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- #include <openssl/evp.h>
- #include <openssl/dh.h>
- #include <openssl/bn.h>
- #include <openssl/err.h>
- #include <openssl/rand.h>
- #include <openssl/ssl.h>
- #include <netinet/in.h>
- #include "crypto.h"
- #include "socks5proxy.h"
- #include "tagging.h"
- #include "ptwist.h"
- static super_data *super;
- /* PRF using sha384, as defined in RFC 5246 */
- int PRF(uint8_t *secret, int32_t secret_len,
- uint8_t *seed1, int32_t seed1_len,
- uint8_t *seed2, int32_t seed2_len,
- uint8_t *seed3, int32_t seed3_len,
- uint8_t *seed4, int32_t seed4_len,
- uint8_t *output, int32_t output_len){
- EVP_MD_CTX ctx, ctx_tmp, ctx_init;
- EVP_PKEY *mac_key;
- const EVP_MD *md = EVP_sha256();
- uint8_t A[EVP_MAX_MD_SIZE];
- size_t len, A_len;
- int chunk = EVP_MD_size(md);
- int remaining = output_len;
- uint8_t *out = output;
- EVP_MD_CTX_init(&ctx);
- EVP_MD_CTX_init(&ctx_tmp);
- EVP_MD_CTX_init(&ctx_init);
- EVP_MD_CTX_set_flags(&ctx_init, EVP_MD_CTX_FLAG_NON_FIPS_ALLOW);
- mac_key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL, secret, secret_len);
- /* Calculate first A value */
- EVP_DigestSignInit(&ctx_init, NULL, md, NULL, mac_key);
- EVP_MD_CTX_copy_ex(&ctx, &ctx_init);
- if(seed1 != NULL && seed1_len > 0){
- EVP_DigestSignUpdate(&ctx, seed1, seed1_len);
- }
- if(seed2 != NULL && seed2_len > 0){
- EVP_DigestSignUpdate(&ctx, seed2, seed2_len);
- }
- if(seed3 != NULL && seed3_len > 0){
- EVP_DigestSignUpdate(&ctx, seed3, seed3_len);
- }
- if(seed4 != NULL && seed4_len > 0){
- EVP_DigestSignUpdate(&ctx, seed4, seed4_len);
- }
- EVP_DigestSignFinal(&ctx, A, &A_len);
- //iterate until desired length is achieved
- while(remaining > 0){
- /* Now compute SHA384(secret, A+seed) */
- EVP_MD_CTX_copy_ex(&ctx, &ctx_init);
- EVP_DigestSignUpdate(&ctx, A, A_len);
- EVP_MD_CTX_copy_ex(&ctx_tmp, &ctx);
- if(seed1 != NULL && seed1_len > 0){
- EVP_DigestSignUpdate(&ctx, seed1, seed1_len);
- }
- if(seed2 != NULL && seed2_len > 0){
- EVP_DigestSignUpdate(&ctx, seed2, seed2_len);
- }
- if(seed3 != NULL && seed3_len > 0){
- EVP_DigestSignUpdate(&ctx, seed3, seed3_len);
- }
- if(seed4 != NULL && seed4_len > 0){
- EVP_DigestSignUpdate(&ctx, seed4, seed4_len);
- }
-
- if(remaining > chunk){
- EVP_DigestSignFinal(&ctx, out, &len);
- out += len;
- remaining -= len;
- /* Next A value */
- EVP_DigestSignFinal(&ctx_tmp, A, &A_len);
- } else {
- EVP_DigestSignFinal(&ctx, A, &A_len);
- memcpy(out, A, remaining);
- remaining -= remaining;
- }
- }
- return 1;
- }
- /*
- * Generate the keys for the super encryption layer, based on the slitheen ID
- */
- int generate_super_keys(uint8_t *secret){
- super = calloc(1, sizeof(super_data));
-
- EVP_MD_CTX *mac_ctx;
- const EVP_MD *md = EVP_sha256();
- /* Generate Keys */
- uint8_t *hdr_key, *bdy_key;
- uint8_t *mac_secret;
- EVP_PKEY *mac_key;
- int32_t mac_len, key_len;
- key_len = EVP_CIPHER_key_length(EVP_aes_256_cbc());
- mac_len = EVP_MD_size(md);
- int32_t total_len = 2*key_len + mac_len;
- uint8_t *key_block = calloc(1, total_len);
- PRF(secret, SLITHEEN_SUPER_SECRET_SIZE,
- (uint8_t *) SLITHEEN_SUPER_CONST, SLITHEEN_SUPER_CONST_SIZE,
- NULL, 0,
- NULL, 0,
- NULL, 0,
- key_block, total_len);
- #ifdef DEBUG
- int i;
- printf("secret: \n");
