aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
Diffstat
-rw-r--r--aes.cpp265
-rw-r--r--aes.h10
-rw-r--r--gf28.cpp119
-rw-r--r--gf28.h39
-rw-r--r--main.cpp9
-rw-r--r--rng.cpp4
-rw-r--r--rng.h2
-rw-r--r--rsa.cpp2
8 files changed, 413 insertions, 37 deletions
diff --git a/aes.cpp b/aes.cpp
index 13659e6..e226a3c 100644
--- a/aes.cpp
+++ b/aes.cpp
@@ -1,79 +1,288 @@
+#include <iostream>
+#include <iomanip>
+#include <stdexcept>
#include <cstring>
#include <cassert>
#include "aes.h"
+#include "gf28.h"
+#include "rng.h"
using namespace std;
namespace AES{
- //http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf
+ //http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf (AES)
+ //https://tools.ietf.org/html/rfc3602 (CBC)
- void subWord(uint8_t *word);
+ //State is represented in bytes, as is the key schedule (which is represented in words in the AES spec).
+ //State is in column-major order.
- void keyExpand(uint8_t *keysched,const uint8_t *key,int keylen,int numrounds);
+ uint32_t roundconstant[10]={};
+ uint8_t sbox[256]={};
+ uint8_t invsbox[256]={};
- void addRoundKey(uint8_t *state,const uint8_t *roundkey);
+ void printstate(const uint8_t *state){
+ for(int i=0;i<16;i++){
+ cout<<setw(2)<<setfill('0')<<hex<<(int)state[i]<<dec;
+ }
+ cout<<endl;
+ }
+
+ void initTables(){
+ //generated tables have been checked with AES spec
+ int term=0x01;
+ for(int i=0;i<10;i++){
+ roundconstant[i]=term<<24;
+ term=GF28::multiply(term,0x02);
+ }
+
+ for(int i=0;i<256;i++){
+ uint8_t inv=(uint8_t)GF28(i).inverse();
+ uint8_t res=0;
+ for(int j=0;j<8;j++){
+ uint8_t bit=((inv>>j)&1)^
+ ((inv>>((j+4)%8))&1)^
+ ((inv>>((j+5)%8))&1)^
+ ((inv>>((j+6)%8))&1)^
+ ((inv>>((j+7)%8))&1);
+ res|=bit<<j;
+ }
+ res^=0x63;
+ sbox[i]=res;
+ invsbox[res]=i;
+ }
+ }
+
+ uint32_t subWord(uint32_t word){
+ return (sbox[word>>24]<<24)|(sbox[(word>>16)&0xff]<<16)|(sbox[(word>>8)&0xff]<<8)|sbox[word&0xff];
+ }
+
+ uint32_t rotWord(uint32_t word){
+ return (word<<8)|(word>>24);
+ }
+
+ void keyExpand(uint8_t *keysched,const uint8_t *key,int keylen,int numrounds){
+ memcpy(keysched,key,4*keylen);
+ for(int i=keylen;i<4*(numrounds+1);i++){
+ uint32_t temp=(keysched[4*i-4]<<24)|(keysched[4*i-3]<<16)|(keysched[4*i-2]<<8)|keysched[4*i-1];
+ if(i%keylen==0){
+ temp=subWord(rotWord(temp))^roundconstant[i/keylen-1];
+ } else if(keylen>6&&i%keylen==4){
+ temp=subWord(temp);
+ }
+ keysched[4*i+0]=keysched[4*(i-keylen)+0]^(temp>>24);
+ keysched[4*i+1]=keysched[4*(i-keylen)+1]^((temp>>16)&0xff);
+ keysched[4*i+2]=keysched[4*(i-keylen)+2]^((temp>>8)&0xff);
+ keysched[4*i+3]=keysched[4*(i-keylen)+3]^(temp&0xff);
+ }
+ }
+
+ void addRoundKey(uint8_t *state,const uint8_t *roundkey){
+ for(int i=0;i<16;i++)state[i]^=roundkey[i];
+ }
void subBytes(uint8_t *state){
- subWord(state);
- subWord(state+4);
- subWord(state+8);
- subWord(state+12);
+ for(int i=0;i<16;i++)state[i]=sbox[state[i]];
}
- void shiftRows(uint8_t *state);
+ void shiftRows(uint8_t *state){
+ uint8_t t=state[1]; state[1]=state[5]; state[5]=state[9]; state[9]=state[13]; state[13]=t;
+ swap(state[2],state[10]); swap(state[6],state[14]);
