diff options
Diffstat (limited to 'grub-core/lib/libgcrypt/cipher/rsa.c')
| -rw-r--r-- | grub-core/lib/libgcrypt/cipher/rsa.c | 1390 |
1 files changed, 1390 insertions, 0 deletions
diff --git a/grub-core/lib/libgcrypt/cipher/rsa.c b/grub-core/lib/libgcrypt/cipher/rsa.c new file mode 100644 index 0000000..ccc9f96 --- /dev/null +++ b/grub-core/lib/libgcrypt/cipher/rsa.c @@ -0,0 +1,1390 @@ +/* rsa.c - RSA implementation + * Copyright (C) 1997, 1998, 1999 by Werner Koch (dd9jn) + * Copyright (C) 2000, 2001, 2002, 2003, 2008 Free Software Foundation, Inc. + * + * This file is part of Libgcrypt. + * + * Libgcrypt is free software; you can redistribute it and/or modify + * it under the terms of the GNU Lesser General Public License as + * published by the Free Software Foundation; either version 2.1 of + * the License, or (at your option) any later version. + * + * Libgcrypt is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this program; if not, see <http://www.gnu.org/licenses/>. + */ + +/* This code uses an algorithm protected by U.S. Patent #4,405,829 + which expired on September 20, 2000. The patent holder placed that + patent into the public domain on Sep 6th, 2000. +*/ + +#include <config.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <errno.h> + +#include "g10lib.h" +#include "mpi.h" +#include "cipher.h" + + +typedef struct +{ + gcry_mpi_t n; /* modulus */ + gcry_mpi_t e; /* exponent */ +} RSA_public_key; + + +typedef struct +{ + gcry_mpi_t n; /* public modulus */ + gcry_mpi_t e; /* public exponent */ + gcry_mpi_t d; /* exponent */ + gcry_mpi_t p; /* prime p. */ + gcry_mpi_t q; /* prime q. */ + gcry_mpi_t u; /* inverse of p mod q. */ +} RSA_secret_key; + + +/* A sample 1024 bit RSA key used for the selftests. */ +static const char sample_secret_key[] = +"(private-key" +" (rsa" +" (n #00e0ce96f90b6c9e02f3922beada93fe50a875eac6bcc18bb9a9cf2e84965caa" +" 2d1ff95a7f542465c6c0c19d276e4526ce048868a7a914fd343cc3a87dd74291" +" ffc565506d5bbb25cbac6a0e2dd1f8bcaab0d4a29c2f37c950f363484bf269f7" +" 891440464baf79827e03a36e70b814938eebdc63e964247be75dc58b014b7ea251#)" +" (e #010001#)" +" (d #046129f2489d71579be0a75fe029bd6cdb574ebf57ea8a5b0fda942cab943b11" +" 7d7bb95e5d28875e0f9fc5fcc06a72f6d502464dabded78ef6b716177b83d5bd" +" c543dc5d3fed932e59f5897e92e6f58a0f33424106a3b6fa2cbf877510e4ac21" +" c3ee47851e97d12996222ac3566d4ccb0b83d164074abf7de655fc2446da1781#)" +" (p #00e861b700e17e8afe6837e7512e35b6ca11d0ae47d8b85161c67baf64377213" +" fe52d772f2035b3ca830af41d8a4120e1c1c70d12cc22f00d28d31dd48a8d424f1#)" +" (q #00f7a7ca5367c661f8e62df34f0d05c10c88e5492348dd7bddc942c9a8f369f9" +" 35a07785d2db805215ed786e4285df1658eed3ce84f469b81b50d358407b4ad361#)" +" (u #304559a9ead56d2309d203811a641bb1a09626bc8eb36fffa23c968ec5bd891e" +" ebbafc73ae666e01ba7c8990bae06cc2bbe10b75e69fcacb353a6473079d8e9b#)))"; +/* A sample 1024 bit RSA key used for the selftests (public only). */ +static const char sample_public_key[] = +"(public-key" +" (rsa" +" (n #00e0ce96f90b6c9e02f3922beada93fe50a875eac6bcc18bb9a9cf2e84965caa" +" 2d1ff95a7f542465c6c0c19d276e4526ce048868a7a914fd343cc3a87dd74291" +" ffc565506d5bbb25cbac6a0e2dd1f8bcaab0d4a29c2f37c950f363484bf269f7" +" 891440464baf79827e03a36e70b814938eebdc63e964247be75dc58b014b7ea251#)" +" (e #010001#)))"; + + + + +static int test_keys (RSA_secret_key *sk, unsigned nbits); +static int check_secret_key (RSA_secret_key *sk); +static void public (gcry_mpi_t output, gcry_mpi_t input, RSA_public_key *skey); +static void secret (gcry_mpi_t output, gcry_mpi_t input, RSA_secret_key *skey); + + +/* Check that a freshly generated key actually works. Returns 0 on success. */ +static int +test_keys (RSA_secret_key *sk, unsigned int nbits) +{ + int result = -1; /* Default to failure. */ + RSA_public_key pk; + gcry_mpi_t plaintext = gcry_mpi_new (nbits); + gcry_mpi_t ciphertext = gcry_mpi_new (nbits); + gcry_mpi_t decr_plaintext = gcry_mpi_new (nbits); + gcry_mpi_t signature = gcry_mpi_new (nbits); + + /* Put the relevant parameters into a public key structure. */ + pk.n = sk->n; + pk.e = sk->e; + + /* Create a random plaintext. */ + gcry_mpi_randomize (plaintext, nbits, GCRY_WEAK_RANDOM); + + /* Encrypt using the public key. */ + public (ciphertext, plaintext, &pk); + + /* Check that the cipher text does not match the plaintext. */ + if (!gcry_mpi_cmp (ciphertext, plaintext)) + goto leave; /* Ciphertext is identical to the plaintext. */ + + /* Decrypt using the secret key. */ + secret (decr_plaintext, ciphertext, sk); + + /* Check that the decrypted plaintext matches the original plaintext. */ + if (gcry_mpi_cmp (decr_plaintext, plaintext)) + goto leave; /* Plaintext does not match. */ + + /* Create another random plaintext as data for signature checking. */ + gcry_mpi_randomize (plaintext, nbits, GCRY_WEAK_RANDOM); + + /* Use the RSA secret function to create a signature of the plaintext. */ + secret (signature, plaintext, sk); + + /* Use the RSA public function to verify this signature. */ + public (decr_plaintext, signature, &pk); + if (gcry_mpi_cmp (decr_plaintext, plaintext)) + goto leave; /* Signature does not match. */ + + /* Modify the signature and check that the signing fails. */ + gcry_mpi_add_ui (signature, signature, 1); + public (decr_plaintext, signature, &pk); + if (!gcry_mpi_cmp (decr_plaintext, plaintext)) + goto leave; /* Signature matches but should not. */ + + result = 0; /* All tests succeeded. */ + + leave: + gcry_mpi_release (signature); + gcry_mpi_release (decr_plaintext); + gcry_mpi_release (ciphertext); + gcry_mpi_release (plaintext); + return result; +} + + +/* Callback used by the prime generation to test whether the exponent + is suitable. Returns 0 if the test has been passed. */ +static int +check_exponent (void *arg, gcry_mpi_t a) +{ + gcry_mpi_t e = arg; + gcry_mpi_t tmp; + int result; + + mpi_sub_ui (a, a, 1); + tmp = _gcry_mpi_alloc_like (a); + result = !gcry_mpi_gcd(tmp, e, a); /* GCD is not 1. */ + gcry_mpi_release (tmp); + mpi_add_ui (a, a, 1); + return result; +} + +/**************** + * Generate a key pair with a key of size NBITS. + * USE_E = 0 let Libcgrypt decide what exponent to use. + * = 1 request the use of a "secure" exponent; this is required by some + * specification to be 65537. + * > 2 Use this public exponent. If the given exponent + * is not odd one is internally added to it. + * TRANSIENT_KEY: If true, generate the primes using the standard RNG. + * Returns: 2 structures filled with all needed values + */ +static gpg_err_code_t +generate_std (RSA_secret_key *sk, unsigned int nbits, unsigned long use_e, + int transient_key) +{ + gcry_mpi_t p, q; /* the two primes */ + gcry_mpi_t d; /* the private key */ + gcry_mpi_t u; + gcry_mpi_t t1, t2; + gcry_mpi_t n; /* the public key */ + gcry_mpi_t e; /* the exponent */ + gcry_mpi_t phi; /* helper: (p-1)(q-1) */ + gcry_mpi_t g; + gcry_mpi_t f; + gcry_random_level_t random_level; + + if (fips_mode ()) + { + if (nbits < 1024) + return GPG_ERR_INV_VALUE; + if (transient_key) + return GPG_ERR_INV_VALUE; + } + + /* The random quality depends on the transient_key flag. */ + random_level = transient_key ? GCRY_STRONG_RANDOM : GCRY_VERY_STRONG_RANDOM; + + /* Make sure that nbits is even so that we generate p, q of equal size. */ + if ( (nbits&1) ) + nbits++; + + if (use_e == 1) /* Alias for a secure value */ + use_e = 65537; /* as demanded by Sphinx. */ + + /* Public exponent: + In general we use 41 as this is quite fast and more secure than the + commonly used 17. Benchmarking the RSA verify function + with a 1024 bit key yields (2001-11-08): + e=17 0.54 ms + e=41 0.75 ms + e=257 0.95 ms + e=65537 1.80 ms + */ + e = mpi_alloc( (32+BITS_PER_MPI_LIMB-1)/BITS_PER_MPI_LIMB ); + if (!use_e) + mpi_set_ui (e, 41); /* This is a reasonable secure and fast value */ + else + { + use_e |= 1; /* make sure this is odd */ + mpi_set_ui (e, use_e); + } + + n = gcry_mpi_new (nbits); + + p = q = NULL; + do + { + /* select two (very secret) primes */ + if (p) + gcry_mpi_release (p); + if (q) + gcry_mpi_release (q); + if (use_e) + { /* Do an extra test to ensure that the