/* 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/. */

/*
 * RSA key generation, public key op, private key op.
 */
#ifdef FREEBL_NO_DEPEND
#include "stubs.h"
#endif

#include "secerr.h"

#include "prclist.h"
#include "nssilock.h"
#include "prinit.h"
#include "blapi.h"
#include "mpi.h"
#include "mpprime.h"
#include "mplogic.h"
#include "secmpi.h"
#include "secitem.h"
#include "blapii.h"

/*
** Number of times to attempt to generate a prime (p or q) from a random
** seed (the seed changes for each iteration).
*/
#define MAX_PRIME_GEN_ATTEMPTS 10
/*
** Number of times to attempt to generate a key.  The primes p and q change
** for each attempt.
*/
#define MAX_KEY_GEN_ATTEMPTS 10

/* Blinding Parameters max cache size  */
#define RSA_BLINDING_PARAMS_MAX_CACHE_SIZE 20

/* exponent should not be greater than modulus */
#define BAD_RSA_KEY_SIZE(modLen, expLen) \
    ((expLen) > (modLen) || (modLen) > RSA_MAX_MODULUS_BITS/8 || \
    (expLen) > RSA_MAX_EXPONENT_BITS/8)

struct blindingParamsStr;
typedef struct blindingParamsStr blindingParams;

struct blindingParamsStr {
    blindingParams *next;
    mp_int         f, g;             /* blinding parameter                 */
    int            counter;          /* number of remaining uses of (f, g) */
};

/*
** RSABlindingParamsStr
**
** For discussion of Paul Kocher's timing attack against an RSA private key
** operation, see http://www.cryptography.com/timingattack/paper.html.  The 
** countermeasure to this attack, known as blinding, is also discussed in 
** the Handbook of Applied Cryptography, 11.118-11.119.
*/
struct RSABlindingParamsStr
{
    /* Blinding-specific parameters */
    PRCList   link;                  /* link to list of structs            */
    SECItem   modulus;               /* list element "key"                 */
    blindingParams *free, *bp;       /* Blinding parameters queue          */
    blindingParams array[RSA_BLINDING_PARAMS_MAX_CACHE_SIZE];
};
typedef struct RSABlindingParamsStr RSABlindingParams;

/*
** RSABlindingParamsListStr
**
** List of key-specific blinding params.  The arena holds the volatile pool
** of memory for each entry and the list itself.  The lock is for list
** operations, in this case insertions and iterations, as well as control
** of the counter for each set of blinding parameters.
*/
struct RSABlindingParamsListStr
{
    PZLock  *lock;   /* Lock for the list   */
    PRCondVar *cVar; /* Condidtion Variable */
    int  waitCount;  /* Number of threads waiting on cVar */
    PRCList  head;   /* Pointer to the list */
};

/*
** The master blinding params list.
*/
static struct RSABlindingParamsListStr blindingParamsList = { 0 };

/* Number of times to reuse (f, g).  Suggested by Paul Kocher */
#define RSA_BLINDING_PARAMS_MAX_REUSE 50

/* Global, allows optional use of blinding.  On by default. */
/* Cannot be changed at the moment, due to thread-safety issues. */
static PRBool nssRSAUseBlinding = PR_TRUE;

static SECStatus
rsa_build_from_primes(const mp_int *p, const mp_int *q,
		mp_int *e, PRBool needPublicExponent,
		mp_int *d, PRBool needPrivateExponent,
		RSAPrivateKey *key, unsigned int keySizeInBits)
{
    mp_int n, phi;
    mp_int psub1, qsub1, tmp;
    mp_err   err = MP_OKAY;
    SECStatus rv = SECSuccess;
    MP_DIGITS(&n)     = 0;
    MP_DIGITS(&phi)   = 0;
    MP_DIGITS(&psub1) = 0;
    MP_DIGITS(&qsub1) = 0;
    MP_DIGITS(&tmp)   = 0;
    CHECK_MPI_OK( mp_init(&n)     );
    CHECK_MPI_OK( mp_init(&phi)   );
    CHECK_MPI_OK( mp_init(&psub1) );
    CHECK_MPI_OK( mp_init(&qsub1) );
    CHECK_MPI_OK( mp_init(&tmp)   );
    /* p and q must be distinct. */
    if (mp_cmp(p, q) == 0) {
	PORT_SetError(SEC_ERROR_NEED_RANDOM);
	rv = SECFailure;
	goto cleanup;
    }
    /* 1.  Compute n = p*q */
    CHECK_MPI_OK( mp_mul(p, q, &n) );
    /*     verify that the modulus has the desired number of bits */
    if ((unsigned)mpl_significant_bits(&n) != keySizeInBits) {
	PORT_SetError(SEC_ERROR_NEED_RANDOM);
	rv = SECFailure;
	goto cleanup;
    }

    /* at least one exponent must be given */
    PORT_Assert(!(needPublicExponent && needPrivateExponent));

    /* 2.  Compute phi = (p-1)*(q-1) */
    CHECK_MPI_OK( mp_sub_d(p, 1, &psub1) );
    CHECK_MPI_OK( mp_sub_d(q, 1, &qsub1) );
    if (needPublicExponent || needPrivateExponent) {
	CHECK_MPI_OK( mp_lcm(&psub1, &qsub1, &phi) );
	/* 3.  Compute d = e**-1 mod(phi) */
	/*     or      e = d**-1 mod(phi) as necessary */
	if (needPublicExponent) {
	    err = mp_invmod(d, &phi, e);
	} else {
	    err = mp_invmod(e, &phi, d);
	}
    } else {
	err = MP_OKAY;
    }
    /*     Verify that phi(n) and e have no common divisors */
    if (err != MP_OKAY) {
	if (err == MP_UNDEF) {
	    PORT_SetError(SEC_ERROR_NEED_RANDOM);
	    err = MP_OKAY; /* to keep PORT_SetError from being called again */
	    rv = SECFailure;
	}
	goto cleanup;
    }

    /* 4.  Compute exponent1 = d mod (p-1) */
    CHECK_MPI_OK( mp_mod(d, &psub1, &tmp) );
    MPINT_TO_SECITEM(&tmp, &key->exponent1, key->arena);
    /* 5.  Compute exponent2 = d mod (q-1) */
    CHECK_MPI_OK( mp_mod(d, &qsub1, &tmp) );
    MPINT_TO_SECITEM(&tmp, &key->exponent2, key->arena);
    /* 6.  Compute coefficient = q**-1 mod p */
    CHECK_MPI_OK( mp_invmod(q, p, &tmp) );
    MPINT_TO_SECITEM(&tmp, &key->coefficient, key->arena);

    /* copy our calculated results, overwrite what is there */
    key->modulus.data = NULL;
    MPINT_TO_SECITEM(&n, &key->modulus, key->arena);
    key->privateExponent.data = NULL;
    MPINT_TO_SECITEM(d, &key->privateExponent, key->arena);
    key->publicExponent.data = NULL;
    MPINT_TO_SECITEM(e, &key->publicExponent, key->arena);
    key->prime1.data = NULL;
    MPINT_TO_SECITEM(p, &key->prime1, key->arena);
    key->prime2.data = NULL;
    MPINT_TO_SECITEM(q, &key->prime2, key->arena);
cleanup:
    mp_clear(&n);
    mp_clear(&phi);
    mp_clear(&psub1);
    mp_clear(&qsub1);
    mp_clear(&tmp);
    if (err) {
	MP_TO_SEC_ERROR(err);
	rv = SECFailure;
    }
    return rv;
}
static SECStatus
generate_prime(mp_int *prime, int primeLen)
{
    mp_err   err = MP_OKAY;
    SECStatus rv = SECSuccess;
    unsigned long counter = 0;
    int piter;
    unsigned char *pb = NULL;
    pb = PORT_Alloc(primeLen);
    if (!pb) {
	PORT_SetError(SEC_ERROR_NO_MEMORY);
	goto cleanup;
    }
    for (piter = 0; piter < MAX_PRIME_GEN_ATTEMPTS; piter++) {
	CHECK_SEC_OK( RNG_GenerateGlobalRandomBytes(pb, primeLen) );
	pb[0]          |= 0xC0; /* set two high-order bits */
	pb[primeLen-1] |= 0x01; /* set low-order bit       */
	CHECK_MPI_OK( mp_read_unsigned_octets(prime, pb, primeLen) );
	err = mpp_make_prime(prime, primeLen * 8, PR_FALSE, &counter);
	if (err != MP_NO)
	    goto cleanup;
	/* keep going while err == MP_NO */
    }
cleanup:
    if (pb)
	PORT_ZFree(pb, primeLen);
    if (err) {
	MP_TO_SEC_ERROR(err);
	rv = SECFailure;
    }
    return rv;
}

