TanSanC

CPP aes128 cbc mode Encryption Decryption

AES

Encryption Block  : 

128 비트

192 비트 

256 비트

Mode :    

1. ECB ( Electric Code Book )

http://jo.centis1504.net/wp-content/uploads/2010/11/Encryption-ECB_MODE.swf

2. CBC ( Cipher Block Chaining )

http://jo.centis1504.net/wp-content/uploads/2010/11/Encryption-CBC_MODE.swf

3. OFB ( Output Feed Back )

http://jo.centis1504.net/wp-content/uploads/2010/11/Encryption-OFB_MODE.swf

4. CFB ( Cipher Feed Back )

5. CTR ( CounTeR )

모드별 설명은

관련 자료 참고 : http://www.parkjonghyuk.net/lecture/modernCrypto/lecturenote/chap04.pdf

구현에서는 CTR 모드로 구현하였다.

개발 환경 : Windows 7 64bit, VS 2013

최신버전으로 직접 빌드하시려면 아래의 링크를 참조하시기 바랍니다.

귀찮으신 분은 빌드된 버전을 사용합시다.

OpenSSL 빌드 : http://yokkohama.tistory.com/entry/OpenSSL-%EB%B9%8C%EB%93%9C%ED%95%98%EA%B8%B0-Visual-Studio-2010-%EB%98%90%EB%8A%94-libeay32dll-ssleay32dll-%EB%8B%A4%EC%9A%B4%EB%A1%9C%EB%93%9C

"openssl-1.0.1f_vc_no-idea no-mdc2 no-rc5_build.zip" 는 no-idea no-mdc2 no-rc5  로 빌드된, 특허문제가 해결 된 바이너리입니다.

openssl-1.0.1f_vc_no-idea no-mdc2 no-rc5_build.zip

압축 해제 후 파일을 프로젝트 폴더로 이동

프로젝트속성 > VC++ 디렉터리 > 디렉터리 설정 (포함 디렉터리, 라이브러리 디렉터리)

별도의 클래스를 만들어 사용 하였습니다.

#pragma once

#include 
#include 
#include 
#include 


struct ctr_state {
	unsigned char ivec[AES_BLOCK_SIZE];
	unsigned int num;
	unsigned char ecount[AES_BLOCK_SIZE];
};



class CAESCTR
{
public:
	AES_KEY key;
	int BYTES_SIZE = 1024;
	int KEY_SIZE = 128;
	unsigned char ckey[32];
	unsigned char iv[8];
	int init_ctr(struct ctr_state *state, const unsigned char iv[8]);
	void encrypt(unsigned char *indata, unsigned char *outdata, int bytes_read);
	void encrypt(CString& indata, CString& outdata, int bytes_read);
	CAESCTR();
	CAESCTR::CAESCTR(unsigned char* iv, unsigned char* ckey);
	~CAESCTR();
};

#include "stdafx.h"
#include "AESCTR.h"

int CAESCTR::init_ctr(struct ctr_state *state, const unsigned char iv[8]){
	state->num = 0;
	memset(state->ecount, 0, AES_BLOCK_SIZE);
	memset(state->ivec + 8, 0, 8);
	memcpy(state->ivec, iv, 8);

	return 0;
}
// encrypt twice  == decrypt

void CAESCTR::encrypt(unsigned char *indata, unsigned char *outdata, int bytes_read){

	int i = 0;
	int mod_len = 0;

	AES_set_encrypt_key(ckey, KEY_SIZE, &key);

	if (bytes_read < BYTES_SIZE){
		struct ctr_state state;
		init_ctr(&state, iv);
		AES_ctr128_encrypt(indata, outdata, bytes_read, &key, state.ivec, state.ecount, &state.num);
		return;
	}
	// loop block size  = [ BYTES_SIZE ]
	for (i = BYTES_SIZE; i <= bytes_read; i += BYTES_SIZE){
		struct ctr_state state;
		init_ctr(&state, iv);
		AES_ctr128_encrypt(indata, outdata, BYTES_SIZE, &key, state.ivec, state.ecount, &state.num);
		indata += BYTES_SIZE;
		outdata += BYTES_SIZE;
	}

	mod_len = bytes_read % BYTES_SIZE;
	if (mod_len != 0){
		struct ctr_state state;
		init_ctr(&state, iv);
		AES_ctr128_encrypt(indata, outdata, mod_len, &key, state.ivec, state.ecount, &state.num);
	}
}

void CAESCTR::encrypt(CString& instr, CString& outstr, int bytes_read){

	int i = 0;
	int mod_len = 0;
	unsigned char *indata;
	unsigned char *outdata;

	indata = (unsigned char *)malloc(instr.GetLength() + 1);
	outdata = (unsigned char *)malloc(instr.GetLength() + 1);



	strncpy((char*)indata, (LPSTR)(LPCSTR)instr, instr.GetLength());
	indata[instr.GetLength()] = NULL;