given exponent is + suitable. */ + p = _gcry_generate_secret_prime (nbits/2, random_level, + check_exponent, e); + q = _gcry_generate_secret_prime (nbits/2, random_level, + check_exponent, e); + } + else + { /* We check the exponent later. */ + p = _gcry_generate_secret_prime (nbits/2, random_level, NULL, NULL); + q = _gcry_generate_secret_prime (nbits/2, random_level, NULL, NULL); + } + if (mpi_cmp (p, q) > 0 ) /* p shall be smaller than q (for calc of u)*/ + mpi_swap(p,q); + /* calculate the modulus */ + mpi_mul( n, p, q ); + } + while ( mpi_get_nbits(n) != nbits ); + + /* calculate Euler totient: phi = (p-1)(q-1) */ + t1 = mpi_alloc_secure( mpi_get_nlimbs(p) ); + t2 = mpi_alloc_secure( mpi_get_nlimbs(p) ); + phi = gcry_mpi_snew ( nbits ); + g = gcry_mpi_snew ( nbits ); + f = gcry_mpi_snew ( nbits ); + mpi_sub_ui( t1, p, 1 ); + mpi_sub_ui( t2, q, 1 ); + mpi_mul( phi, t1, t2 ); + gcry_mpi_gcd(g, t1, t2); + mpi_fdiv_q(f, phi, g); + + while (!gcry_mpi_gcd(t1, e, phi)) /* (while gcd is not 1) */ + { + if (use_e) + BUG (); /* The prime generator already made sure that we + never can get to here. */ + mpi_add_ui (e, e, 2); + } + + /* calculate the secret key d = e^1 mod phi */ + d = gcry_mpi_snew ( nbits ); + mpi_invm(d, e, f ); + /* calculate the inverse of p and q (used for chinese remainder theorem)*/ + u = gcry_mpi_snew ( nbits ); + mpi_invm(u, p, q ); + + if( DBG_CIPHER ) + { + log_mpidump(" p= ", p ); + log_mpidump(" q= ", q ); + log_mpidump("phi= ", phi ); + log_mpidump(" g= ", g ); + log_mpidump(" f= ", f ); + log_mpidump(" n= ", n ); + log_mpidump(" e= ", e ); + log_mpidump(" d= ", d ); + log_mpidump(" u= ", u ); + } + + gcry_mpi_release (t1); + gcry_mpi_release (t2); + gcry_mpi_release (phi); + gcry_mpi_release (f); + gcry_mpi_release (g); + + sk->n = n; + sk->e = e; + sk->p = p; + sk->q = q; + sk->d = d; + sk->u = u; + + /* Now we can test our keys. */ + if (test_keys (sk, nbits - 64)) + { + gcry_mpi_release (sk->n); sk->n = NULL; + gcry_mpi_release (sk->e); sk->e = NULL; + gcry_mpi_release (sk->p); sk->p = NULL; + gcry_mpi_release (sk->q); sk->q = NULL; + gcry_mpi_release (sk->d); sk->d = NULL; + gcry_mpi_release (sk->u); sk->u = NULL; + fips_signal_error ("self-test after key generation failed"); + return GPG_ERR_SELFTEST_FAILED; + } + + return 0; +} + + +/* Helper for generate_x931. */ +static gcry_mpi_t +gen_x931_parm_xp (unsigned int nbits) +{ + gcry_mpi_t xp; + + xp = gcry_mpi_snew (nbits); + gcry_mpi_randomize (xp, nbits, GCRY_VERY_STRONG_RANDOM); + + /* The requirement for Xp is: + + sqrt{2}*2^{nbits-1} <= xp <= 2^{nbits} - 1 + + We set the two high order bits to 1 to satisfy the lower bound. + By using mpi_set_highbit we make sure that the upper bound is + satisfied as well. */ + mpi_set_highbit (xp, nbits-1); + mpi_set_bit (xp, nbits-2); + gcry_assert ( mpi_get_nbits (xp) == nbits ); + + return xp; +} + + +/* Helper for generate_x931. */ +static gcry_mpi_t +gen_x931_parm_xi (void) +{ + gcry_mpi_t xi; + + xi = gcry_mpi_snew (101); + gcry_mpi_randomize (xi, 101, GCRY_VERY_STRONG_RANDOM); + mpi_set_highbit (xi, 100); + gcry_assert ( mpi_get_nbits (xi) == 101 ); + + return xi; +} + + + +/* Variant of the standard key generation code using the algorithm + from X9.31. Using this algorithm has the advantage that the + generation can be made deterministic which is required for CAVS + testing. */ +static gpg_err_code_t +generate_x931 (RSA_secret_key *sk, unsigned int nbits, unsigned long e_value, + gcry_sexp_t deriveparms, int *swapped) +{ + gcry_mpi_t p, q; /* The two primes. */ + gcry_mpi_t e; /* The public exponent. */ + gcry_mpi_t n; /* The public key. */ + gcry_mpi_t d; /* The private key */ + gcry_mpi_t u; /* The inverse of p and q. */ + gcry_mpi_t pm1; /* p - 1 */ + gcry_mpi_t qm1; /* q - 1 */ + gcry_mpi_t phi; /* Euler totient. */ + gcry_mpi_t f, g; /* Helper. */ + + *swapped = 0; + + if (e_value == 1) /* Alias for a secure value. */ + e_value = 65537; + + /* Point 1 of section 4.1: k = 1024 + 256s with S >= 0 */ + if (nbits < 1024 || (nbits % 256)) + return GPG_ERR_INV_VALUE; + + /* Point 2: 2 <= bitlength(e) < 2^{k-2} + Note that we do not need to check the upper bound because we use + an unsigned long for E and thus there is no way for E to reach + that limit. */ + if (e_value < 3) + return GPG_ERR_INV_VALUE; + + /* Our implementaion requires E to be odd. */ + if (!