pgp-mpi-internal.c File Reference

#include "postgres.h"
#include "imath.h"
#include "px.h"
#include "pgp.h"

Include dependency graph for pgp-mpi-internal.c:

Go to the source code of this file.

Functions
static mpz_t *	mp_new ()
static void	mp_clear_free (mpz_t *a)
static int	mp_px_rand (uint32 bits, mpz_t *res)
static void	mp_modmul (mpz_t *a, mpz_t *b, mpz_t *p, mpz_t *res)
static mpz_t *	mpi_to_bn (PGP_MPI *n)
static PGP_MPI *	bn_to_mpi (mpz_t *bn)
static int	decide_k_bits (int p_bits)
int	pgp_elgamal_encrypt (PGP_PubKey *pk, PGP_MPI *_m, PGP_MPI **c1_p, PGP_MPI **c2_p)
int	pgp_elgamal_decrypt (PGP_PubKey *pk, PGP_MPI *_c1, PGP_MPI *_c2, PGP_MPI **msg_p)
int	pgp_rsa_encrypt (PGP_PubKey *pk, PGP_MPI *_m, PGP_MPI **c_p)
int	pgp_rsa_decrypt (PGP_PubKey *pk, PGP_MPI *_c, PGP_MPI **m_p)

Function Documentation

static PGP_MPI* bn_to_mpi ( mpz_t *  bn )

static

Definition at line 121 of file pgp-mpi-internal.c.

References PGP_MPI::bytes, PGP_MPI::data, mp_int_count_bits(), mp_int_to_unsigned(), pgp_mpi_alloc(), pgp_mpi_free(), and px_debug().

Referenced by pgp_elgamal_decrypt(), pgp_elgamal_encrypt(), pgp_rsa_decrypt(), and pgp_rsa_encrypt().

{
    int         res;
    PGP_MPI    *n;
    int         bytes;

    res = pgp_mpi_alloc(mp_int_count_bits(bn), &n);
    if (res < 0)
        return NULL;

    bytes = (mp_int_count_bits(bn) + 7) / 8;
    if (bytes != n->bytes)
    {
        px_debug("bn_to_mpi: bignum conversion failed: bn=%d, mpi=%d",
                 bytes, n->bytes);
        pgp_mpi_free(n);
        return NULL;
    }
    mp_int_to_unsigned(bn, n->data, n->bytes);
    return n;
}

static int decide_k_bits ( int  p_bits )

static

Definition at line 159 of file pgp-mpi-internal.c.

Referenced by pgp_elgamal_encrypt().

{
    if (p_bits <= 5120)
        return p_bits / 10 + 160;
    else
        return (p_bits / 8 + 200) * 3 / 2;
}

static void mp_clear_free ( mpz_t *  a )

static

Definition at line 48 of file pgp-mpi-internal.c.

References mp_int_free().

Referenced by mp_modmul(), mpi_to_bn(), pgp_elgamal_decrypt(), pgp_elgamal_encrypt(), pgp_rsa_decrypt(), and pgp_rsa_encrypt().

{
    if (!a)
        return;
    /* fixme: no clear? */
    mp_int_free(a);
}

static void mp_modmul ( mpz_t *  a, mpz_t *  b, mpz_t *  p, mpz_t *  res  )

static

Definition at line 92 of file pgp-mpi-internal.c.

References mp_clear_free(), mp_int_mod(), mp_int_mul(), and mp_new().

Referenced by pgp_elgamal_decrypt(), and pgp_elgamal_encrypt().

{
    mpz_t      *tmp = mp_new();

    mp_int_mul(a, b, tmp);
    mp_int_mod(tmp, p, res);
    mp_clear_free(tmp);
}

static mpz_t* mp_new ( )

static

Definition at line 39 of file pgp-mpi-internal.c.

References mp_int_alloc(), and mp_int_init_size().

Referenced by mp_modmul(), mpi_to_bn(), pgp_elgamal_decrypt(), pgp_elgamal_encrypt(), pgp_rsa_decrypt(), and pgp_rsa_encrypt().

{
    mpz_t      *mp = mp_int_alloc();

    mp_int_init_size(mp, 256);
    return mp;
}

static int mp_px_rand ( uint32  bits, mpz_t *  res  )

static

Definition at line 58 of file pgp-mpi-internal.c.

References buf, mp_int_read_unsigned(), pg_strong_random(), px_alloc, px_free, and PXE_NO_RANDOM.

Referenced by pgp_elgamal_encrypt().

{
#ifdef HAVE_STRONG_RANDOM
    unsigned    bytes = (bits + 7) / 8;
    int         last_bits = bits & 7;
    uint8      *buf;

    buf = px_alloc(bytes);
    if (!pg_strong_random((char *) buf, bytes))
    {
        px_free(buf);
        return PXE_NO_RANDOM;
    }

    /* clear unnecessary bits and set last bit to one */
    if (last_bits)
    {
        buf[0] >>= 8 - last_bits;
        buf[0] |= 1 << (last_bits - 1);
    }
    else
        buf[0] |= 1 << 7;

    mp_int_read_unsigned(res, buf, bytes);

    px_free(buf);

    return 0;
#else
    return PXE_NO_RANDOM;
#endif
}

static mpz_t* mpi_to_bn ( PGP_MPI *  n )

static

Definition at line 102 of file pgp-mpi-internal.c.

References PGP_MPI::bits, PGP_MPI::bytes, PGP_MPI::data, mp_clear_free(), mp_int_count_bits(), mp_int_read_unsigned(), mp_new(), and px_debug().

Referenced by pgp_elgamal_decrypt(), pgp_elgamal_encrypt(), pgp_rsa_decrypt(), and pgp_rsa_encrypt().