/*
 *  make sure the key components meet fips186 requirements.
 */
static PRBool
rsa_fips186_verify(mp_int *p, mp_int *q, mp_int *d, int keySizeInBits)
{
    mp_int pq_diff;
    mp_err   err = MP_OKAY;
    PRBool ret=PR_FALSE;

    if (keySizeInBits < 250) {
 	/* not a valid FIPS length, no point in our other tests */
	/* if you are here, and in FIPS mode, you are outside the security 
  	 * policy */
	return PR_TRUE;
    }

    /* p & q are already known to be greater then sqrt(2)*2^(keySize/2-1) */
    /* we also know that gcd(p-1,e) = 1 and gcd(q-1,e) = 1 because the 
     * mp_invmod() function will fail. */
    /* now check p-q > 2^(keysize/2-100) */
    MP_DIGITS(&pq_diff) = 0;
    CHECK_MPI_OK( mp_init(&pq_diff) );
    /* NSS always has p > q, so we know pq_diff is positive */
    CHECK_MPI_OK( mp_sub(p,q,&pq_diff) );
    if ((unsigned)mpl_significant_bits(&pq_diff) < (keySizeInBits/2 - 100)) {
	goto cleanup;
    }
    /* now verify d is large enough*/
    if ((unsigned)mpl_significant_bits(d) < (keySizeInBits/2)) {
	goto cleanup;
    }
    ret = PR_TRUE;

cleanup:
    mp_clear(&pq_diff);
    return ret;
}

/*
** Generate and return a new RSA public and private key.
**	Both keys are encoded in a single RSAPrivateKey structure.
**	"cx" is the random number generator context
**	"keySizeInBits" is the size of the key to be generated, in bits.
**	   512, 1024, etc.
**	"publicExponent" when not NULL is a pointer to some data that
**	   represents the public exponent to use. The data is a byte
**	   encoded integer, in "big endian" order.
*/
RSAPrivateKey *
RSA_NewKey(int keySizeInBits, SECItem *publicExponent)
{
    unsigned int primeLen;
    mp_int p, q, e, d;
    int kiter;
    int max_attempts;
    mp_err   err = MP_OKAY;
    SECStatus rv = SECSuccess;
    int prerr = 0;
    RSAPrivateKey *key = NULL;
    PLArenaPool *arena = NULL;
    /* Require key size to be a multiple of 16 bits. */
    if (!publicExponent || keySizeInBits % 16 != 0 ||
	    BAD_RSA_KEY_SIZE((unsigned int)keySizeInBits/8, publicExponent->len)) {
	PORT_SetError(SEC_ERROR_INVALID_ARGS);
	return NULL;
    }
    /* 1. Allocate arena & key */
    arena = PORT_NewArena(NSS_FREEBL_DEFAULT_CHUNKSIZE);
    if (!arena) {
	PORT_SetError(SEC_ERROR_NO_MEMORY);
	return NULL;
    }
    key = PORT_ArenaZNew(arena, RSAPrivateKey);
    if (!key) {
	PORT_SetError(SEC_ERROR_NO_MEMORY);
	PORT_FreeArena(arena, PR_TRUE);
	return NULL;
    }
    key->arena = arena;
    /* length of primes p and q (in bytes) */
    primeLen = keySizeInBits / (2 * PR_BITS_PER_BYTE);
    MP_DIGITS(&p) = 0;
    MP_DIGITS(&q) = 0;
    MP_DIGITS(&e) = 0;
    MP_DIGITS(&d) = 0;
    CHECK_MPI_OK( mp_init(&p) );
    CHECK_MPI_OK( mp_init(&q) );
    CHECK_MPI_OK( mp_init(&e) );
    CHECK_MPI_OK( mp_init(&d) );
    /* 2.  Set the version number (PKCS1 v1.5 says it should be zero) */
    SECITEM_AllocItem(arena, &key->version, 1);
    key->version.data[0] = 0;
    /* 3.  Set the public exponent */
    SECITEM_TO_MPINT(*publicExponent, &e);
    kiter = 0;
    max_attempts = 5*(keySizeInBits/2); /* FIPS 186-4 B.3.3 steps 4.7 and 5.8 */
    do {
	prerr = 0;
	PORT_SetError(0);
	CHECK_SEC_OK( generate_prime(&p, primeLen) );
	CHECK_SEC_OK( generate_prime(&q, primeLen) );
	/* Assure p > q */
	/* NOTE: PKCS #1 does not require p > q, and NSS doesn't use any
	 * implementation optimization that requires p > q. We can remove
	 * this code in the future.
	 */
	if (mp_cmp(&p, &q) < 0)
	    mp_exch(&p, &q);
	/* Attempt to use these primes to generate a key */
	rv = rsa_build_from_primes(&p, &q, 
			&e, PR_FALSE,  /* needPublicExponent=false */
			&d, PR_TRUE,   /* needPrivateExponent=true */
			key, keySizeInBits);
	if (rv == SECSuccess) {
	    if (rsa_fips186_verify(&p, &q, &d, keySizeInBits) ){
		break;
	    }
	    prerr = SEC_ERROR_NEED_RANDOM; /* retry with different values */
	} else {
	    prerr = PORT_GetError();
	}
	kiter++;
	/* loop until have primes */
    } while (prerr == SEC_ERROR_NEED_RANDOM && kiter < max_attempts);
    if (prerr)
	goto cleanup;
cleanup:
    mp_clear(&p);
    mp_clear(&q);
    mp_clear(&e);
    mp_clear(&d);
    if (err) {
	MP_TO_SEC_ERROR(err);
	rv = SECFailure;
    }
    if (rv && arena) {
	PORT_FreeArena(arena, PR_TRUE);
	key = NULL;
    }
    return key;
}

mp_err
rsa_is_prime(mp_int *p) {
    int res;

    /* run a Fermat test */
    res = mpp_fermat(p, 2);
    if (res != MP_OKAY) {
	return res;
    }

    /* If that passed, run some Miller-Rabin tests */
    res = mpp_pprime(p, 2);
    return res;
}

