Algoritmo de cifrado CryptoGear
CryptoGear es un cifrado de cifrado desarrollado por BreakingSecurity.
Diseñado para ser simple y rápido, al tiempo que proporciona un nivel decente de seguridad.
Publicado de forma gratuita y de código abierto.

 

Características principales:

Tipo de algoritmo: cifrado de bloque de clave simétrica
Modos de operaciones: BCECBC
Tamaño del bloque: 4 bytes
Tamaño de clave: hasta 256 bytes como máximo
Tamaño del flujo de claves: 256 bytes
Relleno: manejado automáticamente

Este cifrado de bloque maneja automáticamente el relleno:
el tamaño del texto sin formato y el texto cifrado será siempre el mismo y no es necesario que sea un múltiplo del tamaño del bloque.

 

El proyecto incluye:
  • aplicación GUI (en Delphi) para el cifrado/descifrado de archivos
  • Aplicación de línea de comandos (en C++) para el cifrado/descifrado de archivos
  • Implementación de C ++
  • Delphi implementación

 

Descripción

Puedes imaginar el mecanismo CryptoGear como un engranaje de bicicleta giratorio:

  • El engranaje circular es el flujo de claves,
  • La cadena que se desliza por el engranaje son los datos que se cifrarán.

Cada rueda dentada y anillo de cadena representa un byte.
Entonces tenemos un engranaje circular con 256 dientes (el tamaño del flujo de clave es de 256 bytes),
y una cadena de datos de cualquier longitud posible.

  1. Al inicializar el cifrado, se genera un flujo de claves único, basado en la clave proporcionada y el vector de inicialización.
  2. Cada vez que una rueda dentada transmite los datos, los datos se modifican.
  3. En el modo CBC, el byte correspondiente del flujo de claves también cambia cada vez que cifra un byte.
    De esta forma, en cada ronda el engranaje (keystream) será diferente al anterior, y encriptará el bloque de forma diferente (incluso si los datos del bloque son idénticos a los de la ronda anterior).
    Además de esto, en el modo CBC cada bloque se vincula con el bloque anterior.

Descargar “CryptoGear Delphi" CryptoGear-Delphi.zip – Descargado 2703 veces – 251 KB

Fuente CryptoGear y Delphi muestra completa, un cifrador de archivos.
Puede cifrar cualquier archivo para protegerlo, y es posible descifrarlo solo si usa la misma clave, modo de operación y vector de inicialización. 

Descargar “CryptoGear C++” CryptoGear-C.zip – Descargado 1653 veces – 65 KB

Proyecto completo de C++, incluye herramienta de línea de comandos para cifrar/descifrar archivos.

Implementación de C ++

CryptoGear.h :

/*****************************************************************************\
*
*  CryptoGear Encryption Algorithm
*
*	Author: Viotto
*	Official website: Breaking-Security.Net
*
*	This algorithm and code can be freely used,
*	as long as you keep reference and credit to author and website.
*
******************************************************************************/

// Cipher Modes of operation:
#define MODE_ECB 0  // Electronic Codebook
#define MODE_CBC 1  // Cipher Block Chaining
class CCryptoGear
{
private:
	static const unsigned char m_InitializationVector = 0; // 0-255
	static const unsigned short m_lenKeystream = 256;
	unsigned char m_ModeOfOperation;
	unsigned char m_KeyStream[m_lenKeystream];
public:
	CCryptoGear(unsigned char* pKey, 
		unsigned int lenKey, 
		unsigned char ModeOfOperation = MODE_CBC,
		unsigned char InitializationVector = m_InitializationVector);
	CCryptoGear();
	void Initialize(unsigned char* pKey, unsigned int lenKey, 
		unsigned char ModeOfOperation = MODE_CBC,
		unsigned char InitializationVector = m_InitializationVector);
	void Encrypt(unsigned char pData[], unsigned long lenData);
	void Decrypt(unsigned char pData[], unsigned long lenData);
};

CryptoGear.cpp :

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/*****************************************************************************\
*
*  CryptoGear Encryption Algorithm
*
*	Author: Viotto
*	Official website: Breaking-Security.Net
*
*	This algorithm and code can be freely used,
*	as long as you keep reference and credit to author and website.
*
******************************************************************************/
#include <windows.h> // For memcpy
#include "CryptoGear.h"

