#include <stdio.h>
#include <stdlib.h>
#include <string.h>
const unsigned char sbox_enc[256]={0x63,0x7c,0x77,0x7b,0xf2,0x6b,0x6f,0xc5,0x30,0x01,0x67,0x2b,0xfe,0xd7,0xab,0x76,0xca,0x82,0xc9,0x7d,0xfa,0x59,0x47,0xf0,0xad,0xd4,0xa2,0xaf,0x9c,0xa4,0x72,0xc0,0xb7,0xfd,0x93,0x26,0x36,0x3f,0xf7,0xcc,0x34,0xa5,0xe5,0xf1,0x71,0xd8,0x31,0x15,0x04,0xc7,0x23,0xc3,0x18,0x96,0x05,0x9a,0x07,0x12,0x80,0xe2,0xeb,0x27,0xb2,0x75,0x09,0x83,0x2c,0x1a,0x1b,0x6e,0x5a,0xa0,0x52,0x3b,0xd6,0xb3,0x29,0xe3,0x2f,0x84,0x53,0xd1,0x00,0xed,0x20,0xfc,0xb1,0x5b,0x6a,0xcb,0xbe,0x39,0x4a,0x4c,0x58,0xcf,0xd0,0xef,0xaa,0xfb,0x43,0x4d,0x33,0x85,0x45,0xf9,0x02,0x7f,0x50,0x3c,0x9f,0xa8,0x51,0xa3,0x40,0x8f,0x92,0x9d,0x38,0xf5,0xbc,0xb6,0xda,0x21,0x10,0xff,0xf3,0xd2,0xcd,0x0c,0x13,0xec,0x5f,0x97,0x44,0x17,0xc4,0xa7,0x7e,0x3d,0x64,0x5d,0x19,0x73,0x60,0x81,0x4f,0xdc,0x22,0x2a,0x90,0x88,0x46,0xee,0xb8,0x14,0xde,0x5e,0x0b,0xdb,0xe0,0x32,0x3a,0x0a,0x49,0x06,0x24,0x5c,0xc2,0xd3,0xac,0x62,0x91,0x95,0xe4,0x79,0xe7,0xc8,0x37,0x6d,0x8d,0xd5,0x4e,0xa9,0x6c,0x56,0xf4,0xea,0x65,0x7a,0xae,0x08,0xba,0x78,0x25,0x2e,0x1c,0xa6,0xb4,0xc6,0xe8,0xdd,0x74,0x1f,0x4b,0xbd,0x8b,0x8a,0x70,0x3e,0xb5,0x66,0x48,0x03,0xf6,0x0e,0x61,0x35,0x57,0xb9,0x86,0xc1,0x1d,0x9e,0xe1,0xf8,0x98,0x11,0x69,0xd9,0x8e,0x94,0x9b,0x1e,0x87,0xe9,0xce,0x55,0x28,0xdf,0x8c,0xa1,0x89,0x0d,0xbf,0xe6,0x42,0x68,0x41,0x99,0x2d,0x0f,0xb0,0x54,0xbb,0x16};
const unsigned char sbox_dec[256]={0x52,0x09,0x6a,0xd5,0x30,0x36,0xa5,0x38,0xbf,0x40,0xa3,0x9e,0x81,0xf3,0xd7,0xfb,0x7c,0xe3,0x39,0x82,0x9b,0x2f,0xff,0x87,0x34,0x8e,0x43,0x44,0xc4,0xde,0xe9,0xcb,0x54,0x7b,0x94,0x32,0xa6,0xc2,0x23,0x3d,0xee,0x4c,0x95,0x0b,0x42,0xfa,0xc3,0x4e,0x08,0x2e,0xa1,0x66,0x28,0xd9,0x24,0xb2,0x76,0x5b,0xa2,0x49,0x6d,0x8b,0xd1,0x25,0x72,0xf8,0xf6,0x64,0x86,0x68,0x98,0x16,0xd4,0xa4,0x5c,0xcc,0x5d,0x65,0xb6,0x92,0x6c,0x70,0x48,0x50,0xfd,0xed,0xb9,0xda,0x5e,0x15,0x46,0x57,0xa7,0x8d,0x9d,0x84,0x90,0xd8,0xab,0x00,0x8c,0xbc,0xd3,0x0a,0xf7,0xe4,0x58,0x05,0xb8,0xb3,0x45,0x06,0xd0,0x2c,0x1e,0x8f,0xca,0x3f,0x0f,0x02,0xc1,0xaf,0xbd,0x03,0x01,0x13,0x8a,0x6b,0x3a,0x91,0x11,0x41,0x4f,0x67,0xdc,0xea,0x97,0xf2,0xcf,0xce,0xf0,0xb4,0xe6,0x73,0x96,0xac,0x74,0x22,0xe7,0xad,0x35,0x85,0xe2,0xf9,0x37,0xe8,0x1c,0x