DES算法设计
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代码实现
注:理解整个过程,实现简单
#include <iostream>#include <bitset>#include <cstdlib>using namespace std;bitset<48> subkeys[16];// initial IP permutation table// notice: values in IP are from 1 to 64int IP[] = { 58, 50, 42, 34, 26, 18, 10, 2, 60, 52, 44, 36, 28, 20, 12, 4, 62, 54, 46, 38, 30, 22, 14, 6, 64, 56, 48, 40, 32, 24, 16, 8, 57, 49, 41, 33, 25, 17, 9, 1, 59, 51, 43, 35, 27, 19, 11, 3, 61, 53, 45, 37, 29, 21, 13, 5, 63, 55, 47, 39, 31, 23, 15, 7};int IPInverse[] = { 40, 8, 48, 16, 56, 24, 64, 32, 39, 7, 47, 15, 55, 23, 63, 31, 38, 6, 46, 14, 54, 22, 62, 30, 37, 5, 45, 13, 53, 21, 61, 29, 36, 4, 44, 12, 52, 20, 60, 28, 35, 3, 43, 11, 51, 19, 59, 27, 34, 2, 42, 10, 50, 18, 58, 26, 33, 1, 41, 9, 49, 17, 57, 25};int P1[] = { 57, 49, 41, 33, 25, 17, 9, 1, 58, 50, 42, 34, 26, 18, 10, 2, 59, 51, 43, 35, 27, 19, 11, 3, 60, 52, 44, 36, 63, 55, 47, 39, 31, 23, 15, 7, 62, 54, 46, 38, 30, 22, 14, 6, 61, 53, 45, 37, 29, 21, 13, 5, 28, 20, 12, 4};// 56 bits to 48 bitsint P2[] = { 14, 17, 11, 24, 1, 5, 3, 28, 15, 6, 21, 10, 23, 19, 12, 4, 26, 8, 16, 7, 27, 20, 13, 2, 41, 52, 31, 37, 47, 55, 30, 40, 51, 45, 33, 48, 44, 49, 39, 56, 34, 53, 46, 42, 50, 36, 29, 32};// 32 bits to 48 bitsint expand[] = { 32, 1, 2, 3, 4, 5, 4, 5, 6, 7, 8, 9, 8, 9, 10, 11, 12, 13, 12, 13, 14, 15, 16, 17, 16, 17, 18, 19, 20, 21, 20, 21, 22, 23, 24, 25, 24, 25, 26, 27, 28, 29, 28, 29, 30, 31, 32, 1};// feistel final permutationint fp[] = { 16, 7, 20, 21, 29, 12, 28, 17, 1, 15, 23, 26, 5, 18, 31, 10, 2, 8, 24, 14, 32, 27, 3, 9, 19, 13, 30, 6, 22, 11, 4, 25};// 48 bits to 32 bitsint boxes[8][4][16] = { { { 14,4,13,1,2,15,11,8,3,10,6,12,5,9,0,7 }, { 0,15,7,4,14,2,13,1,10,6,12,11,9,5,3,8 }, { 4,1,14,8,13,6,2,11,15,12,9,7,3,10,5,0 }, { 15,12,8,2,4,9,1,7,5,11,3,14,10,0,6,13 } }, { { 15,1,8,14,6,11,3,4,9,7,2,13,12,0,5,10 }, { 3,13,4,7,15,2,8,14,12,0,1,10,6,9,11,5 }, { 0,14,7,11,10,4,13,1,5,8,12,6,9,3,2,15 }, { 13,8,10,1,3,15,4,2,11,6,7,12,0,5,14,9 } }, { { 10,0,9,14,6,3,15,5,1,13,12,7,11,4,2,8 }, { 13,7,0,9,3,4,6,10,2,8,5,14,12,11,15,1 }, { 13,6,4,9,8,15,3,0,11,1,2,12,5,10,14,7 }, { 1,10,13,0,6,9,8,7,4,15,14,3,11,5,2,12 } }, { { 7,13,14,3,0,6,9,10,1,2,8,5,11,12,4,15 }, { 13,8,11,5,6,15,0,3,4,7,2,12,1,10,14,9 }, { 10,6,9,0,12,11,7,13,15,1,3,14,5,2,8,4 }, { 3,15,0,6,10,1,13,8,9,4,5,11,12,7,2,14 } }, { { 2,12,4,1,7,10,11,6,8,5,3,15,13,0,14,9 }, { 14,11,2,12,4,7,13,1,5,0,15,10,3,9,8,6 }, { 4,2,1,11,10,13,7,8,15,9,12,5,6,3,0,14 }, { 11,8,12,7,1,14,2,13,6,15,0,9,10,4,5,3 } }, { { 12,1,10,15,9,2,6,8,0,13,3,4,14,7,5,11 }, { 10,15,4,2,7,12,9,5,6,1,13,14,0,11,3,8 }, { 9,14,15,5,2,8,12,3,7,0,4,10,1,13,11,6 }, { 4,3,2,12,9,5,15,10,11,14,1,7,6,0,8,13 } }, { { 4,11,2,14,15,0,8,13,3,12,9,7,5,10,6,1 }, { 13,0,11,7,4,9,1,10,14,3,5,12,2,15,8,6 }, { 1,4,11,13,12,3,7,14,10,15,6,8,0,5,9,2 }, { 6,11,13,8,1,4,10,7,9,5,0,15,14,2,3,12 } }, { { 13,2,8,4,6,15,11,1,10,9,3,14,5,0,12,7 }, { 