CTR_DRBG: Don't use functions before they're defined
Move the definitions of mbedtls_ctr_drbg_seed_entropy_len() and
mbedtls_ctr_drbg_seed() to after they are used. This makes the code
easier to read and to maintain.
diff --git a/library/ctr_drbg.c b/library/ctr_drbg.c
index 069303f..9222f4e 100644
--- a/library/ctr_drbg.c
+++ b/library/ctr_drbg.c
@@ -62,68 +62,6 @@
#endif
}
-/*
- * Non-public function wrapped by mbedtls_ctr_drbg_seed(). Necessary to allow
- * NIST tests to succeed (which require known length fixed entropy)
- */
-/* CTR_DRBG_Instantiate with derivation function (SP 800-90A §10.2.1.3.2)
- * mbedtls_ctr_drbg_seed_entropy_len(ctx, f_entropy, p_entropy,
- * custom, len, entropy_len)
- * implements
- * CTR_DRBG_Instantiate(entropy_input, nonce, personalization_string,
- * security_strength) -> initial_working_state
- * with inputs
- * custom[:len] = nonce || personalization_string
- * where entropy_input comes from f_entropy for entropy_len bytes
- * and with outputs
- * ctx = initial_working_state
- */
-int mbedtls_ctr_drbg_seed_entropy_len(
- mbedtls_ctr_drbg_context *ctx,
- int (*f_entropy)(void *, unsigned char *, size_t),
- void *p_entropy,
- const unsigned char *custom,
- size_t len,
- size_t entropy_len )
-{
- int ret;
- unsigned char key[MBEDTLS_CTR_DRBG_KEYSIZE];
-
- mbedtls_platform_memset( key, 0, MBEDTLS_CTR_DRBG_KEYSIZE );
-
- mbedtls_aes_init( &ctx->aes_ctx );
-
- ctx->f_entropy = f_entropy;
- ctx->p_entropy = p_entropy;
-
- ctx->entropy_len = entropy_len;
- ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;
-
- /*
- * Initialize with an empty key
- */
- if( ( ret = mbedtls_aes_setkey_enc( &ctx->aes_ctx, key, MBEDTLS_CTR_DRBG_KEYBITS ) ) != 0 )
- {
- return( ret );
- }
-
- if( ( ret = mbedtls_ctr_drbg_reseed( ctx, custom, len ) ) != 0 )
- {
- return( ret );
- }
- return( 0 );
-}
-
-int mbedtls_ctr_drbg_seed( mbedtls_ctr_drbg_context *ctx,
- int (*f_entropy)(void *, unsigned char *, size_t),
- void *p_entropy,
- const unsigned char *custom,
- size_t len )
-{
- return( mbedtls_ctr_drbg_seed_entropy_len( ctx, f_entropy, p_entropy, custom, len,
- MBEDTLS_CTR_DRBG_ENTROPY_LEN ) );
-}
-
void mbedtls_ctr_drbg_free( mbedtls_ctr_drbg_context *ctx )
{
if( ctx == NULL )
@@ -427,6 +365,68 @@
return( ret );
}
+/*
+ * Non-public function wrapped by mbedtls_ctr_drbg_seed(). Necessary to allow
+ * NIST tests to succeed (which require known length fixed entropy)
+ */
+/* CTR_DRBG_Instantiate with derivation function (SP 800-90A §10.2.1.3.2)
+ * mbedtls_ctr_drbg_seed_entropy_len(ctx, f_entropy, p_entropy,
+ * custom, len, entropy_len)
+ * implements
+ * CTR_DRBG_Instantiate(entropy_input, nonce, personalization_string,
+ * security_strength) -> initial_working_state
+ * with inputs
+ * custom[:len] = nonce || personalization_string
+ * where entropy_input comes from f_entropy for entropy_len bytes
+ * and with outputs
+ * ctx = initial_working_state
+ */
+int mbedtls_ctr_drbg_seed_entropy_len(
+ mbedtls_ctr_drbg_context *ctx,
+ int (*f_entropy)(void *, unsigned char *, size_t),
+ void *p_entropy,
+ const unsigned char *custom,
+ size_t len,
+ size_t entropy_len )
+{
+ int ret;
+ unsigned char key[MBEDTLS_CTR_DRBG_KEYSIZE];
+
+ memset( key, 0, MBEDTLS_CTR_DRBG_KEYSIZE );
+
+ mbedtls_aes_init( &ctx->aes_ctx );
+
+ ctx->f_entropy = f_entropy;
+ ctx->p_entropy = p_entropy;
+
+ ctx->entropy_len = entropy_len;
+ ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;
+
+ /*
+ * Initialize with an empty key
+ */
+ if( ( ret = mbedtls_aes_setkey_enc( &ctx->aes_ctx, key, MBEDTLS_CTR_DRBG_KEYBITS ) ) != 0 )
+ {
+ return( ret );
+ }
+
+ if( ( ret = mbedtls_ctr_drbg_reseed( ctx, custom, len ) ) != 0 )
+ {
+ return( ret );
+ }
+ return( 0 );
+}
+
+int mbedtls_ctr_drbg_seed( mbedtls_ctr_drbg_context *ctx,
+ int (*f_entropy)(void *, unsigned char *, size_t),
+ void *p_entropy,
+ const unsigned char *custom,
+ size_t len )
+{
+ return( mbedtls_ctr_drbg_seed_entropy_len( ctx, f_entropy, p_entropy, custom, len,
+ MBEDTLS_CTR_DRBG_ENTROPY_LEN ) );
+}
+
/* CTR_DRBG_Generate with derivation function (SP 800-90A §10.2.1.5.2)
* mbedtls_ctr_drbg_random_with_add(ctx, output, output_len, additional, add_len)
* implements