/*
 * Try to find the two primes based on 2 exponents plus either a prime
 *   or a modulus.
 *
 * In: e, d and either p or n (depending on the setting of hasModulus).
 * Out: p,q.
 * 
 * Step 1, Since d = e**-1 mod phi, we know that d*e == 1 mod phi, or
 *	d*e = 1+k*phi, or d*e-1 = k*phi. since d is less than phi and e is
 *	usually less than d, then k must be an integer between e-1 and 1 
 *	(probably on the order of e).
 * Step 1a, If we were passed just a prime, we can divide k*phi by that
 *      prime-1 and get k*(q-1). This will reduce the size of our division
 *      through the rest of the loop.
 * Step 2, Loop through the values k=e-1 to 1 looking for k. k should be on
 *	the order or e, and e is typically small. This may take a while for
 *	a large random e. We are looking for a k that divides kphi
 *	evenly. Once we find a k that divides kphi evenly, we assume it 
 *	is the true k. It's possible this k is not the 'true' k but has 
 *	swapped factors of p-1 and/or q-1. Because of this, we 
 *	tentatively continue Steps 3-6 inside this loop, and may return looking
 *	for another k on failure.
 * Step 3, Calculate are tentative phi=kphi/k. Note: real phi is (p-1)*(q-1).
 * Step 4a, if we have a prime, kphi is already k*(q-1), so phi is or tenative
 *      q-1. q = phi+1. If k is correct, q should be the right length and 
 *      prime.
 * Step 4b, It's possible q-1 and k could have swapped factors. We now have a
 * 	possible solution that meets our criteria. It may not be the only 
 *      solution, however, so we keep looking. If we find more than one, 
 *      we will fail since we cannot determine which is the correct
 *      solution, and returning the wrong modulus will compromise both
 *      moduli. If no other solution is found, we return the unique solution.
 * Step 5a, If we have the modulus (n=pq), then use the following formula to 
 * 	calculate  s=(p+q): , phi = (p-1)(q-1) = pq  -p-q +1 = n-s+1. so
 *	s=n-phi+1.
 * Step 5b, Use n=pq and s=p+q to solve for p and q as follows:
 *	since q=s-p, then n=p*(s-p)= sp - p^2, rearranging p^2-s*p+n = 0.
 *	from the quadratic equation we have p=1/2*(s+sqrt(s*s-4*n)) and
 *	q=1/2*(s-sqrt(s*s-4*n)) if s*s-4*n is a perfect square, we are DONE.
 *	If it is not, continue in our look looking for another k. NOTE: the
 *	code actually distributes the 1/2 and results in the equations:
 *	sqrt = sqrt(s/2*s/2-n), p=s/2+sqrt, q=s/2-sqrt. The algebra saves us
 *	and extra divide by 2 and a multiply by 4.
 * 
 * This will return p & q. q may be larger than p in the case that p was given
 * and it was the smaller prime.
 */
static mp_err
rsa_get_primes_from_exponents(mp_int *e, mp_int *d, mp_int *p, mp_int *q,
			      mp_int *n, PRBool hasModulus, 
			      unsigned int keySizeInBits)
{
    mp_int kphi; /* k*phi */
    mp_int k;    /* current guess at 'k' */
    mp_int phi;  /* (p-1)(q-1) */
    mp_int s;    /* p+q/2 (s/2 in the algebra) */
    mp_int r;    /* remainder */
    mp_int tmp; /* p-1 if p is given, n+1 is modulus is given */
    mp_int sqrt; /* sqrt(s/2*s/2-n) */
    mp_err err = MP_OKAY;
    unsigned int order_k;

    MP_DIGITS(&kphi) = 0;
    MP_DIGITS(&phi) = 0;
    MP_DIGITS(&s) = 0;
    MP_DIGITS(&k) = 0;
    MP_DIGITS(&r) = 0;
    MP_DIGITS(&tmp) = 0;
    MP_DIGITS(&sqrt) = 0;
    CHECK_MPI_OK( mp_init(&kphi) );
    CHECK_MPI_OK( mp_init(&phi) );
    CHECK_MPI_OK( mp_init(&s) );
    CHECK_MPI_OK( mp_init(&k) );
    CHECK_MPI_OK( mp_init(&r) );
    CHECK_MPI_OK( mp_init(&tmp) );
    CHECK_MPI_OK( mp_init(&sqrt) );

    /* our algorithm looks for a factor k whose maximum size is dependent
     * on the size of our smallest exponent, which had better be the public
     * exponent (if it's the private, the key is vulnerable to a brute force
     * attack).
     * 
     * since our factor search is linear, we need to limit the maximum
     * size of the public key. this should not be a problem normally, since 
     * public keys are usually small. 
     *
     * if we want to handle larger public key sizes, we should have
     * a version which tries to 'completely' factor k*phi (where completely
     * means 'factor into primes, or composites with which are products of
     * large primes). Once we have all the factors, we can sort them out and
     * try different combinations to form our phi. The risk is if (p-1)/2,
     * (q-1)/2, and k are all large primes. In any case if the public key
     * is small (order of 20 some bits), then a linear search for k is 
     * manageable.
     */
    if (mpl_significant_bits(e) > 23) {
	err=MP_RANGE;
	goto cleanup;
    }

    /* calculate k*phi = e*d - 1 */
    CHECK_MPI_OK( mp_mul(e, d, &kphi) );
    CHECK_MPI_OK( mp_sub_d(&kphi, 1, &kphi) );


    /* kphi is (e*d)-1, which is the same as k*(p-1)(q-1)
     * d < (p-1)(q-1), therefor k must be less than e-1
     * We can narrow down k even more, though. Since p and q are odd and both 
     * have their high bit set, then we know that phi must be on order of 
     * keySizeBits.
     */
    order_k = (unsigned)mpl_significant_bits(&kphi) - keySizeInBits;

    /* for (k=kinit; order(k) >= order_k; k--) { */
    /* k=kinit: k can't be bigger than  kphi/2^(keySizeInBits -1) */
    CHECK_MPI_OK( mp_2expt(&k,keySizeInBits-1) );
    CHECK_MPI_OK( mp_div(&kphi, &k, &k, NULL));
    if (mp_cmp(&k,e) >= 0) {
	/* also can't be bigger then e-1 */
        CHECK_MPI_OK( mp_sub_d(e, 1, &k) );
    }

    /* calculate our temp value */
    /* This saves recalculating this value when the k guess is wrong, which
     * is reasonably frequent. */
    /* for the modulus case, tmp = n+1 (used to calculate p+q = tmp - phi) */
    /* for the prime case, tmp = p-1 (used to calculate q-1= phi/tmp) */
    if (hasModulus) {
	CHECK_MPI_OK( mp_add_d(n, 1, &tmp) );
    } else {
	CHECK_MPI_OK( mp_sub_d(p, 1, &tmp) );
	CHECK_MPI_OK(mp_div(&kphi,&tmp,&kphi,&r));
	if (mp_cmp_z(&r) != 0) {
	    /* p-1 doesn't divide kphi, some parameter wasn't correct */
	    err=MP_RANGE;
	    goto cleanup;
	}
	mp_zero(q);
	/* kphi is now k*(q-1) */
    }

    /* rest of the for loop */
    for (; (err == MP_OKAY) && (mpl_significant_bits(&k) >= order_k); 
						err = mp_sub_d(&k, 1, &k)) {
	/* looking for k as a factor of kphi */
	CHECK_MPI_OK(mp_div(&kphi,&k,&phi,&r));
	if (mp_cmp_z(&r) != 0) {
	    /* not a factor, try the next one */
	    continue;
	}
	/* we have a possible phi, see if it works */
	if (!hasModulus) {
	    if ((unsigned)mpl_significant_bits(&phi) != keySizeInBits/2) {
		/* phi is not the right size */
		continue;
	    }
	    /* phi should be divisible by 2, since
	     * q is odd and phi=(q-1). */
	    if (mpp_divis_d(&phi,2) == MP_NO) {
		/* phi is not divisible by 4 */
		continue;
	    }
	    /* we now have a candidate for the second prime */
	    CHECK_MPI_OK(mp_add_d(&phi, 1, &tmp));
	    
	    /* check to make sure it is prime */
	    err = rsa_is_prime(&tmp);
	    if (err != MP_OKAY) {
		if (err == MP_NO) {
		    /* No, then we still have the wrong phi */
        	    continue;
		}
		goto cleanup;
	    }
	    /*
	     * It is possible that we have the wrong phi if 
	     * k_guess*(q_guess-1) = k*(q-1) (k and q-1 have swapped factors).
	     * since our q_quess is prime, however. We have found a valid
	     * rsa key because:
	     *   q is the correct order of magnitude.
	     *   phi = (p-1)(q-1) where p and q are both primes.
	     *   e*d mod phi = 1.
	     * There is no way to know from the info given if this is the 
	     * original key. We never want to return the wrong key because if
	     * two moduli with the same factor is known, then euclid's gcd
	     * algorithm can be used to find that factor. Even though the 
	     * caller didn't pass the original modulus, it doesn't mean the
	     * modulus wasn't known or isn't available somewhere. So to be safe
	     * if we can't be sure we have the right q, we don't return any.
	     * 
	     * So to make sure we continue looking for other valid q's. If none
	     * are found, then we can safely return this one, otherwise we just
	     * fail */
	    if (mp_cmp_z(q) != 0) {
		/* this is the second valid q, don't return either, 
		 * just fail */
		err = MP_RANGE;
		break;
	    }
	    /* we only have one q so far, save it and if no others are found,
	     * it's safe to return it */
	    CHECK_MPI_OK(mp_copy(&tmp, q));
	    continue;
	}
	/* test our tentative phi */
	/* phi should be the correct order */
	if ((unsigned)mpl_significant_bits(&phi) != keySizeInBits) {
	    /* phi is not the right size */
	    continue;
	}
	/* phi should be divisible by 4, since
	 * p and q are odd and phi=(p-1)(q-1). */
	if (mpp_divis_d(&phi,4) == MP_NO) {
	    /* phi is not divisible by 4 */
	    continue;
	}
	/* n was given, calculate s/2=(p+q)/2 */
	CHECK_MPI_OK( mp_sub(&tmp, &phi, &s) );
	CHECK_MPI_OK( mp_div_2(&s, &s) );

