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Diffstat (limited to 'contrib/pgcrypto/pgp-mpi-internal.c')
| -rw-r--r-- | contrib/pgcrypto/pgp-mpi-internal.c | 304 |
1 files changed, 304 insertions, 0 deletions
diff --git a/contrib/pgcrypto/pgp-mpi-internal.c b/contrib/pgcrypto/pgp-mpi-internal.c new file mode 100644 index 0000000..0cea514 --- /dev/null +++ b/contrib/pgcrypto/pgp-mpi-internal.c @@ -0,0 +1,304 @@ +/* + * pgp-mpi-internal.c + * OpenPGP MPI functions. + * + * Copyright (c) 2005 Marko Kreen + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * contrib/pgcrypto/pgp-mpi-internal.c + */ +#include "postgres.h" + +#include "imath.h" +#include "pgp.h" +#include "px.h" + +static mpz_t * +mp_new(void) +{ + mpz_t *mp = mp_int_alloc(); + + mp_int_init_size(mp, 256); + return mp; +} + +static void +mp_clear_free(mpz_t *a) +{ + if (!a) + return; + /* fixme: no clear? */ + mp_int_free(a); +} + + +static int +mp_px_rand(uint32 bits, mpz_t *res) +{ + unsigned bytes = (bits + 7) / 8; + int last_bits = bits & 7; + uint8 *buf; + + buf = px_alloc(bytes); + if (!pg_strong_random(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; +} + +static void +mp_modmul(mpz_t *a, mpz_t *b, mpz_t *p, mpz_t *res) +{ + mpz_t *tmp = mp_new(); + + mp_int_mul(a, b, tmp); + mp_int_mod(tmp, p, res); + mp_clear_free(tmp); +} + +static mpz_t * +mpi_to_bn(PGP_MPI *n) +{ + 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; +} + +static PGP_MPI * +bn_to_mpi(mpz_t *bn) +{ + 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; +} + +/* + * Decide the number of bits in the random component k + * + * It should be in the same range as p for signing (which + * is deprecated), but can be much smaller for encrypting. + * + * Until I research it further, I just mimic gpg behaviour. + * It has a special mapping table, for values <= 5120, + * above that it uses 'arbitrary high number'. Following + * algorithm hovers 10-70 bits above gpg values. And for + * larger p, it uses gpg's algorithm. + * + * The point is - if k gets large, encryption will be + * really slow. It does not matter for decryption. + */ +static int +decide_k_bits(int p_bits) +{ + if (p_bits <= 5120) + return p_bits / 10 + 160; + else + return (p_bits / 8 + 200) * 3 / 2; +} + +int +pgp_elgamal_encrypt(PGP_PubKey *pk, PGP_MPI *_m, + PGP_MPI **c1_p, PGP_MPI **c2_p) +{ + 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_elgamal_decrypt(PGP_PubKey *pk, PGP_MPI *_c1, PGP_MPI *_c2, + PGP_MPI **msg_p) +{ + 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_rsa_encrypt(PGP_PubKey *pk, PGP_MPI *_m, PGP_MPI **c_p) +{ + 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; +} + +int +pgp_rsa_decrypt(PGP_PubKey *pk, PGP_MPI *_c, PGP_MPI **m_p) +{ + 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; +} |