//  Constructor.
CCryptoGear::CCryptoGear(unsigned char* pKey, unsigned int lenKey, unsigned char ModeOfOperation, unsigned char InitializationVector)
{
	Initialize(pKey, lenKey, ModeOfOperation, InitializationVector);
}

//  Overloaded costructor with no arguments.
//  Must manually initialize keystream.
CCryptoGear::CCryptoGear()
{}

//  Cipher Initialization.
//  Generates keystream and set mode of operation.
void CCryptoGear::Initialize(unsigned char* pKey, unsigned int lenKey, unsigned char ModeOfOperation,unsigned char InitializationVector)
{
	m_ModeOfOperation = ModeOfOperation;
	unsigned int i;
	for (i = 0; i < m_lenKeystream; i++)
	{
		m_KeyStream[i] = i + InitializationVector;
	}
	for (i = 0; i < m_lenKeystream; i++)
	{
		// xor initial keystream element value(0 - 255) with corresponding byte from key offset
		m_KeyStream[i] ^= (lenKey + pKey[i % lenKey]) % 256;
	}
}

void CCryptoGear::Encrypt(unsigned char pData[], unsigned long lenData)
{
	unsigned long Offset;
	unsigned char KeyStream[m_lenKeystream];
	//Create a local copy of the original KeyStream.
	memcpy(KeyStream, m_KeyStream, m_lenKeystream * sizeof(unsigned char));
	// Calculate padding
	unsigned char extra = lenData % 4;
	// If plain-text data size is not a multiple of block size,
	// then we must add a temporary padding (will be removed after finishing encrypting)
	if (extra)
	{
		extra = 4 - extra;
		lenData += extra;
		pData = (unsigned char*)realloc(pData, lenData);
	}
	//Encrypt the data.
	for (Offset = 0; Offset < lenData; Offset = Offset + 4)
	{
		pData[Offset]                 ^= KeyStream[Offset % m_lenKeystream];
		pData[(Offset + 1) % lenData] += (pData[Offset]                 + KeyStream[ (Offset + 1) % m_lenKeystream]) % 256;
		pData[(Offset + 2) % lenData] += (pData[(Offset + 1) % lenData] - KeyStream[ (Offset + 2) % m_lenKeystream]) % 256;
		pData[(Offset + 3) % lenData] += (pData[(Offset + 2) % lenData] ^ KeyStream[ (Offset + 3) % m_lenKeystream]) % 256;
		if (m_ModeOfOperation == MODE_CBC)
		{
			if (Offset > 0)
			{
				// xor block with previous block.
				pData[Offset]                 ^= (pData[(Offset - 4) % lenData]) % 256;
				pData[(Offset + 1) % lenData] ^= (pData[(Offset - 3) % lenData]) % 256;
				pData[(Offset + 2) % lenData] ^= (pData[(Offset - 2) % lenData]) % 256;
				pData[(Offset + 3) % lenData] ^= (pData[(Offset - 1) % lenData]) % 256;
			}
			// keystream elements used in this block are shifted. 
			// This way on next key round the corresponding keystream byte will be different.
			for (unsigned char i = 0; i < 4; i++)
			{
				KeyStream[(Offset + i) % m_lenKeystream] += pData[(Offset + i) % lenData] % 256;
			}
		}
	}
	// Remove padding.
	if (extra)
	{
		lenData -= extra;
		pData = (unsigned char*)realloc(pData, lenData);
	}
}