+ t=state[3]; state[3]=state[15]; state[15]=state[11]; state[11]=state[7]; state[7]=t;
+ }
- void mixColumns(uint8_t *state);
+ void mixColumns(uint8_t *state){
+ for(int i=0;i<4;i++){
+ uint8_t a=GF28::multiply(0x02,state[4*i+0]) ^ GF28::multiply(0x03,state[4*i+1]) ^ state[4*i+2] ^ state[4*i+3];
+ uint8_t b=state[4*i+0] ^ GF28::multiply(0x02,state[4*i+1]) ^ GF28::multiply(0x03,state[4*i+2]) ^ state[4*i+3];
+ uint8_t c=state[4*i+0] ^ state[4*i+1] ^ GF28::multiply(0x02,state[4*i+2]) ^ GF28::multiply(0x03,state[4*i+3]);
+ uint8_t d=GF28::multiply(0x03,state[4*i+0]) ^ state[4*i+1] ^ state[4*i+2] ^ GF28::multiply(0x02,state[4*i+3]);
+ state[4*i+0]=a;
+ state[4*i+1]=b;
+ state[4*i+2]=c;
+ state[4*i+3]=d;
+ }
+ }
+ void invShiftRows(uint8_t *state){
+ uint8_t t=state[1]; state[1]=state[13]; state[13]=state[9]; state[9]=state[5]; state[5]=t;
+ swap(state[2],state[10]); swap(state[6],state[14]);
+ t=state[3]; state[3]=state[7]; state[7]=state[11]; state[11]=state[15]; state[15]=t;
+ }
- 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);
+ void invSubBytes(uint8_t *state){
+ for(int i=0;i<16;i++)state[i]=invsbox[state[i]];
+ }
+
+ void invMixColumns(uint8_t *state){
+ for(int i=0;i<4;i++){
+ uint8_t a=GF28::multiply(0x0e,state[4*i+0])^
+ GF28::multiply(0x0b,state[4*i+1])^
+ GF28::multiply(0x0d,state[4*i+2])^
+ GF28::multiply(0x09,state[4*i+3]);
+ uint8_t b=GF28::multiply(0x09,state[4*i+0])^
+ GF28::multiply(0x0e,state[4*i+1])^
+ GF28::multiply(0x0b,state[4*i+2])^
+ GF28::multiply(0x0d,state[4*i+3]);
+ uint8_t c=GF28::multiply(0x0d,state[4*i+0])^
+ GF28::multiply(0x09,state[4*i+1])^
+ GF28::multiply(0x0e,state[4*i+2])^
+ GF28::multiply(0x0b,state[4*i+3]);
+ uint8_t d=GF28::multiply(0x0b,state[4*i+0])^
+ GF28::multiply(0x0d,state[4*i+1])^
+ GF28::multiply(0x09,state[4*i+2])^
+ GF28::multiply(0x0e,state[4*i+3]);
+ state[4*i+0]=a;
+ state[4*i+1]=b;
+ state[4*i+2]=c;
+ state[4*i+3]=d;
+ }
+ }
+
+
+ void encryptBlock(uint8_t *state,const uint8_t *keysched,const uint8_t *data,int numrounds){
memcpy(state,data,16);
addRoundKey(state,keysched);
for(int round=0;round<numrounds-1;round++){
+ //cout<<"round["<<setw(2)<<setfill(' ')<<round+1<<"].start "; printstate(state);
subBytes(state);
shiftRows(state);
mixColumns(state);
addRoundKey(state,keysched+16*(round+1));
}
+ //cout<<"round["<<setw(2)<<setfill(' ')<<numrounds<<"].start "; printstate(state);
subBytes(state);
shiftRows(state);
addRoundKey(state,keysched+16*numrounds);
}
- string encrypt(const string &key,const string &data,int numrounds){
+ void decryptBlock(uint8_t *state,const uint8_t *keysched,const uint8_t *data,int numrounds){
+ memcpy(state,data,16);
+
+ addRoundKey(state,keysched+16*numrounds);
+ for(int round=numrounds-2;round>=0;round--){
+ //cout<<"round["<<setw(2)<<setfill(' ')<<round+1<<"].start "; printstate(state);
+ invShiftRows(state);
+ invSubBytes(state);
+ addRoundKey(state,keysched+16*(round+1));
+ invMixColumns(state);
+ }
+ //cout<<"round["<<setw(2)<<setfill(' ')<<numrounds<<"].start "; printstate(state);
+ invShiftRows(state);
+ invSubBytes(state);
+ addRoundKey(state,keysched);
+ }
+
+ string encryptCBC(const string &key,const string &data,int numrounds){