	/* calculate sqrt(s/2*s/2-n) */
	CHECK_MPI_OK(mp_sqr(&s,&sqrt));
	CHECK_MPI_OK(mp_sub(&sqrt,n,&r));  /* r as a tmp */
	CHECK_MPI_OK(mp_sqrt(&r,&sqrt));
	/* make sure it's a perfect square */
	/* r is our original value we took the square root of */
	/* q is the square of our tentative square root. They should be equal*/
	CHECK_MPI_OK(mp_sqr(&sqrt,q)); /* q as a tmp */
	if (mp_cmp(&r,q) != 0) {
	    /* sigh according to the doc, mp_sqrt could return sqrt-1 */
	   CHECK_MPI_OK(mp_add_d(&sqrt,1,&sqrt));
	   CHECK_MPI_OK(mp_sqr(&sqrt,q));
	   if (mp_cmp(&r,q) != 0) {
		/* s*s-n not a perfect square, this phi isn't valid, find 			 * another.*/
		continue;
	    }
	}

	/* NOTE: In this case we know we have the one and only answer.
	 * "Why?", you ask. Because:
	 *    1) n is a composite of two large primes (or it wasn't a
	 *       valid RSA modulus).
	 *    2) If we know any number such that x^2-n is a perfect square 
	 *       and x is not (n+1)/2, then we can calculate 2 non-trivial
	 *       factors of n.
	 *    3) Since we know that n has only 2 non-trivial prime factors, 
	 *       we know the two factors we have are the only possible factors.
	 */

	/* Now we are home free to calculate p and q */
	/* p = s/2 + sqrt, q= s/2 - sqrt */
	CHECK_MPI_OK(mp_add(&s,&sqrt,p));
	CHECK_MPI_OK(mp_sub(&s,&sqrt,q));
	break;
    }
    if ((unsigned)mpl_significant_bits(&k) < order_k) {
	if (hasModulus || (mp_cmp_z(q) == 0)) {
	    /* If we get here, something was wrong with the parameters we 
	     * were given */
	    err = MP_RANGE; 
	}
    }
cleanup:
    mp_clear(&kphi);
    mp_clear(&phi);
    mp_clear(&s);
    mp_clear(&k);
    mp_clear(&r);
    mp_clear(&tmp);
    mp_clear(&sqrt);
    return err;
}
     
/*
 * take a private key with only a few elements and fill out the missing pieces.
 *
 * All the entries will be overwritten with data allocated out of the arena
 * If no arena is supplied, one will be created.
 *
 * The following fields must be supplied in order for this function
 * to succeed:
 *   one of either publicExponent or privateExponent
 *   two more of the following 5 parameters.
 *      modulus (n)
 *      prime1  (p)
 *      prime2  (q)
 *      publicExponent (e)
 *      privateExponent (d)
 *
 * NOTE: if only the publicExponent, privateExponent, and one prime is given,
 * then there may be more than one RSA key that matches that combination.
 *
 * All parameters will be replaced in the key structure with new parameters
 * Allocated out of the arena. There is no attempt to free the old structures.
 * Prime1 will always be greater than prime2 (even if the caller supplies the
 * smaller prime as prime1 or the larger prime as prime2). The parameters are
 * not overwritten on failure.
 *
 *  How it works:
 *     We can generate all the parameters from:
 *        one of the exponents, plus the two primes. (rsa_build_key_from_primes) *
 *     If we are given one of the exponents and both primes, we are done.
 *     If we are given one of the exponents, the modulus and one prime, we 
 *        caclulate the second prime by dividing the modulus by the given 
 *        prime, giving us and exponent and 2 primes.
 *     If we are given 2 exponents and either the modulus or one of the primes
 *        we calculate k*phi = d*e-1, where k is an integer less than d which 
 *        divides d*e-1. We find factor k so we can isolate phi.
 *            phi = (p-1)(q-1)
 *       If one of the primes are given, we can use phi to find the other prime
 *        as follows: q = (phi/(p-1)) + 1. We now have 2 primes and an 
 *        exponent. (NOTE: if more then one prime meets this condition, the
 *        operation will fail. See comments elsewhere in this file about this).
 *       If the modulus is given, then we can calculate the sum of the primes
 *        as follows: s := (p+q), phi = (p-1)(q-1) = pq -p - q +1, pq = n ->
 *        phi = n - s + 1, s = n - phi +1.  Now that we have s = p+q and n=pq,
 *	  we can solve our 2 equations and 2 unknowns as follows: q=s-p ->
 *        n=p*(s-p)= sp -p^2 -> p^2-sp+n = 0. Using the quadratic to solve for
 *        p, p=1/2*(s+ sqrt(s*s-4*n)) [q=1/2*(s-sqrt(s*s-4*n)]. We again have
 *        2 primes and an exponent.
 *
 */
SECStatus
RSA_PopulatePrivateKey(RSAPrivateKey *key)
{
    PLArenaPool *arena = NULL;
    PRBool needPublicExponent = PR_TRUE;
    PRBool needPrivateExponent = PR_TRUE;
    PRBool hasModulus = PR_FALSE;
    unsigned int keySizeInBits = 0;
    int prime_count = 0;
    /* standard RSA nominclature */
    mp_int p, q, e, d, n;
    /* remainder */
    mp_int r;
    mp_err err = 0;
    SECStatus rv = SECFailure;

    MP_DIGITS(&p) = 0;
    MP_DIGITS(&q) = 0;
    MP_DIGITS(&e) = 0;
    MP_DIGITS(&d) = 0;
    MP_DIGITS(&n) = 0;
    MP_DIGITS(&r) = 0;
    CHECK_MPI_OK( mp_init(&p) );
    CHECK_MPI_OK( mp_init(&q) );
    CHECK_MPI_OK( mp_init(&e) );
    CHECK_MPI_OK( mp_init(&d) );
    CHECK_MPI_OK( mp_init(&n) );
    CHECK_MPI_OK( mp_init(&r) );
 
    /* if the key didn't already have an arena, create one. */
    if (key->arena == NULL) {
	arena = PORT_NewArena(NSS_FREEBL_DEFAULT_CHUNKSIZE);
	if (!arena) {
	    goto cleanup;
	}
	key->arena = arena;
    }

    /* load up the known exponents */
    if (key->publicExponent.data) {
        SECITEM_TO_MPINT(key->publicExponent, &e);
	needPublicExponent = PR_FALSE;
    } 
    if (key->privateExponent.data) {
        SECITEM_TO_MPINT(key->privateExponent, &d);
	needPrivateExponent = PR_FALSE;
    }
    if (needPrivateExponent && needPublicExponent) {
	/* Not enough information, we need at least one exponent */
	err = MP_BADARG;
	goto cleanup;
    }

