(C) JWE using ECDH-ES, BP-256, A256GCM

See more JSON Web Encryption (JWE) Examples

Create a JWE with the following header:

	{
	  "alg": "ECDH-ES",
	  "enc": "A256GCM",
	  "exp": 1621957030,
	  "cty": "NJWT",
	  "epk": {
	    "kty": "EC",
	    "x": "QLpJ_LpFx-6yJhsb4OvHwU1khLnviiOwYOvmf5clK7w"
	    "y": "AJh7pJ3zZKDJkm8rbeG69GBooTosXJgSsvNFH0i3Vxnu"
	    "crv": "BP-256"
	  }
	}

Note: This example requires Chilkat v9.5.0.87 or greater.

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#include <C_CkJsonObject.h>
#include <C_CkPublicKey.h>
#include <C_CkJwt.h>
#include <C_CkJwe.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkJsonObject json;
    HCkPublicKey pubkey;
    HCkJwt jwt;
    HCkJsonObject jweProtHdr;
    HCkJwe jwe;
    const char *plainText;
    const char *strJwe;

    // This requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // Load our brainpool BP-256 public key.

    // 	{
    // 	  "use": "enc",
    // 	  "kid": "puk_idp_enc",
    // 	  "kty": "EC",
    // 	  "crv": "BP-256",
    // 	  "x": "QLpJ_LpFx-6yJhsb4OvHwU1khLnviiOwYOvmf5clK7w",
    // 	  "y": "AJh7pJ3zZKDJkm8rbeG69GBooTosXJgSsvNFH0i3Vxnu"
    // 	}

    json = CkJsonObject_Create();
    CkJsonObject_UpdateString(json,"use","enc");
    CkJsonObject_UpdateString(json,"kid","puk_idp_enc");
    CkJsonObject_UpdateString(json,"kty","EC");
    CkJsonObject_UpdateString(json,"crv","BP-256");
    CkJsonObject_UpdateString(json,"x","QLpJ_LpFx-6yJhsb4OvHwU1khLnviiOwYOvmf5clK7w");
    CkJsonObject_UpdateString(json,"y","AJh7pJ3zZKDJkm8rbeG69GBooTosXJgSsvNFH0i3Vxnu");

    pubkey = CkPublicKey_Create();

    success = CkPublicKey_LoadFromString(pubkey,CkJsonObject_emit(json));
    if (success == FALSE) {
        printf("%s\n",CkPublicKey_lastErrorText(pubkey));
        CkJsonObject_Dispose(json);
        CkPublicKey_Dispose(pubkey);
        return;
    }

    // Build our protected header:

    // 	{
    // 	  "alg": "ECDH-ES",
    // 	  "enc": "A256GCM",
    // 	  "exp": 1621957030,
    // 	  "cty": "NJWT",
    // 	  "epk": {
    // 	    "kty": "EC",
    // 	    "x": "QLpJ_LpFx-6yJhsb4OvHwU1khLnviiOwYOvmf5clK7w"
    // 	    "y": "AJh7pJ3zZKDJkm8rbeG69GBooTosXJgSsvNFH0i3Vxnu"
    // 	    "crv": "BP-256"
    // 	  }
    // 	}

    // Use jwt only for getting the current date/time + 3600 seconds.
    jwt = CkJwt_Create();

    jweProtHdr = CkJsonObject_Create();
    CkJsonObject_UpdateString(jweProtHdr,"alg","ECDH-ES");
    CkJsonObject_UpdateString(jweProtHdr,"enc","A256GCM");
    CkJsonObject_UpdateInt(jweProtHdr,"exp",CkJwt_GenNumericDate(jwt,3600));
    CkJsonObject_UpdateString(jweProtHdr,"cty","NJWT");
    CkJsonObject_UpdateString(jweProtHdr,"epk.kty","EC");
    CkJsonObject_UpdateString(jweProtHdr,"epk.x","QLpJ_LpFx-6yJhsb4OvHwU1khLnviiOwYOvmf5clK7w");
    CkJsonObject_UpdateString(jweProtHdr,"epk.y","AJh7pJ3zZKDJkm8rbeG69GBooTosXJgSsvNFH0i3Vxnu");
    CkJsonObject_UpdateString(jweProtHdr,"epk.crv","BP-256");

    jwe = CkJwe_Create();
    CkJwe_SetProtectedHeader(jwe,jweProtHdr);
    CkJwe_SetPublicKey(jwe,0,pubkey);

    plainText = "This is the text to be encrypted.";
    strJwe = CkJwe_encrypt(jwe,plainText,"utf-8");
    if (CkJwe_getLastMethodSuccess(jwe) != TRUE) {
        printf("%s\n",CkJwe_lastErrorText(jwe));
        CkJsonObject_Dispose(json);
        CkPublicKey_Dispose(pubkey);
        CkJwt_Dispose(jwt);
        CkJsonObject_Dispose(jweProtHdr);
        CkJwe_Dispose(jwe);
        return;
    }

    printf("%s\n",strJwe);

    printf("Success.\n");


    CkJsonObject_Dispose(json);
    CkPublicKey_Dispose(pubkey);
    CkJwt_Dispose(jwt);
    CkJsonObject_Dispose(jweProtHdr);
    CkJwe_Dispose(jwe);

    }