encrypt.cpp

#include "lib/aes-common.h"
#include "lib/md5.h"
#include "lib/pbkdf2-sha1.h"
#include "lib/pbkdf2-sha256.h"
#include <string.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include "encrypt.h"
#include "common.h"
#include "log.h"

// static uint64_t seq=1;

static int8_t zero_iv[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};  // this prog use zero iv,you should make sure first block of data contains a random/nonce data
/****
 * security of zero_iv + nonce first data block
 * https://crypto.stackexchange.com/questions/5421/using-cbc-with-a-fixed-iv-and-a-random-first-plaintext-block
 ****/

char normal_key[16 + 100];    // generated from key_string by md5. reserved for compatiblity
const int hmac_key_len = 64;  // generate 512bit long keys, use first n chars when needed
const int cipher_key_len = 64;
unsigned char hmac_key_encrypt[hmac_key_len + 100];      // key for hmac
unsigned char hmac_key_decrypt[hmac_key_len + 100];      // key for hmac
unsigned char cipher_key_encrypt[cipher_key_len + 100];  // key for aes etc.
unsigned char cipher_key_decrypt[cipher_key_len + 100];  // key for aes etc.

char gro_xor[256 + 100];  // dirty fix for gro

unordered_map<int, const char *> auth_mode_tostring = {
    {auth_none, "none"},
    {auth_md5, "md5"},
    {auth_crc32, "crc32"},
    {auth_simple, "simple"},
    {auth_hmac_sha1, "hmac_sha1"},
};

unordered_map<int, const char *> cipher_mode_tostring = {
    {cipher_none, "none"},
    {cipher_aes128cfb, "aes128cfb"},
    {cipher_aes128cbc, "aes128cbc"},
    {cipher_xor, "xor"},
};
// TODO aes-gcm

auth_mode_t auth_mode = auth_md5;
cipher_mode_t cipher_mode = cipher_aes128cbc;
int is_hmac_used = 0;

int aes128cfb_old = 0;

// TODO key negotiation and forward secrecy

int my_init_keys(const char *user_passwd, int is_client) {
    char tmp[1000] = "";
    int len = strlen(user_passwd);

    strcat(tmp, user_passwd);

    strcat(tmp, "key1");

    md5((uint8_t *)tmp, strlen(tmp), (uint8_t *)normal_key);

    if (auth_mode == auth_hmac_sha1)
        is_hmac_used = 1;
    if (is_hmac_used || g_fix_gro || 1) {
        unsigned char salt[400] = "";
        char salt_text[400] = "udp2raw_salt1";
        md5((uint8_t *)(salt_text), strlen(salt_text), salt);  // TODO different salt per session

        unsigned char pbkdf2_output1[400] = "";
        PKCS5_PBKDF2_HMAC_SHA256((uint8_t *)user_passwd, len, salt, 16, 10000, 32, pbkdf2_output1);  // TODO argon2 ?

        // unsigned char pbkdf2_output2[400]="";
        // PKCS5_PBKDF2_HMAC_SHA256(pbkdf2_output1,32,0,0,1, hmac_key_len*2+cipher_key_len*2,pbkdf2_output2);  //stretch it

        const char *info_hmac_encrypt = "hmac_key server-->client";
        const char *info_hmac_decrypt = "hmac_key client-->server";
        const char *info_cipher_encrypt = "cipher_key server-->client";
        const char *info_cipher_decrypt = "cipher_key client-->server";

        if (is_client) {
            const char *tmp;
            tmp = info_hmac_encrypt;
            info_hmac_encrypt = info_hmac_decrypt;
            info_hmac_decrypt = tmp;
            tmp = info_cipher_encrypt;
            info_cipher_encrypt = info_cipher_decrypt;
            info_cipher_decrypt = tmp;
        } else {
            // nop
        }

        assert(hkdf_sha256_expand(pbkdf2_output1, 32, (unsigned char *)info_cipher_encrypt, strlen(info_cipher_encrypt), cipher_key_encrypt, cipher_key_len) == 0);
        assert(hkdf_sha256_expand(pbkdf2_output1, 32, (unsigned char *)info_cipher_decrypt, strlen(info_cipher_decrypt), cipher_key_decrypt, cipher_key_len) == 0);
        assert(hkdf_sha256_expand(pbkdf2_output1, 32, (unsigned char *)info_hmac_encrypt, strlen(info_hmac_encrypt), hmac_key_encrypt, hmac_key_len) == 0);
        assert(hkdf_sha256_expand(pbkdf2_output1, 32, (unsigned char *)info_hmac_decrypt, strlen(info_hmac_decrypt), hmac_key_decrypt, hmac_key_len) == 0);

