Remove un-necessarry HMAC implementation, use SDK provided implementation

5 years ago · a4220d631d
4 changed files with 36 additions and 219 deletions
--- a/src/ArduinoJsonJWT.cpp
+++ b/src/ArduinoJsonJWT.cpp
@ -6,13 +6,35 @@ void ArduinoJsonJWT::setSecret(String secret){
    _secret = secret;
 }

-String ArduinoJsonJWT::sign(String &value) {
-  // create signature
-  Sha256.initHmac((uint8_t*) _secret.c_str(), _secret.length());
-  Sha256.print(value);
-
-  // trim and return
-  return encode(Sha256.resultHmac(), 32);
+/*
+ * ESP32 uses mbedtls, ESP2866 uses bearssl.
+ * 
+ * Both come with decent HMAC implmentations supporting sha256, as well as others.
+ * 
+ * No need to pull in additional crypto libraries - lets use what we already have.
+ */
+String ArduinoJsonJWT::sign(String &payload) {
+  unsigned char hmacResult[32];
+  {
+  #if defined(ESP_PLATFORM)
+    mbedtls_md_context_t ctx;
+    mbedtls_md_type_t md_type = MBEDTLS_MD_SHA256;  
+    mbedtls_md_init(&ctx);
+    mbedtls_md_setup(&ctx, mbedtls_md_info_from_type(md_type), 1);
+    mbedtls_md_hmac_starts(&ctx, (unsigned char *) _secret.c_str(), _secret.length());
+    mbedtls_md_hmac_update(&ctx, (unsigned char *) payload.c_str(), payload.length());
+    mbedtls_md_hmac_finish(&ctx, hmacResult);
+    mbedtls_md_free(&ctx);
+  #else
+    br_hmac_key_context keyCtx;
+    br_hmac_key_init(&keyCtx, &br_sha256_vtable, _secret.c_str(), _secret.length());
+    br_hmac_context hmacCtx;
+    br_hmac_init(&hmacCtx, &keyCtx, 0);
+    br_hmac_update(&hmacCtx, payload.c_str(), payload.length());
+    br_hmac_out(&hmacCtx, hmacResult);
+  #endif
+  }
+  return encode(hmacResult, 32);
 }

 String ArduinoJsonJWT::decode(unsigned char * value) {
@ -52,7 +74,7 @@ String ArduinoJsonJWT::buildJWT(JsonObject &payload) {

  // add the header to payload
  jwt = JWT_HEADER + '.' + jwt;
- 
+  
  // add signature
  jwt  += '.' + sign(jwt);

--- a/src/ArduinoJsonJWT.h
+++ b/src/ArduinoJsonJWT.h
@ -1,12 +1,17 @@
 #ifndef ArduinoJsonJWT_H
 #define ArduinoJsonJWT_H

-#include "sha256.h"
 #include "base64.h"

 #include <Arduino.h>
 #include <ArduinoJson.h>

+#if defined(ESP_PLATFORM)
+  #include <mbedtls/md.h>
+#else
+  #include <bearssl/bearssl_hmac.h>
+#endif 
+
 #define JWT_HEADER_SIZE 36
 #define JWT_SIG_SIZE 43

