fips.c

#include <openssl/evp.h>
#include <openssl/err.h>

void print_ssl_error_stack(void)
{
	int err;
	while ((err = ERR_get_error()) != 0) {
		fprintf(stderr, "ERR lib=%d reason=%d err=%s\n", ERR_GET_LIB(err), ERR_GET_REASON(err), ERR_reason_error_string(err));
	}
}

int main(int argc, char *argv[])
{
	unsigned char key[] = "0123456789abcdeF";
	unsigned char iv[] = "1234567887654321";
	unsigned char data[] = "this is a secret";
	unsigned char *out;

	int size, outlen, tmplen, err;

	EVP_CIPHER_CTX *ctx = EVP_CIPHER_CTX_new();

	err = EVP_CipherInit_ex(ctx, EVP_chacha20_poly1305(), NULL, key, iv, 1);
	if (err != 1) {
		print_ssl_error_stack();
		return 1;
	}

	size = sizeof(data);
	out = malloc(size);

	err = EVP_CipherUpdate(ctx, out, &outlen, data, size);
	if (!err) {
		print_ssl_error_stack();
		return 1;
	}

	err = EVP_CipherFinal_ex(ctx, out, &outlen);
	if (!err) {
		print_ssl_error_stack();
		return 1;
	}

	return 0;
}

[root@localhost ~]# gcc fips.c -o fips -lssl -lcrypto
[root@localhost ~]# ./fips 
ERR lib=6 reason=200 err=disabled for FIPS