DCPcrypt

Cryptographic Component Library for Free Pascal/Lazarus

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Overview

DCPcrypt is a collection of cryptographic components originally written for Borland Delphi by David Barton, ported to Lazarus/Free Pascal and maintained by multiple contributors.

The idea behind DCPcrypt is that it should be possible to "drop in" any algorithm implementation to replace another with minimum or no code changes. All cryptographic components are descended from one of several base classes: TDCP_cipher for encryption algorithms and TDCP_hash for message digest algorithms.

Key Features

• 20 Cipher Algorithms - Rijndael (AES), Blowfish, Twofish, Serpent, DES, 3DES, RC4, and more
• 10 Hash Algorithms - SHA-1, SHA-256, SHA-384, SHA-512, MD5, RipeMD-160, Tiger, and more
• 6 Block Cipher Modes - ECB, CBC, CFB8bit, CFBblock, OFB, CTR
• Stream Encryption - Salt+IV EncryptStream/DecryptStream with progress callbacks
• Base64 - Encoding and decoding
• Cross-Platform - Linux, Windows, and macOS support
• No External Dependencies - Pure Pascal implementation

Screenshots

String Encryption — Encrypt/decrypt strings with any cipher+hash combination:

Initial state	After encryption

File Encryption — Encrypt/decrypt files with progress bar (threaded):

Ready to encrypt	Encryption in progress

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Quick Start

Installation

Option 1 - Packages (IDE)

Open src/dcpcrypt.lpk (runtime) and src/dcpcrypt_laz.lpk (design-time) in the Lazarus IDE. Cipher and hash components will appear on the component palette.

Option 2 - Direct use (no IDE)

Add the source paths to your project:

-Fupath/to/dcpcrypt-lazarus/src -Fupath/to/dcpcrypt-lazarus/src/Ciphers -Fupath/to/dcpcrypt-lazarus/src/Hashes

Basic Usage

program QuickDemo;

{$MODE ObjFPC}{$H+}

uses
  DCPrijndael, DCPsha256, DCPcrypt2;

var
  Cipher: TDCP_rijndael;
  Encrypted, Decrypted: string;
begin
  Cipher := TDCP_rijndael.Create(nil);
  try
    // Initialize with a passphrase (hashed with SHA-256)
    Cipher.InitStr('my secret passphrase', TDCP_sha256);

    // Encrypt a string (result is Base64-encoded)
    Encrypted := Cipher.EncryptString('Hello World');
    WriteLn('Encrypted: ', Encrypted);

    // Decrypt
    Cipher.Reset;
    Decrypted := Cipher.DecryptString(Encrypted);
    WriteLn('Decrypted: ', Decrypted);

    Cipher.Burn;
  finally
    Cipher.Free;
  end;
end.

Compile with:

fpc -Fusrc -Fusrc/Ciphers -Fusrc/Hashes quickdemo.lpr

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Algorithms

Ciphers

Name	Block Size	Max Key Size
Rijndael (AES)	128 bits	256 bits
Blowfish	64 bits	448 bits
Twofish	128 bits	256 bits
Serpent	128 bits	256 bits
Cast128	64 bits	128 bits
Cast256	128 bits	256 bits
DES	64 bits	64 bits
3DES	64 bits	192 bits
RC2	64 bits	1024 bits
RC4	N/A (stream)	2048 bits
RC5	64 bits	2048 bits
RC6	128 bits	2048 bits
MARS	128 bits	1248 bits
IDEA	64 bits	128 bits
Misty1	64 bits	128 bits
Ice / Thin Ice / Ice2	64 bits	64-128 bits
Gost	64 bits	256 bits
TEA	64 bits	128 bits

Hash Algorithms

Name	Digest Size
SHA-1	160 bits
SHA-256	256 bits
SHA-384	384 bits
SHA-512	512 bits
MD4	128 bits
MD5	128 bits
RipeMD-128	128 bits
RipeMD-160	160 bits
Haval	128-256 bits
Tiger	192 bits

