readability code clean-up (#532)

include/speck.h

@@ -17,7 +17,7 @@
  */
 
 
-// cipher SPECK -- 128 bit block size -- 256 bit key size
+// cipher SPECK -- 128 bit block size -- 256 bit key size -- CTR mode
 // taken from (and modified: removed pure crypto-stream generation and seperated key expansion)
 // https://github.com/nsacyber/simon-speck-supercop/blob/master/crypto_stream/speck128256ctr/
 
@@ -25,10 +25,13 @@
 #ifndef SPECK_H
 #define SPECK_H
 
+
 #include <stdint.h>
 #include <stdlib.h>
+
 #include "portable_endian.h"
 
+
 #define u32 uint32_t
 #define u64 uint64_t
 
@@ -36,45 +39,60 @@
 #define SPECK_KEY_BYTES       (256/8)
 
 
-#if defined (__AVX2__)
+#if defined (__AVX2__) // AVX support -----------------------------------------------------------------------------
+
 
 #include <immintrin.h>
-#define SPECK_ALIGNED_CTX	32
+
 #define u256 __m256i
+
+#define SPECK_ALIGNED_CTX	32
+
 typedef struct {
-  u256 rk[34];
-  u64 key[34];
+    u256 rk[34];
+    u64 key[34];
 } speck_context_t;
 
-#elif defined (__SSE2__)
+
+#elif defined (__SSE2__) // SSE support ---------------------------------------------------------------------------
+
 
 #include <immintrin.h>
+
+#define u128 __m128i
+
 #define SPECK_ALIGNED_CTX	16
 #define SPECK_CTX_BYVAL		 1
-#define u128 __m128i
+
 typedef struct {
-  u128 rk[34];
-  u64 key[34];
+    u128 rk[34];
+    u64 key[34];
 } speck_context_t;
 
-#elif defined (__ARM_NEON)
+
+#elif defined (__ARM_NEON) // NEON support ------------------------------------------------------------------------
+
 
 #include <arm_neon.h>
+
 #define u128 uint64x2_t
-typedef struct {
-  u128 rk[34];
-  u64 key[34];
-} speck_context_t;
-
-#else
 
 typedef struct {
-  u64 key[34];
+   u128 rk[34];
+   u64 key[34];
 } speck_context_t;
 
-#endif
 
-// -----
+#else // plain C --------------------------------------------------------------------------------------------------
+
+
+typedef struct {
+    u64 key[34];
+} speck_context_t;
+
+
+#endif // ---------------------------------------------------------------------------------------------------------
+
 
 int speck_ctr (unsigned char *out, const unsigned char *in, unsigned long long inlen,
                const unsigned char *n,
@@ -84,14 +102,29 @@ int speck_init (const unsigned char *k, speck_context_t **ctx);
 
 int speck_deinit (speck_context_t *ctx);
 
-// -----
+
+// ----------------------------------------------------------------------------------------------------------------
+
+
+// cipher SPECK -- 128 bit block size -- 128 bit key size -- CTR mode
+// used for header encryption, thus the postfix '_he'
+// for now: just plain C -- AVX, SSE, NEON do not make sense for short header
+
 
 int speck_he (unsigned char *out, const unsigned char *in, unsigned long long inlen,
               const unsigned char *n, speck_context_t *ctx);
 
 int speck_expand_key_he (const unsigned char *k, speck_context_t *ctx);
 
-// -----
+
+// ----------------------------------------------------------------------------------------------------------------
+
+
+// cipher SPECK -- 96 bit block size -- 96 bit key size -- ECB mode
+// follows endianess rules as used in official implementation guide and NOT as in original 2013 cipher presentation
+// used for IV in header encryption, thus the in/postfix 'he_iv'
+// for now: just plain C -- probably no need for AVX, SSE, NEON
+
 
 int speck_he_iv_encrypt (unsigned char *inout, speck_context_t *ctx);