The MarshallSoft Advanced Encryption Standard (AES) Library for Visual FoxPro (AES4FP) is a commercial component library that allows FoxPro developers to seamlessly implement strong 256-bit AES encryption and decryption into their applications. Core Security & Technical Features
The library is a wrappers collection around native Windows DLLs (AES32.DLL and AES64.DLL) that interact directly with the Windows API without relying on external frameworks like .NET.
Encryption Standard: Implements robust 256-bit AES (Rijndael) block encryption, officially verified by the NIST Advanced Encryption Standard Algorithm Validation Suite (AESAVS).
Supported Cipher Modes: Includes support for both CBC (Cipher Block Chaining, which requires initialization vectors) and ECB (Electronic Codebook) modes.
Data Types: Capable of encrypting and decrypting standalone files, strings, or raw byte data arrays.
Key & Hash Management: Features key generation natively from plaintext passphrases, supports SHA-256 cryptographic hashing, and features Diffie-Hellman Key Exchange functions to safely transmit keys over the web.
Formatting Rules: Automates PKCS7 padding handling and incorporates a cryptographically secure pseudo-random number generator for random byte data generation. Visual FoxPro Implementation Rules
When integrating the MarshallSoft library into Visual FoxPro, you must follow specific environment constraints:
The @ Prefix Constraint: Because Visual FoxPro passes variables by value natively, all strings passed to MarshallSoft AES functions must be prefixed with the @ character to pass them by reference.
Control Buffers: The library relies heavily on an internal “AES Control Buffer” allocation. This buffer holds the configurations and parameter matrices required to execute the cryptographic functions, which can safely live in FoxPro’s data space.
Compatibility: The library supports all versions of 32-bit Visual FoxPro and runs on Windows operating systems ranging from Windows XP up to Windows 11.
Thread Safety: The engine is fully thread-safe, allowing your VFP apps to complete concurrent encryption/decryption threads without data collision. Functional Code Flow Example
A typical programmatic flow inside your Visual FoxPro project follows these sequential initialization and processing steps:
Attach the Library: You must invoke the attachment function before calling any other library features to load the DLL into memory. lnStatus = aesAttach(lnKeyCode, AES_PKCS7_MASK) Use code with caution.
Initialize the Cipher: Configure the key, choose the mode (such as AES_CBC_MODE or AES_ECB_MODE), and declare the operation intent (Encrypt or Decrypt).
lnStatus = aesInitAES(@lcKeyBuffer, @lcInitVector, AES_ECB_MODE, AES_ENCRYPT, Null) Use code with caution. Execute Data Processing: Process your file or text assets.
Detach: Clear buffers and release the DLL handle safely upon application closure. Licensing and Logistics
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