本文主要是介绍c++ DES ECB加密算法pkcs5padding填充实现，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
我主要的实现的pkcs5padding填充，其他填充方式自己实现就好了，都不难。
使用的是静态连接的方法，使用的是openssl的libcrypto库，网上一大堆，这里就不贴了。
windows库：https://download.csdn.net/download/suhiymof/11247287
头文件这样包含即可:
#ifdef WIN32
#include "des.h"
#pragma comment(lib, "libcrypt" )
#else
#include "openssl/des.h"
#endif // WIN32填充代码
//填充
char* PKCS5Padding(string strParams, uint32 unBlockSize)
{int nRaw_size = strParams.size();int i=0, j=nRaw_size/8+1, k=nRaw_size%8;int nPidding_size = 8 - k;char* szArray;szArray = (char *)malloc(nRaw_size + nPidding_size);memcpy(szArray, strParams.c_str(), nRaw_size);for (int i1=nRaw_size; i1<(nRaw_size+nPidding_size); i1++) {// PKCS5Padding 算法：szArray[i1] = nPidding_size;}return szArray;
}windows加密：
//strParams:加密字符串
//szKey:加密的密码，我用的是八字节的密码
string Des_Encrypt(string strParams, char* szKey)
{using namespace CryptoPP;char szCommand[1024];memset(szCommand, 0, 1024);int nRaw_size = strParams.size();char* szArray = PKCS5Padding(strParams, DES::BLOCKSIZE);int j=nRaw_size/DES::BLOCKSIZE + 1;unsigned char key[DES::DEFAULT_KEYLENGTH];memcpy(key, szKey, DES::BLOCKSIZE);unsigned char szInput[ DES::BLOCKSIZE];unsigned char szOutput[ DES::BLOCKSIZE];for (int i = 0; i < j; ++i){memset(szInput, 0, 8);memset(szOutput, 0, 8);memcpy(szInput, szArray+(i*8), 8);DESEncryption encryption_DES;//因此，设置密匙。encryption_DES.SetKey(key, DES::KEYLENGTH );//进行加密encryption_DES.ProcessBlock( szInput, szOutput);memcpy(szCommand+(i*8), szOutput, 8);}int nLen = j * 8;//base64编码std::string strTmp = base64_encode(reinterpret_cast<const unsigned char*>(szCommand), nLen);return strTmp;
}linux加密：
string Des_Encrypt(string strParams, char* szKey)
{char szCommand[1024];memset(szCommand, 0, 1024);int nRaw_size = strParams.size();char* szArray = PKCS5Padding(strParams, sizeof(DES_cblock));int j=nRaw_size/8 + 1;DES_cblock sKey;// = "12341234";memcpy(sKey, szKey, 8);const_DES_cblock sInput;DES_cblock sOutput;DES_key_schedule sSchedule;//转换成scheduleDES_set_key_unchecked(&sKey, &sSchedule); for (int i = 0; i < j; ++i){memset(sInput, 0, 8);memset(sOutput, 0, 8);memcpy(sInput, szArray+(i*8), 8);DES_ecb_encrypt(&sInput, &sOutput, &sSchedule, DES_ENCRYPT);memcpy(szCommand+(i*8), sOutput, 8);}int nLen = j * 8;//base64编码std::string strTmp = base64_encode(reinterpret_cast<const unsigned char*>(szCommand), nLen);return strTmp;
}这里包含了base64位编码，这里贴一下源码
static const std::string base64_chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ""abcdefghijklmnopqrstuvwxyz""0123456789+/";static inline bool is_base64(unsigned char c) {return (isalnum(c) || (c == '+') || (c == '/'));