(e_value & 1)) + return GPG_ERR_INV_VALUE; + + /* Point 3: e > 0 or e 0 if it is to be randomly generated. + We support only a fixed E and thus there is no need for an extra test. */ + + + /* Compute or extract the derive parameters. */ + { + gcry_mpi_t xp1 = NULL; + gcry_mpi_t xp2 = NULL; + gcry_mpi_t xp = NULL; + gcry_mpi_t xq1 = NULL; + gcry_mpi_t xq2 = NULL; + gcry_mpi_t xq = NULL; + gcry_mpi_t tmpval; + + if (!deriveparms) + { + /* Not given: Generate them. */ + xp = gen_x931_parm_xp (nbits/2); + /* Make sure that |xp - xq| > 2^{nbits - 100} holds. */ + tmpval = gcry_mpi_snew (nbits/2); + do + { + gcry_mpi_release (xq); + xq = gen_x931_parm_xp (nbits/2); + mpi_sub (tmpval, xp, xq); + } + while (mpi_get_nbits (tmpval) <= (nbits/2 - 100)); + gcry_mpi_release (tmpval); + + xp1 = gen_x931_parm_xi (); + xp2 = gen_x931_parm_xi (); + xq1 = gen_x931_parm_xi (); + xq2 = gen_x931_parm_xi (); + + } + else + { + /* Parameters to derive the key are given. */ + /* Note that we explicitly need to setup the values of tbl + because some compilers (e.g. OpenWatcom, IRIX) don't allow + to initialize a structure with automatic variables. */ + struct { const char *name; gcry_mpi_t *value; } tbl[] = { + { "Xp1" }, + { "Xp2" }, + { "Xp" }, + { "Xq1" }, + { "Xq2" }, + { "Xq" }, + { NULL } + }; + int idx; + gcry_sexp_t oneparm; + + tbl[0].value = &xp1; + tbl[1].value = &xp2; + tbl[2].value = &xp; + tbl[3].value = &xq1; + tbl[4].value = &xq2; + tbl[5].value = &xq; + + for (idx=0; tbl[idx].name; idx++) + { + oneparm = gcry_sexp_find_token (deriveparms, tbl[idx].name, 0); + if (oneparm) + { + *tbl[idx].value = gcry_sexp_nth_mpi (oneparm, 1, + GCRYMPI_FMT_USG); + gcry_sexp_release (oneparm); + } + } + for (idx=0; tbl[idx].name; idx++) + if (!*tbl[idx].value) + break; + if (tbl[idx].name) + { + /* At least one parameter is missing. */ + for (idx=0; tbl[idx].name; idx++) + gcry_mpi_release (*tbl[idx].value); + return GPG_ERR_MISSING_VALUE; + } + } + + e = mpi_alloc_set_ui (e_value); + + /* Find two prime numbers. */ + p = _gcry_derive_x931_prime (xp, xp1, xp2, e, NULL, NULL); + q = _gcry_derive_x931_prime (xq, xq1, xq2, e, NULL, NULL); + gcry_mpi_release (xp); xp = NULL; + gcry_mpi_release (xp1); xp1 = NULL; + gcry_mpi_release (xp2); xp2 = NULL; + gcry_mpi_release (xq); xq = NULL; + gcry_mpi_release (xq1); xq1 = NULL; + gcry_mpi_release (xq2); xq2 = NULL; + if (!p || !q) + { + gcry_mpi_release (p); + gcry_mpi_release (q); + gcry_mpi_release (e); + return GPG_ERR_NO_PRIME; + } + } + + + /* Compute the public modulus. We make sure that p is smaller than + q to allow the use of the CRT. */ + if (mpi_cmp (p, q) > 0 ) + { + mpi_swap (p, q); + *swapped = 1; + } + n = gcry_mpi_new (nbits); + mpi_mul (n, p, q); + + /* Compute the Euler totient: phi = (p-1)(q-1) */ + pm1 = gcry_mpi_snew (nbits/2); + qm1 = gcry_mpi_snew (nbits/2); + phi = gcry_mpi_snew (nbits); + mpi_sub_ui (pm1, p, 1); + mpi_sub_ui (qm1, q, 1); + mpi_mul (phi, pm1, qm1); + + g = gcry_mpi_snew (nbits); + gcry_assert (gcry_mpi_gcd (g, e, phi)); + + /* Compute: f = lcm(p-1,q-1) = phi / gcd(p-1,q-1) */ + gcry_mpi_gcd (g, pm1, qm1); + f = pm1; pm1 = NULL; + gcry_mpi_release (qm1); qm1 = NULL; + mpi_fdiv_q (f, phi, g); + gcry_mpi_release (phi); phi = NULL; + d = g; g = NULL; + /* Compute the secret key: d = e^{-1} mod lcm(p-1,q-1) */ + mpi_invm (d, e, f); + + /* Compute the inverse of p and q. */ + u = f; f = NULL; + mpi_invm (u, p, q ); + + if( DBG_CIPHER ) + { + if (*swapped) + log_debug ("p and q are swapped\n"); + log_mpidump(" p", p ); + log_mpidump(" q", q ); + log_mpidump(" n", n ); + log_mpidump(" e", e ); + log_mpidump(" d", d ); + log_mpidump(" u", u ); + } + + + sk->n = n; + sk->e = e; + sk->p = p; + sk->q = q; + sk->d = d; + sk->u = u; + + /* Now we can test our keys. */ + if (test_keys (sk, nbits - 64)) + { + gcry_mpi_release (sk->n); sk->n = NULL; + gcry_mpi_release (sk->e); sk->e = NULL; + gcry_mpi_release (sk->p); sk->p = NULL; + gcry_mpi_release (sk->q); sk->q = NULL; + gcry_mpi_release (sk->d); sk->d = NULL; + gcry_mpi_release (sk->u); sk->u = NULL; + fips_signal_error ("self-test after key generation failed"); + return GPG_ERR_SELFTEST_FAILED; + } + + return 0; +} + + +/**************** + * Test whether the secret key is valid. + * Returns: true if this is a valid key. + */ +static int +check_secret_key( RSA_secret_key *sk ) +{ + int rc; + gcry_mpi_t temp = mpi_alloc( mpi_get_nlimbs(sk->p)*2 ); + + mpi_mul(temp, sk->p, sk->q ); + rc = mpi_cmp( temp, sk->n ); + mpi_free(temp); + return !rc; +} + + + +/**************** + * Public key operation. Encrypt INPUT with PKEY and put result into OUTPUT. + * + * c = m^e mod n + * + * Where c is OUTPUT, m is INPUT and e,n are elements of PKEY. + */ +static void +public(gcry_mpi_t output, gcry_mpi_t input, RSA_public_key *pkey ) +{ + if( output == input ) /* powm doesn't like output and input the same */ + { + gcry_mpi_t x = mpi_alloc( mpi_get_nlimbs(input)*2 ); + mpi_powm( x, input, pkey->e, pkey->n ); + mpi_set(output, x); + mpi_free(x); + } + else + mpi_powm( output, input, pkey->e, pkey->n ); +} + +#if 0 +static void +stronger_key_check ( RSA_secret_key *skey ) +{ + gcry_mpi_t t = mpi_alloc_secure ( 0 ); + gcry_mpi_t t1 = mpi_alloc_secure ( 0 ); + gcry_mpi_t t2 = mpi_alloc_secure ( 0 ); + gcry_mpi_t phi = mpi_alloc_secure ( 0 ); + + /* check that n == p * q */ + mpi_mul( t, skey->p, skey->q); + if (mpi_cmp( t, skey->n) ) + log_info ( "RSA Oops: n != p * q\n" ); + + /* check that p is less than q */ + if( mpi_cmp( skey->p, skey->q ) > 0 ) + { + log_info ("RSA Oops: p >= q - fixed\n"); + _gcry_mpi_swap ( skey->p, skey->q); + } + + /* check that e divides neither p-1 nor q-1 */ + mpi_sub_ui(t, skey->p, 1 ); + mpi_fdiv_r(t, t, skey->e ); + if ( !mpi_cmp_ui( t, 0) ) + log_info ( "RSA Oops: e divides p-1\n" ); + mpi_sub_ui(t, skey->q, 1 ); + mpi_fdiv_r(t, t, skey->e ); + if ( !mpi_cmp_ui( t, 0) ) + log_info ( "RSA Oops: e divides q-1\n" ); + + /* check that d is correct */ + mpi_sub_ui( t1, skey->p, 1 ); + mpi_sub_ui( t2, skey->q, 1 ); + mpi_mul( phi, t1, t2 ); + gcry_mpi_gcd(t, t1, t2); + mpi_fdiv_q(t, phi, t); + mpi_invm(t, skey->e, t ); + if ( mpi_cmp(t, skey->d ) ) + { + log_info ( "RSA Oops: d is wrong - fixed\n"); + mpi_set (skey->d, t); + _gcry_log_mpidump (" fixed d", skey->d); + } + + /* check for correctness of u */ + mpi_invm(t, skey->p, skey->q ); + if ( mpi_cmp(t, skey->u ) ) + { + log_info ( "RSA Oops: u is wrong - fixed\n"); + mpi_set (skey->u, t); + _gcry_log_mpidump (" fixed u", skey->u); + } + + log_info ( "RSA secret key check finished\n"); + + mpi_free (t); + mpi_free (t1); + mpi_free (t2); + mpi_free (phi); +} +#endif + + + +/**************** + * Secret key operation. Encrypt INPUT with SKEY and put result into OUTPUT. + * + * m = c^d mod n + * + * Or faster: + * + * m1 = c ^ (d mod (p-1)) mod p + * m2 = c ^ (d mod (q-1)) mod q + * h = u * (m2 - m1) mod q + * m = m1 + h * p + * + * Where m is OUTPUT, c is INPUT and d,n,p,q,u are elements of SKEY. + */ +static void +secret(gcry_mpi_t output, gcry_mpi_t input, RSA_secret_key *skey ) +{ + if (!skey->p || !skey->q || !skey->u) + { + mpi_powm (output, input, skey->d, skey->n); + } + else + { + gcry_mpi_t m1 = mpi_alloc_secure( mpi_get_nlimbs(skey->n)+1 ); + gcry_mpi_t m2 = mpi_alloc_secure( mpi_get_nlimbs(skey->n)+1 ); + gcry_mpi_t h = mpi_alloc_secure( mpi_get_nlimbs(skey->n)+1 ); + + /* m1 = c ^ (d mod (p-1)) mod p */ + mpi_sub_ui( h, skey->p, 1 ); + mpi_fdiv_r( h, skey->d, h ); + mpi_powm( m1, input, h, skey->p ); + /* m2 = c ^ (d mod (q-1)) mod q */ + mpi_sub_ui( h, skey->q, 1 ); + mpi_fdiv_r( h, skey->d, h ); + mpi_powm( m2, input, h, skey->q ); + /* h = u * ( m2 - m1 ) mod q */ + mpi_sub( h, m2, m1 ); + if ( mpi_is_neg( h ) ) + mpi_add ( h, h, skey->q ); + mpi_mulm( h, skey->u, h, skey->q ); + /* m = m2 + h * p */ + mpi_mul ( h, h, skey->p ); + mpi_add ( output, m1, h ); + + mpi_free ( h ); + mpi_free ( m1 ); + mpi_free ( m2 ); + } +} + + + +/* Perform RSA blinding. */ +static gcry_mpi_t +rsa_blind (gcry_mpi_t x, gcry_mpi_t r, gcry_mpi_t e, gcry_mpi_t n) +{ + /* A helper. */ + gcry_mpi_t a; + + /* Result. */ + gcry_mpi_t y; + + a = gcry_mpi_snew (gcry_mpi_get_nbits (n)); + y = gcry_mpi_snew (gcry_mpi_get_nbits (n)); + + /* Now we calculate: y = (x * r^e) mod n, where r is the random + number, e is the public exponent, x is the non-blinded data and n + is the RSA modulus. */ + gcry_mpi_powm (a, r, e, n); + gcry_mpi_mulm (y, a, x, n); + + gcry_mpi_release (a); + + return y; +} + +/* Undo RSA blinding. */ +static gcry_mpi_t +rsa_unblind (gcry_mpi_t x, gcry_mpi_t ri, gcry_mpi_t n) +{ + gcry_mpi_t y; + + y = gcry_mpi_snew (gcry_mpi_get_nbits (n)); + + /* Here we calculate: y = (x * r^-1) mod n, where x is the blinded + decrypted data, ri is the modular multiplicative inverse of r and + n is the RSA modulus. */ + + gcry_mpi_mulm (y, ri, x, n); + + return y; +} + +/********************************************* + ************** interface ****************** + *********************************************/ + +static gcry_err_code_t +rsa_generate_ext (int algo, unsigned int nbits, unsigned long evalue, + const gcry_sexp_t genparms, + gcry_mpi_t *skey, gcry_mpi_t **retfactors, + gcry_sexp_t *r_extrainfo) +{ + RSA_secret_key sk; + gpg_err_code_t ec; + gcry_sexp_t deriveparms; + int transient_key = 0; + int use_x931 = 0; + gcry_sexp_t l1; + + (void)algo; + + *retfactors = NULL; /* We don't return them. */ + + deriveparms = (genparms? + gcry_sexp_find_token (genparms, "derive-parms", 0) : NULL); + if (!deriveparms) + { + /* Parse the optional "use-x931" flag. */ + l1 = gcry_sexp_find_token (genparms, "use-x931", 0); + if (l1) + { + use_x931 = 1; + gcry_sexp_release (l1); + } + } + + if (deriveparms || use_x931 || fips_mode ()) + { + int swapped; + ec = generate_x931 (&sk, nbits, evalue, deriveparms, &swapped); + gcry_sexp_release (deriveparms); + if (!ec && r_extrainfo && swapped) + { + ec = gcry_sexp_new (r_extrainfo, + "(misc-key-info(p-q-swapped))", 0, 1); + if (ec) + { + gcry_mpi_release (sk.n); sk.n = NULL; + gcry_mpi_release (sk.e); sk.e = NULL; + gcry_mpi_release (sk.p); sk.p = NULL; + gcry_mpi_release (sk.q); sk.q = NULL; + gcry_mpi_release (sk.d); sk.d = NULL; + gcry_mpi_release (sk.u); sk.u = NULL; + } + } + } + else + { + /* Parse the optional "transient-key" flag. */ + l1 = gcry_sexp_find_token (genparms, "transient-key", 0); + if (l1) + { + transient_key = 1; + gcry_sexp_release (l1); + } + /* Generate. */ + ec = generate_std (&sk, nbits, evalue, transient_key); + } + + if (!ec) + { + skey[0] = sk.n; + skey[1] = sk.e; + skey[2] = sk.d; + skey[3] = sk.p; + skey[4] = sk.q; + skey[5] = sk.u; + } + + return ec; +} + + +static gcry_err_code_t +rsa_generate (int algo, unsigned int nbits, unsigned long evalue, + gcry_mpi_t *skey, gcry_mpi_t **retfactors) +{ + return rsa_generate_ext (algo, nbits, evalue, NULL, skey, retfactors, NULL); +} + + +static gcry_err_code_t +rsa_check_secret_key (int algo, gcry_mpi_t *skey) +{ + gcry_err_code_t err = GPG_ERR_NO_ERROR; + RSA_secret_key sk; + + (void)algo; + + sk.n = skey[0]; + sk.e = skey[1]; + sk.d = skey[2]; + sk.p = skey[3]; + sk.q = skey[4]; + sk.u = skey[5]; + + if (!sk.p || !sk.q || !sk.u) + err = GPG_ERR_NO_OBJ; /* To check the key we need the optional + parameters. */ + else if (!check_secret_key (&sk)) + err = GPG_ERR_BAD_SECKEY; + + return err; +} + + +static gcry_err_code_t +rsa_encrypt (int algo, gcry_mpi_t *resarr, gcry_mpi_t data, + gcry_mpi_t *pkey, int flags) +{ + RSA_public_key pk; + + (void)algo; + (void)flags; + + pk.n = pkey[0]; + pk.e = pkey[1]; + resarr[0] = mpi_alloc (mpi_get_nlimbs (pk.n)); + public (resarr[0], data, &pk); + + return GPG_ERR_NO_ERROR; +} + + +static gcry_err_code_t +rsa_decrypt (int algo, gcry_mpi_t *result, gcry_mpi_t *data, + gcry_mpi_t *skey, int flags) +{ + RSA_secret_key