#include "seccomon.h"
#include "secoid.h"
#include "secasn1.h"
#include "pkcs11.h"
#include "pk11func.h"
#include "pk11sdr.h"

/*
 * Data structure and template for encoding the result of an SDR operation
 *  This is temporary.  It should include the algorithm ID of the encryption mechanism
 */
struct SDRResult
{
  SECItem keyid;
  SECAlgorithmID alg;
  SECItem data;
};
typedef struct SDRResult SDRResult;

........
..........
.............
static unsigned char keyID[] = {
  0xF8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01
};

static SECItem keyIDItem = {
  0,
  keyID,
  sizeof keyID
};

...............
........................
............................... some more code........
/*
 * PK11SDR_Encrypt
 *  Encrypt a block of data using the symmetric key identified.  The result
 *  is an ASN.1 (DER) encoded block of keyid, params and data.
 */
SECStatus
PK11SDR_Encrypt(SECItem *keyid, SECItem *data, SECItem *result, void *cx)
{
  SECStatus rv = SECSuccess;
  PK11SlotInfo *slot = 0;
  PK11SymKey *key = 0;
  SECItem *params = 0;
  PK11Context *ctx = 0;
  CK_MECHANISM_TYPE type;
  SDRResult sdrResult;
  SECItem paddedData;
  SECItem *pKeyID;
  PLArenaPool *arena = 0;

  /* Initialize */
  paddedData.len = 0;
  paddedData.data = 0;

  arena = PORT_NewArena(SEC_ASN1_DEFAULT_ARENA_SIZE);
  if (!arena) { rv = SECFailure; goto loser; }

  /* 1. Locate the requested keyid, or the default key (which has a keyid)
   * 2. Create an encryption context
   * 3. Encrypt
   * 4. Encode the results (using ASN.1)
   */

  slot = PK11_GetInternalKeySlot();
  if (!slot) { rv = SECFailure; goto loser; }

  /* Use triple-DES */
  type = CKM_DES3_CBC;

  /*
   * Login to the internal token before we look for the key, otherwise we
   * won't find it.
   */
  rv = PK11_Authenticate(slot, PR_TRUE, cx);
  if (rv != SECSuccess) goto loser;

  /* Find the key to use */
  pKeyID = keyid;
  if (pKeyID->len == 0) {
      pKeyID = &keyIDItem;  /* Use default value */

      /* put in a course lock to prevent a race between not finding the
       * key and creating  one.
       */

      if (pk11sdrLock) PR_Lock(pk11sdrLock);

      /* Try to find the key */
      key = PK11_FindFixedKey(slot, type, pKeyID, cx);

      /* If the default key doesn't exist yet, try to create it */
      if (!key) key = PK11_GenDES3TokenKey(slot, pKeyID, cx);
      if (pk11sdrLock) PR_Unlock(pk11sdrLock);
  } else {
      key = PK11_FindFixedKey(slot, type, pKeyID, cx);
  }

  if (!key) { rv = SECFailure; goto loser; }

  params = PK11_GenerateNewParam(type, key);
  if (!params) { rv = SECFailure; goto loser; }

  ctx = PK11_CreateContextBySymKey(type, CKA_ENCRYPT, key, params);
  if (!ctx) { rv = SECFailure; goto loser; }

  rv = padBlock(data, PK11_GetBlockSize(type, 0), &paddedData);
  if (rv != SECSuccess) goto loser;

  sdrResult.data.len = paddedData.len;
  sdrResult.data.data = (unsigned char *)PORT_ArenaAlloc(arena, sdrResult.data.len);

  rv = PK11_CipherOp(ctx, sdrResult.data.data, (int*)&sdrResult.data.len, sdrResult.data.len,
                     paddedData.data, paddedData.len);
  if (rv != SECSuccess) goto loser;

