/* tlsprf.c - TLS Pseudo Random Function (PRF) implementation

 *

 * This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "pkcs11i.h"

#include "blapi.h"

#include "secerr.h"

static void

sftk_TLSPRFNull(void *data, PRBool freeit)

{

    return;

}

typedef struct {

    PRUint32 cxSize;          /* size of allocated block, in bytes.        */

    PRUint32 cxBufSize;       /* sizeof buffer at cxBufPtr.                */

    unsigned char *cxBufPtr;  /* points to real buffer, may be cxBuf.      */

    PRUint32 cxKeyLen;        /* bytes of cxBufPtr containing key.         */

    PRUint32 cxDataLen;       /* bytes of cxBufPtr containing data.        */

    SECStatus cxRv;           /* records failure of void functions.        */

    PRBool cxIsFIPS;          /* true if conforming to FIPS 198.           */

    HASH_HashType cxHashAlg;  /* hash algorithm to use for TLS 1.2+        */

    unsigned int cxOutLen;    /* bytes of output if nonzero                */

    unsigned char cxBuf[512]; /* actual size may be larger than 512.       */

} TLSPRFContext;

static void

sftk_TLSPRFHashUpdate(TLSPRFContext *cx, const unsigned char *data,

                      unsigned int data_len)

{

    PRUint32 bytesUsed = cx->cxKeyLen + cx->cxDataLen;

    if (cx->cxRv != SECSuccess) /* function has previously failed. */

        return;

    if (bytesUsed + data_len > cx->cxBufSize) {

        /* We don't use realloc here because

        ** (a) realloc doesn't zero out the old block, and

        ** (b) if realloc fails, we lose the old block.

        */

        PRUint32 newBufSize = bytesUsed + data_len + 512;

        unsigned char *newBuf = (unsigned char *)PORT_Alloc(newBufSize);

        if (!newBuf) {

            cx->cxRv = SECFailure;

            return;

        }

        PORT_Memcpy(newBuf, cx->cxBufPtr, bytesUsed);

        if (cx->cxBufPtr != cx->cxBuf) {

            PORT_ZFree(cx->cxBufPtr, bytesUsed);

        }

        cx->cxBufPtr = newBuf;

        cx->cxBufSize = newBufSize;

    }

    PORT_Memcpy(cx->cxBufPtr + bytesUsed, data, data_len);

    cx->cxDataLen += data_len;

}

static void

sftk_TLSPRFEnd(TLSPRFContext *ctx, unsigned char *hashout,

               unsigned int *pDigestLen, unsigned int maxDigestLen)

{

    *pDigestLen = 0; /* tells Verify that no data has been input yet. */

}

/* Compute the PRF values from the data previously input. */

static SECStatus

sftk_TLSPRFUpdate(TLSPRFContext *cx,

                  unsigned char *sig,   /* output goes here. */

                  unsigned int *sigLen, /* how much output.  */

                  unsigned int maxLen,  /* output buffer size */

                  unsigned char *hash,  /* unused. */

                  unsigned int hashLen) /* unused. */

{

    SECStatus rv;

    SECItem sigItem;

    SECItem seedItem;

    SECItem secretItem;

    if (cx->cxRv != SECSuccess)

        return cx->cxRv;

    secretItem.data = cx->cxBufPtr;

    secretItem.len = cx->cxKeyLen;

    seedItem.data = cx->cxBufPtr + cx->cxKeyLen;

    seedItem.len = cx->cxDataLen;

    sigItem.data = sig;

    if (cx->cxOutLen == 0) {

        sigItem.len = maxLen;

    } else if (cx->cxOutLen <= maxLen) {

        sigItem.len = cx->cxOutLen;

    } else {

        PORT_SetError(SEC_ERROR_OUTPUT_LEN);

        return SECFailure;

    }

    if (cx->cxHashAlg != HASH_AlgNULL) {

        rv = TLS_P_hash(cx->cxHashAlg, &secretItem, NULL, &seedItem, &sigItem,

                        cx->cxIsFIPS);