sk; + gcry_mpi_t r = MPI_NULL; /* Random number needed for blinding. */ + gcry_mpi_t ri = MPI_NULL; /* Modular multiplicative inverse of + r. */ + gcry_mpi_t x = MPI_NULL; /* Data to decrypt. */ + gcry_mpi_t y; /* Result. */ + + (void)algo; + + /* Extract private key. */ + sk.n = skey[0]; + sk.e = skey[1]; + sk.d = skey[2]; + sk.p = skey[3]; /* Optional. */ + sk.q = skey[4]; /* Optional. */ + sk.u = skey[5]; /* Optional. */ + + y = gcry_mpi_snew (gcry_mpi_get_nbits (sk.n)); + + /* We use blinding by default to mitigate timing attacks which can + be practically mounted over the network as shown by Brumley and + Boney in 2003. */ + if (! (flags & PUBKEY_FLAG_NO_BLINDING)) + { + /* Initialize blinding. */ + + /* First, we need a random number r between 0 and n - 1, which + is relatively prime to n (i.e. it is neither p nor q). The + random number needs to be only unpredictable, thus we employ + the gcry_create_nonce function by using GCRY_WEAK_RANDOM with + gcry_mpi_randomize. */ + r = gcry_mpi_snew (gcry_mpi_get_nbits (sk.n)); + ri = gcry_mpi_snew (gcry_mpi_get_nbits (sk.n)); + + gcry_mpi_randomize (r, gcry_mpi_get_nbits (sk.n), GCRY_WEAK_RANDOM); + gcry_mpi_mod (r, r, sk.n); + + /* Calculate inverse of r. It practically impossible that the + following test fails, thus we do not add code to release + allocated resources. */ + if (!gcry_mpi_invm (ri, r, sk.n)) + return GPG_ERR_INTERNAL; + } + + if (! (flags & PUBKEY_FLAG_NO_BLINDING)) + x = rsa_blind (data[0], r, sk.e, sk.n); + else + x = data[0]; + + /* Do the encryption. */ + secret (y, x, &sk); + + if (! (flags & PUBKEY_FLAG_NO_BLINDING)) + { + /* Undo blinding. */ + gcry_mpi_t a = gcry_mpi_copy (y); + + gcry_mpi_release (y); + y = rsa_unblind (a, ri, sk.n); + + gcry_mpi_release (a); + } + + if (! (flags & PUBKEY_FLAG_NO_BLINDING)) + { + /* Deallocate resources needed for blinding. */ + gcry_mpi_release (x); + gcry_mpi_release (r); + gcry_mpi_release (ri); + } + + /* Copy out result. */ + *result = y; + + return GPG_ERR_NO_ERROR; +} + + +static gcry_err_code_t +rsa_sign (int algo, gcry_mpi_t *resarr, gcry_mpi_t data, gcry_mpi_t *skey) +{ + RSA_secret_key sk; + + (void)algo; + + sk.n = skey[0]; + sk.e = skey[1]; + sk.d = skey[2]; + sk.p = skey[3]; + sk.q = skey[4]; + sk.u = skey[5]; + resarr[0] = mpi_alloc( mpi_get_nlimbs (sk.n)); + secret (resarr[0], data, &sk); + + return GPG_ERR_NO_ERROR; +} + + +static gcry_err_code_t +rsa_verify (int algo, gcry_mpi_t hash, gcry_mpi_t *data, gcry_mpi_t *pkey, + int (*cmp) (void *opaque, gcry_mpi_t tmp), + void *opaquev) +{ + RSA_public_key pk; + gcry_mpi_t result; + gcry_err_code_t rc; + + (void)algo; + (void)cmp; + (void)opaquev; + + pk.n = pkey[0]; + pk.e = pkey[1]; + result = gcry_mpi_new ( 160 ); + public( result, data[0], &pk ); +#ifdef IS_DEVELOPMENT_VERSION + if (DBG_CIPHER) + { + log_mpidump ("rsa verify result:", result ); + log_mpidump (" hash:", hash ); + } +#endif /*IS_DEVELOPMENT_VERSION*/ + if (cmp) + rc = (*cmp) (opaquev, result); + else + rc = mpi_cmp (result, hash) ? GPG_ERR_BAD_SIGNATURE : GPG_ERR_NO_ERROR; + gcry_mpi_release (result); + + return rc; +} + + +static unsigned int +rsa_get_nbits (int algo, gcry_mpi_t *pkey) +{ + (void)algo; + + return mpi_get_nbits (pkey[0]); +} + + +/* Compute a keygrip. MD is the hash context which we are going to + update. KEYPARAM is an S-expression with the key parameters, this + is usually a public key but may also be a secret key. An example + of such an S-expression is: + + (rsa + (n #00B...