75,0xdf,0x6e,0x47,0xf1,0x1a,0x71,0x1d,0x29,0xc5,0x89,0x6f,0xb7,0x62,0x0e,0xaa,0x18,0xbe,0x1b,0xfc,0x56,0x3e,0x4b,0xc6,0xd2,0x79,0x20,0x9a,0xdb,0xc0,0xfe,0x78,0xcd,0x5a,0xf4,0x1f,0xdd,0xa8,0x33,0x88,0x07,0xc7,0x31,0xb1,0x12,0x10,0x59,0x27,0x80,0xec,0x5f,0x60,0x51,0x7f,0xa9,0x19,0xb5,0x4a,0x0d,0x2d,0xe5,0x7a,0x9f,0x93,0xc9,0x9c,0xef,0xa0,0xe0,0x3b,0x4d,0xae,0x2a,0xf5,0xb0,0xc8,0xeb,0xbb,0x3c,0x83,0x53,0x99,0x61,0x17,0x2b,0x04,0x7e,0xba,0x77,0xd6,0x26,0xe1,0x69,0x14,0x63,0x55,0x21,0x0c,0x7d};
unsigned char xtime(unsigned char a,unsigned char b)
{
int i;
unsigned int res1=0;
unsigned int res2=a;
for (i=0;i<8;i++)
{
if (b&1) res1^=res2;
b>>=1;
res2<<=1;
if (res2&0x100) res2^=0x11b;
}
return (res1&0xff);
}
void subBytes(unsigned char* ptr,const unsigned char* subst)
{
int i;
for (i=0;i<16;i++) ptr[i]=subst[ptr[i]];
}
void shiftRows(unsigned char* ptr)
{
unsigned char c0,c1,c2,c3;
c0=ptr[ 1];c1=ptr[ 5];c2=ptr[ 9];c3=ptr[13];
ptr[ 1]=c1;ptr[ 5]=c2;ptr[ 9]=c3;ptr[13]=c0;
c0=ptr[ 2];c1=ptr[ 6];c2=ptr[10];c3=ptr[14];
ptr[ 2]=c2;ptr[ 6]=c3;ptr[10]=c0;ptr[14]=c1;
c0=ptr[ 3];c1=ptr[ 7];c2=ptr[11];c3=ptr[15];
ptr[ 3]=c3;ptr[ 7]=c0;ptr[11]=c1;ptr[15]=c2;
}
void mixColumns(unsigned char* ptr)
{
unsigned char c0,c1,c2,c3;
int i;
for (i=0;i<4;i++)
{
c0=ptr[0+i*4];c1=ptr[1+i*4];c2=ptr[2+i*4];c3=ptr[3+i*4];
ptr[0+i*4]=xtime(c0,0x02)^xtime(c1,0x03)^c2^c3;
ptr[1+i*4]=c0^xtime(c1,0x02)^xtime(c2,0x03)^c3;
ptr[2+i*4]=c0^c1^xtime(c2,0x02)^xtime(c3,0x03);
ptr[3+i*4]=xtime(c0,0x03)^c1^c2^xtime(c3,0x02);
}
}
void addRoundKey(unsigned char* ptr,unsigned char* key)
{
int i;
for (i=0;i<16;i++) ptr[i]^=key[i];
}
void expandKey(unsigned char* key,int round)
{
unsigned char temp[4];
unsigned char rcon=0x01;
int i;
for (i=0;i<round;i++) rcon=xtime(rcon,0x02);
temp[3]=sbox_enc[(key[12])];
temp[0]=sbox_enc[(key[13])]^rcon;
temp[1]=sbox_enc[(key[14])];
temp[2]=sbox_enc[(key[15])];
for (i=0;i<4;i++)
{
key[i+ 0]^=temp[i];
key[i+ 4]^=key[i+0];
key[i+ 8]^=key[i+4];
key[i+12]^=key[i+8];
}
}
void aes128encrypt(unsigned char* block,unsigned char* key,int rounds)
{
int i;
addRoundKey(block,key); // first round
for (i=0;i<rounds-2;i++)
{
expandKey(key,i);
subBytes(block,sbox_enc);
shiftRows(block);
