ESP32 Forum

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mbedtls_pk_init(&_context);                                     // this just zeros out the internal pointers

int rc = mbedtls_pk_parse_key(
    &_context,
    (const uint8_t *) privateKey.c_str(),
    privateKey.length() + 1,
    nullptr,
    0);

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{
  "alg": "RS256",
  "typ": "JWT"
}

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{
  "iat": 1535218434,
  "exp": 1535222034,
  "aud": "YOUR-GCP-PROJECT-ID"
}

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ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_

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  uint8_t hash[32];
  int rc = mbedtls_md(
  		mbedtls_md_info_from_type(MBEDTLS_MD_SHA256),
  		(const uint8_t *)str.c_str(), str.length(), hash);

  size_t sig_len = mbedtls_pk_get_len(context);
  uint8_t *sig=(uint8_t *)calloc(sig_len,1);

  // sign the hash

  rc = mbedtls_pk_sign(
  		context,
  		MBEDTLS_MD_SHA256,
      hash,
      sizeof(hash),
      sig,
      &sig_len,
      NULL,NULL);

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using System.Security;
using System.Text;
using System.IdentityModel;
using Microsoft.IdentityModel;
using Microsoft.IdentityModel.Tokens;
using System.IdentityModel.Tokens;
using System.IdentityModel.Tokens.Jwt;

           // Create Security key  using private key above:
           // not that latest version of JWT using Microsoft namespace instead of System
            var securityKey = new Microsoft
               .IdentityModel.Tokens.SymmetricSecurityKey(Encoding.UTF8.GetBytes(key));

            // Also note that securityKey length should be >256b
            // so you have to make sure that your private key has a proper length
            //
            var credentials = new Microsoft.IdentityModel.Tokens.SigningCredentials
                              (securityKey, SecurityAlgorithms.HmacSha256Signature);

            //  Finally create a Token
            var header = new JwtHeader(credentials);
            string alg = header.Alg;

            //Some PayLoad that contain information about the  customer
            var payload = new JwtPayload
           {
               { "some ", "hello "},
               { "scope", "http://dummy.com/"},
           };

            //
            var secToken = new JwtSecurityToken(header, payload);
            var handler = new JwtSecurityTokenHandler();

            // Token to String so you can use it in your client
            string tokenString = handler.WriteToken(secToken);