+ if(roundconstant[0]==0)initTables();
+
int sz=data.size();
- if(sz==0)return {};
+ if(sz==0)return {}; //if nothing to encrypt, don't even give an IV
int blocks=sz/16;
- int padding=sz%16==0?16:16-sz%16;
+ int padding=16-sz%16;
string res;
assert((sz+padding)%16==0);
- res.reserve(sz+padding);
- uint8_t buf[16];
+ res.reserve(16+sz+padding);
+
+ res.resize(16);
+ CryptoRng crng;
+ *(uint32_t*)&res[0]=crng.get(); //IV
+ *(uint32_t*)&res[4]=crng.get(); //endianness doesn't matter, since the data is random anyway
+ *(uint32_t*)&res[8]=crng.get();
+ *(uint32_t*)&res[12]=crng.get();
+
+ uint8_t keysched[16*(numrounds+1)];
+ keyExpand(keysched,(const uint8_t*)key.data(),key.size()/4,numrounds);
+
+ uint8_t buf[16],inbuf[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);
+ memcpy(inbuf,data.data()+16*i,16);
+ for(int j=0;j<16;j++)inbuf[j]^=res[res.size()-16+j]; //the CBC xor step
+ encryptBlock(buf,keysched,inbuf,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);
+ for(int j=0;j<16;j++)inbuf[j]^=res[res.size()-16+j]; //the CBC xor step
+ encryptBlock(buf,keysched,inbuf,numrounds);
res.insert(res.size(),(char*)buf,16);
return res;
}
- string decrypt(const string &key,const string &data,int numrounds);
+ string decryptCBC(const string &key,const string &data,int numrounds){
+ if(roundconstant[0]==0)initTables();
+
+ if(data.size()==0)return {};
+ if(data.size()%16!=0)throw invalid_argument("AES encrypted data not multiple of block size");
+ int blocks=data.size()/16-1; //the IV is not counted as a block
+ string res(16*blocks,'\0');
+
+ uint8_t keysched[16*(numrounds+1)];
+ keyExpand(keysched,(const uint8_t*)key.data(),key.size()/4,numrounds);
+
+ for(int i=blocks-1;i>=0;i--){
+ decryptBlock((uint8_t*)&res[16*i],keysched,(const uint8_t*)data.data()+(16+16*i),numrounds);
+ for(int j=0;j<16;j++)res[16*i+j]^=data[16*i+j]; //CBC: xor with the previous (remember the IV taking up space)
+ }
+ int padsize=res.back();
+ if(padsize>16||padsize<0)throw invalid_argument("Malformed AES padding");
+ res.resize(res.size()-padsize);
+ return res;
+ }
string encrypt(const string &key,const string &data,Algorithm algo){
- assert(key.size()==4+2*algo);
- return encrypt(key,data,10+2*algo);
+ int increment;
+ switch(algo){
+ case AES_128_CBC: increment=0; break;
+ case AES_192_CBC: increment=1; break;
+ case AES_256_CBC: increment=2; break;
+ default: assert(false);
+ }
+ assert((int)key.size()==4*(4+2*increment));
+ return encryptCBC(key,data,10+2*increment);
+ }
+
+ string decrypt(const string &key,const string &data,Algorithm algo){
+ int increment;
+ switch(algo){
+ case AES_128_CBC: increment=0; break;
+ case AES_192_CBC: increment=1; break;
+ case AES_256_CBC: increment=2; break;
+ default: assert(false);
+ }
+ assert((int)key.size()==4*(4+2*increment));
+ return decryptCBC(key,data,10+2*increment);
}
- string decrypt(const string &key,const string &data,Algorithm algo)/*{
- assert(key.size()==4+2*algo);
- return decrypt(key,data,10+2*algo);
- }*/;
+ void test(){
+ #if 0
+ // Test encryption
+ initTables();
+ const int numrounds=10;
+ uint8_t keysched[16*(numrounds+1)];