mixColumns(block);
addRoundKey(block,key);
}
expandKey(key,rounds-2); // final round
subBytes(block,sbox_enc);
shiftRows(block);
addRoundKey(block,key);
}
void mixColumnsInv(unsigned char* ptr)
{
unsigned char c0,c1,c2,c3;
int i;
for (i=0;i<4;i++)
{
c0=ptr[0+i*4];c1=ptr[1+i*4];c2=ptr[2+i*4];c3=ptr[3+i*4];
ptr[0+i*4]=xtime(c0,0x0e)^xtime(c1,0x0b)^xtime(c2,0x0d)^xtime(c3,0x09);
ptr[1+i*4]=xtime(c0,0x09)^xtime(c1,0x0e)^xtime(c2,0x0b)^xtime(c3,0x0d);
ptr[2+i*4]=xtime(c0,0x0d)^xtime(c1,0x09)^xtime(c2,0x0e)^xtime(c3,0x0b);
ptr[3+i*4]=xtime(c0,0x0b)^xtime(c1,0x0d)^xtime(c2,0x09)^xtime(c3,0x0e);
}
}
void shiftRowsInv(unsigned char* ptr)
{
unsigned char c0,c1,c2,c3;
c0=ptr[ 1];c1=ptr[ 5];c2=ptr[ 9];c3=ptr[13];
ptr[ 1]=c3;ptr[ 5]=c0;ptr[ 9]=c1;ptr[13]=c2;
c0=ptr[ 2];c1=ptr[ 6];c2=ptr[10];c3=ptr[14];
ptr[ 2]=c2;ptr[ 6]=c3;ptr[10]=c0;ptr[14]=c1;
c0=ptr[ 3];c1=ptr[ 7];c2=ptr[11];c3=ptr[15];
ptr[ 3]=c1;ptr[ 7]=c2;ptr[11]=c3;ptr[15]=c0;
}
void aes128decrypt(unsigned char* block,unsigned char* key,int rounds)
{
int i,j;
unsigned char keys[256][16];
for (i=0;i<rounds-1 && i<256;i++)
{
memcpy(keys[i],key,16);
expandKey(key,i);
}
memcpy(keys[i],key,16);
rounds--;
addRoundKey(block,keys[rounds]);
shiftRowsInv(block);
subBytes(block,sbox_dec);
j=rounds-1;
for (i=0;i<j;i++)
{
rounds--;
addRoundKey(block,keys[rounds]);
mixColumnsInv(block);
shiftRowsInv(block);
subBytes(block,sbox_dec);
}
addRoundKey(block,keys[0]);
memset(keys,0,sizeof(keys));
}
int main(int argc,char** argv)
{
unsigned char key[16];
unsigned char block;
int rounds=11;
int i;
unsigned char lc;
unsigned char gotkey=0;
unsigned char enc0dec1=0;
unsigned char buf[1024];
unsigned int len;
fprintf(stderr,"*** aes128toy\n");
fprintf(stderr,"*** (This is just a toy)\n");
lc=0;
for (i=1;i<argc;i++)
{
if (lc=='k')
{
int l;
int j;
l=strlen(argv[i]);
if (l==32)
{
unsigned char c1;
unsigned char c2;
gotkey=1;
for (j=0;j<16;j++)
{
unsigned char x;
c1=argv[i][j*2];
c2=argv[i][j*2+1];
if (c1>='0' && c1<='9') x=c1-'0';
else if (c1>='a' && c1<='f') x=c1-'a'+10;
else if (c1>='A' && c1<='F') x=c1-'A'+10;
else gotkey=0;
x<<=4;
if (c2>='0' && c2<='9') x|=c2-'0';
else if (c2>='a' && c2<='f') x|=c2-'a'+10;
else if (c2>='A' && c2<='F') x|=c2-'A'+10;