--- a/src/sha256.cpp
+++ b/src/sha256.cpp
@ -1,168 +0,0 @@
-#include "sha256.h"
-
-#include <string.h>
-
-uint32_t sha256K[] PROGMEM = {
-  0x428a2f98,0x71374491,0xb5c0fbcf,0xe9b5dba5,0x3956c25b,0x59f111f1,0x923f82a4,0xab1c5ed5,
-  0xd807aa98,0x12835b01,0x243185be,0x550c7dc3,0x72be5d74,0x80deb1fe,0x9bdc06a7,0xc19bf174,
-  0xe49b69c1,0xefbe4786,0x0fc19dc6,0x240ca1cc,0x2de92c6f,0x4a7484aa,0x5cb0a9dc,0x76f988da,
-  0x983e5152,0xa831c66d,0xb00327c8,0xbf597fc7,0xc6e00bf3,0xd5a79147,0x06ca6351,0x14292967,
-  0x27b70a85,0x2e1b2138,0x4d2c6dfc,0x53380d13,0x650a7354,0x766a0abb,0x81c2c92e,0x92722c85,
-  0xa2bfe8a1,0xa81a664b,0xc24b8b70,0xc76c51a3,0xd192e819,0xd6990624,0xf40e3585,0x106aa070,
-  0x19a4c116,0x1e376c08,0x2748774c,0x34b0bcb5,0x391c0cb3,0x4ed8aa4a,0x5b9cca4f,0x682e6ff3,
-  0x748f82ee,0x78a5636f,0x84c87814,0x8cc70208,0x90befffa,0xa4506ceb,0xbef9a3f7,0xc67178f2
-};
-
-#define BUFFER_SIZE 64
-
-uint8_t sha256InitState[] PROGMEM = {
-  0x67,0xe6,0x09,0x6a, // H0
-  0x85,0xae,0x67,0xbb, // H1
-  0x72,0xf3,0x6e,0x3c, // H2
-  0x3a,0xf5,0x4f,0xa5, // H3
-  0x7f,0x52,0x0e,0x51, // H4
-  0x8c,0x68,0x05,0x9b, // H5
-  0xab,0xd9,0x83,0x1f, // H6
-  0x19,0xcd,0xe0,0x5b  // H7
-};
-
-void Sha256Class::init(void) {
-  memcpy_P(state.b,sha256InitState,32);
-  byteCount = 0;
-  bufferOffset = 0;
-}
-
-uint32_t Sha256Class::ror32(uint32_t number, uint8_t bits) {
-  return ((number << (32-bits)) | (number >> bits));
-}
-
-void Sha256Class::hashBlock() {
-  uint8_t i;
-  uint32_t a,b,c,d,e,f,g,h,t1,t2;
-
-  a=state.w[0];
-  b=state.w[1];
-  c=state.w[2];
-  d=state.w[3];
-  e=state.w[4];
-  f=state.w[5];
-  g=state.w[6];
-  h=state.w[7];
-  
-  for (i=0; i<64; i++) {
-    if (i>=16) {
-      t1 = buffer.w[i&15] + buffer.w[(i-7)&15];
-      t2 = buffer.w[(i-2)&15];
-      t1 += ror32(t2,17) ^ ror32(t2,19) ^ (t2>>10);
-      t2 = buffer.w[(i-15)&15];
-      t1 += ror32(t2,7) ^ ror32(t2,18) ^ (t2>>3);
-      buffer.w[i&15] = t1;
-    }
-    t1 = h;
-    t1 += ror32(e,6) ^ ror32(e,11) ^ ror32(e,25); // ∑1(e)
-    t1 += g ^ (e & (g ^ f)); // Ch(e,f,g)
-    t1 += pgm_read_dword(sha256K+i); // Ki
-    t1 += buffer.w[i&15]; // Wi
-    t2 = ror32(a,2) ^ ror32(a,13) ^ ror32(a,22); // ∑0(a)
-    t2 += ((b & c) | (a & (b | c))); // Maj(a,b,c)
-    h=g; g=f; f=e; e=d+t1; d=c; c=b; b=a; a=t1+t2;
-  }
-  state.w[0] += a;
-  state.w[1] += b;
-  state.w[2] += c;
-  state.w[3] += d;
-  state.w[4] += e;
-  state.w[5] += f;
-  state.w[6] += g;
-  state.w[7] += h;
-}
-
-void Sha256Class::addUncounted(uint8_t data) {
-  buffer.b[bufferOffset ^ 3] = data;
-  bufferOffset++;
-  if (bufferOffset == BUFFER_SIZE) {
-    hashBlock();
-    bufferOffset = 0;
-  }
-}
-
-size_t Sha256Class::write(uint8_t data) {
-  ++byteCount;
-  addUncounted(data);
-  return 1;
-}
-
-void Sha256Class::pad() {
-  // Implement SHA-256 padding (fips180-2 §5.1.1)
-