    /* load up the known primes. If only one prime is given, it will be
     * assigned 'p'. Once we have both primes, well make sure p is the larger.
     * The value prime_count tells us howe many we have acquired.
     */
    if (key->prime1.data) {
	int primeLen = key->prime1.len;
	if (key->prime1.data[0] == 0) {
	   primeLen--;
	}
	keySizeInBits = primeLen * 2 * PR_BITS_PER_BYTE;
        SECITEM_TO_MPINT(key->prime1, &p);
	prime_count++;
    }
    if (key->prime2.data) {
	int primeLen = key->prime2.len;
	if (key->prime2.data[0] == 0) {
	   primeLen--;
	}
	keySizeInBits = primeLen * 2 * PR_BITS_PER_BYTE;
        SECITEM_TO_MPINT(key->prime2, prime_count ? &q : &p);
	prime_count++;
    }
    /* load up the modulus */
    if (key->modulus.data) {
	int modLen = key->modulus.len;
	if (key->modulus.data[0] == 0) {
	   modLen--;
	}
	keySizeInBits = modLen * PR_BITS_PER_BYTE;
	SECITEM_TO_MPINT(key->modulus, &n);
	hasModulus = PR_TRUE;
    }
    /* if we have the modulus and one prime, calculate the second. */
    if ((prime_count == 1) && (hasModulus)) {
	if (mp_div(&n,&p,&q,&r) != MP_OKAY || mp_cmp_z(&r) != 0) {
	   /* p is not a factor or n, fail */
	   err = MP_BADARG;
	   goto cleanup;
	}
	prime_count++;
    }

    /* If we didn't have enough primes try to calculate the primes from
     * the exponents */
    if (prime_count < 2) {
	/* if we don't have at least 2 primes at this point, then we need both
	 * exponents and one prime or a modulus*/
	if (!needPublicExponent && !needPrivateExponent &&
		((prime_count > 0) || hasModulus)) {
	    CHECK_MPI_OK(rsa_get_primes_from_exponents(&e,&d,&p,&q,
			&n,hasModulus,keySizeInBits));
	} else {
	    /* not enough given parameters to get both primes */
	    err = MP_BADARG;
	    goto cleanup;
	}
     }

     /* Assure p > q */
     /* NOTE: PKCS #1 does not require p > q, and NSS doesn't use any
      * implementation optimization that requires p > q. We can remove
      * this code in the future.
      */
     if (mp_cmp(&p, &q) < 0)
	mp_exch(&p, &q);

     /* we now have our 2 primes and at least one exponent, we can fill
      * in the key */
     rv = rsa_build_from_primes(&p, &q, 
			&e, needPublicExponent,
			&d, needPrivateExponent,
			key, keySizeInBits);
cleanup:
    mp_clear(&p);
    mp_clear(&q);
    mp_clear(&e);
    mp_clear(&d);
    mp_clear(&n);
    mp_clear(&r);
    if (err) {
	MP_TO_SEC_ERROR(err);
	rv = SECFailure;
    }
    if (rv && arena) {
	PORT_FreeArena(arena, PR_TRUE);
	key->arena = NULL;
    }
    return rv;
}

static unsigned int
rsa_modulusLen(SECItem *modulus)
{
    unsigned char byteZero = modulus->data[0];
    unsigned int modLen = modulus->len - !byteZero;
    return modLen;
}

/*
** Perform a raw public-key operation 
**	Length of input and output buffers are equal to key's modulus len.
*/
SECStatus 
RSA_PublicKeyOp(RSAPublicKey  *key, 
                unsigned char *output, 
                const unsigned char *input)
{
    unsigned int modLen, expLen, offset;
    mp_int n, e, m, c;
    mp_err err   = MP_OKAY;
    SECStatus rv = SECSuccess;
    if (!key || !output || !input) {
	PORT_SetError(SEC_ERROR_INVALID_ARGS);
	return SECFailure;
    }
    MP_DIGITS(&n) = 0;
    MP_DIGITS(&e) = 0;
    MP_DIGITS(&m) = 0;
    MP_DIGITS(&c) = 0;
    CHECK_MPI_OK( mp_init(&n) );
    CHECK_MPI_OK( mp_init(&e) );
    CHECK_MPI_OK( mp_init(&m) );
    CHECK_MPI_OK( mp_init(&c) );
    modLen = rsa_modulusLen(&key->modulus);
    expLen = rsa_modulusLen(&key->publicExponent);
    /* 1.  Obtain public key (n, e) */
    if (BAD_RSA_KEY_SIZE(modLen, expLen)) {
    	PORT_SetError(SEC_ERROR_INVALID_KEY);
	rv = SECFailure;
	goto cleanup;
    }
    SECITEM_TO_MPINT(key->modulus, &n);
    SECITEM_TO_MPINT(key->publicExponent, &e);
    if (e.used > n.used) {
	/* exponent should not be greater than modulus */
    	PORT_SetError(SEC_ERROR_INVALID_KEY);
	rv = SECFailure;
	goto cleanup;
    }
    /* 2. check input out of range (needs to be in range [0..n-1]) */
    offset = (key->modulus.data[0] == 0) ? 1 : 0; /* may be leading 0 */
    if (memcmp(input, key->modulus.data + offset, modLen) >= 0) {
        PORT_SetError(SEC_ERROR_INPUT_LEN);
        rv = SECFailure;
        goto cleanup;
    }
    /* 2 bis.  Represent message as integer in range [0..n-1] */
    CHECK_MPI_OK( mp_read_unsigned_octets(&m, input, modLen) );
    /* 3.  Compute c = m**e mod n */
#ifdef USE_MPI_EXPT_D
    /* XXX see which is faster */
    if (MP_USED(&e) == 1) {
	CHECK_MPI_OK( mp_exptmod_d(&m, MP_DIGIT(&e, 0), &n, &c) );
    } else
#endif
    CHECK_MPI_OK( mp_exptmod(&m, &e, &n, &c) );
    /* 4.  result c is ciphertext */
    err = mp_to_fixlen_octets(&c, output, modLen);
    if (err >= 0) err = MP_OKAY;
cleanup:
    mp_clear(&n);
    mp_clear(&e);
    mp_clear(&m);
    mp_clear(&c);
    if (err) {
	MP_TO_SEC_ERROR(err);
	rv = SECFailure;
    }
    return rv;
}

/*
**  RSA Private key operation (no CRT).
*/
static SECStatus 
rsa_PrivateKeyOpNoCRT(RSAPrivateKey *key, mp_int *m, mp_int *c, mp_int *n,
                      unsigned int modLen)
{
    mp_int d;
    mp_err   err = MP_OKAY;
    SECStatus rv = SECSuccess;
    MP_DIGITS(&d) = 0;
    CHECK_MPI_OK( mp_init(&d) );
    SECITEM_TO_MPINT(key->privateExponent, &d);
    /* 1. m = c**d mod n */
    CHECK_MPI_OK( mp_exptmod(c, &d, n, m) );
cleanup:
    mp_clear(&d);
    if (err) {
	MP_TO_SEC_ERROR(err);
	rv = SECFailure;
    }
    return rv;
}