        const char *gro_info = "gro";
        assert(hkdf_sha256_expand(pbkdf2_output1, 32, (unsigned char *)gro_info, strlen(gro_info), (unsigned char *)gro_xor, 256) == 0);
    }

    print_binary_chars(normal_key, 16);
    print_binary_chars((char *)hmac_key_encrypt, hmac_key_len);
    print_binary_chars((char *)hmac_key_decrypt, hmac_key_len);
    print_binary_chars((char *)cipher_key_encrypt, cipher_key_len);
    print_binary_chars((char *)cipher_key_decrypt, cipher_key_len);

    return 0;
}
/*
 *  this function comes from  http://www.hackersdelight.org/hdcodetxt/crc.c.txt
 */
unsigned int crc32h(unsigned char *message, int len) {
    int i, crc;
    unsigned int byte, c;
    const unsigned int g0 = 0xEDB88320, g1 = g0 >> 1,
                       g2 = g0 >> 2, g3 = g0 >> 3, g4 = g0 >> 4, g5 = g0 >> 5,
                       g6 = (g0 >> 6) ^ g0, g7 = ((g0 >> 6) ^ g0) >> 1;

    i = 0;
    crc = 0xFFFFFFFF;
    while (i != len) {  // Get next byte.
        byte = message[i];
        crc = crc ^ byte;
        c = ((crc << 31 >> 31) & g7) ^ ((crc << 30 >> 31) & g6) ^
            ((crc << 29 >> 31) & g5) ^ ((crc << 28 >> 31) & g4) ^
            ((crc << 27 >> 31) & g3) ^ ((crc << 26 >> 31) & g2) ^
            ((crc << 25 >> 31) & g1) ^ ((crc << 24 >> 31) & g0);
        crc = ((unsigned)crc >> 8) ^ c;
        i = i + 1;
    }
    return ~crc;
}

/*
 void sum(const unsigned  char *data,int len,unsigned char*  res) {
   memset(res,0,sizeof(int));
   for(int i=0,j=0;i<len;i++,j++)
   {
           if(j==4) j=0;
           res[j]+=data[i];
   }

   return ;
}*/

void simple_hash(unsigned char *str, int len, unsigned char res[8])  // djb2+ sdbm
{
    u32_t hash = 5381;
    u32_t hash2 = 0;
    int c;
    int i = 0;
    while (c = *str++, i++ != len) {
        // hash = ((hash << 5) + hash) + c; /* hash * 33 + c */
        hash = ((hash << 5) + hash) ^ c; /* (hash * 33) ^ c */
        hash2 = c + (hash2 << 6) + (hash2 << 16) - hash2;
    }

    hash = htonl(hash);
    hash2 = htonl(hash2);
    memcpy(res, &hash, sizeof(hash));
    memcpy(res + sizeof(hash), &hash2, sizeof(hash2));
}

int auth_md5_cal(const char *data, char *output, int &len) {
    memcpy(output, data, len);  // TODO inefficient code
    md5((unsigned char *)output, len, (unsigned char *)(output + len));
    len += 16;
    return 0;
}

int auth_hmac_sha1_cal(const char *data, char *output, int &len) {
    mylog(log_trace, "auth_hmac_sha1_cal() is called\n");
    memcpy(output, data, len);  // TODO inefficient code
    sha1_hmac(hmac_key_encrypt, 20, (const unsigned char *)data, len, (unsigned char *)(output + len));
    // use key len of 20 instead of hmac_key_len, "extra length would not significantly increase the function strength" (rfc2104)
    len += 20;
    return 0;
}

int auth_hmac_sha1_verify(const char *data, int &len) {
    mylog(log_trace, "auth_hmac_sha1_verify() is called\n");
    if (len < 20) {
        mylog(log_trace, "auth_hmac_sha1_verify len<20\n");
        return -1;
    }
    char res[20];

    sha1_hmac(hmac_key_decrypt, 20, (const unsigned char *)data, len - 20, (unsigned char *)(res));

    if (memcmp(res, data + len - 20, 20) != 0) {
        mylog(log_trace, "auth_hmac_sha1 check failed\n");
        return -2;
    }
    len -= 20;
    return 0;
}

