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#include <cstring>
#include <cassert>
#include "aes.h"
using namespace std;
namespace AES{
//http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf
void subWord(uint8_t *word);
void keyExpand(uint8_t *keysched,const uint8_t *key,int keylen,int numrounds);
void addRoundKey(uint8_t *state,const uint8_t *roundkey);
void subBytes(uint8_t *state){
subWord(state);
subWord(state+4);
subWord(state+8);
subWord(state+12);
}
void shiftRows(uint8_t *state);
void mixColumns(uint8_t *state);
void encryptBlock(uint8_t *state,const uint8_t *key,const uint8_t *data,int keylen,int numrounds){
uint8_t keysched[16*(numrounds+1)];
keyExpand(keysched,key,keylen,numrounds);
memcpy(state,data,16);
addRoundKey(state,keysched);
for(int round=0;round<numrounds-1;round++){
subBytes(state);
shiftRows(state);
mixColumns(state);
addRoundKey(state,keysched+16*(round+1));
}
subBytes(state);
shiftRows(state);
addRoundKey(state,keysched+16*numrounds);
}
string encrypt(const string &key,const string &data,int numrounds){
int sz=data.size();
if(sz==0)return {};
int blocks=sz/16;
int padding=sz%16==0?16:16-sz%16;
string res;
assert((sz+padding)%16==0);
res.reserve(sz+padding);
uint8_t buf[16];
for(int i=0;i<blocks;i++){
encryptBlock(buf,(const uint8_t*)key.data(),(const uint8_t*)data.data()+16*i,key.size(),numrounds);
res.insert(res.size(),(char*)buf,16);
}
uint8_t inbuf[16];
if(padding<16)memcpy(inbuf,data.data()+16*blocks,16-padding);
memset(inbuf+16-padding,padding,padding);
encryptBlock(buf,(const uint8_t*)key.data(),inbuf,key.size(),numrounds);
res.insert(res.size(),(char*)buf,16);
return res;
}
string decrypt(const string &key,const string &data,int numrounds);
string encrypt(const string &key,const string &data,Algorithm algo){
assert(key.size()==4+2*algo);
return encrypt(key,data,10+2*algo);
}
string decrypt(const string &key,const string &data,Algorithm algo)/*{
assert(key.size()==4+2*algo);
return decrypt(key,data,10+2*algo);
}*/;
}
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