    } else {

        rv = TLS_PRF(&secretItem, NULL, &seedItem, &sigItem, cx->cxIsFIPS);

    }

    if (rv == SECSuccess && sigLen != NULL)

        *sigLen = sigItem.len;

    return rv;

}

static SECStatus

sftk_TLSPRFVerify(TLSPRFContext *cx,

                  unsigned char *sig,   /* input, for comparison. */

                  unsigned int sigLen,  /* length of sig.         */

                  unsigned char *hash,  /* data to be verified.   */

                  unsigned int hashLen) /* size of hash data.     */

{

    unsigned char *tmp = (unsigned char *)PORT_Alloc(sigLen);

    unsigned int tmpLen = sigLen;

    SECStatus rv;

    if (!tmp)

        return SECFailure;

    if (hashLen) {

        /* hashLen is non-zero when the user does a one-step verify.

        ** In this case, none of the data has been input yet.

        */

        sftk_TLSPRFHashUpdate(cx, hash, hashLen);

    }

    rv = sftk_TLSPRFUpdate(cx, tmp, &tmpLen, sigLen, NULL, 0);

    if (rv == SECSuccess) {

        rv = (SECStatus)(1 - !NSS_SecureMemcmp(tmp, sig, sigLen));

    }

    PORT_ZFree(tmp, sigLen);

    return rv;

}

static void

sftk_TLSPRFHashDestroy(TLSPRFContext *cx, PRBool freeit)

{

    if (freeit) {

        if (cx->cxBufPtr != cx->cxBuf)

            PORT_ZFree(cx->cxBufPtr, cx->cxBufSize);

        PORT_ZFree(cx, cx->cxSize);

    }

}

CK_RV

sftk_TLSPRFInit(SFTKSessionContext *context,

                SFTKObject *key,

                CK_KEY_TYPE key_type,

                HASH_HashType hash_alg,

                unsigned int out_len)

{

    SFTKAttribute *keyVal;

    TLSPRFContext *prf_cx;

    CK_RV crv = CKR_HOST_MEMORY;

    PRUint32 keySize;

    PRUint32 blockSize;

    if (key_type != CKK_GENERIC_SECRET)

        return CKR_KEY_TYPE_INCONSISTENT; /* CKR_KEY_FUNCTION_NOT_PERMITTED */

    context->multi = PR_TRUE;

    keyVal = sftk_FindAttribute(key, CKA_VALUE);

    keySize = (!keyVal) ? 0 : keyVal->attrib.ulValueLen;

    blockSize = keySize + sizeof(TLSPRFContext);

    prf_cx = (TLSPRFContext *)PORT_Alloc(blockSize);

    if (!prf_cx)

        goto done;

    prf_cx->cxSize = blockSize;

    prf_cx->cxKeyLen = keySize;

    prf_cx->cxDataLen = 0;

    prf_cx->cxBufSize = blockSize - offsetof(TLSPRFContext, cxBuf);

    prf_cx->cxRv = SECSuccess;

    prf_cx->cxIsFIPS = sftk_isFIPS(key->slot->slotID);

    prf_cx->cxBufPtr = prf_cx->cxBuf;

    prf_cx->cxHashAlg = hash_alg;

    prf_cx->cxOutLen = out_len;

    if (keySize)

        PORT_Memcpy(prf_cx->cxBufPtr, keyVal->attrib.pValue, keySize);

    context->hashInfo = (void *)prf_cx;

    context->cipherInfo = (void *)prf_cx;

    context->hashUpdate = (SFTKHash)sftk_TLSPRFHashUpdate;

    context->end = (SFTKEnd)sftk_TLSPRFEnd;

    context->update = (SFTKCipher)sftk_TLSPRFUpdate;

    context->verify = (SFTKVerify)sftk_TLSPRFVerify;

    context->destroy = (SFTKDestroy)sftk_TLSPRFNull;

    context->hashdestroy = (SFTKDestroy)sftk_TLSPRFHashDestroy;

    crv = CKR_OK;

done:

    if (keyVal)

        sftk_FreeAttribute(keyVal);

    return crv;

}