else gotkey=0;
key[j]=x;
}
}
}
if (lc=='r')
{
rounds=atoi(argv[i]);
}
if (strncmp("-k",argv[i],2)==0) lc='k';
else if (strncmp("-K",argv[i],2)==0) lc='k';
else if (strncmp("-r",argv[i],2)==0) lc='r';
else if (strncmp("-R",argv[i],2)==0) lc='R';
else if (strncmp("-e",argv[i],2)==0) enc0dec1=0;
else if (strncmp("-E",argv[i],2)==0) enc0dec1=0;
else if (strncmp("-d",argv[i],2)==0) enc0dec1=1;
else if (strncmp("-D",argv[i],2)==0) enc0dec1=1;
else lc=0;
}
if (!gotkey) fprintf(stderr,"sorry. illegal key.\n");
if (rounds<11 || rounds>255) fprintf(stderr,"sorry. please choose a number between 11 and 256 for the rounds.\n");
if (rounds<11 || rounds>255 || !gotkey)
{
fprintf(stderr," %s -k KEY -r ROUNDS -e: encrypt\n",argv[0]);
fprintf(stderr," %s -k KEY -r ROUNDS -d: decrypt\n",argv[0]);
fprintf(stderr,"\n");
fprintf(stderr," KEY is supposed to be a hexadecimal value 128bit long.\n");
fprintf(stderr," for example 2b7e151628aed2a6abf7158809cf4f3c\n");
fprintf(stderr,"\n");
fprintf(stderr," ROUNDS is a number between 11 and 255.\n");
return 0;
}
if (!enc0dec1)
{
fprintf(stderr,"starting encryption with %i rounds\n",rounds);
fprintf(stderr,"please type in your secret message\n");
while (!feof(stdin))
{
fgets(buf,sizeof(buf),stdin);
len=strlen(buf);
len=((len+15)/16)*16;
for (i=0;i<len;i+=16)
{
aes128encrypt(&buf[i],key,rounds);
}
printf("[");
for (i=0;i<len;i++)
{
printf("%02x",((unsigned int)buf[i])&0xff);
}
printf("]\n");
}
} else {
int nibble=0;
int j=0;
unsigned char x;
fprintf(stderr,"starting decryption with %i rounds\n",rounds);
fprintf(stderr,"please type in the ciphertext\n");
while (!feof(stdin))
{
fgets(buf,sizeof(buf),stdin);
len=strlen(buf);
j=0;
for (i=0;i<len;i++)
{
unsigned char c=buf[i];
if (c>='0' && c<='9') {x<<=4;x|=(c-'0');nibble++;}
else if (c>='a' && c<='f') {x<<=4;x|=(c-'a'+10);nibble++;}
else if (c>='A' && c<='F') {x<<=4;x|=(c-'A'+10);nibble++;}
if (nibble==2)
{
nibble=0;
buf[j++]=x;
}
}
if (j&0xf) fprintf(stderr,"sorry, that was not a multiple of 128bit\n");
len=j;
for (i=0;i<len;i+=16)
{
aes128decrypt(&buf[i],key,rounds);
}
for (i=0;i<len;i++)
{
x=buf[i];
if (x>=' ' && x<127) printf("%c",x); else printf(".");
}
printf("\n");
}
}
return 1;
}
