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133 lines
2.6 KiB
133 lines
2.6 KiB
#include "rsa.h"
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Rsa::Rsa()
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{
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m_keySet = false;
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mpz_init2(m_p, 1024);
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mpz_init2(m_q, 1024);
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mpz_init2(m_d, 1024);
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mpz_init2(m_u, 1024);
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mpz_init2(m_dp, 1024);
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mpz_init2(m_dq, 1024);
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mpz_init2(m_mod, 1024);
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}
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Rsa::~Rsa()
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{
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mpz_clear(m_p);
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mpz_clear(m_q);
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mpz_clear(m_d);
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mpz_clear(m_u);
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mpz_clear(m_dp);
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mpz_clear(m_dq);
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mpz_clear(m_mod);
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}
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bool Rsa::setKey(const std::string& file)
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{
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//loads p,q and d from a file
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FILE* f = fopen(file.c_str(), "r");
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if(!f){
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return false;
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}
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char p[512];
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char q[512];
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char d[512];
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delete fgets(p, 512, f);
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delete fgets(q, 512, f);
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delete fgets(d, 512, f);
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setKey(p, q, d);
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return true;
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}
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void Rsa::setKey(const char* p, const char* q, const char* d)
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{
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mpz_set_str(m_p, p, 10);
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mpz_set_str(m_q, q, 10);
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mpz_set_str(m_d, d, 10);
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mpz_t pm1,qm1;
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mpz_init2(pm1,520);
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mpz_init2(qm1,520);
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mpz_sub_ui(pm1, m_p, 1);
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mpz_sub_ui(qm1, m_q, 1);
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mpz_invert(m_u, m_p, m_q);
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mpz_mod(m_dp, m_d, pm1);
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mpz_mod(m_dq, m_d, qm1);
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mpz_mul(m_mod, m_p, m_q);
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mpz_clear(pm1);
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mpz_clear(qm1);
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}
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bool Rsa::encrypt(char* msg, int32_t size, const char* key)
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{
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mpz_t plain, c;
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mpz_init2(plain, 1024);
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mpz_init2(c, 1024);
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mpz_t e;
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mpz_init(e);
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mpz_set_ui(e,65537);
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mpz_t mod;
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mpz_init2(mod, 1024);
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mpz_set_str(mod, key, 10);
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mpz_import(plain, 128, 1, 1, 0, 0, msg);
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mpz_powm(c, plain, e, mod);
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size_t count = (mpz_sizeinbase(c, 2) + 7)/8;
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memset(msg, 0, 128 - count);
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mpz_export(&msg[128 - count], NULL, 1, 1, 0, 0, c);
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mpz_clear(c);
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mpz_clear(plain);
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mpz_clear(e);
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mpz_clear(mod);
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return true;
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}
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bool Rsa::decrypt(char* msg, int32_t size)
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{
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mpz_t c,v1,v2,u2,tmp;
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mpz_init2(c, 1024);
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mpz_init2(v1, 1024);
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mpz_init2(v2, 1024);
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mpz_init2(u2, 1024);
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mpz_init2(tmp, 1024);
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mpz_import(c, 128, 1, 1, 0, 0, msg);
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mpz_mod(tmp, c, m_p);
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mpz_powm(v1, tmp, m_dp, m_p);
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mpz_mod(tmp, c, m_q);
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mpz_powm(v2, tmp, m_dq, m_q);
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mpz_sub(u2, v2, v1);
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mpz_mul(tmp, u2, m_u);
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mpz_mod(u2, tmp, m_q);
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if(mpz_cmp_si(u2, 0) < 0){
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mpz_add(tmp, u2, m_q);
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mpz_set(u2, tmp);
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}
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mpz_mul(tmp, u2, m_p);
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mpz_set_ui(c, 0);
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mpz_add(c, v1, tmp);
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size_t count = (mpz_sizeinbase(c, 2) + 7)/8;
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memset(msg, 0, 128 - count);
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mpz_export(&msg[128 - count], NULL, 1, 1, 0, 0, c);
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mpz_clear(c);
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mpz_clear(v1);
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mpz_clear(v2);
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mpz_clear(u2);
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mpz_clear(tmp);
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return true;
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}
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