}
+int aes_128_cbc_encrypt(const u8 *key, const u8 *iv, u8 *data, size_t data_len)
+{
+ EVP_CIPHER_CTX ctx;
+ int clen, len;
+ u8 buf[16];
+
+ EVP_CIPHER_CTX_init(&ctx);
+ if (EVP_EncryptInit_ex(&ctx, EVP_aes_128_cbc(), NULL, key, iv) != 1)
+ return -1;
+ EVP_CIPHER_CTX_set_padding(&ctx, 0);
+
+ clen = data_len;
+ if (EVP_EncryptUpdate(&ctx, data, &clen, data, data_len) != 1 ||
+ clen != (int) data_len)
+ return -1;
+
+ len = sizeof(buf);
+ if (EVP_EncryptFinal_ex(&ctx, buf, &len) != 1 || len != 0)
+ return -1;
+ EVP_CIPHER_CTX_cleanup(&ctx);
+
+ return 0;
+}
+
+
+int aes_128_cbc_decrypt(const u8 *key, const u8 *iv, u8 *data, size_t data_len)
+{
+ EVP_CIPHER_CTX ctx;
+ int plen, len;
+ u8 buf[16];
+
+ EVP_CIPHER_CTX_init(&ctx);
+ if (EVP_DecryptInit_ex(&ctx, EVP_aes_128_cbc(), NULL, key, iv) != 1)
+ return -1;
+ EVP_CIPHER_CTX_set_padding(&ctx, 0);
+
+ plen = data_len;
+ if (EVP_DecryptUpdate(&ctx, data, &plen, data, data_len) != 1 ||
+ plen != (int) data_len)
+ return -1;
+
+ len = sizeof(buf);
+ if (EVP_DecryptFinal_ex(&ctx, buf, &len) != 1 || len != 0)
+ return -1;
+ EVP_CIPHER_CTX_cleanup(&ctx);
+
+ return 0;
+}
+
+
int crypto_mod_exp(const u8 *base, size_t base_len,
const u8 *power, size_t power_len,
const u8 *modulus, size_t modulus_len,