int auth_crc32_cal(const char *data, char *output, int &len) {
    memcpy(output, data, len);  // TODO inefficient code
    unsigned int ret = crc32h((unsigned char *)output, len);
    unsigned int ret_n = htonl(ret);
    memcpy(output + len, &ret_n, sizeof(unsigned int));
    len += sizeof(unsigned int);
    return 0;
}

int auth_simple_cal(const char *data, char *output, int &len) {
    // char res[4];
    memcpy(output, data, len);  // TODO inefficient code
    simple_hash((unsigned char *)output, len, (unsigned char *)(output + len));
    len += 8;
    return 0;
}
int auth_simple_verify(const char *data, int &len) {
    if (len < 8) return -1;
    unsigned char res[8];
    len -= 8;
    simple_hash((unsigned char *)data, len, res);
    if (memcmp(res, data + len, 8) != 0)
        return -1;
    return 0;
}

int auth_none_cal(const char *data, char *output, int &len) {
    memcpy(output, data, len);
    return 0;
}
int auth_md5_verify(const char *data, int &len) {
    if (len < 16) {
        mylog(log_trace, "auth_md5_verify len<16\n");
        return -1;
    }
    char md5_res[16];

    md5((unsigned char *)data, len - 16, (unsigned char *)md5_res);

    if (memcmp(md5_res, data + len - 16, 16) != 0) {
        mylog(log_trace, "auth_md5_verify md5 check failed\n");
        return -2;
    }
    len -= 16;
    return 0;
}
int auth_none_verify(const char *data, int &len) {
    return 0;
}

int cipher_xor_encrypt(const char *data, char *output, int &len, char *key) {
    int i, j;
    for (i = 0, j = 0; i < len; i++, j++) {
        if (j == 16) j = 0;
        output[i] = data[i] ^ key[j];
    }
    return 0;
}
int cipher_xor_decrypt(const char *data, char *output, int &len, char *key) {
    int i, j;
    // char tmp[buf_len];
    // len=len/16*16+1;
    // AES128_CBC_decrypt_buffer((uint8_t *)tmp, (uint8_t *)input, len, (uint8_t *)key, (uint8_t *)iv);
    // for(i=0;i<len;i++)
    // input[i]=tmp[i];
    for (i = 0, j = 0; i < len; i++, j++) {
        if (j == 16) j = 0;
        output[i] = data[i] ^ key[j];
    }
    return 0;
}

int padding(char *data, int &data_len, int padding_num) {
    int old_len = data_len;
    data_len += 1;
    if (data_len % padding_num != 0) {
        data_len = (data_len / padding_num) * padding_num + padding_num;
    }
    unsigned char *p = (unsigned char *)&data[data_len - 1];
    *p = (data_len - old_len);
    return 0;
}

int de_padding(const char *data, int &data_len, int padding_num) {
    if (data_len == 0) return -1;
    if ((uint8_t)data[data_len - 1] > padding_num) return -1;
    data_len -= (uint8_t)data[data_len - 1];
    if (data_len < 0) {
        return -1;
    }
    return 0;
}
void aes_ecb_encrypt(const char *data, char *output) {
    static int first_time = 1;
    char *key = (char *)cipher_key_encrypt;
    if (aes_key_optimize) {
        if (first_time == 0)
            key = 0;
        else
            first_time = 0;
    }
    AES_ECB_encrypt_buffer((uint8_t *)data, (uint8_t *)key, (uint8_t *)output);
}
void aes_ecb_encrypt1(char *data) {
    char buf[16];
    memcpy(buf, data, 16);
    aes_ecb_encrypt(buf, data);
}
void aes_ecb_decrypt(const char *data, char *output) {
    static int first_time = 1;
    char *key = (char *)cipher_key_decrypt;
    if (aes_key_optimize) {
        if (first_time == 0)
            key = 0;
        else
            first_time = 0;
    }
    AES_ECB_decrypt_buffer((uint8_t *)data, (uint8_t *)key, (uint8_t *)output);
}
void aes_ecb_decrypt1(char *data) {
    char buf[16];
    memcpy(buf, data, 16);
    aes_ecb_decrypt(buf, data);
}
int cipher_aes128cbc_encrypt(const char *data, char *output, int &len, char *key) {
    static int first_time = 1;

    char buf[buf_len];
    memcpy(buf, data, len);  // TODO inefficient code

    if (padding(buf, len, 16) < 0) return -1;

    if (aes_key_optimize) {
        if (first_time == 0)
            key = 0;
        else
            first_time = 0;
    }