+ uint8_t plaintext[16]={0x32,0x43,0xf6,0xa8,0x88,0x5a,0x30,0x8d,0x31,0x31,0x98,0xa2,0xe0,0x37,0x07,0x34};
+ const int keylen=4;
+ uint8_t key[4*keylen]={0x2b,0x7e,0x15,0x16,0x28,0xae,0xd2,0xa6,0xab,0xf7,0x15,0x88,0x09,0xcf,0x4f,0x3c};
+ keyExpand(keysched,key,keylen,numrounds);
+ uint8_t dest[16];
+ encryptBlock(dest,keysched,plaintext,numrounds);
+ printstate(dest);
+ #endif
+ #if 1
+ // Test decryption
+ initTables();
+ const int numrounds=14;
+ uint8_t keysched[16*(numrounds+1)];
+ uint8_t plaintext[16]={0x8e,0xa2,0xb7,0xca,0x51,0x67,0x45,0xbf,0xea,0xfc,0x49,0x90,0x4b,0x49,0x60,0x89};
+ const int keylen=8;
+ uint8_t key[4*keylen]={0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f,0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f};
+ keyExpand(keysched,key,keylen,numrounds);
+ uint8_t dest[16];
+ decryptBlock(dest,keysched,plaintext,numrounds);
+ printstate(dest);
+ #endif
+ }
}
diff --git a/aes.h b/aes.h
index 012c9ed..b2064f2 100644
--- a/aes.h
+++ b/aes.h
@@ -5,12 +5,16 @@
namespace AES{
enum Algorithm{
- AES_128,
- AES_192,
- AES_256,
+ AES_128_CBC,
+ AES_192_CBC,
+ AES_256_CBC,
};
std::string encrypt(const std::string &key,const std::string &data,Algorithm algo);
+
+ //throws invalid_argument for an invalid ciphertext (length not a multiple of block size, or padding malformed)
std::string decrypt(const std::string &key,const std::string &data,Algorithm algo);
+ void test();
+
}
diff --git a/gf28.cpp b/gf28.cpp
new file mode 100644
index 0000000..e65c20a
--- /dev/null
+++ b/gf28.cpp
@@ -0,0 +1,119 @@
+#include <cassert>
+#include "gf28.h"
+
+using namespace std;
+
+int GF28::reduce(int v,int m){
+ assert(m);
+ while(true){
+ int sh=__builtin_clz(m)-__builtin_clz(v);
+ if(sh<0)break;
+ v^=m<<sh;
+ if(v==0)break;
+ }
+ return v;
+}
+
+uint8_t GF28::multiply(uint8_t x,uint8_t y){
+ if(x==0||y==0)return 0;
+ int res=0;
+ int addend=x;
+ while(y){
+ if(y&1)res^=addend;
+ addend<<=1;
+ if(addend&0x100)addend^=modulus;
+ y>>=1;
+ }
+ return res;
+}
+
+GF28::GF28()
+ :value(0){}
+
+GF28::GF28(int v)
+ :value(reduce(v,modulus)){}
+
+GF28::operator uint8_t() const {
+ return value;
+}
+
+GF28& GF28::operator+=(GF28 o){
+ value^=o.value;
+ return *this;
+}
+
+GF28& GF28::operator-=(GF28 o){
+ value^=o.value;
+ return *this;
+}
+
+GF28& GF28::operator<<=(int n){ //multiplication by x^n
+ assert(n>=0);
+ value<<=n;
+ if(value&0x100)value^=modulus;
+ return *this;
+}
+
+GF28 GF28::operator+(GF28 o) const {
+ return GF28(value^o.value);
+}
+
+GF28 GF28::operator-(GF28 o) const {
+ return GF28(value^o.value);
+}
+
+GF28 GF28::operator*(GF28 o) const {
+ if(value==0||o.value==0)return GF28(0);
+ GF28 res;
+ GF28 addend(*this);
+ while(o.value){
+ if(o.value&1)res+=addend;
+ addend<<=1;
+ o.value>>=1;
+ }
+ return res;
+}
+GF28 GF28::operator<<(int n) const {
+ return GF28(*this)<<=n;
+}
+
+bool GF28::operator==(GF28 o) const {
+ return value==o.value;
+}
+
+GF28 GF28::inverse() const {
+ if(value==0)return *this;
+ int x=1,y=0,x2=0,y2=1,r=modulus,r2=value;
+ while(r2!=0){
+ assert(r!=0);
+ int ex=__builtin_clz(r2)-__builtin_clz(r);
+ if(ex<0){
+ swap(x,x2);
+ swap(y,y2);
+ swap(r,r2);
+ } else {