{
    mpz_t      *bn = mp_new();

    mp_int_read_unsigned(bn, n->data, n->bytes);

    if (!bn)
        return NULL;
    if (mp_int_count_bits(bn) != n->bits)
    {
        px_debug("mpi_to_bn: bignum conversion failed: mpi=%d, bn=%d",
                 n->bits, mp_int_count_bits(bn));
        mp_clear_free(bn);
        return NULL;
    }
    return bn;
}

int pgp_elgamal_decrypt	(	PGP_PubKey *	pk,
		PGP_MPI *	_c1,
		PGP_MPI *	_c2,
		PGP_MPI **	msg_p
	)

Definition at line 218 of file pgp-mpi-internal.c.

Referenced by decrypt_elgamal().

{
    int         res = PXE_PGP_MATH_FAILED;
    mpz_t      *c1 = mpi_to_bn(_c1);
    mpz_t      *c2 = mpi_to_bn(_c2);
    mpz_t      *p = mpi_to_bn(pk->pub.elg.p);
    mpz_t      *x = mpi_to_bn(pk->sec.elg.x);
    mpz_t      *c1x = mp_new();
    mpz_t      *div = mp_new();
    mpz_t      *m = mp_new();

    if (!c1 || !c2 || !p || !x || !c1x || !div || !m)
        goto err;

    /*
     * m = c2 / (c1^x)
     */
    mp_int_exptmod(c1, x, p, c1x);
    mp_int_invmod(c1x, p, div);
    mp_modmul(c2, div, p, m);

    /* result */
    *msg_p = bn_to_mpi(m);
    if (*msg_p)
        res = 0;
err:
    mp_clear_free(m);
    mp_clear_free(div);
    mp_clear_free(c1x);
    mp_clear_free(x);
    mp_clear_free(p);
    mp_clear_free(c2);
    mp_clear_free(c1);
    return res;
}

int pgp_elgamal_encrypt	(	PGP_PubKey *	pk,
		PGP_MPI *	_m,
		PGP_MPI **	c1_p,
		PGP_MPI **	c2_p
	)

Definition at line 168 of file pgp-mpi-internal.c.

Referenced by encrypt_and_write_elgamal().

{
    int         res = PXE_PGP_MATH_FAILED;
    int         k_bits;
    mpz_t      *m = mpi_to_bn(_m);
    mpz_t      *p = mpi_to_bn(pk->pub.elg.p);
    mpz_t      *g = mpi_to_bn(pk->pub.elg.g);
    mpz_t      *y = mpi_to_bn(pk->pub.elg.y);
    mpz_t      *k = mp_new();
    mpz_t      *yk = mp_new();
    mpz_t      *c1 = mp_new();
    mpz_t      *c2 = mp_new();

    if (!m || !p || !g || !y || !k || !yk || !c1 || !c2)
        goto err;

    /*
     * generate k
     */
    k_bits = decide_k_bits(mp_int_count_bits(p));
    res = mp_px_rand(k_bits, k);
    if (res < 0)
        return res;

    /*
     * c1 = g^k c2 = m * y^k
     */
    mp_int_exptmod(g, k, p, c1);
    mp_int_exptmod(y, k, p, yk);
    mp_modmul(m, yk, p, c2);

    /* result */
    *c1_p = bn_to_mpi(c1);
    *c2_p = bn_to_mpi(c2);
    if (*c1_p && *c2_p)
        res = 0;
err:
    mp_clear_free(c2);
    mp_clear_free(c1);
    mp_clear_free(yk);
    mp_clear_free(k);
    mp_clear_free(y);
    mp_clear_free(g);
    mp_clear_free(p);
    mp_clear_free(m);
    return res;
}

int pgp_rsa_decrypt	(	PGP_PubKey *	pk,
		PGP_MPI *	_c,
		PGP_MPI **	m_p
	)

Definition at line 284 of file pgp-mpi-internal.c.

Referenced by decrypt_rsa().

{
    int         res = PXE_PGP_MATH_FAILED;
    mpz_t      *c = mpi_to_bn(_c);
    mpz_t      *d = mpi_to_bn(pk->sec.rsa.d);
    mpz_t      *n = mpi_to_bn(pk->pub.rsa.n);
    mpz_t      *m = mp_new();

    if (!m || !d || !n || !c)
        goto err;

    /*
     * m = c ^ d
     */
    mp_int_exptmod(c, d, n, m);

    *m_p = bn_to_mpi(m);
    if (*m_p)
        res = 0;
err:
    mp_clear_free(m);
    mp_clear_free(n);
    mp_clear_free(d);
    mp_clear_free(c);
    return res;
}

int pgp_rsa_encrypt	(	PGP_PubKey *	pk,
		PGP_MPI *	_m,
		PGP_MPI **	c_p
	)

Definition at line 256 of file pgp-mpi-internal.c.

Referenced by encrypt_and_write_rsa().

{
    int         res = PXE_PGP_MATH_FAILED;
    mpz_t      *m = mpi_to_bn(_m);
    mpz_t      *e = mpi_to_bn(pk->pub.rsa.e);
    mpz_t      *n = mpi_to_bn(pk->pub.rsa.n);
    mpz_t      *c = mp_new();

    if (!m || !e || !n || !c)
        goto err;

    /*
     * c = m ^ e
     */
    mp_int_exptmod(m, e, n, c);

    *c_p = bn_to_mpi(c);
    if (*c_p)
        res = 0;
err:
    mp_clear_free(c);
    mp_clear_free(n);
    mp_clear_free(e);
    mp_clear_free(m);
    return res;
}