/*
**  RSA Private key operation using CRT.
*/
static SECStatus 
rsa_PrivateKeyOpCRTNoCheck(RSAPrivateKey *key, mp_int *m, mp_int *c)
{
    mp_int p, q, d_p, d_q, qInv;
    mp_int m1, m2, h, ctmp;
    mp_err   err = MP_OKAY;
    SECStatus rv = SECSuccess;
    MP_DIGITS(&p)    = 0;
    MP_DIGITS(&q)    = 0;
    MP_DIGITS(&d_p)  = 0;
    MP_DIGITS(&d_q)  = 0;
    MP_DIGITS(&qInv) = 0;
    MP_DIGITS(&m1)   = 0;
    MP_DIGITS(&m2)   = 0;
    MP_DIGITS(&h)    = 0;
    MP_DIGITS(&ctmp) = 0;
    CHECK_MPI_OK( mp_init(&p)    );
    CHECK_MPI_OK( mp_init(&q)    );
    CHECK_MPI_OK( mp_init(&d_p)  );
    CHECK_MPI_OK( mp_init(&d_q)  );
    CHECK_MPI_OK( mp_init(&qInv) );
    CHECK_MPI_OK( mp_init(&m1)   );
    CHECK_MPI_OK( mp_init(&m2)   );
    CHECK_MPI_OK( mp_init(&h)    );
    CHECK_MPI_OK( mp_init(&ctmp) );
    /* copy private key parameters into mp integers */
    SECITEM_TO_MPINT(key->prime1,      &p);    /* p */
    SECITEM_TO_MPINT(key->prime2,      &q);    /* q */
    SECITEM_TO_MPINT(key->exponent1,   &d_p);  /* d_p  = d mod (p-1) */
    SECITEM_TO_MPINT(key->exponent2,   &d_q);  /* d_q  = d mod (q-1) */
    SECITEM_TO_MPINT(key->coefficient, &qInv); /* qInv = q**-1 mod p */
    /* 1. m1 = c**d_p mod p */
    CHECK_MPI_OK( mp_mod(c, &p, &ctmp) );
    CHECK_MPI_OK( mp_exptmod(&ctmp, &d_p, &p, &m1) );
    /* 2. m2 = c**d_q mod q */
    CHECK_MPI_OK( mp_mod(c, &q, &ctmp) );
    CHECK_MPI_OK( mp_exptmod(&ctmp, &d_q, &q, &m2) );
    /* 3.  h = (m1 - m2) * qInv mod p */
    CHECK_MPI_OK( mp_submod(&m1, &m2, &p, &h) );
    CHECK_MPI_OK( mp_mulmod(&h, &qInv, &p, &h)  );
    /* 4.  m = m2 + h * q */
    CHECK_MPI_OK( mp_mul(&h, &q, m) );
    CHECK_MPI_OK( mp_add(m, &m2, m) );
cleanup:
    mp_clear(&p);
    mp_clear(&q);
    mp_clear(&d_p);
    mp_clear(&d_q);
    mp_clear(&qInv);
    mp_clear(&m1);
    mp_clear(&m2);
    mp_clear(&h);
    mp_clear(&ctmp);
    if (err) {
	MP_TO_SEC_ERROR(err);
	rv = SECFailure;
    }
    return rv;
}

/*
** An attack against RSA CRT was described by Boneh, DeMillo, and Lipton in:
** "On the Importance of Eliminating Errors in Cryptographic Computations",
** http://theory.stanford.edu/~dabo/papers/faults.ps.gz
**
** As a defense against the attack, carry out the private key operation, 
** followed up with a public key operation to invert the result.  
** Verify that result against the input.
*/
static SECStatus 
rsa_PrivateKeyOpCRTCheckedPubKey(RSAPrivateKey *key, mp_int *m, mp_int *c)
{
    mp_int n, e, v;
    mp_err   err = MP_OKAY;
    SECStatus rv = SECSuccess;
    MP_DIGITS(&n) = 0;
    MP_DIGITS(&e) = 0;
    MP_DIGITS(&v) = 0;
    CHECK_MPI_OK( mp_init(&n) );
    CHECK_MPI_OK( mp_init(&e) );
    CHECK_MPI_OK( mp_init(&v) );
    CHECK_SEC_OK( rsa_PrivateKeyOpCRTNoCheck(key, m, c) );
    SECITEM_TO_MPINT(key->modulus,        &n);
    SECITEM_TO_MPINT(key->publicExponent, &e);
    /* Perform a public key operation v = m ** e mod n */
    CHECK_MPI_OK( mp_exptmod(m, &e, &n, &v) );
    if (mp_cmp(&v, c) != 0) {
	rv = SECFailure;
    }
cleanup:
    mp_clear(&n);
    mp_clear(&e);
    mp_clear(&v);
    if (err) {
	MP_TO_SEC_ERROR(err);
	rv = SECFailure;
    }
    return rv;
}

static PRCallOnceType coBPInit = { 0, 0, 0 };
static PRStatus 
init_blinding_params_list(void)
{
    blindingParamsList.lock = PZ_NewLock(nssILockOther);
    if (!blindingParamsList.lock) {
	PORT_SetError(SEC_ERROR_NO_MEMORY);
	return PR_FAILURE;
    }
    blindingParamsList.cVar = PR_NewCondVar( blindingParamsList.lock );
    if (!blindingParamsList.cVar) {
	PORT_SetError(SEC_ERROR_NO_MEMORY);
	return PR_FAILURE;
    }
    blindingParamsList.waitCount = 0;
    PR_INIT_CLIST(&blindingParamsList.head);
    return PR_SUCCESS;
}

static SECStatus
generate_blinding_params(RSAPrivateKey *key, mp_int* f, mp_int* g, mp_int *n, 
                         unsigned int modLen)
{
    SECStatus rv = SECSuccess;
    mp_int e, k;
    mp_err err = MP_OKAY;
    unsigned char *kb = NULL;

    MP_DIGITS(&e) = 0;
    MP_DIGITS(&k) = 0;
    CHECK_MPI_OK( mp_init(&e) );
    CHECK_MPI_OK( mp_init(&k) );
    SECITEM_TO_MPINT(key->publicExponent, &e);
    /* generate random k < n */
    kb = PORT_Alloc(modLen);
    if (!kb) {
	PORT_SetError(SEC_ERROR_NO_MEMORY);
	goto cleanup;
    }
    CHECK_SEC_OK( RNG_GenerateGlobalRandomBytes(kb, modLen) );
    CHECK_MPI_OK( mp_read_unsigned_octets(&k, kb, modLen) );
    /* k < n */
    CHECK_MPI_OK( mp_mod(&k, n, &k) );
    /* f = k**e mod n */
    CHECK_MPI_OK( mp_exptmod(&k, &e, n, f) );
    /* g = k**-1 mod n */
    CHECK_MPI_OK( mp_invmod(&k, n, g) );
cleanup:
    if (kb)
	PORT_ZFree(kb, modLen);
    mp_clear(&k);
    mp_clear(&e);
    if (err) {
	MP_TO_SEC_ERROR(err);
	rv = SECFailure;
    }
    return rv;
}

static SECStatus
init_blinding_params(RSABlindingParams *rsabp, RSAPrivateKey *key,
                     mp_int *n, unsigned int modLen)
{
    blindingParams * bp = rsabp->array;
    int i = 0;

    /* Initialize the list pointer for the element */
    PR_INIT_CLIST(&rsabp->link);
    for (i = 0; i < RSA_BLINDING_PARAMS_MAX_CACHE_SIZE; ++i, ++bp) {
    	bp->next = bp + 1;
	MP_DIGITS(&bp->f) = 0;
	MP_DIGITS(&bp->g) = 0;
	bp->counter = 0;
    }
    /* The last bp->next value was initialized with out
     * of rsabp->array pointer and must be set to NULL 
     */ 
    rsabp->array[RSA_BLINDING_PARAMS_MAX_CACHE_SIZE - 1].next = NULL;
    
    bp          = rsabp->array;
    rsabp->bp   = NULL;
    rsabp->free = bp;

    /* List elements are keyed using the modulus */
    return SECITEM_CopyItem(NULL, &rsabp->modulus, &key->modulus);
}

static SECStatus
get_blinding_params(RSAPrivateKey *key, mp_int *n, unsigned int modLen,
                    mp_int *f, mp_int *g)
{
    RSABlindingParams *rsabp           = NULL;
    blindingParams    *bpUnlinked      = NULL;
    blindingParams    *bp;
    PRCList           *el;
    SECStatus          rv              = SECSuccess;
    mp_err             err             = MP_OKAY;
    int                cmp             = -1;
    PRBool             holdingLock     = PR_FALSE;

    do {
	if (blindingParamsList.lock == NULL) {
	    PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
	    return SECFailure;
	}
	/* Acquire the list lock */
	PZ_Lock(blindingParamsList.lock);
	holdingLock = PR_TRUE;

