---
name: "sc_get_challenge"
section: "3"
platform: "linux"
package: "libopensc2-dev"
version: "0.11.13-1.1"
release: "Debian 6.0 (Squeeze)"
platforms: ["linux"]
url: "https://new.carta.tech/sc_get_challenge"
---

# sc\_get\_challenge(3)

Request a challenge from a card

## NAME

sc\_get\_challenge - Request a challenge from a card

## SYNOPSIS

```
#include <opensc.h>
int sc_get_challenge(struct sc_card *card, unsigned char *rnd, size_t len);
```

## DESCRIPTION

This function requests a challenge (i.e. random bytes) from *card*. The returned data will be stored in *rnd*, and will be *len* bytes long.

## RETURN VALUE

Returns 0 if successful, or a negative value in case of error.