void CCryptoGear::Decrypt(unsigned char pData[], unsigned long lenData)
{
	unsigned char KeyStream[m_lenKeystream];
	unsigned long Offset;
	unsigned char a, b, c, d;
	unsigned char e, f, g, h;
	unsigned char i, j, k;
	//Create a local copy of the original keystream.
	memcpy(KeyStream, m_KeyStream, m_lenKeystream * sizeof(unsigned char));
	// Calculate padding
	unsigned char extra = lenData % 4;
	// If data size is not a multiple of block size,
	// then we must temporarely add padding (will be removed after finishing decryption)
	if (extra)
	{
		extra = 4 - extra;
		lenData += extra;
		pData = (unsigned char*)realloc(pData, lenData);
	}
	//Decrypt the data.
	for (Offset = 0; Offset < lenData; Offset = Offset + 4)
	{
		if (m_ModeOfOperation == MODE_CBC)
		{
			// Save original encrypted bytes, used for key shifting later
			a = pData[Offset];
			b = pData[(Offset + 1) % lenData];
			c = pData[(Offset + 2) % lenData];
			d = pData[(Offset + 3) % lenData];
			// Do from second cycle
			if (Offset > 0)
			{
				// xor block with previous block
				pData[Offset] ^= e % 256;
				pData[(Offset + 1) % lenData] ^= f % 256;
				pData[(Offset + 2) % lenData] ^= g % 256;
				pData[(Offset + 3) % lenData] ^= h % 256;
			}
			// Store encrypted bytes of this block for next cycle
			e = a;
			f = b;
			g = c;
			h = d;
		}
		// Save xored bytes (or original encrypted bytes if we are using ECB). 
		// With those we can shift back keystream operations and obtain clear-text.
		i = pData[Offset];
		j = pData[(Offset + 1) % lenData];
		k = pData[(Offset + 2) % lenData];
		pData[Offset]                 ^= KeyStream[Offset % m_lenKeystream];
		pData[(Offset + 1) % lenData] -= (i	+ KeyStream[(Offset + 1) % m_lenKeystream]) % 256;
		pData[(Offset + 2) % lenData] -= (j - KeyStream[(Offset + 2) % m_lenKeystream]) % 256;
		pData[(Offset + 3) % lenData] -= (k ^ KeyStream[(Offset + 3) % m_lenKeystream]) % 256;
		if (m_ModeOfOperation == MODE_CBC)
		{
			// Values of KeyStream elements used in this block are modified. 
			// This way on each key round the corresponding key byte will be different.
			KeyStream[Offset % m_lenKeystream]		 += a;
			KeyStream[(Offset + 1) % m_lenKeystream] += b;
			KeyStream[(Offset + 2) % m_lenKeystream] += c;
			KeyStream[(Offset + 3) % m_lenKeystream] += d;
		}
	}
	// Remove padding.
	if (extra)
	{
		lenData -= extra;
		pData = (unsigned char*)realloc(pData, lenData);
	}
}

Cómo utilizar el programa de línea de comandos CryptoGear.exe:

cryptogear.exe direction key [mode] [iv] type target
  direction:
	-e to encrypt
	-d to decrypt
  key:
	your password
  mode (optional, default is CBC):
    -ECB
    -CBC
  iv: Initialization Vector. (optional, default is 0):
    -v 0-255
    Value can be a number in the range of 0-255.
  type:
	-s to encrypt string
	-f to encrypt file
  target:
	with -s option: input string
	with -f option: input file
---------------------------------------------------------
Examples:
cryptogear -e pass -f "C:\myfile.exe"                   // Encrypt file with password "pass"
cryptogear -d pass -f "C:\myfile.exe.encrypted"         // Decrypt file with password "pass"
cryptogear -e pass -ECB -v 10 -f "C:\myfile.exe"        // Encrypt with password "pass", using ECB mode and initialization vector 10
cryptogear -e pass -s Hello World                       // Encrypt string with password "pass"
Delphi implementación
unit uCryptoGear;
{*****************************************************************************
*
*  CryptoGear Encryption Algorithm v1.0
*  Delphi version
*
*	 Author: Viotto
*	 Official website: Breaking-Security.Net
*
*	 This algorithm and code can be freely used,
*	 as long as you keep reference and credit to author and website.
*
******************************************************************************}
interface
const
  MODE_ECB = 0;
  MODE_CBC = 1;
  g_lenKeystream = 256;
type
  TByteArray = array of Byte;
  CCryptoGear = class
  private
    m_KeyStream: array[0..g_lenKeystream-1] of Byte;
    m_InitializationVector: Byte;
    m_ModeOfOperation: Byte;
  public
    constructor Initialize(sKey: AnsiString; ModeOfOperation: Byte = MODE_CBC; InitializationVector: Byte = 0);
    procedure Encrypt(var pData: TByteArray); overload;
    procedure Decrypt(var pData: TByteArray); overload;
    function Encrypt(sData: AnsiString): AnsiString; overload;
    function Decrypt(sData: AnsiString): AnsiString; overload;
end;