- for(i=0; i< SLITHEEN_SUPER_SECRET_SIZE; i++){
- printf("%02x ", secret[i]);
- }
- printf("\n");
- printf("keyblock: \n");
- for(i=0; i< total_len; i++){
- printf("%02x ", key_block[i]);
- }
- printf("\n");
- #endif
- hdr_key = key_block;
- bdy_key = key_block + key_len;
- mac_secret = key_block + 2*key_len;
- /* Initialize MAC Context */
- mac_ctx = EVP_MD_CTX_create();
- EVP_DigestInit_ex(mac_ctx, md, NULL);
- mac_key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL, mac_secret, mac_len);
- EVP_DigestSignInit(mac_ctx, NULL, md, NULL, mac_key);
- super->header_key = malloc(key_len);
- super->body_key = malloc(key_len);
- memcpy(super->header_key, hdr_key, key_len);
- memcpy(super->body_key, bdy_key, key_len);
- super->body_mac_ctx = mac_ctx;
- //Free everything
- free(key_block);
- EVP_PKEY_free(mac_key);
- return 0;
- }
- int super_decrypt(uint8_t *data){
- EVP_CIPHER_CTX *bdy_ctx;
- EVP_CIPHER_CTX *hdr_ctx;
- uint8_t *p = data;
- int32_t out_len, len;
- uint8_t output[EVP_MAX_MD_SIZE];
- size_t mac_len;
- int i;
- //decrypt header
- #ifdef DEBUG
- printf("Encrypted header:\n");
- for(i=0; i< SLITHEEN_HEADER_LEN; i++){
- printf("%02x ", p[i]);
- }
- printf("\n");
- #endif
- hdr_ctx = EVP_CIPHER_CTX_new();
- EVP_CipherInit_ex(hdr_ctx, EVP_aes_256_ecb(), NULL, super->header_key, NULL, 0);
- if(!EVP_CipherUpdate(hdr_ctx, p, &out_len, p, SLITHEEN_HEADER_LEN)){
- printf("Decryption failed!");
- return 0;
- }
- EVP_CIPHER_CTX_free(hdr_ctx);
- struct slitheen_hdr *sl_hdr = (struct slitheen_hdr *) p;
- len = htons(sl_hdr->len);
- if(!sl_hdr->len){//there are no data to be decrypted
- return 1;
- }
- if(len %16){ //add padding to len
- len += 16 - len%16;
- }
- //#ifdef DEBUG_PARSE
- printf("Decrypted header (%d bytes):\n", SLITHEEN_HEADER_LEN);
- for(i=0; i< SLITHEEN_HEADER_LEN; i++){
- printf("%02x ", p[i]);
- }
- printf("\n");
- fflush(stdout);
- //#endif
-
- p += SLITHEEN_HEADER_LEN;
- //initialize body cipher context with IV
- bdy_ctx = EVP_CIPHER_CTX_new();
- EVP_CipherInit_ex(bdy_ctx, EVP_aes_256_cbc(), NULL, super->body_key, p, 0);
- p+=16;
- //compute mac
- EVP_MD_CTX mac_ctx;
- EVP_MD_CTX_init(&mac_ctx);
- EVP_MD_CTX_copy_ex(&mac_ctx, super->body_mac_ctx);
- EVP_DigestSignUpdate(&mac_ctx, p, len);
- EVP_DigestSignFinal(&mac_ctx, output, &mac_len);
- EVP_MD_CTX_cleanup(&mac_ctx);
- #ifdef DEBUG_PARSE
- printf("Received mac:\n");
- for(i=0; i< 16; i++){
- printf("%02x ", p[len+i]);
- }
- printf("\n");
- fflush(stdout);
- #endif
- #ifdef DEBUG_PARSE
- printf("Computed mac:\n");
- for(i=0; i< 16; i++){
- printf("%02x ", output[i]);
- }
- printf("\n");
- fflush(stdout);
- #endif
- if(memcmp(p+len, output, 16)){
- printf("MAC verification failed\n");
- return 0;
- }
- //decrypt body
- #ifdef DEBUG_PARSE
- printf("Encrypted data (%d bytes):\n", len);
- for(i=0; i< len; i++){
- printf("%02x ", p[i]);
- }
- printf("\n");
- #endif
- if(!EVP_CipherUpdate(bdy_ctx, p, &out_len, p, len)){
- printf("Decryption failed!");
- return 0;
- }
- EVP_CIPHER_CTX_free(bdy_ctx);
- #ifdef DEBUG_PARSE
- printf("Decrypted data (%d bytes):\n", out_len);
- for(i=0; i< out_len; i++){
- printf("%02x ", p[i]);
- }
- printf("\n");
- fflush(stdout);
- #endif
- p += out_len;
- return 1;
- }
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