NSS Sample Code 5: PKI Encryption with a raw public & private key in DER format
/* 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);
}