Skip to content

ACCESS_ENCRYPTION_PROFILE.md

Latest commit

 

History

History
67 lines (55 loc) · 3.14 KB

ACCESS_ENCRYPTION_PROFILE.md

File metadata and controls

67 lines (55 loc) · 3.14 KB
Raw

Pure .NET Access encryption profile

JustyBase.UCanAccess.AccessCrypto is an optional package. It contains no COM, ACE or ODBC dependency and is not referenced by the core provider. Applications install it explicitly and configure the existing opener seam:

using UCanAccess;
using UCanAccess.AccessCrypto;

using var connection = new UCanAccessConnection
{
    ConnectionString = "Data Source=C:\\data\\secure.accdb;Password=...;Read Only=false",
    DatabaseOpener = new AccessCryptoOpener(),
};
connection.Open();

The first implementation targets the modern Agile password profile used by current .accdb files. The root page contains the EncryptionInfo XML and an encoding key; Access protects the header region with its fixed RC4 stream. Pages after the root are transformed independently with AES-CBC; the password envelope uses the Agile SHA-based key derivation and verifier. The codec operates directly in PageChannel, so staged writes and transactions never create an unencrypted intermediate database.

The Microsoft documentation confirms that password encryption is an .accdb feature and that the password is the encryption key for Access 2007+ files:

Scope and failure behavior

  • encrypted .accdb formats 14 and 16 (Access 2010 and later) are recognized; legacy .mdb encryption and encrypted Access 2007 format 12 are rejected rather than silently treated as plaintext.
  • Plaintext databases can still be opened through the optional opener, which is useful when an application uses one connection configuration for mixed files.
  • Wrong passwords, malformed EncryptionInfo, unsupported algorithms and truncated pages produce AccessEncryptionException.
  • Keys and derived password buffers are cleared after use. Passwords are not included in exception text or diagnostic output.
  • The codec supports read-only and read/write operations, including provider staging, transactions, page allocation and DDL. It does not add a separate encrypt/decrypt conversion API.
  • A Mirror Mode=file SQLite mirror is a provider cache and is not encrypted by this codec; protect its directory or use the default in-memory mirror for sensitive data.

COM interoperability test

The fixture generator uses Microsoft Access/DAO only in developer or opt-in CI tests:

$env:UCANACCESS_ACCESS_COM = 'true'
$env:UCANACCESS_ACCESS_FIXTURE_PASSWORD = 'Uca!fixture-2026'
dotnet test tests/UCanAccess.AccessCrypto.Tests/UCanAccess.AccessCrypto.Tests.csproj `
  --filter 'Category=AccessCom'

The test creates an encrypted fixture with tools/AccessFixtures/Generate-EncryptedFixture.ps1, reads and modifies it in .NET, verifies those changes through Access COM, then modifies it through COM and verifies the result after reopening it in .NET. Normal CI skips this test unless the explicit environment flag is set and Access COM is installed.