mlkem_test: add mlkem-native

sdk/software/examples/mlkem_test/mlkem_native/src/randombytes.h

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) The mlkem-native project authors
+ * SPDX-License-Identifier: Apache-2.0 OR ISC OR MIT
+ */
+#ifndef MLK_RANDOMBYTES_H
+#define MLK_RANDOMBYTES_H
+
+
+#include "cbmc.h"
+#include "common.h"
+
+#if !defined(MLK_CONFIG_NO_RANDOMIZED_API)
+#if !defined(MLK_CONFIG_CUSTOM_RANDOMBYTES)
+/**
+ * Fill a buffer with cryptographically secure random bytes.
+ *
+ * mlkem-native does not provide an implementation of this function.
+ * It must be provided by the consumer.
+ *
+ * To use a custom random byte source with a different name or signature,
+ * set MLK_CONFIG_CUSTOM_RANDOMBYTES and define mlk_randombytes directly.
+ *
+ * @param[out] out    Output buffer.
+ * @param      outlen Number of random bytes to write.
+ *
+ * @retval 0     Success.
+ * @retval other Failure; top-level APIs propagate this as MLK_ERR_RNG_FAIL.
+ */
+int randombytes(uint8_t *out, size_t outlen);
+
+/**
+ * Internal wrapper around randombytes().
+ *
+ * Fills a buffer with cryptographically secure random bytes.
+ *
+ * This function can be replaced by setting MLK_CONFIG_CUSTOM_RANDOMBYTES
+ * and defining mlk_randombytes directly.
+ *
+ * @param[out] out    Output buffer.
+ * @param      outlen Number of random bytes to write.
+ *
+ * @retval 0     Success.
+ * @retval other Failure; top-level APIs propagate this as MLK_ERR_RNG_FAIL.
+ */
+MLK_MUST_CHECK_RETURN_VALUE
+static MLK_INLINE int mlk_randombytes(uint8_t *out, size_t outlen)
+__contract__(
+  requires(memory_no_alias(out, outlen))
+  assigns(memory_slice(out, outlen))) { return randombytes(out, outlen); }
+#endif /* !MLK_CONFIG_CUSTOM_RANDOMBYTES */
+#endif /* !MLK_CONFIG_NO_RANDOMIZED_API */
+#endif /* !MLK_RANDOMBYTES_H */