    AES_CBC_encrypt_buffer((unsigned char *)output, (unsigned char *)buf, len, (unsigned char *)key, (unsigned char *)zero_iv);
    return 0;
}
int cipher_aes128cfb_encrypt(const char *data, char *output, int &len, char *key) {
    static int first_time = 1;
    assert(len >= 16);

    char buf[buf_len];
    memcpy(buf, data, len);  // TODO inefficient code
    if (aes_key_optimize) {
        if (first_time == 0)
            key = 0;
        else
            first_time = 0;
    }
    if (!aes128cfb_old) {
        aes_ecb_encrypt(data, buf);  // encrypt the first block
    }

    AES_CFB_encrypt_buffer((unsigned char *)output, (unsigned char *)buf, len, (unsigned char *)key, (unsigned char *)zero_iv);
    return 0;
}
int auth_crc32_verify(const char *data, int &len) {
    if (len < int(sizeof(unsigned int))) {
        mylog(log_debug, "auth_crc32_verify len<%d\n", int(sizeof(unsigned int)));
        return -1;
    }
    unsigned int ret = crc32h((unsigned char *)data, len - sizeof(unsigned int));
    unsigned int ret_n = htonl(ret);

    if (memcmp(data + len - sizeof(unsigned int), &ret_n, sizeof(unsigned int)) != 0) {
        mylog(log_debug, "auth_crc32_verify memcmp fail\n");
        return -1;
    }
    len -= sizeof(unsigned int);
    return 0;
}
int cipher_none_encrypt(const char *data, char *output, int &len, char *key) {
    memcpy(output, data, len);
    return 0;
}
int cipher_aes128cbc_decrypt(const char *data, char *output, int &len, char *key) {
    static int first_time = 1;
    if (len % 16 != 0) {
        mylog(log_debug, "len%%16!=0\n");
        return -1;
    }
    if (aes_key_optimize) {
        if (first_time == 0)
            key = 0;
        else
            first_time = 0;
    }
    AES_CBC_decrypt_buffer((unsigned char *)output, (unsigned char *)data, len, (unsigned char *)key, (unsigned char *)zero_iv);
    if (de_padding(output, len, 16) < 0) return -1;
    return 0;
}
int cipher_aes128cfb_decrypt(const char *data, char *output, int &len, char *key) {
    static int first_time = 1;
    if (len < 16) return -1;

    if (aes_key_optimize) {
        if (first_time == 0)
            key = 0;
        else
            first_time = 0;
    }

    AES_CFB_decrypt_buffer((unsigned char *)output, (unsigned char *)data, len, (unsigned char *)key, (unsigned char *)zero_iv);

    if (!aes128cfb_old)
        aes_ecb_decrypt1(output);  // decrypt the first block
    // if(de_padding(output,len,16)<0) return -1;
    return 0;
}

int cipher_none_decrypt(const char *data, char *output, int &len, char *key) {
    memcpy(output, data, len);
    return 0;
}

