- if (EVP_CIPHER_CTX_encrypting(ctx)) {
- /*
- * OpenSSL increments seq after mac calculation.
- * As we have Mac-Then-Encrypt, we need decrement it here on encryption
- * to derive the key correctly.
- * */
- if (memcmp(seq, zeroseq, 8) != 0)
- {
- for(j=7; j>=0; j--)
- {
- if (seq[j] != 0) {seq[j]--; break;}
- else seq[j] = 0xFF;
- }
- }
+ decrement_arg = arg;
+ if (!decrement_sequence(seq, decrement_arg))
+ {
+ GOSTerr(GOST_F_GOST_GRASSHOPPER_CIPHER_CTL, GOST_R_CTRL_CALL_FAILED);
+ return -1;