/* C implementation of RC2 encryption algorithm, as described in RFC2268 */ /* By Matthew Palmer */ /* $Id: krc2.cpp,v 1.1.1.1 2003/07/22 19:23:17 zcarsten Exp $ */ #include "krc2.h" unsigned char _rc2_pitable[] = { 0xd9, 0x78, 0xf9, 0xc4, 0x19, 0xdd, 0xb5, 0xed, 0x28, 0xe9, 0xfd, 0x79, 0x4a, 0xa0, 0xd8, 0x9d, 0xc6, 0x7e, 0x37, 0x83, 0x2b, 0x76, 0x53, 0x8e, 0x62, 0x4c, 0x64, 0x88, 0x44, 0x8b, 0xfb, 0xa2, 0x17, 0x9a, 0x59, 0xf5, 0x87, 0xb3, 0x4f, 0x13, 0x61, 0x45, 0x6d, 0x8d, 0x09, 0x81, 0x7d, 0x32, 0xbd, 0x8f, 0x40, 0xeb, 0x86, 0xb7, 0x7b, 0x0b, 0xf0, 0x95, 0x21, 0x22, 0x5c, 0x6b, 0x4e, 0x82, 0x54, 0xd6, 0x65, 0x93, 0xce, 0x60, 0xb2, 0x1c, 0x73, 0x56, 0xc0, 0x14, 0xa7, 0x8c, 0xf1, 0xdc, 0x12, 0x75, 0xca, 0x1f, 0x3b, 0xbe, 0xe4, 0xd1, 0x42, 0x3d, 0xd4, 0x30, 0xa3, 0x3c, 0xb6, 0x26, 0x6f, 0xbf, 0x0e, 0xda, 0x46, 0x69, 0x07, 0x57, 0x27, 0xf2, 0x1d, 0x9b, 0xbc, 0x94, 0x43, 0x03, 0xf8, 0x11, 0xc7, 0xf6, 0x90, 0xef, 0x3e, 0xe7, 0x06, 0xc3, 0xd5, 0x2f, 0xc8, 0x66, 0x1e, 0xd7, 0x08, 0xe8, 0xea, 0xde, 0x80, 0x52, 0xee, 0xf7, 0x84, 0xaa, 0x72, 0xac, 0x35, 0x4d, 0x6a, 0x2a, 0x96, 0x1a, 0xd2, 0x71, 0x5a, 0x15, 0x49, 0x74, 0x4b, 0x9f, 0xd0, 0x5e, 0x04, 0x18, 0xa4, 0xec, 0xc2, 0xe0, 0x41, 0x6e, 0x0f, 0x51, 0xcb, 0xcc, 0x24, 0x91, 0xaf, 0x50, 0xa1, 0xf4, 0x70, 0x39, 0x99, 0x7c, 0x3a, 0x85, 0x23, 0xb8, 0xb4, 0x7a, 0xfc, 0x02, 0x36, 0x5b, 0x25, 0x55, 0x97, 0x31, 0x2d, 0x5d, 0xfa, 0x98, 0xe3, 0x8a, 0x92, 0xae, 0x05, 0xdf, 0x29, 0x10, 0x67, 0x6c, 0xba, 0xc9, 0xd3, 0x00, 0xe6, 0xcf, 0xe1, 0x9e, 0xa8, 0x2c, 0x63, 0x16, 0x01, 0x3f, 0x58, 0xe2, 0x89, 0xa9, 0x0d, 0x38, 0x34, 0x1b, 0xab, 0x33, 0xff, 0xb0, 0xbb, 0x48, 0x0c, 0x5f, 0xb9, 0xb1, 0xcd, 0x2e, 0xc5, 0xf3, 0xdb, 0x47, 0xe5, 0xa5, 0x9c, 0x77, 0x0a, 0xa6, 0x20, 0x68, 0xfe, 0x7f, 0xc1, 0xad }; unsigned char _rc2_expkey[128]; /* Expanded Key */ int _rc2_counter; /* global integer variable used in mixing */ int _rc2_s[] = {1, 2, 3, 5}; Krc2::Krc2() { } Krc2::~Krc2() { } void Krc2::rc2_expandkey(char key[], int length, int ekl) { int ekl8, keymask, i; /* Put supplied key into first length - 1 bytes of the key buffer */ for (i = 0; i < length; i++) { _rc2_expkey[i] = key[i]; } ekl8 = (ekl + 7) / 8; i = _rc2_pow(2, (8 + ekl - 8 * ekl8)); keymask = 255 % i; /* First expansion step */ for (i = length; i < 128; i++) { _rc2_expkey[i] = _rc2_pitable[(_rc2_expkey[i - 1] + _rc2_expkey[i - length]) % 256]; } /* Expansion intermediate step */ _rc2_expkey[128 - ekl8] = _rc2_pitable[_rc2_expkey[128 - ekl8] & keymask]; /* Third Expansion step */ for (i = 127 - ekl8; i >= 0; i--) { _rc2_expkey[i] = _rc2_pitable[_rc2_expkey[i + 1] ^ _rc2_expkey[i + ekl8]]; } } void Krc2::rc2_encrypt(unsigned short input[4]) { int i; _rc2_counter = 0; for (i = 0; i < 5; i++) { _rc2_mix(input); } _rc2_mash(input); for (i = 0; i < 6; i++) { _rc2_mix(input); } _rc2_mash(input); for (i = 0; i < 5; i++) { _rc2_mix(input); } } void Krc2::_rc2_mix(unsigned short input[]) { unsigned short K, i; for (i = 0; i < 4; i++) { K = _rc2_expkey[_rc2_counter * 2] + 256 * _rc2_expkey[_rc2_counter * 2 + 1]; input[i] = input[i] + K + (input[(i + 3) % 4] & input[(i + 2) % 4]) + ((~input[(i + 3) % 4]) & input[(i + 1) % 4]); _rc2_counter++; input[i] = _rc2_rol(input[i], _rc2_s[i]); } } void Krc2::_rc2_mash(unsigned short input[]) { unsigned short K, i, x; for (i = 0; i < 4; i++) { x = input[(i + 3) % 4] & 63; K = _rc2_expkey[2 * x] + 256 * _rc2_expkey[2 * x + 1]; input[i] = input[i] + K; } } void Krc2::rc2_decrypt(unsigned short input[4]) { int i; _rc2_counter = 63; for (i = 0; i < 5; i++) { _rc2_rmix(input); } _rc2_rmash(input); for (i = 0; i < 6; i++) { _rc2_rmix(input); } _rc2_rmash(input); for (i = 0; i < 5; i++) { _rc2_rmix(input); } } void Krc2::_rc2_rmix(unsigned short input[]) { unsigned short K; int i; for (i = 3; i >= 0; i--) { input[i] = _rc2_ror(input[i], _rc2_s[i]); K = _rc2_expkey[_rc2_counter * 2] + 256 * _rc2_expkey[_rc2_counter * 2 + 1]; input[i] = input[i] - K - (input[(i + 3) % 4] & input[(i + 2) % 4]) - ((~input[(i + 3) % 4]) & input[(i + 1) % 4]); _rc2_counter--; } } void Krc2::_rc2_rmash(unsigned short input[]) { unsigned short K, x; int i; for (i = 3; i >= 0; i--) { x = input[(i + 3) % 4] & 63; K = _rc2_expkey[2 * x] + 256 * _rc2_expkey[2 * x + 1]; input[i] = input[i] - K; } } int Krc2::_rc2_pow(int base, int exponent) { int i, result; if (exponent == 0) { return 1; } result = 1; for (i = 0; i < exponent; i++) { result = result * base; } return result; } unsigned short Krc2::_rc2_rol(unsigned short input, int places) { unsigned short temp, i; for (i = 0; i < places; i++) { temp = input & 0x8000; input = input << 1; if (temp) { input++; } } return input; } unsigned short Krc2::_rc2_ror(unsigned short input, int places) { unsigned short temp, i; for (i = 0; i < places; i++) { temp = input & 0x1; input = input >> 1; if (temp) { input = input + 0x8000; } } return input; }