README

CryptoPP Delphi Wrapper

CryptoPP_Lib.pas + CryptoPP.pas give Delphi applications a high-level, TArray<Byte>-based API on top of the cryptopp.dll built from main.h/main.cpp in my other repo.

Files

• CryptoPP_Lib.pas — thin, 1:1 cdecl external import declarations matching the DLL's exported C functions. Low-level: raw pointers (PByte/PAnsiChar), manual output-buffer sizing, manual delete_byte_array calls. You normally should not need to call this unit directly.
• CryptoPP.pas — the high-level API. Wraps every DLL call with TArray<Byte> parameters/results, allocates/frees buffers for you, and exposes a single global Crypto: TCrypto record as the entry point.

Requirements

• cryptopp.dll (built from the C++ side of this repo) must be present on the search path (same directory as the executable, or on PATH). The expected file name is defined by DllName = 'cryptopp.dll' in CryptoPP_Lib.pas.
• The DLL bitness (x86/x64) must match your Delphi application.
• System.SysUtils and System.Math (used for DER length handling in TECDSA).

Usage

Add both units to your project's uses clause (only CryptoPP is normally needed; it pulls in CryptoPP_Lib itself) and call through the global Crypto variable:

uses
  CryptoPP;

var
  Key, IV, PlainText, CipherText: TArray<Byte>;
begin
  Key := TEncoding.UTF8.GetBytes('0123456789abcdef'); // 16 bytes = AES-128
  IV := TEncoding.UTF8.GetBytes('abcdef9876543210');  // 16 bytes
  PlainText := TEncoding.UTF8.GetBytes('Hello, Crypto++!');

  CipherText := Crypto.AES.Cbc_Encrypt(PlainText, Key, IV);
  PlainText := Crypto.AES.Cbc_Decrypt(CipherText, Key, IV);
end;

API overview (Crypto: TCrypto)

Hash method strings

ECDSA.Sign/Verify and RSA.Sign/Verify/Oaep_*/Pss_* take a HashMethod: string selecting the underlying digest. Matching is case-insensitive (HashMethod.ToLower()). Supported values depend on the operation:

• ECDSA sign/verify: 'sha1', 'sha256'.
• RSA OAEP: 'md2', 'md4', 'md5', 'sha1', 'sha224', 'sha256', 'sha384', 'sha512'.
• RSA PSS: 'sha1', 'sha224', 'sha256', 'sha384', 'sha512'.
• RSA PKCS#1v1.5 sign/verify: 'md2', 'md5', 'sha1', 'sha224', 'sha256', 'sha384', 'sha512'.

An unrecognized HashMethod results in an empty TArray<Byte> (for sign/encrypt operations) or False (for verify operations) — it will not raise an exception, so check the result size/value before use.

AEAD verification (TXSalsa20.Poly1305_Tls_Decrypt)

function Poly1305_Tls_Decrypt(const CipherData: TArray<Byte>; const Key: TArray<Byte>;
  const IV: TArray<Byte>; out Verified: Boolean; const Verify: Boolean = True): TArray<Byte>;

Always inspect the Verified out-parameter. When Verify = True (the default) and the Poly1305 tag does not match, Verified is False and the returned plaintext buffer is all zero bytes — do not use the returned data unless Verified is True.

Elliptic curve selector

ECDH/ECDSA take an EllipticCurve: Byte parameter:

Memory management

All high-level functions in CryptoPP.pas manage the DLL-allocated buffers for you (calling delete_byte_array internally) — you only ever work with regular Delphi TArray<Byte> values with normal ARC/refcount lifetime. You do not need to call anything in CryptoPP_Lib.pas directly unless you are extending the wrapper.