1,15,13,8,10,3,7,4,12,5,6,11,0,14,9,2 }, { 7,11,4,1,9,12,14,2,0,6,10,13,15,3,5,8 }, { 2,1,14,7,4,10,8,13,15,12,9,0,3,5,6,11 } }};int shiftBits[] = { 1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1 };// functionsbitset<64> charToBit(const char plain[8]);bitset<64> initialPermutation(bitset<64> plainBits);void getSubKeys(bitset<64> key);void getDecryptionSubKeys();bitset<64> transform16(bitset<64> text);bitset<32> feistel(bitset<32> lastRight, bitset<48> oneSubKey);bitset<32> sBoxCompress(bitset<48> xorResult);bitset<4> intToBit(int value);bitset<56> PC1Permutation(bitset<64> key);bitset<48> PC2Permutation(bitset<56> tempkey);bitset<28> LSCirculation(bitset<28> halftemp, int shiftBit);bitset<64> finalPermutation(bitset<64> afterTrans);// change the char array to 64 bitsbitset<64> charToBit(const char plain[8]) { bitset<64> bits; for (int i = 0; i < 8; ++i) { for (int j = 0; j < 8; ++j) { // here save the ascii binary bits of "12345678" bits[i * 8 + j] = ((plain[i] >> j) & 1); } } return bits;}// initial permutationbitset<64> initialPermutation(bitset<64> plainBits) { bitset<64> result; for (int i = 0; i < 64; ++i) { result[i] = plainBits[IP[i] - 1]; } return result;}// 16 times transformationbitset<64> transform16(bitset<64> text) { // call feistel function bitset<32> lefts[17], rights[17]; bitset<64> result; bitset<32> feistelRes; // L0 for (int i = 0; i < 32; ++i) { lefts[0][i] = text[i]; } // R0 for (int i = 32; i < 64; ++i) { rights[0][i - 32] = text[i]; } int count = 0; while (count < 16) { count++; // Li = Rгиi-1) lefts[count] = rights[count - 1]; feistelRes = feistel(rights[count - 1], subkeys[count - 1]); for (int i = 0; i < 32; ++i) { rights[count] = lefts[count - 1] ^ feistelRes; } } // result = R16L16 for (int i = 0; i < 32; ++i) result[i] = rights[16][i]; for (int i = 0; i < 32; ++i) result[i + 32] = lefts[16][i]; return result;}// feistel bitset<32> feistel(bitset<32> lastRight, bitset<48> oneSubKey) { // call sBoxCompress // expand and make lastRight to 48 bits bitset<48> expandRight; for (int i = 0; i < 48; ++i) { expandRight[i] = lastRight[expand[i] - 1]; } bitset<48> xorResult = expandRight ^ oneSubKey; bitset<32> fromSBox = sBoxCompress(xorResult); bitset<32> result; // there is a P-permutation in the last for (int i = 0; i < 32; ++i) { result[i] = fromSBox[fp[i] - 1]; } return result;}// change 48 bits to 32 bits by using s-boxsbitset<32> sBoxCompress(bitset<48> xorResult) { bitset<32> result; bitset<6> subGroups[8]; for (int i = 0; i < 48; ++i) { subGroups[i / 6][i % 6] = xorResult[i]; } int indexI, indexJ; int values[8]; for (int i = 0; i < 8; ++i) { indexI = subGroups[i][0] * 2 + subGroups[i][5]; indexJ = subGroups[i][1] * 8 + subGroups[i][2] * 4 + subGroups[i][3] * 2 + subGroups[i][4]; values[i] = boxes[i][indexI][indexJ]; } for (int i = 0; i < 8; ++i) { bitset<4> temp = intToBit(values[i]); for (int k = 0; k < 4; ++k) result[i * 4 + k] = temp[k]; } return