-  // Pad with 0x80 followed by 0x00 until the end of the block
-  addUncounted(0x80);
-  while (bufferOffset != 56) addUncounted(0x00);
-
-  // Append length in the last 8 bytes
-  addUncounted(0); // We're only using 32 bit lengths
-  addUncounted(0); // But SHA-1 supports 64 bit lengths
-  addUncounted(0); // So zero pad the top bits
-  addUncounted(byteCount >> 29); // Shifting to multiply by 8
-  addUncounted(byteCount >> 21); // as SHA-1 supports bitstreams as well as
-  addUncounted(byteCount >> 13); // byte.
-  addUncounted(byteCount >> 5);
-  addUncounted(byteCount << 3);
-}
-
-
-uint8_t* Sha256Class::result(void) {
-  // Pad to complete the last block
-  pad();
-  
-  // Swap byte order back
-  for (int i=0; i<8; i++) {
-    uint32_t a,b;
-    a=state.w[i];
-    b=a<<24;
-    b|=(a<<8) & 0x00ff0000;
-    b|=(a>>8) & 0x0000ff00;
-    b|=a>>24;
-    state.w[i]=b;
-  }
-  
-  // Return pointer to hash (20 characters)
-  return state.b;
-}
-
-#define HMAC_IPAD 0x36
-#define HMAC_OPAD 0x5c
-
-uint8_t keyBuffer[BLOCK_LENGTH]; // K0 in FIPS-198a
-uint8_t innerHash[HASH_LENGTH];
-
-void Sha256Class::initHmac(const uint8_t* key, int keyLength) {
-  uint8_t i;
-  memset(keyBuffer,0,BLOCK_LENGTH);
-  if (keyLength > BLOCK_LENGTH) {
-    // Hash long keys
-    init();
-    for (;keyLength--;) write(*key++);
-    memcpy(keyBuffer,result(),HASH_LENGTH);
-  } else {
-    // Block length keys are used as is
-    memcpy(keyBuffer,key,keyLength);
-  }
-  // Start inner hash
-  init();
-  for (i=0; i<BLOCK_LENGTH; i++) {
-    write(keyBuffer[i] ^ HMAC_IPAD);
-  }
-}
-
-uint8_t* Sha256Class::resultHmac(void) {
-  uint8_t i;
-  // Complete inner hash
-  memcpy(innerHash,result(),HASH_LENGTH);
-  // Calculate outer hash
-  init();
-  for (i=0; i<BLOCK_LENGTH; i++) write(keyBuffer[i] ^ HMAC_OPAD);
-  for (i=0; i<HASH_LENGTH; i++) write(innerHash[i]);
-  return result();
-}
-Sha256Class Sha256;
--- a/src/sha256.h
+++ b/src/sha256.h
@ -1,42 +0,0 @@
-#ifndef Sha256_h
-#define Sha256_h
-
-#include <inttypes.h>
-#include "Print.h"
-
-#define HASH_LENGTH 32
-#define BLOCK_LENGTH 64
-
-union _buffer {
-  uint8_t b[BLOCK_LENGTH];
-  uint32_t w[BLOCK_LENGTH/4];
-};
-union _state {
-  uint8_t b[HASH_LENGTH];
-  uint32_t w[HASH_LENGTH/4];
-};
-
-class Sha256Class : public Print
-{
-  public:
-    void init(void);
-    void initHmac(const uint8_t* secret, int secretLength);
-    uint8_t* result(void);
-    uint8_t* resultHmac(void);
-    virtual size_t write(uint8_t);
-    using Print::write;
-  private:
-    void pad();
-    void addUncounted(uint8_t data);
-    void hashBlock();
-    uint32_t ror32(uint32_t number, uint8_t bits);
-    _buffer buffer;
-    uint8_t bufferOffset;
-    _state state;
-    uint32_t byteCount;
-    uint8_t keyBuffer[BLOCK_LENGTH];
-    uint8_t innerHash[HASH_LENGTH];
-};
-extern Sha256Class Sha256;
-
-#endif