Add JWS utility

src/ECP256Certificate.cpp

@@ -15,6 +15,7 @@
 /* This is needed for memmem */
 #define _GNU_SOURCE
 #include <string.h>
+#include <utility/SElementBase64.h>
 #include "ECP256Certificate.h"
 
 /******************************************************************************
@@ -29,58 +30,6 @@
 #define ASN1_SEQUENCE          0x30
 #define ASN1_SET               0x31
 
-/******************************************************************************
- * LOCAL MODULE FUNCTIONS
- ******************************************************************************/
-
-static String base64Encode(const byte in[], unsigned int length, const char* prefix, const char* suffix) {
-  static const char* CODES = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
-
-  int b;
-  String out;
-
-  int reserveLength = 4 * ((length + 2) / 3) + ((length / 3 * 4) / 76) + strlen(prefix) + strlen(suffix);
-  out.reserve(reserveLength);
-
-  if (prefix) {
-    out += prefix;
-  }
-
-  for (unsigned int i = 0; i < length; i += 3) {
-    if (i > 0 && (i / 3 * 4) % 76 == 0) {
-      out += '\n';
-    }
-
-    b = (in[i] & 0xFC) >> 2;
-    out += CODES[b];
-
-    b = (in[i] & 0x03) << 4;
-    if (i + 1 < length) {
-      b |= (in[i + 1] & 0xF0) >> 4;
-      out += CODES[b];
-      b = (in[i + 1] & 0x0F) << 2;
-      if (i + 2 < length) {
-        b |= (in[i + 2] & 0xC0) >> 6;
-        out += CODES[b];
-        b = in[i + 2] & 0x3F;
-        out += CODES[b];
-      } else {
-        out += CODES[b];
-        out += '=';
-      }
-    } else {
-      out += CODES[b];
-      out += "==";
-    }
-  }
-
-  if (suffix) {
-    out += suffix;
-  }
-
-  return out;
-}
-
 /******************************************************************************
  * CTOR/DTOR
  ******************************************************************************/
@@ -184,7 +133,7 @@ int ECP256Certificate::signCSR(byte * signature)
 
 String ECP256Certificate::getCSRPEM()
 {
-  return base64Encode(_certBuffer, _certBufferLen, "-----BEGIN CERTIFICATE REQUEST-----\n", "\n-----END CERTIFICATE REQUEST-----\n");
+  return b64::encode(_certBuffer, _certBufferLen, "-----BEGIN CERTIFICATE REQUEST-----\n", "\n-----END CERTIFICATE REQUEST-----\n");
 }
 
 int ECP256Certificate::buildCert()
@@ -323,7 +272,7 @@ int ECP256Certificate::signCert()
 
 String ECP256Certificate::getCertPEM()
 {
-  return base64Encode(_certBuffer, _certBufferLen, "-----BEGIN CERTIFICATE-----\n", "\n-----END CERTIFICATE-----\n");
+  return b64::encode(_certBuffer, _certBufferLen, "-----BEGIN CERTIFICATE-----\n", "\n-----END CERTIFICATE-----\n");
 }
 
 void ECP256Certificate::getDateFromCompressedData(DateInfo& date) {

src/ECP256Certificate.h

@@ -101,6 +101,11 @@ class ECP256Certificate {
   /* Import DER buffer into CertClass*/
   int importCert(const byte certDER[], size_t derLen);
 
+protected:
+
+  int publicKeyLength();
+  int appendPublicKey(const byte publicKey[], byte out[]);
+
 private:
 
   struct CertInfo {
@@ -154,7 +159,6 @@ class ECP256Certificate {
   int versionLength();
   int issuerOrSubjectLength(const CertInfo& issuerOrSubjectData);
   int sequenceHeaderLength(int length);
-  int publicKeyLength();
   int signatureLength(const byte signature[]);
   int serialNumberLength(const byte serialNumber[], int length);
   int authorityKeyIdLength(const byte authorityKeyId[], int length);
@@ -171,7 +175,6 @@ class ECP256Certificate {
   int appendVersion(int version, byte out[]);
   int appendName(const String& name, int type, byte out[]);
   int appendIssuerOrSubject(const CertInfo& issuerOrSubjectData, byte out[]);
-  int appendPublicKey(const byte publicKey[], byte out[]);
   int appendSignature(const byte signature[], byte out[]);
   int appendSerialNumber(const byte serialNumber[], int length, byte out[]);
   int appendDate(int year, int month, int day, int hour, int minute, int second, byte out[]);

