compress ciphertext slightly and add way more tests

[software/DIPE.git] / src / DIPE.cxx

diff --git a/src/DIPE.cxx b/src/DIPE.cxx
index f278f5008857d195d565a1b0b299735b33f66daf..e06f2f3b4b95eeba42176062f70aa74c1b892fa9 100644 (file)
--- a/src/DIPE.cxx
+++ b/src/DIPE.cxx
@@ -78,18 +78,14 @@ namespace {
 
        /* Data format is iv | enc(4 byte len | ptxt | 0 padding) | tag
         */
-       int dipe_aes_encrypt(uint8_t* key, size_t ptxt_len, uint8_t* ptxt, size_t ctxt_len, uint8_t* ctxt) {
+       int dipe_aes_encrypt(uint8_t* key, uint8_t* iv, size_t ptxt_len, uint8_t* ptxt, size_t ctxt_len, uint8_t* ctxt) {
                struct gcm_aes128_ctx ctx;
-               uint8_t iv[12];
                uint8_t block[16];
                uint32_t coded_ptxtlen;
 
-               ctxt_len -= (12 + 16); /* IV + Tag */
-               if (ctxt_len < ptxt_len) return -1;
+               ctxt_len -= 16; /* Tag */
+               if (ctxt_len < ptxt_len + 4) return 0;
                
-               getrandom(iv, 12, 0);
-               memcpy(ctxt, iv, 12);
-               ctxt += 12;
                memset(block, 0, 16);
                gcm_aes128_set_key(&ctx, key);
                gcm_aes128_set_iv(&ctx, 12, iv);
@@ -123,13 +119,12 @@ namespace {
                return 0;
        }
 
-       int dipe_aes_decrypt(uint8_t* key, size_t len, uint8_t* ctxt, uint8_t* ptxt) {
+       int dipe_aes_decrypt(uint8_t* key, uint8_t* iv, size_t len, uint8_t* ctxt, uint8_t* ptxt) {
                struct gcm_aes128_ctx ctx;
                uint8_t block[16];
 
                gcm_aes128_set_key(&ctx, key);
-               gcm_aes128_set_iv(&ctx, 12, ctxt);
-               ctxt += 12; len -= 12;
+               gcm_aes128_set_iv(&ctx, 12, iv);
                len -= 16; /* GCM tag */
 
                
@@ -332,7 +327,7 @@ void dipe_encrypt(dipe_param_t param, dipe_master_publickey_t mpk, element_t* x,
        cap_len = dipe_serialize_ctxt(param, cap, (uint8_t*)ctxt);
        ctxt += cap_len; ctxt_len -= cap_len;
        
-       dipe_aes_encrypt(aes, ptxt_len, (uint8_t*)ptxt, ctxt_len, (uint8_t*)ctxt);
+       dipe_aes_encrypt(aes, aes+16, ptxt_len, (uint8_t*)ptxt, ctxt_len, (uint8_t*)ctxt);
 
        dipe_free_ctxt(cap);
        element_clear(key);
@@ -354,7 +349,7 @@ size_t dipe_decrypt(dipe_param_t param, dipe_secretkey_t sk, char* cid, element_
        dipe_free_ctxt(cap);
        element_clear(key);
 
-       return dipe_aes_decrypt(aes, ctxt_len, (uint8_t*)ctxt, (uint8_t*)ptxt);
+       return dipe_aes_decrypt(aes, aes+16, ctxt_len, (uint8_t*)ctxt, (uint8_t*)ptxt);
 }
 
 /* Note: we're generating random-looking bytes here. Therefore we
@@ -408,7 +403,7 @@ size_t dipe_deserialize_ctxt(dipe_param_t param, size_t dimension, dipe_ctxt_t*
 }
 
 size_t dipe_ciphertext_overhead(dipe_param_t param, size_t dimension) {
-       size_t overhead = 12 + 16 + 4 /* IV + Tag + Size */;
+       size_t overhead = 16 + 4 /* IV + Tag + Size */;
        element_t t;
 
        element_init_G1(t, param->pairing);