int auth_cal(const char *data, char *output, int &len) {
    mylog(log_trace, "auth:%d\n", auth_mode);
    switch (auth_mode) {
        case auth_crc32:
            return auth_crc32_cal(data, output, len);
        case auth_md5:
            return auth_md5_cal(data, output, len);
        case auth_simple:
            return auth_simple_cal(data, output, len);
        case auth_none:
            return auth_none_cal(data, output, len);
        case auth_hmac_sha1:
            return auth_hmac_sha1_cal(data, output, len);
        // default:	return auth_md5_cal(data,output,len);//default;
        default:
            assert(0 == 1);
    }
    return -1;
}
int auth_verify(const char *data, int &len) {
    mylog(log_trace, "auth:%d\n", auth_mode);
    switch (auth_mode) {
        case auth_crc32:
            return auth_crc32_verify(data, len);
        case auth_md5:
            return auth_md5_verify(data, len);
        case auth_simple:
            return auth_simple_verify(data, len);
        case auth_none:
            return auth_none_verify(data, len);
        case auth_hmac_sha1:
            return auth_hmac_sha1_verify(data, len);
        // default:	return auth_md5_verify(data,len);//default
        default:
            assert(0 == 1);
    }
    return -1;
}
int cipher_encrypt(const char *data, char *output, int &len, char *key) {
    mylog(log_trace, "cipher:%d\n", cipher_mode);
    switch (cipher_mode) {
        case cipher_aes128cbc:
            return cipher_aes128cbc_encrypt(data, output, len, key);
        case cipher_aes128cfb:
            return cipher_aes128cfb_encrypt(data, output, len, key);
        case cipher_xor:
            return cipher_xor_encrypt(data, output, len, key);
        case cipher_none:
            return cipher_none_encrypt(data, output, len, key);
        // default:return cipher_aes128cbc_encrypt(data,output,len, key);
        default:
            assert(0 == 1);
    }
    return -1;
}
int cipher_decrypt(const char *data, char *output, int &len, char *key) {
    mylog(log_trace, "cipher:%d\n", cipher_mode);
    switch (cipher_mode) {
        case cipher_aes128cbc:
            return cipher_aes128cbc_decrypt(data, output, len, key);
        case cipher_aes128cfb:
            return cipher_aes128cfb_decrypt(data, output, len, key);
        case cipher_xor:
            return cipher_xor_decrypt(data, output, len, key);
        case cipher_none:
            return cipher_none_decrypt(data, output, len, key);
        //	default:	return cipher_aes128cbc_decrypt(data,output,len,key);
        default:
            assert(0 == 1);
    }
    return -1;
}

int encrypt_AE(const char *data, char *output, int &len /*,char * key*/) {
    mylog(log_trace, "encrypt_AE is called\n");
    char buf[buf_len];
    char buf2[buf_len];
    memcpy(buf, data, len);
    if (cipher_encrypt(buf, buf2, len, (char *)cipher_key_encrypt) != 0) {
        mylog(log_debug, "cipher_encrypt failed ");
        return -1;
    }
    if (auth_cal(buf2, output, len) != 0) {
        mylog(log_debug, "auth_cal failed ");
        return -1;
    }

    // printf("%d %x %x\n",len,(int)(output[0]),(int)(output[1]));
    // print_binary_chars(output,len);

    // use encrypt-then-MAC scheme
    return 0;
}

int decrypt_AE(const char *data, char *output, int &len /*,char * key*/) {
    mylog(log_trace, "decrypt_AE is called\n");
    // printf("%d %x %x\n",len,(int)(data[0]),(int)(data[1]));
    // print_binary_chars(data,len);

    if (auth_verify(data, len) != 0) {
        mylog(log_debug, "auth_verify failed\n");
        return -1;
    }
    if (cipher_decrypt(data, output, len, (char *)cipher_key_decrypt) != 0) {
        mylog(log_debug, "cipher_decrypt failed \n");
        return -1;
    }
    return 0;
}

int my_encrypt(const char *data, char *output, int &len /*,char * key*/) {
    if (len < 0) {
        mylog(log_trace, "len<0");
        return -1;
    }
    if (len > max_data_len) {
        mylog(log_warn, "len>max_data_len");
        return -1;
    }

    if (is_hmac_used)
        return encrypt_AE(data, output, len);

    char buf[buf_len];
    char buf2[buf_len];
    memcpy(buf, data, len);
    if (auth_cal(buf, buf2, len) != 0) {
        mylog(log_debug, "auth_cal failed ");
        return -1;
    }
    if (cipher_encrypt(buf2, output, len, normal_key) != 0) {
        mylog(log_debug, "cipher_encrypt failed ");
        return -1;
    }
    return 0;
}

int my_decrypt(const char *data, char *output, int &len /*,char * key*/) {
    if (len < 0) return -1;
    if (len > max_data_len) {
        mylog(log_warn, "len>max_data_len");
        return -1;
    }

    if (is_hmac_used)
        return decrypt_AE(data, output, len);

    if (cipher_decrypt(data, output, len, normal_key) != 0) {
        mylog(log_debug, "cipher_decrypt failed \n");
        return -1;
    }
    if (auth_verify(output, len) != 0) {
        mylog(log_debug, "auth_verify failed\n");
        return -1;
    }

    return 0;
}

int encrypt_AEAD(uint8_t *data, uint8_t *output, int &len, uint8_t *key, uint8_t *header, int hlen) {
    // TODO
    return -1;
}

int decrypt_AEAD(uint8_t *data, uint8_t *output, int &len, uint8_t *key, uint8_t *header, int hlen) {
    // TODO
    return -1;
}