src/utility/SElementArduinoCloudJWT.cpp

@@ -0,0 +1,23 @@
+/*
+  This file is part of the Arduino_SecureElement library.
+
+  Copyright (c) 2024 Arduino SA
+
+  This Source Code Form is subject to the terms of the Mozilla Public
+  License, v. 2.0. If a copy of the MPL was not distributed with this
+  file, You can obtain one at http://mozilla.org/MPL/2.0/.
+*/
+#include "SElementArduinoCloudJWT.h"
+
+constexpr char JWT_HEADER[] = "{\"alg\":\"ES256\",\"typ\":\"JWT\"}";
+String getAIoTCloudJWT(SecureElement &se, String issuer, uint64_t iat, uint8_t slot)
+{
+  SElementJWS jws;
+  String jwtClaim = "{\"iat\":";
+  jwtClaim += String((uint32_t)iat);
+  jwtClaim += ",\"iss\":\"";
+  jwtClaim += issuer;
+  jwtClaim += "\"}";
+  String token = jws.sign(se, slot, JWT_HEADER, jwtClaim.c_str());
+  return token;
+}

src/utility/SElementArduinoCloudJWT.h

@@ -0,0 +1,17 @@
+/*
+  This file is part of the Arduino_SecureElement library.
+
+  Copyright (c) 2024 Arduino SA
+
+  This Source Code Form is subject to the terms of the Mozilla Public
+  License, v. 2.0. If a copy of the MPL was not distributed with this
+  file, You can obtain one at http://mozilla.org/MPL/2.0/.
+*/
+
+#ifndef SECURE_ELEMENT_AIoTCloud_JWT_H_
+#define SECURE_ELEMENT_AIoTCloud_JWT_H_
+#include "SElementJWS.h"
+
+String getAIoTCloudJWT(SecureElement &se, String issuer, uint64_t iat, uint8_t slot = 1);
+
+#endif

src/utility/SElementBase64.cpp

@@ -0,0 +1,101 @@
+/*
+    This file is part of the Arduino_SecureElement library.
+
+    Copyright (c) 2024 Arduino SA
+
+    This Source Code Form is subject to the terms of the Mozilla Public
+    License, v. 2.0. If a copy of the MPL was not distributed with this
+    file, You can obtain one at http://mozilla.org/MPL/2.0/.
+*/
+
+#include <utility/SElementBase64.h>
+
+namespace arduino { namespace b64 {
+
+String urlEncode(const byte in[], unsigned int length) {
+  static const char* CODES = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_=";
+
+  int b;
+  String out;
+
+  int reserveLength = 4 * ((length + 2) / 3);
+  out.reserve(reserveLength);
+
+  for (unsigned int i = 0; i < length; i += 3) {
+    b = (in[i] & 0xFC) >> 2;
+    out += CODES[b];
+
+    b = (in[i] & 0x03) << 4;
+    if (i + 1 < length) {
+      b |= (in[i + 1] & 0xF0) >> 4;
+      out += CODES[b];
+      b = (in[i + 1] & 0x0F) << 2;
+      if (i + 2 < length) {
+         b |= (in[i + 2] & 0xC0) >> 6;
+         out += CODES[b];
+         b = in[i + 2] & 0x3F;
+         out += CODES[b];
+      } else {
+        out += CODES[b];
+      }
+    } else {
+      out += CODES[b];
+    }
+  }
+
+  while (out.lastIndexOf('=') != -1) {
+    out.remove(out.length() - 1);
+  }
+
+  return out;
+}
+
+String encode(const byte in[], unsigned int length, const char* prefix, const char* suffix) {
+static const char* CODES = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
+
+  int b;
+  String out;
+
+  int reserveLength = 4 * ((length + 2) / 3) + ((length / 3 * 4) / 76) + strlen(prefix) + strlen(suffix);
+  out.reserve(reserveLength);
+
+  if (prefix) {
+    out += prefix;
+  }
+
+  for (unsigned int i = 0; i < length; i += 3) {
+    if (i > 0 && (i / 3 * 4) % 76 == 0) {
+      out += '\n';
+    }
+
+    b = (in[i] & 0xFC) >> 2;
+    out += CODES[b];
+
+    b = (in[i] & 0x03) << 4;
+    if (i + 1 < length) {
+      b |= (in[i + 1] & 0xF0) >> 4;
+      out += CODES[b];
+      b = (in[i + 1] & 0x0F) << 2;
+      if (i + 2 < length) {
+        b |= (in[i + 2] & 0xC0) >> 6;
+        out += CODES[b];
+        b = in[i + 2] & 0x3F;
+        out += CODES[b];
+      } else {
+        out += CODES[b];
+        out += '=';
+      }
+    } else {
+      out += CODES[b];
+      out += "==";
+    }
+  }
+
+  if (suffix) {
+    out += suffix;
+  }
+
+  return out;
+}
+
+}} // arduino::b64

