Remove duplicated sha1 implementation (Fixes #6568)

The Hash library had its own copy of a loop-unrolled sha1 implementation
adding a large code footprint for no good reason, as there are several
sha1 implementations already in tree (one in NONOS-SDK as well as one
in bearssl). Switching to the bearssl one is straightforward and removes
about 3kb of code size overhead.

Also cleanup some obvious inefficiencies (copy by value, string
summing, no reservation causing repeated reallocations) in the
implementation.

Author: dirkmueller

libraries/Hash/src/Hash.cpp

@@ -23,13 +23,10 @@
  */
 
 #include <Arduino.h>
+#include <bearssl/bearssl_hash.h>
 
 #include "Hash.h"
 
-extern "C" {
-#include "sha1/sha1.h"
-}
-
 /**
  * create a sha1 hash from data
  * @param data uint8_t *
@@ -38,7 +35,7 @@ extern "C" {
  */
 void sha1(uint8_t * data, uint32_t size, uint8_t hash[20]) {
 
-    SHA1_CTX ctx;
+    br_sha1_context ctx;
 
 #ifdef DEBUG_SHA1
     os_printf("DATA:");
@@ -53,9 +50,9 @@ void sha1(uint8_t * data, uint32_t size, uint8_t hash[20]) {
     os_printf("\n");
 #endif
 
-    SHA1Init(&ctx);
-    SHA1Update(&ctx, data, size);
-    SHA1Final(hash, &ctx);
+    br_sha1_init(&ctx);
+    br_sha1_update(&ctx, data, size);
+    br_sha1_out(&ctx, hash);
 
 #ifdef DEBUG_SHA1
     os_printf("SHA1:");
@@ -78,20 +75,21 @@ void sha1(const char * data, uint32_t size, uint8_t hash[20]) {
     sha1((uint8_t *) data, size, hash);
 }
 
-void sha1(String data, uint8_t hash[20]) {
+void sha1(const String& data, uint8_t hash[20]) {
     sha1(data.c_str(), data.length(), hash);
 }
 
 String sha1(uint8_t* data, uint32_t size) {
     uint8_t hash[20];
-    String hashStr = "";
+    String hashStr((const char*)nullptr);
+    hashStr.reserve(20 * 2 + 1);
 
     sha1(&data[0], size, &hash[0]);
 
     for(uint16_t i = 0; i < 20; i++) {
         String hex = String(hash[i], HEX);
-        if(hex.length() < 2) {
-            hex = "0" + hex;
+        if(hash[i] < 0x10) {
+            hashStr += '0';
         }
         hashStr += hex;
     }
@@ -111,7 +109,7 @@ String sha1(const char* data, uint32_t size) {
     return sha1((uint8_t*) data, size);
 }
 
-String sha1(String data) {
+String sha1(const String& data) {
     return sha1(data.c_str(), data.length());
 }
 

libraries/Hash/src/Hash.h

@@ -31,12 +31,12 @@ void sha1(uint8_t * data, uint32_t size, uint8_t hash[20]);
 void sha1(char * data, uint32_t size, uint8_t hash[20]);
 void sha1(const uint8_t * data, uint32_t size, uint8_t hash[20]);
 void sha1(const char * data, uint32_t size, uint8_t hash[20]);
-void sha1(String data, uint8_t hash[20]);
+void sha1(const String& data, uint8_t hash[20]);
 
 String sha1(uint8_t* data, uint32_t size);
 String sha1(char* data, uint32_t size);
 String sha1(const uint8_t* data, uint32_t size);
 String sha1(const char* data, uint32_t size);
-String sha1(String data);
+String sha1(const String& data);
 
 #endif /* HASH_H_ */