.. _mozilla_projects_nss_nss_sample_code_nss_sample_code_sample5:

NSS Sample Code sample5
=======================

.. _nss_sample_code_5_pki_encryption_with_a_raw_public_private_key_in_der_format:

`NSS Sample Code 5: PKI Encryption with a raw public & private key in DER format <#nss_sample_code_5_pki_encryption_with_a_raw_public_private_key_in_der_format>`__
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.. container::

   .. code::

      /* Example code to illustrate PKI crypto ops (encrypt with public key,
       * decrypt with private key)
       *
       * No NSS db needed. The Public Key & Private Key to use are
       * sourced from a base64-encoded DER SubjectPublicKeyInfo structure,
       * and a base64-encoded DER PrivateKeyInfo structure.
       *
       * There is no attempt to link the public & private key together
       *
       * This example does not do any padding. It simply encrypts/decrypts a block
       * of length equal to modulus length of the public/private key.
       */


      #include "nss.h"
      #include "pk11pub.h"

      #define BASE64_ENCODED_SUBJECTPUBLICKEYINFO "MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBAL3F6TIc3JEYsugo+a2fPU3W+Epv/FeIX21DC86WYnpFtW4srFtz2oNUzyLUzDHZdb+k//8dcT3IAOzUUi3R2eMCAwEAAQ=="

      #define BASE64_ENCODED_PRIVATEKEYINFO "MIIBVQIBADANBgkqhkiG9w0BAQEFAASCAT8wggE7AgEAAkEAvcXpMhzckRiy6Cj5rZ89Tdb4Sm/8V4hfbUMLzpZiekW1biysW3Pag1TPItTMMdl1v6T//x1xPcgA7NRSLdHZ4wIDAQABAkEAjh8+4qncwcmGivnM6ytbpQT+k/jEOeXG2bQhjojvnXN3FazGCEFXvpuIBcJVfaIJS9YBCMOzzrAtO0+k2hWnOQIhAOC4NVbo8FQhZS4yXM1M86kMl47FA9ui//OUfbhlAdw1AiEA2DBmIXnsboKB+OHver69p0gNeWlvcJc9bjDVfdLVsLcCIQCPtV3vGYJv2vdwxqZQaHC+YB4gIGAqOqBCbmjD3lyFLQIgA+VTYdUNoqwtZWvE4gRf7IzK2V5CCNhg3gR5RGwxN58CIGCcafoRrUKsM66ISg0ITI04G9V/w+wMx91wjEEB+QBz"


      int main(int argc, char **argv)
      {
        SECStatus          rv;
        CERTCertificate   *cert = NULL;
        SECKEYPublicKey   *pubkey = NULL;
        CERTSubjectPublicKeyInfo *spki = NULL;
        SECKEYPrivateKey  *pvtkey = NULL;
        int                modulus_len, i, outlen;
        char              *buf1 = NULL;
        char              *buf2 = NULL;
        char              *pubkstr = BASE64_ENCODED_SUBJECTPUBLICKEYINFO;
        char              *pvtkstr = BASE64_ENCODED_PRIVATEKEYINFO;
        SECItem            der;
        SECItem            nickname;
        PK11SlotInfo      *slot = NULL;

        /* Initialize NSS
         * You need to explicitly authenticate to the internal token if you use
         * NSS_Init insteadf of NSS_NoDB_Init
         * Invoke this after getting the internal token handle
         *      PK11_Authenticate(slot, PR_FALSE, NULL);
         */
        rv = NSS_NoDB_Init(".");
        if (rv != SECSuccess)
        {
          fprintf(stderr, "NSS initialization failed (err %d)\n",
                  PR_GetError());
          goto cleanup;
        }

        /* get internal slot */
        slot = PK11_GetInternalKeySlot();
        if (slot == NULL)
        {
          fprintf(stderr, "Couldn't find slot (err %d)\n", PR_GetError());
          goto cleanup;
        }

        rv = ATOB_ConvertAsciiToItem(&der, pubkstr);
        if (rv!= SECSuccess)
        {
          fprintf(stderr, "ATOB_ConvertAsciiToItem failed %d\n", PR_GetError());
          goto cleanup;
        }
        spki = SECKEY_DecodeDERSubjectPublicKeyInfo(&der);
        SECITEM_FreeItem(&der, PR_FALSE);
        pubkey = SECKEY_ExtractPublicKey(spki);

        if (pubkey == NULL)
        {
          fprintf(stderr, "Couldn't extract public key (err %d)\n", PR_GetError());
          goto cleanup;
        }

        modulus_len = SECKEY_PublicKeyStrength(pubkey);
        fprintf(stderr, "Public Key Modulus %d bytes\n", modulus_len);
        buf1 = (char *)malloc(modulus_len);
        buf2 = (char *)malloc(modulus_len);

        /* initialize buf1 */
        for (i=0;i<modulus_len;i++)
        {
          buf1[i]= (i %26) + 'A';
        }
        buf1[modulus_len-1] = '\0';
        fprintf(stderr, "Buffer being encrypted = \n%s\n", buf1);

        /* encrypt buf1, result will be in buf2 */
        rv = PK11_PubEncryptRaw(pubkey, buf2, buf1, modulus_len, NULL);
        if (rv != SECSuccess)
        {
          fprintf(stderr, "Encrypt with Public Key failed (err %d)\n",
                  PR_GetError());
          goto cleanup;
        }

        nickname.type = siBuffer;
        nickname.data = "pvtkeynickname";
        nickname.len = strlen("pvtkeynickname");
        rv = ATOB_ConvertAsciiToItem(&der, pvtkstr);
        if (rv!= SECSuccess)
        {
          fprintf(stderr, "ATOB_ConvertAsciiToItem failed %d\n", PR_GetError());
          goto cleanup;
        }

        /* KU_ALL includes a lot of different key usages, KU_DATA_ENCIPHERMENT
         * is enough for just RSA encryption.
         * publicValue arg (4th) can be NULL for RSA key - I think it is even
         * ignored
         */
        PK11_ImportDERPrivateKeyInfoAndReturnKey(slot, &der, NULL,
                                                 NULL, PR_FALSE, PR_TRUE,
                                                 KU_ALL, &pvtkey, NULL);
        SECITEM_FreeItem(&der, PR_FALSE);

        if (pvtkey == NULL)
        {
          fprintf(stderr, "Couldn't extract private key (err %d)\n", PR_GetError());
          goto cleanup;
        }

        /* clear buf1 */
        for (i=0;i<modulus_len;i++)
        {
          buf1[i]= '\0';
        }

        /* decrypt buf2, result will be in buf1 */
        rv = PK11_PubDecryptRaw(pvtkey, buf1, &outlen, modulus_len, buf2,
                                modulus_len);
        if (rv != SECSuccess)
        {
          fprintf(stderr, "Decrypt with Private Key failed (err %d)\n",
                  PR_GetError());
          goto cleanup;
        }

        fprintf(stderr, "Result of decryption, outlen = %d\n", outlen);
        fprintf(stderr, "Result of decryption, buf = \n%s\n", buf1);

      cleanup:
        if (cert)
          CERT_DestroyCertificate(cert);
        if (pubkey)
          SECKEY_DestroyPublicKey(pubkey);
        if (pvtkey)
          SECKEY_DestroyPrivateKey(pvtkey);
        if (spki)
          SECKEY_DestroySubjectPublicKeyInfo(spki);
        if (slot)
          PK11_FreeSlot(slot);
        if (buf1)
          free(buf1);
        if (buf2)
          free(buf2);
        exit(1);
      }