+ int xn=x^(x2<<ex); x=x2; x2=xn;
+ int yn=y^(y2<<ex); y=y2; y2=yn;
+ int rn=r^(r2<<ex); r=r2; r2=rn;
+ }
+ }
+ assert(r==1);
+ return GF28(y);
+}
+
+ostream& operator<<(ostream &os,GF28 p){
+ if(os.flags()&ios_base::hex){
+ return os<<p.value;
+ }
+ if(p.value==0)return os<<'0';
+ bool first=true;
+ for(int m=1<<16,i=16;m!=0;m>>=1,i--){
+ if(p.value&m){
+ if(!first)os<<'+';
+ first=false;
+ if(i==0)os<<'1';
+ else os<<"x^"<<i;
+ }
+ }
+ return os;
+}
diff --git a/gf28.h b/gf28.h
new file mode 100644
index 0000000..194cd57
--- /dev/null
+++ b/gf28.h
@@ -0,0 +1,39 @@
+#pragma once
+
+#include <iostream>
+#include <cstdint>
+
+//The GF(2^8) field used in AES
+
+class GF28{
+ int value;
+
+ static int reduce(int v,int m);
+
+public:
+ static const int modulus=0x11b;
+
+ static uint8_t multiply(uint8_t x,uint8_t y); //for when the class is overkill
+
+ GF28();
+ explicit GF28(int v);
+
+ explicit operator uint8_t() const;
+
+ GF28& operator+=(GF28 o);
+ GF28& operator-=(GF28 o);
+ GF28& operator<<=(int n); //multiplication by x^n
+
+ GF28 operator+(GF28 o) const;
+ GF28 operator-(GF28 o) const;
+ GF28 operator*(GF28 o) const;
+ GF28 operator<<(int n) const; //multiplication by x^n
+
+ bool operator==(GF28 o) const;
+
+ GF28 inverse() const;
+
+ friend std::ostream& operator<<(std::ostream&,GF28);
+};
+
+std::ostream& operator<<(std::ostream &os,GF28 p);
diff --git a/main.cpp b/main.cpp
index f818c48..2cd31ec 100644
--- a/main.cpp
+++ b/main.cpp
@@ -6,6 +6,7 @@
#include <cctype>
#include <ctime>
#include <cassert>
+#include "aes.h"
#include "base64.h"
#include "bigint.h"
#include "numalgo.h"
@@ -211,12 +212,16 @@ int main(int argc,char **argv){
fwrite(data,1,4,stdout);
}*/
- string s;
+ /*string s;
while(true){
char c=cin.get();
if(!cin)break;
s.push_back(c);
}
cout<<Base64::encode(s)<<endl;
- // cout<<Base64::decode(s)<<flush;
+ // cout<<Base64::decode(s)<<flush;*/
+
+ // AES::test();
+ cout<<Base64::encode(AES::encrypt("123456789abcdefx","goeiemorgen dit is leuke data enzoo",AES::AES_128_CBC))<<endl;
+ cout<<AES::decrypt("123456789abcdefx",Base64::decode("dv2N3n2FHsD7LU2PAZnZm/bLQQSaaZoDDFjy3VrSu2JCHN5KuyBlinlh9C71IGTbT4/WvRKLp6dp1TfrKXIG2w=="),AES::AES_128_CBC)<<endl;
}
diff --git a/rng.cpp b/rng.cpp
index c9e7f03..aba1c02 100644
--- a/rng.cpp
+++ b/rng.cpp
@@ -69,10 +69,10 @@ uint32_t KeyRng::get_uniform(uint32_t upbound){
}
-uint32_t Arc4Rng::get(){
+uint32_t CryptoRng::get(){
return arc4random();
}
-uint32_t Arc4Rng::get_uniform(uint32_t upbound){
+uint32_t CryptoRng::get_uniform(uint32_t upbound){
return arc4random_uniform(upbound);
}
diff --git a/rng.h b/rng.h
index 105e390..e843bbd 100644
--- a/rng.h
+++ b/rng.h
@@ -27,7 +27,7 @@ public:
uint32_t get_uniform(uint32_t upbound);
};
-class Arc4Rng : public Rng{
+class CryptoRng : public Rng{
public:
uint32_t get();
uint32_t get_uniform(uint32_t upbound);
diff --git a/rsa.cpp b/rsa.cpp
index ec79e72..b6ad5ed 100644
--- a/rsa.cpp
+++ b/rsa.cpp
@@ -30,7 +30,7 @@ namespace RSA{
}
PrivateKey genkey(int nbits){
- Arc4Rng rng;
+ CryptoRng rng;
return genkey(nbits,rng);
}
generated by cgit v1.2.3-70-g09d2 (git 2.47.0) at 2024-11-22 11:34:26 +0100