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Documentation

Document	Description
Full Documentation	Detailed project documentation
Ciphers API	TDCP_cipher reference
Block Ciphers API	TDCP_blockcipher reference
Hashes API	TDCP_hash reference
Changelog	Version history
Building	Compilation instructions
Table of Contents	Full documentation index

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Examples

Console

Example	Description
demo_encrypt_string	Salt+IV string encryption/decryption
demo_file_encrypt	File encryption with progress callback
demo_hash_file	Hash files using all 10 hash algorithms
demo_hash_large_file	Hash large files (>5 GB) with real-time progress (--size=N, --dir=path)

cd examples/console
fpc -Fusrc -Fusrc/Ciphers -Fusrc/Hashes demo_encrypt_string.lpr
./demo_encrypt_string

GUI (Lazarus LCL)

Example	Description
EncryptStrings	String encryption/decryption using EncryptStream
FileEncrypt	File encryption/decryption with thread support

lazbuild examples/gui/EncryptStrings/EncryptStringsViaEncryptStream.lpi

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Testing

A functional test suite (282 tests) is provided in tests/. It requires only fpc and no IDE.

make test             # build and run all tests
make build-examples   # compile all examples (console + GUI)
make build-all        # compile everything (tests + examples)
make check            # clean, build and run (full verification)

Program	Tests	Coverage
test_hashes	90	SelfTest, digest, determinism, Burn for 10 hashes
test_ciphers	139	SelfTest, roundtrip, Burn, properties for 20 ciphers
test_block_modes	28	ECB, CBC, CFB8bit, CFBblock, OFB, CTR
test_base64	11	RFC 4648, binary data, edge cases
test_stream_encrypt	14	Salt+IV, PartialEncryptStream, OnProgressEvent

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Requirements

• Compiler: Free Pascal 3.2.0 or later
• IDE: Lazarus 2.0+ (optional, for GUI examples and packages)
• Dependencies: None (pure Pascal)

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Project Structure

dcpcrypt-lazarus/
├── src/                    # Source code
│   ├── Ciphers/            # 17 cipher units
│   ├── Hashes/             # 9 hash units
│   ├── Docs/               # Original HTML docs and license
│   ├── dcpcrypt2.pas       # Base classes (TDCP_cipher, TDCP_hash)
│   ├── dcpblockciphers.pas # Block cipher modes
│   ├── dcpbase64.pas       # Base64 encoding/decoding
│   ├── dcpcrypt.lpk        # Runtime package
│   └── dcpcrypt_laz.lpk    # Design-time package
├── tests/                  # Functional test suite (282 tests)
├── examples/               # Console and GUI examples
│   ├── console/            # 4 console demos
│   └── gui/                # 2 GUI examples (LCL)
├── docs/                   # Markdown documentation
├── .github/workflows/      # CI/CD configuration
└── Makefile                # Build, test, clean targets

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Platform Support

Platform	Architecture	Status
Linux	x86_64, aarch64	Supported
Windows	x86, x64	Supported
macOS	Intel, Apple Silicon	Supported
Linux Snap	x86_64	Supported
Linux Flatpak	x86_64	Supported

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Contributing

Contributions are welcome. Please ensure:

1. Code compiles without warnings
2. All 282 tests pass (make test)
3. Examples compile correctly
4. Documentation is updated

See CONTRIBUTING.md for details.

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License

MIT License - See LICENSE for details.

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Contributors

Name	Contribution
David Barton	Original DCPcrypt author (1999-2003)
Barko	Lazarus port (2006)
Graeme Geldenhuys	Package split, 64-bit support (2009-2010)
Werner Pamler	Large file hash fix (2022)
Nicolas Deoux	GUI examples VCL-to-LCL port, console demos, large-file hashing demo, test suite, Makefile, CI/CD, docs (2026)

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Author (v2.0.6)

Nicolas DEOUX

• NDXDev@gmail.com
• LinkedIn
• GitHub

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DCPcrypt is copyrighted by its respective authors. Released under the MIT license. All trademarks are property of their respective owners.

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Last updated: February 2026 | FPC 3.2.0+