implementation

constructor CCryptoGear.Initialize(sKey: AnsiString; ModeOfOperation: Byte = MODE_CBC; InitializationVector: Byte = 0);
var
  pKey: TByteArray;
  i, lenKey: Cardinal;
begin
  m_ModeOfOperation := ModeOfOperation;
  lenKey := Length(sKey);
  SetLength(pKey, lenKey);
  Move(sKey[1], pKey[0], lenKey);
  for i := 0 to g_lenKeystream - 1 do
  begin
    m_KeyStream[i] := (i + InitializationVector) mod 256;
  end;
  for i := 0 to (g_lenKeystream - 1) do
  begin
    // xor initial keystream element value(0 - 255) with corresponding byte from key offset
    m_KeyStream[i] := (m_KeyStream[i] xor (lenKey + pKey[i mod lenKey])) mod 256;
  end;
end;

function CCryptoGear.Encrypt( sData: AnsiString): AnsiString;
var
  pData: TByteArray;
  lenData: Cardinal;
begin
  lenData := Length(sData);
  SetLength(pData, lenData);
  Move(sData[1], pData[0], lenData);
  Encrypt(pData);
  SetString(sData, PAnsiChar(@pData[0]), lenData);
  Result := sData;
end;

function CCryptoGear.Decrypt( sData: AnsiString): AnsiString;
var
  pData: TByteArray;
  lenData: Cardinal;
begin
  lenData := Length(sData);
  SetLength(pData, lenData);
  Move(sData[1], pData[0], lenData);
  Decrypt(pData);
  SetString(sData, PAnsiChar(@pData[0]), lenData);
  Result := sData;
end;

procedure CCryptoGear.Encrypt( var pData: TByteArray);
var
  lenData, Offset: Cardinal;
  i: Cardinal;
  KeyStream: array[0..g_lenKeystream-1] of Byte;
  extra: Byte;
begin
  Offset := 0;
  lenData := Length(pData);
  //Create a local copy of the original KeyStream.
  for i := 0 to g_lenKeystream - 1 do
  begin
    KeyStream[i] := m_KeyStream[i];
  end;
  // Calculate padding
  extra := lenData mod 4;
  // If plain-text data size is not a multiple of block size,
  // then we must add a temporary padding (will be removed after finishing encrypting)
  if (extra > 0) then
  begin
    extra := 4 - extra;
    lenData := lenData + extra;
    SetLength(pData, lenData);
  end;
  //Encrypt the data.
  repeat
    pData[Offset]                   :=  pData[Offset] xor KeyStream[Offset mod g_lenKeystream];
    pData[(Offset + 1) mod lenData] := (pData[(Offset + 1) mod lenData] +  pData[Offset] + KeyStream[ (Offset + 1) mod g_lenKeystream]) mod 256;
    pData[(Offset + 2) mod lenData] := Byte(pData[(Offset + 2) mod lenData] + (pData[(Offset + 1) mod lenData] - KeyStream[ (Offset + 2) mod g_lenKeystream]) mod 256);
    pData[(Offset + 3) mod lenData] := (pData[(Offset + 3) mod lenData] + (pData[(Offset + 2) mod lenData] xor KeyStream[ (Offset + 3) mod g_lenKeystream])) mod 256;
    if (m_ModeOfOperation = MODE_CBC) then
    begin
      if (Offset > 0) then
      begin
      // xor block with previous block.
        pData[Offset]                   := (pData[Offset] xor pData[(Offset - 4) mod lenData]) mod 256;
        pData[(Offset + 1) mod lenData] := (pData[(Offset + 1) mod lenData] xor pData[(Offset - 3) mod lenData]) mod 256;
        pData[(Offset + 2) mod lenData] := (pData[(Offset + 2) mod lenData] xor pData[(Offset - 2) mod lenData]) mod 256;
        pData[(Offset + 3) mod lenData] := (pData[(Offset + 3) mod lenData] xor pData[(Offset - 1) mod lenData]) mod 256;
      end;
      // keystream elements used in this block are shifted.
      // This way on next key round the corresponding keystream byte will be different.
      for i := 0 to 3 do
      begin
        KeyStream[(Offset + i) mod g_lenKeystream] := Byte(KeyStream[(Offset + i) mod g_lenKeystream] + pData[(Offset + i) mod lenData] mod 256);
      end;
    end;
    Inc(Offset, 4);
  until Offset >= lenData;
  // Remove padding.
  if (extra > 0) then
  begin
    lenData := lenData - extra;
    setlength(pData, lenData);
  end;
end;