	/* Walk the list looking for the private key */
	for (el = PR_NEXT_LINK(&blindingParamsList.head);
	     el != &blindingParamsList.head;
	     el = PR_NEXT_LINK(el)) {
	    rsabp = (RSABlindingParams *)el;
	    cmp = SECITEM_CompareItem(&rsabp->modulus, &key->modulus);
	    if (cmp >= 0) {
		/* The key is found or not in the list. */
		break;
	    }
	}

	if (cmp) {
	    /* At this point, the key is not in the list.  el should point to 
	    ** the list element before which this key should be inserted. 
	    */
	    rsabp = PORT_ZNew(RSABlindingParams);
	    if (!rsabp) {
		PORT_SetError(SEC_ERROR_NO_MEMORY);
		goto cleanup;
	    }

	    rv = init_blinding_params(rsabp, key, n, modLen);
	    if (rv != SECSuccess) {
		PORT_ZFree(rsabp, sizeof(RSABlindingParams));
		goto cleanup;
	    }

	    /* Insert the new element into the list
	    ** If inserting in the middle of the list, el points to the link
	    ** to insert before.  Otherwise, the link needs to be appended to
	    ** the end of the list, which is the same as inserting before the
	    ** head (since el would have looped back to the head).
	    */
	    PR_INSERT_BEFORE(&rsabp->link, el);
	}

	/* We've found (or created) the RSAblindingParams struct for this key.
	 * Now, search its list of ready blinding params for a usable one.
	 */
	while (0 != (bp = rsabp->bp)) {
	    if (--(bp->counter) > 0) {
		/* Found a match and there are still remaining uses left */
		/* Return the parameters */
		CHECK_MPI_OK( mp_copy(&bp->f, f) );
		CHECK_MPI_OK( mp_copy(&bp->g, g) );

		PZ_Unlock(blindingParamsList.lock); 
		return SECSuccess;
	    }
	    /* exhausted this one, give its values to caller, and
	     * then retire it.
	     */
	    mp_exch(&bp->f, f);
	    mp_exch(&bp->g, g);
	    mp_clear( &bp->f );
	    mp_clear( &bp->g );
	    bp->counter = 0;
	    /* Move to free list */
	    rsabp->bp   = bp->next;
	    bp->next    = rsabp->free;
	    rsabp->free = bp;
	    /* In case there're threads waiting for new blinding
	     * value - notify 1 thread the value is ready
	     */
	    if (blindingParamsList.waitCount > 0) {
		PR_NotifyCondVar( blindingParamsList.cVar );
		blindingParamsList.waitCount--;
	    }
	    PZ_Unlock(blindingParamsList.lock); 
	    return SECSuccess;
	}
	/* We did not find a usable set of blinding params.  Can we make one? */
	/* Find a free bp struct. */
	if ((bp = rsabp->free) != NULL) {
	    /* unlink this bp */
	    rsabp->free  = bp->next;
	    bp->next     = NULL;
	    bpUnlinked   = bp;  /* In case we fail */

	    PZ_Unlock(blindingParamsList.lock); 
	    holdingLock = PR_FALSE;
	    /* generate blinding parameter values for the current thread */
	    CHECK_SEC_OK( generate_blinding_params(key, f, g, n, modLen ) );

	    /* put the blinding parameter values into cache */
	    CHECK_MPI_OK( mp_init( &bp->f) );
	    CHECK_MPI_OK( mp_init( &bp->g) );
	    CHECK_MPI_OK( mp_copy( f, &bp->f) );
	    CHECK_MPI_OK( mp_copy( g, &bp->g) );

	    /* Put this at head of queue of usable params. */
	    PZ_Lock(blindingParamsList.lock);
            holdingLock = PR_TRUE;
            (void)holdingLock;
	    /* initialize RSABlindingParamsStr */
	    bp->counter = RSA_BLINDING_PARAMS_MAX_REUSE;
	    bp->next    = rsabp->bp;
	    rsabp->bp   = bp;
	    bpUnlinked  = NULL;
	    /* In case there're threads waiting for new blinding value
	     * just notify them the value is ready
	     */
	    if (blindingParamsList.waitCount > 0) {
		PR_NotifyAllCondVar( blindingParamsList.cVar );
		blindingParamsList.waitCount = 0;
	    }
	    PZ_Unlock(blindingParamsList.lock);
	    return SECSuccess;
	}
	/* Here, there are no usable blinding parameters available,
	 * and no free bp blocks, presumably because they're all 
	 * actively having parameters generated for them.
	 * So, we need to wait here and not eat up CPU until some 
	 * change happens. 
	 */
	blindingParamsList.waitCount++;
	PR_WaitCondVar( blindingParamsList.cVar, PR_INTERVAL_NO_TIMEOUT );
	PZ_Unlock(blindingParamsList.lock); 
	holdingLock = PR_FALSE;
        (void)holdingLock;
    } while (1);

cleanup:
    /* It is possible to reach this after the lock is already released.  */
    if (bpUnlinked) {
	if (!holdingLock) {
	    PZ_Lock(blindingParamsList.lock);
	    holdingLock = PR_TRUE;
	}
	bp = bpUnlinked;
	mp_clear( &bp->f );
	mp_clear( &bp->g );
	bp->counter = 0;
    	/* Must put the unlinked bp back on the free list */
	bp->next    = rsabp->free;
	rsabp->free = bp;
    }
    if (holdingLock) {
	PZ_Unlock(blindingParamsList.lock);
    }
    if (err) {
	MP_TO_SEC_ERROR(err);
    }
    return SECFailure;
}

/*
** Perform a raw private-key operation 
**	Length of input and output buffers are equal to key's modulus len.
*/
static SECStatus 
rsa_PrivateKeyOp(RSAPrivateKey *key, 
                 unsigned char *output, 
                 const unsigned char *input,
                 PRBool check)
{
    unsigned int modLen;
    unsigned int offset;
    SECStatus rv = SECSuccess;
    mp_err err;
    mp_int n, c, m;
    mp_int f, g;
    if (!key || !output || !input) {
	PORT_SetError(SEC_ERROR_INVALID_ARGS);
	return SECFailure;
    }
    /* check input out of range (needs to be in range [0..n-1]) */
    modLen = rsa_modulusLen(&key->modulus);
    offset = (key->modulus.data[0] == 0) ? 1 : 0; /* may be leading 0 */
    if (memcmp(input, key->modulus.data + offset, modLen) >= 0) {
	PORT_SetError(SEC_ERROR_INVALID_ARGS);
	return SECFailure;
    }
    MP_DIGITS(&n) = 0;
    MP_DIGITS(&c) = 0;
    MP_DIGITS(&m) = 0;
    MP_DIGITS(&f) = 0;
    MP_DIGITS(&g) = 0;
    CHECK_MPI_OK( mp_init(&n) );
    CHECK_MPI_OK( mp_init(&c) );
    CHECK_MPI_OK( mp_init(&m) );
    CHECK_MPI_OK( mp_init(&f) );
    CHECK_MPI_OK( mp_init(&g) );
    SECITEM_TO_MPINT(key->modulus, &n);
    OCTETS_TO_MPINT(input, &c, modLen);
    /* If blinding, compute pre-image of ciphertext by multiplying by
    ** blinding factor
    */
    if (nssRSAUseBlinding) {
	CHECK_SEC_OK( get_blinding_params(key, &n, modLen, &f, &g) );
	/* c' = c*f mod n */
	CHECK_MPI_OK( mp_mulmod(&c, &f, &n, &c) );
    }
    /* Do the private key operation m = c**d mod n */
    if ( key->prime1.len      == 0 ||
         key->prime2.len      == 0 ||
         key->exponent1.len   == 0 ||
         key->exponent2.len   == 0 ||
         key->coefficient.len == 0) {
	CHECK_SEC_OK( rsa_PrivateKeyOpNoCRT(key, &m, &c, &n, modLen) );
    } else if (check) {
	CHECK_SEC_OK( rsa_PrivateKeyOpCRTCheckedPubKey(key, &m, &c) );
    } else {
	CHECK_SEC_OK( rsa_PrivateKeyOpCRTNoCheck(key, &m, &c) );
    }
    /* If blinding, compute post-image of plaintext by multiplying by
    ** blinding factor
    */
    if (nssRSAUseBlinding) {
	/* m = m'*g mod n */
	CHECK_MPI_OK( mp_mulmod(&m, &g, &n, &m) );
    }
    err = mp_to_fixlen_octets(&m, output, modLen);
    if (err >= 0) err = MP_OKAY;
cleanup:
    mp_clear(&n);
    mp_clear(&c);
    mp_clear(&m);
    mp_clear(&f);
    mp_clear(&g);
    if (err) {
	MP_TO_SEC_ERROR(err);
	rv = SECFailure;
    }
    return rv;
}