result;}// decimal to binary(4 bits)bitset<4> intToBit(int value) { bitset<4> result; for (int i = 0; i < 4; ++i) { result[i] = (value >> 1) & 1; } return result;}// inverse permutation in the lastbitset<64> finalPermutation(bitset<64> afterTrans) { bitset<64> result; for (int i = 0; i < 64; ++i) { result[i] = afterTrans[IPInverse[i] - 1]; } return result;}// get 16 sub keys and save them in subkeysvoid getSubKeys(bitset<64> key) { // PC-1 permutation bitset<56> keyAfterPC1 = PC1Permutation(key); bitset<28> tempLeft, tempRight; bitset<28> LSlefts[17], LSrights[17]; bitset<56> keyAfterShift; for (int i = 0; i < 28; ++i) tempLeft[i] = keyAfterPC1[i]; for (int i = 0; i < 28; ++i) tempRight[i] = keyAfterPC1[i + 28]; LSlefts[0] = tempLeft; LSrights[0] = tempRight; int count = 0; while (count < 16) { count++; LSlefts[count] = LSCirculation(LSlefts[count - 1], shiftBits[count - 1]); LSrights[count] = LSCirculation(LSrights[count - 1], shiftBits[count - 1]); for (int i = 0; i < 28; ++i) keyAfterShift[i] = LSlefts[count][i]; for (int i = 0; i < 28; ++i) keyAfterShift[i + 28] = LSrights[count][i]; // now get the 56 bits temp key subkeys[count - 1] = PC2Permutation(keyAfterShift); }}// PC-1 permutationbitset<56> PC1Permutation(bitset<64> key) { bitset<56> result; for (int i = 0; i < 56; ++i) { result[i] = key[P1[i] - 1]; } return result;}// PC-2 permutationbitset<48> PC2Permutation(bitset<56> tempkey) { bitset<48> result; for (int i = 0; i < 48; ++i) { result[i] = tempkey[P2[i] - 1]; } return result;}// left shiftbitset<28> LSCirculation(bitset<28> halftemp, int shiftBit) { bitset<28> result; // left shift 1 or 2 bits for (int i = 0; i < 28; ++i) { result[i] = halftemp[(i + shiftBit) % 28]; } return result;}// decryption subkeysvoid getDecryptionSubKeys() { // PC-1 permutation bitset<48> temp[16]; for (int i = 0; i < 16; ++i) { temp[i] = subkeys[15 - i]; } for (int i = 0; i < 16; ++i) { subkeys[i] = temp[i]; }}bitset<64> encryption(bitset<64> plainBits, bitset<64> keyBits) { getSubKeys(keyBits); bitset<64> afterInitialPer = initialPermutation(plainBits); bitset<64> result = transform16(afterInitialPer); bitset<64> finalResult = finalPermutation(result); return finalResult;}bitset<64> decryption(bitset<64> cipher, bitset<64> keyBits) { getDecryptionSubKeys(); bitset<64> afterInitialPer = initialPermutation(cipher); bitset<64> result = transform16(afterInitialPer); bitset<64> finalResult = finalPermutation(result); return finalResult;}int main() { char plainText[] = "12345678"; char key[] = "89674523"; bitset<64> plainBits = charToBit(plainText); bitset<64> keyBits = charToBit(key); bitset<64> cipher = encryption(plainBits, keyBits); bitset<64> plain = decryption(cipher, keyBits); cout << "initial plain: " << plainBits << endl; cout << "cipher text: " << cipher << endl; cout << "decryption plain text: " << plain << endl; system("pause"); return 0;}
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