procedure CCryptoGear.Decrypt( var pData: TByteArray);
var
  KeyStream: array[0..g_lenKeystream-1] of Byte;
  lenData, Offset: Cardinal;
  extra     : Byte;
  a, b, c, d: Byte;
  e, f, g, h: Byte;
  i, j, k   : Byte;
begin
  Offset := 0;
  lenData := Length(pData);
  //Create a local copy of the original KeyStream.
  for i := 0 to g_lenKeystream -1 do
  begin
    KeyStream[i] := m_KeyStream[i];
  end;
  // Calculate padding
  extra := lenData mod 4;
  // If plain-text data size is not a multiple of block size,
  // then we must add a temporary padding (will be removed after finishing encrypting)
  if (extra > 0) then
  begin
    extra := 4 - extra;
    lenData := lenData + extra;
    SetLength(pData, lenData);
  end;
  //Decrypt the data.
  repeat
    if m_ModeOfOperation = MODE_CBC then
    begin
      // Save original encrypted bytes, used for key shifting later
      a := pData[Offset];
      b := pData[(Offset + 1) mod lenData];
      c := pData[(Offset + 2) mod lenData];
      d := pData[(Offset + 3) mod lenData];
      // Do from second cycle
      if (Offset > 0) then
      begin
        // xor block with previous block
        pData[Offset] :=  pData[Offset] xor e ;
        pData[(Offset + 1) mod lenData] := pData[(Offset + 1) mod lenData] xor f ;
        pData[(Offset + 2) mod lenData] := pData[(Offset + 2) mod lenData] xor g ;
        pData[(Offset + 3) mod lenData] := pData[(Offset + 3) mod lenData] xor h ;
      end;
      // Store encrypted bytes of this block for next cycle
      e := a;
      f := b;
      g := c;
      h := d;
    end;
    // Save xored bytes (or original encrypted bytes if we are using ECB).
    // With those we can shift back keystream operations and obtain clear-text.
    i := pData[Offset];
    j := pData[(Offset + 1) mod lenData];
    k := pData[(Offset + 2) mod lenData];
    pData[Offset]                   := pData[Offset] xor KeyStream[Offset mod g_lenKeystream];
    pData[(Offset + 1) mod lenData] := Byte(pData[(Offset + 1) mod lenData] - (i  + KeyStream[(Offset + 1) mod g_lenKeystream]) mod 256);
    pData[(Offset + 2) mod lenData] := Byte(pData[(Offset + 2) mod lenData] - (j  - KeyStream[(Offset + 2) mod g_lenKeystream]) mod 256);
    pData[(Offset + 3) mod lenData] := Byte(pData[(Offset + 3) mod lenData] - (k xor KeyStream[(Offset + 3) mod g_lenKeystream]) mod 256);
    if m_ModeOfOperation = MODE_CBC then
    begin
      // Values of KeyStream elements used in this block are modified.
      // This way on each key round the corresponding key byte will be different.
      KeyStream[Offset mod g_lenKeystream]       := Byte(KeyStream[Offset mod g_lenKeystream]       + a);
      KeyStream[(Offset + 1) mod g_lenKeystream] := Byte(KeyStream[(Offset + 1) mod g_lenKeystream] + b);
      KeyStream[(Offset + 2) mod g_lenKeystream] := Byte(KeyStream[(Offset + 2) mod g_lenKeystream] + c);
      KeyStream[(Offset + 3) mod g_lenKeystream] := Byte(KeyStream[(Offset + 3) mod g_lenKeystream] + d);
    end;
    Inc(Offset, 4);
  until Offset >= lenData;
  // Remove padding.
  if (extra > 0) then
  begin
    lenData := lenData - extra;
    setlength(pData, lenData);
  end;
end;

end.
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