Add MBEDTLS_ENTROPY_HARDWARE_ALT
Makes it easier for an external module to plug its hardware entropy collector.
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 3c0fb13..f1cfe75 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -278,6 +278,19 @@
//#define MBEDTLS_AES_DECRYPT_ALT
/**
+ * \def MBEDTLS_EMTROPY_HARDWARE_ALT
+ *
+ * Uncomment this macro to let mbed TLS use your own implementation of a
+ * hardware entropy collector.
+ *
+ * Your function must be called \c mbedtls_hardware_poll(), have the same
+ * prototype as declared in entropy_poll.h, and accept NULL as first argument.
+ *
+ * Uncomment to use your own hardware entropy collector.
+ */
+//#define MBEDTLS_ENTROPY_HARDWARE_ALT
+
+/**
* \def MBEDTLS_AES_ROM_TABLES
*
* Store the AES tables in ROM.
diff --git a/include/mbedtls/entropy_poll.h b/include/mbedtls/entropy_poll.h
index 231042e..8ee1e1a 100644
--- a/include/mbedtls/entropy_poll.h
+++ b/include/mbedtls/entropy_poll.h
@@ -42,6 +42,7 @@
#define MBEDTLS_ENTROPY_MIN_PLATFORM 32 /**< Minimum for platform source */
#define MBEDTLS_ENTROPY_MIN_HAVEGE 32 /**< Minimum for HAVEGE */
#define MBEDTLS_ENTROPY_MIN_HARDCLOCK 4 /**< Minimum for mbedtls_timing_hardclock() */
+#define MBEDTLS_ENTROPY_MIN_HARDWARE 32 /**< Minimum for the hardware source */
#if !defined(MBEDTLS_NO_PLATFORM_ENTROPY)
/**
@@ -69,6 +70,19 @@
unsigned char *output, size_t len, size_t *olen );
#endif
+#if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
+/**
+ * \brief Entropy poll callback for a hardware source
+ *
+ * \warning This is not provided by mbed TLS!
+ * See \c MBEDTLS_ENTROPY_HARDWARE_ALT in config.h.
+ *
+ * \note This must accept NULL as its first argument.
+ */
+int mbedtls_hardware_poll( void *data,
+ unsigned char *output, size_t len, size_t *olen );
+#endif
+
#ifdef __cplusplus
}
#endif
diff --git a/library/entropy.c b/library/entropy.c
index fa3dcde..4dddb75 100644
--- a/library/entropy.c
+++ b/library/entropy.c
@@ -86,6 +86,10 @@
mbedtls_entropy_add_source( ctx, mbedtls_havege_poll, &ctx->havege_data,
MBEDTLS_ENTROPY_MIN_HAVEGE );
#endif
+#if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
+ mbedtls_entropy_add_source( ctx, mbedtls_hardware_poll, NULL
+ MBEDTLS_ENTROPY_MIN_HARDWARE );
+#endif
#endif /* MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES */
}