. self-hosted solutions, or
3. a shortlist specifically suitable for ITAR/EAR-style controls.