}std::string base64_encode(unsigned char const* bytes_to_encode, unsigned int in_len) {printf("---%d\n", in_len);std::string ret;int i = 0;int j = 0;unsigned char char_array_3[3];unsigned char char_array_4[4];while (in_len--) {char_array_3[i++] = *(bytes_to_encode++);if (i == 3) {char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);char_array_4[3] = char_array_3[2] & 0x3f;for(i = 0; (i <4) ; i++)ret += base64_chars[char_array_4[i]];i = 0;}}if (i){for(j = i; j < 3; j++)char_array_3[j] = '\0';char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);char_array_4[3] = char_array_3[2] & 0x3f;for (j = 0; (j < i + 1); j++)ret += base64_chars[char_array_4[j]];while((i++ < 3))ret += '=';}//printf("---111%d, %s\n", ret.size(), ret.c_str());return ret;}std::string base64_decode(std::string const& encoded_string) {size_t in_len = encoded_string.size();int i = 0;int j = 0;int in_ = 0;unsigned char char_array_4[4], char_array_3[3];std::string ret;while (in_len-- && ( encoded_string[in_] != '=') && is_base64(encoded_string[in_])) {char_array_4[i++] = encoded_string[in_]; in_++;if (i ==4) {for (i = 0; i <4; i++)char_array_4[i] = base64_chars.find(char_array_4[i]);char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];for (i = 0; (i < 3); i++)ret += char_array_3[i];i = 0;}}if (i) {for (j = i; j <4; j++)char_array_4[j] = 0;for (j = 0; j <4; j++)char_array_4[j] = base64_chars.find(char_array_4[j]);char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];for (j = 0; (j < i - 1); j++) ret += char_array_3[j];}return ret;
}
解密：
windows
string Des_Decrypt(std::string strEncryptData, char* szKey)
{using namespace CryptoPP;//base64解码strEncryptData = base64_decode(strEncryptData);string strRet;std::vector<unsigned char> vecCleartext;int nRaw_size = strEncryptData.length();int j=nRaw_size/DES::BLOCKSIZE;unsigned char key[DES::DEFAULT_KEYLENGTH];memcpy(key, szKey, DES::BLOCKSIZE);unsigned char szInput[ DES::BLOCKSIZE];unsigned char szOutput[ DES::BLOCKSIZE];const char* szData = strEncryptData.c_str();//解密for (int i = 0; i < j; ++i){memset(szInput, 0, DES::BLOCKSIZE);memset(szOutput, 0, DES::BLOCKSIZE);memcpy(szInput, szData+(i*DES::BLOCKSIZE), DES::BLOCKSIZE);DESDecryption decryption_DES;//回忆一下之前的背景，对称加密算法需要一个密匙。加密和解密都会用到。//因此，设置密匙。decryption_DES.SetKey(key, DES::KEYLENGTH );//进行加密decryption_DES.ProcessBlock(szInput, szOutput);for (int k = 0; k < DES::BLOCKSIZE; k++)vecCleartext.push_back(szOutput[k]);}//填充数量int nPadNum = vecCleartext[nRaw_size-1];strRet.clear();strRet.assign(vecCleartext.begin(), vecCleartext.end()-nPadNum);return strRet;
}linux:
string Des_Decrypt(std::string strEncryptData, char* szKey)
{//base64解码strEncryptData = base64_decode(strEncryptData);string strRet;std::vector<unsigned char> vecCleartext;DES_cblock sKey;memcpy(sKey, szKey, 8);DES_key_schedule sSchedule;//转换成scheduleDES_set_key_unchecked(&sKey, &sSchedule); const_DES_cblock sInput;DES_cblock sOutput;int nRaw_size = strEncryptData.length();int j=nRaw_size/8;const char* szData = strEncryptData.c_str();//解密unsigned char szTmp[8];for (int i = 0; i < j; ++i){memset(sInput, 0, 8);memset(sOutput, 0, 8);memcpy(sInput, szData+(i*8), 8);DES_ecb_encrypt(&sInput, &sOutput, &sSchedule, DES_DECRYPT);for (int k = 0; k < 8; k++)vecCleartext.push_back(sOutput[k]);}//填充数量int nPadNum = vecCleartext[nRaw_size-1];strRet.clear();strRet.assign(vecCleartext.begin(), vecCleartext.end()-nPadNum);return strRet;
}
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