SECStatus 
RSA_PrivateKeyOp(RSAPrivateKey *key, 
                 unsigned char *output, 
                 const unsigned char *input)
{
    return rsa_PrivateKeyOp(key, output, input, PR_FALSE);
}

SECStatus 
RSA_PrivateKeyOpDoubleChecked(RSAPrivateKey *key, 
                              unsigned char *output, 
                              const unsigned char *input)
{
    return rsa_PrivateKeyOp(key, output, input, PR_TRUE);
}

SECStatus
RSA_PrivateKeyCheck(const RSAPrivateKey *key)
{
    mp_int p, q, n, psub1, qsub1, e, d, d_p, d_q, qInv, res;
    mp_err   err = MP_OKAY;
    SECStatus rv = SECSuccess;
    MP_DIGITS(&p)    = 0;
    MP_DIGITS(&q)    = 0;
    MP_DIGITS(&n)    = 0;
    MP_DIGITS(&psub1)= 0;
    MP_DIGITS(&qsub1)= 0;
    MP_DIGITS(&e)    = 0;
    MP_DIGITS(&d)    = 0;
    MP_DIGITS(&d_p)  = 0;
    MP_DIGITS(&d_q)  = 0;
    MP_DIGITS(&qInv) = 0;
    MP_DIGITS(&res)  = 0;
    CHECK_MPI_OK( mp_init(&p)    );
    CHECK_MPI_OK( mp_init(&q)    );
    CHECK_MPI_OK( mp_init(&n)    );
    CHECK_MPI_OK( mp_init(&psub1));
    CHECK_MPI_OK( mp_init(&qsub1));
    CHECK_MPI_OK( mp_init(&e)    );
    CHECK_MPI_OK( mp_init(&d)    );
    CHECK_MPI_OK( mp_init(&d_p)  );
    CHECK_MPI_OK( mp_init(&d_q)  );
    CHECK_MPI_OK( mp_init(&qInv) );
    CHECK_MPI_OK( mp_init(&res)  );

    if (!key->modulus.data || !key->prime1.data || !key->prime2.data ||
        !key->publicExponent.data || !key->privateExponent.data ||
        !key->exponent1.data || !key->exponent2.data ||
        !key->coefficient.data) {
        /* call RSA_PopulatePrivateKey first, if the application wishes to
         * recover these parameters */
        err = MP_BADARG;
        goto cleanup;
    }

    SECITEM_TO_MPINT(key->modulus,         &n);
    SECITEM_TO_MPINT(key->prime1,          &p);
    SECITEM_TO_MPINT(key->prime2,          &q);
    SECITEM_TO_MPINT(key->publicExponent,  &e);
    SECITEM_TO_MPINT(key->privateExponent, &d);
    SECITEM_TO_MPINT(key->exponent1,       &d_p);
    SECITEM_TO_MPINT(key->exponent2,       &d_q);
    SECITEM_TO_MPINT(key->coefficient,     &qInv);
    /* p and q must be distinct. */
    if (mp_cmp(&p, &q) == 0) {
	rv = SECFailure;
	goto cleanup;
    }
#define VERIFY_MPI_EQUAL(m1, m2) \
    if (mp_cmp(m1, m2) != 0) {   \
	rv = SECFailure;         \
	goto cleanup;            \
    }
#define VERIFY_MPI_EQUAL_1(m)    \
    if (mp_cmp_d(m, 1) != 0) {   \
	rv = SECFailure;         \
	goto cleanup;            \
    }
    /* n == p * q */
    CHECK_MPI_OK( mp_mul(&p, &q, &res) );
    VERIFY_MPI_EQUAL(&res, &n);
    /* gcd(e, p-1) == 1 */
    CHECK_MPI_OK( mp_sub_d(&p, 1, &psub1) );
    CHECK_MPI_OK( mp_gcd(&e, &psub1, &res) );
    VERIFY_MPI_EQUAL_1(&res);
    /* gcd(e, q-1) == 1 */
    CHECK_MPI_OK( mp_sub_d(&q, 1, &qsub1) );
    CHECK_MPI_OK( mp_gcd(&e, &qsub1, &res) );
    VERIFY_MPI_EQUAL_1(&res);
    /* d*e == 1 mod p-1 */
    CHECK_MPI_OK( mp_mulmod(&d, &e, &psub1, &res) );
    VERIFY_MPI_EQUAL_1(&res);
    /* d*e == 1 mod q-1 */
    CHECK_MPI_OK( mp_mulmod(&d, &e, &qsub1, &res) );
    VERIFY_MPI_EQUAL_1(&res);
    /* d_p == d mod p-1 */
    CHECK_MPI_OK( mp_mod(&d, &psub1, &res) );
    VERIFY_MPI_EQUAL(&res, &d_p);
    /* d_q == d mod q-1 */
    CHECK_MPI_OK( mp_mod(&d, &qsub1, &res) );
    VERIFY_MPI_EQUAL(&res, &d_q);
    /* q * q**-1 == 1 mod p */
    CHECK_MPI_OK( mp_mulmod(&q, &qInv, &p, &res) );
    VERIFY_MPI_EQUAL_1(&res);

cleanup:
    mp_clear(&n);
    mp_clear(&p);
    mp_clear(&q);
    mp_clear(&psub1);
    mp_clear(&qsub1);
    mp_clear(&e);
    mp_clear(&d);
    mp_clear(&d_p);
    mp_clear(&d_q);
    mp_clear(&qInv);
    mp_clear(&res);
    if (err) {
	MP_TO_SEC_ERROR(err);
	rv = SECFailure;
    }
    return rv;
}

static SECStatus RSA_Init(void)
{
    if (PR_CallOnce(&coBPInit, init_blinding_params_list) != PR_SUCCESS) {
        PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
        return SECFailure;
    }
    return SECSuccess;
}

SECStatus BL_Init(void)
{
    return RSA_Init();
}

/* cleanup at shutdown */
void RSA_Cleanup(void)
{
    blindingParams * bp = NULL;
    if (!coBPInit.initialized)
	return;

    while (!PR_CLIST_IS_EMPTY(&blindingParamsList.head)) {
	RSABlindingParams *rsabp = 
	    (RSABlindingParams *)PR_LIST_HEAD(&blindingParamsList.head);
	PR_REMOVE_LINK(&rsabp->link);
	/* clear parameters cache */
	while (rsabp->bp != NULL) {
	    bp = rsabp->bp;
	    rsabp->bp = rsabp->bp->next;
	    mp_clear( &bp->f );
	    mp_clear( &bp->g );
	}
	SECITEM_FreeItem(&rsabp->modulus,PR_FALSE);
	PORT_Free(rsabp);
    }

    if (blindingParamsList.cVar) {
	PR_DestroyCondVar(blindingParamsList.cVar);
	blindingParamsList.cVar = NULL;
    }

    if (blindingParamsList.lock) {
	SKIP_AFTER_FORK(PZ_DestroyLock(blindingParamsList.lock));
	blindingParamsList.lock = NULL;
    }

    coBPInit.initialized = 0;
    coBPInit.inProgress = 0;
    coBPInit.status = 0;
}

/*
 * need a central place for this function to free up all the memory that
 * free_bl may have allocated along the way. Currently only RSA does this,
 * so I've put it here for now.
 */
void BL_Cleanup(void)
{
    RSA_Cleanup();
}

PRBool bl_parentForkedAfterC_Initialize;

/*
 * Set fork flag so it can be tested in SKIP_AFTER_FORK on relevant platforms.
 */
void BL_SetForkState(PRBool forked)
{
    bl_parentForkedAfterC_Initialize = forked;
}