	

	AES_set_encrypt_key(ckey, KEY_SIZE, &key);

	if (bytes_read < BYTES_SIZE){
		struct ctr_state state;
		init_ctr(&state, iv);
		AES_ctr128_encrypt(indata, outdata, bytes_read, &key, state.ivec, state.ecount, &state.num);

		outdata[instr.GetLength()] = NULL;
		outstr = outdata;
		return;
	}
	// loop block size  = [ BYTES_SIZE ]
	for (i = BYTES_SIZE; i <= bytes_read; i += BYTES_SIZE){
		struct ctr_state state;
		init_ctr(&state, iv);
		AES_ctr128_encrypt(indata, outdata, BYTES_SIZE, &key, state.ivec, state.ecount, &state.num);
		indata += BYTES_SIZE;
		outdata += BYTES_SIZE;
	}

	mod_len = bytes_read % BYTES_SIZE;
	if (mod_len != 0){
		struct ctr_state state;
		init_ctr(&state, iv);
		AES_ctr128_encrypt(indata, outdata, mod_len, &key, state.ivec, state.ecount, &state.num);
	}
	outdata[instr.GetLength()] = NULL;
	outstr = outdata;
}

CAESCTR::CAESCTR()
{
	unsigned char temp_iv[8] = { 0x66, 0x61, 0x63, 0x65, 0x73, 0x65, 0x61, 0x00 };
	memcpy(iv, temp_iv, 8);

	unsigned char temp_ckey[32] = { 0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc, 0xde, 0xf0,
		0x34, 0x56, 0x78, 0x9a, 0xbc, 0xde, 0xf0, 0x12,
		0x56, 0x78, 0x9a, 0xbc, 0xde, 0xf0, 0x12, 0x34,
		0x78, 0x9a, 0xbc, 0xde, 0xf0, 0x12, 0x34, 0x56 }; // 32bytes = AES256, 16bytes = AES128
	memcpy(ckey, temp_ckey, 32);
}

CAESCTR::CAESCTR(unsigned char* iv, unsigned char* ckey)
{
	memcpy(this->iv, iv, 8);
	memcpy(this->ckey, ckey, 32);
}

CAESCTR::~CAESCTR()
{
}

그리고, 프로젝트 속성에서

구성 속성 > 문자 집합 > 설정 안 함

으로 하여서 사용하였습니다.

사용예시

void CPasswordEncoderDlg::OnEnChangeEdit1()
{
	// TODO:  RICHEDIT 컨트롤인 경우, 이 컨트롤은
	// CDialogEx::OnInitDialog() 함수를 재지정 
	//하고 마스크에 OR 연산하여 설정된 ENM_CHANGE 플래그를 지정하여 CRichEditCtrl().SetEventMask()를 호출하지 않으면
	// 이 알림 메시지를 보내지 않습니다.

	// TODO:  여기에 컨트롤 알림 처리기 코드를 추가합니다.
	CAESCTR m_AESCTR;

	CString editText;
	m_Edit1.GetWindowTextA(editText);
		
	int editTextLength = editText.GetLength();

	unsigned char* editTextCharSeq;
	editTextCharSeq = (unsigned char *)malloc(editTextLength+1);

	strncpy((char*)editTextCharSeq, (LPSTR)(LPCSTR)editText, editTextLength);
	editTextCharSeq[editTextLength] = NULL;

	unsigned char* outTextCharSeq;
	outTextCharSeq = (unsigned char *)malloc(editTextLength + 1);

	m_AESCTR.encrypt(editTextCharSeq, outTextCharSeq, editTextLength);
	outTextCharSeq[editTextLength] = NULL;
	
	editText = outTextCharSeq;
	m_Edit2.SetWindowTextA(editText);
	
	m_AESCTR.encrypt(editText, editText, editTextLength);

	m_Edit3.SetWindowTextA(editText);

	free(editTextCharSeq);
	free(outTextCharSeq);
}