src/utility/SElementBase64.h

@@ -0,0 +1,20 @@
+/*
+    This file is part of the Arduino_SecureElement library.
+
+    Copyright (c) 2024 Arduino SA
+
+    This Source Code Form is subject to the terms of the Mozilla Public
+    License, v. 2.0. If a copy of the MPL was not distributed with this
+    file, You can obtain one at http://mozilla.org/MPL/2.0/.
+*/
+
+#pragma once
+
+#include <Arduino.h>
+
+namespace arduino { namespace b64 {
+
+    String urlEncode(const byte in[], unsigned int length);
+    String encode(const byte in[], unsigned int length, const char* prefix, const char* suffix);
+
+}} // arduino::b64

src/utility/SElementJWS.cpp

@@ -0,0 +1,85 @@
+/*
+  This file is part of the Arduino_SecureElement library.
+
+  Copyright (c) 2024 Arduino SA
+
+  This Source Code Form is subject to the terms of the Mozilla Public
+  License, v. 2.0. If a copy of the MPL was not distributed with this
+  file, You can obtain one at http://mozilla.org/MPL/2.0/.
+*/
+
+/******************************************************************************
+ * INCLUDE
+ ******************************************************************************/
+
+#include <utility/SElementJWS.h>
+#include <utility/SElementBase64.h>
+
+String SElementJWS::publicKey(SecureElement & se, int slot, bool newPrivateKey)
+{
+  if (slot < 0 || slot > 8) {
+    return "";
+  }
+
+  byte publicKey[64];
+
+  if (newPrivateKey) {
+    if (!se.generatePrivateKey(slot, publicKey)) {
+      return "";
+    }
+  } else {
+    if (!se.generatePublicKey(slot, publicKey)) {
+      return "";
+    }
+  }
+
+  int length = publicKeyLength();
+  byte out[length];
+
+  appendPublicKey(publicKey, out);
+
+  return b64::encode(out, length, "-----BEGIN PUBLIC KEY-----\n", "\n-----END PUBLIC KEY-----\n");
+}
+
+String SElementJWS::sign(SecureElement & se, int slot, const char* header, const char* payload)
+{
+  if (slot < 0 || slot > 8) {
+    return "";
+  }
+
+  String encodedHeader = b64::urlEncode((const byte*)header, strlen(header));
+  String encodedPayload = b64::urlEncode((const byte*)payload, strlen(payload));
+
+  String toSign;
+  toSign.reserve(encodedHeader.length() + 1 + encodedPayload.length());
+
+  toSign += encodedHeader;
+  toSign += '.';
+  toSign += encodedPayload;
+
+
+  byte toSignSha256[32];
+  byte signature[64];
+
+  se.SHA256((const uint8_t*)toSign.c_str(), toSign.length(), toSignSha256);
+
+  if (!se.ecSign(slot, toSignSha256, signature)) {
+    return "";
+  }
+
+  String encodedSignature = b64::urlEncode(signature, sizeof(signature));
+
+  String result;
+  result.reserve(toSign.length() + 1 + encodedSignature.length());
+
+  result += toSign;
+  result += '.';
+  result += encodedSignature;
+
+  return result;
+}
+
+String SElementJWS::sign(SecureElement & se, int slot, const String& header, const String& payload)
+{
+  return sign(se, slot, header.c_str(), payload.c_str());
+}