  PK11_Finalize(ctx);

  sdrResult.keyid = *pKeyID;

  rv = PK11_ParamToAlgid(SEC_OID_DES_EDE3_CBC, params, arena, &sdrResult.alg);
  if (rv != SECSuccess) goto loser;

  if (!SEC_ASN1EncodeItem(0, result, &sdrResult, template)) { rv = SECFailure; goto loser; }

loser:
  SECITEM_ZfreeItem(&paddedData, PR_FALSE);
  if (arena) PORT_FreeArena(arena, PR_TRUE);
  if (ctx) PK11_DestroyContext(ctx, PR_TRUE);
  if (params) SECITEM_ZfreeItem(params, PR_TRUE);
  if (key) PK11_FreeSymKey(key);
  if (slot) PK11_FreeSlot(slot);

  return rv;
}
..........
......................
..............................some more code....
/*
 * PK11SDR_Decrypt
 *  Decrypt a block of data produced by PK11SDR_Encrypt.  The key used is identified
 *  by the keyid field within the input.
 */
SECStatus
PK11SDR_Decrypt(SECItem *data, SECItem *result, void *cx)
{
  SECStatus rv = SECSuccess;
  PK11SlotInfo *slot = 0;
  PK11SymKey *key = 0;
  CK_MECHANISM_TYPE type;
  SDRResult sdrResult;
  SECItem *params = 0;
  SECItem possibleResult = { 0, NULL, 0 };
  PLArenaPool *arena = 0;

  arena = PORT_NewArena(SEC_ASN1_DEFAULT_ARENA_SIZE);
  if (!arena) { rv = SECFailure; goto loser; }

  /* Decode the incoming data */
  memset(&sdrResult, 0, sizeof sdrResult);
  rv = SEC_QuickDERDecodeItem(arena, &sdrResult, template, data);
  if (rv != SECSuccess) goto loser;  /* Invalid format */

  /* Find the slot and key for the given keyid */
  slot = PK11_GetInternalKeySlot();
  if (!slot) { rv = SECFailure; goto loser; }

  rv = PK11_Authenticate(slot, PR_TRUE, cx);
  if (rv != SECSuccess) goto loser;

  /* Get the parameter values from the data */
  params = PK11_ParamFromAlgid(&sdrResult.alg);
  if (!params) { rv = SECFailure; goto loser; }

  /* Use triple-DES (Should look up the algorithm) */
  type = CKM_DES3_CBC;
  key = PK11_FindFixedKey(slot, type, &sdrResult.keyid, cx);
  if (!key) {
    rv = SECFailure;
  } else {
    rv = pk11Decrypt(slot, arena, type, key, params,
            &sdrResult.data, result);
  }

  /*
   * if the pad value was too small (1 or 2), then it's statistically
   * 'likely' that (1 in 256) that we may not have the correct key.
   * Check the other keys for a better match. If we find none, use
   * this result.
   */
  if (rv == SECWouldBlock) {
    possibleResult = *result;
  }

  /*
   * handle the case where your key indicies may have been broken
   */
  if (rv != SECSuccess) {
    PK11SymKey *keyList = PK11_ListFixedKeysInSlot(slot, NULL, cx);
    PK11SymKey *testKey = NULL;
    PK11SymKey *nextKey = NULL;

    for (testKey = keyList; testKey;
                testKey = PK11_GetNextSymKey(testKey)) {
        rv = pk11Decrypt(slot, arena, type, testKey, params,
                 &sdrResult.data, result);
        if (rv == SECSuccess) {
        break;
        }
        /* found a close match. If it's our first remember it */
        if (rv == SECWouldBlock) {
        if (possibleResult.data) {
            /* this is unlikely but possible. If we hit this condition,
             * we have no way of knowing which possibility to prefer.
             * in this case we just match the key the application
             * thought was the right one */
            SECITEM_ZfreeItem(result, PR_FALSE);
        } else {
            possibleResult = *result;
        }
        }
    }

    /* free the list */
    for (testKey = keyList; testKey; testKey = nextKey) {
        nextKey = PK11_GetNextSymKey(testKey);
        PK11_FreeSymKey(testKey);
    }
  }

  /* we didn't find a better key, use the one with a small pad value */
  if ((rv != SECSuccess) && (possibleResult.data)) {
    *result = possibleResult;
    possibleResult.data = NULL;
    rv = SECSuccess;
  }

loser:
  if (arena) PORT_FreeArena(arena, PR_TRUE);
  if (key) PK11_FreeSymKey(key);
  if (params) SECITEM_ZfreeItem(params, PR_TRUE);
  if (slot) PK11_FreeSlot(slot);
  if (possibleResult.data) SECITEM_ZfreeItem(&possibleResult, PR_FALSE);

  return rv;
}