#) + (e #010001#)) + + PKCS-15 says that for RSA only the modulus should be hashed - + however, it is not clear whether this is meant to use the raw bytes + (assuming this is an unsigned integer) or whether the DER required + 0 should be prefixed. We hash the raw bytes. */ +static gpg_err_code_t +compute_keygrip (gcry_md_hd_t md, gcry_sexp_t keyparam) +{ + gcry_sexp_t l1; + const char *data; + size_t datalen; + + l1 = gcry_sexp_find_token (keyparam, "n", 1); + if (!l1) + return GPG_ERR_NO_OBJ; + + data = gcry_sexp_nth_data (l1, 1, &datalen); + if (!data) + { + gcry_sexp_release (l1); + return GPG_ERR_NO_OBJ; + } + + gcry_md_write (md, data, datalen); + gcry_sexp_release (l1); + + return 0; +} + + + + +/* + Self-test section. + */ + +static const char * +selftest_sign_1024 (gcry_sexp_t pkey, gcry_sexp_t skey) +{ + static const char sample_data[] = + "(data (flags pkcs1)" + " (hash sha1 #11223344556677889900aabbccddeeff10203040#))"; + static const char sample_data_bad[] = + "(data (flags pkcs1)" + " (hash sha1 #11223344556677889900aabbccddeeff80203040#))"; + + const char *errtxt = NULL; + gcry_error_t err; + gcry_sexp_t data = NULL; + gcry_sexp_t data_bad = NULL; + gcry_sexp_t sig = NULL; + + err = gcry_sexp_sscan (&data, NULL, + sample_data, strlen (sample_data)); + if (!err) + err = gcry_sexp_sscan (&data_bad, NULL, + sample_data_bad, strlen (sample_data_bad)); + if (err) + { + errtxt = "converting data failed"; + goto leave; + } + + err = gcry_pk_sign (&sig, data, skey); + if (err) + { + errtxt = "signing failed"; + goto leave; + } + err = gcry_pk_verify (sig, data, pkey); + if (err) + { + errtxt = "verify failed"; + goto leave; + } + err = gcry_pk_verify (sig, data_bad, pkey); + if (gcry_err_code (err) != GPG_ERR_BAD_SIGNATURE) + { + errtxt = "bad signature not detected"; + goto leave; + } + + + leave: + gcry_sexp_release (sig); + gcry_sexp_release (data_bad); + gcry_sexp_release (data); + return errtxt; +} + + + +/* Given an S-expression ENCR_DATA of the form: + + (enc-val + (rsa + (a a-value))) + + as returned by gcry_pk_decrypt, return the the A-VALUE. On error, + return NULL. */ +static gcry_mpi_t +extract_a_from_sexp (gcry_sexp_t encr_data) +{ + gcry_sexp_t l1, l2, l3; + gcry_mpi_t a_value; + + l1 = gcry_sexp_find_token (encr_data, "enc-val", 0); + if (!l1) + return NULL; + l2 = gcry_sexp_find_token (l1, "rsa", 0); + gcry_sexp_release (l1); + if (!l2) + return NULL; + l3 = gcry_sexp_find_token (l2, "a", 0); + gcry_sexp_release (l2); + if (!l3) + return NULL; + a_value = gcry_sexp_nth_mpi (l3, 1, 0); + gcry_sexp_release (l3); + + return a_value; +} + + +static const char * +selftest_encr_1024 (gcry_sexp_t pkey, gcry_sexp_t skey) +{ + const char *errtxt = NULL; + gcry_error_t err; + const unsigned int nbits = 1000; /* Encrypt 1000 random bits. */ + gcry_mpi_t plaintext = NULL; + gcry_sexp_t plain = NULL; + gcry_sexp_t encr = NULL; + gcry_mpi_t ciphertext = NULL; + gcry_sexp_t decr = NULL; + gcry_mpi_t decr_plaintext = NULL; + gcry_sexp_t tmplist = NULL; + + /* Create plaintext. The plaintext is actually a big integer number. */ + plaintext = gcry_mpi_new (nbits); + gcry_mpi_randomize (plaintext, nbits, GCRY_WEAK_RANDOM); + + /* Put the plaintext into an S-expression. */ + err = gcry_sexp_build (&plain, NULL, + "(data (flags raw) (value %m))", plaintext); + if (err) + { + errtxt = "converting data failed"; + goto leave; + } + + /* Encrypt. */ + err = gcry_pk_encrypt (&encr, plain, pkey); + if (err) + { + errtxt = "encrypt failed"; + goto leave; + } + + /* Extraxt the ciphertext from the returned S-expression. */ + /*gcry_sexp_dump (encr);*/ + ciphertext = extract_a_from_sexp (encr); + if (!ciphertext) + { + errtxt = "gcry_pk_decrypt returned garbage"; + goto leave; + } + + /* Check that the ciphertext does no match the plaintext. */ + /* _gcry_log_mpidump ("plaintext", plaintext); */ + /* _gcry_log_mpidump ("ciphertxt", ciphertext); */ + if (!gcry_mpi_cmp (plaintext, ciphertext)) + { + errtxt = "ciphertext matches plaintext"; + goto leave; + } + + /* Decrypt. */ + err = gcry_pk_decrypt (&decr, encr, skey); + if (err) + { + errtxt = "decrypt failed"; + goto leave; + } + + /* Extract the decrypted data from the S-expression. Note that the + output of gcry_pk_decrypt depends on whether a flags lists occurs + in its input data. Because we passed the output of + gcry_pk_encrypt directly to gcry_pk_decrypt, such a flag value + won't be there as of today. To be prepared for future changes we + take care of it anyway. */ + tmplist = gcry_sexp_find_token (decr, "value", 0); + if (tmplist) + decr_plaintext = gcry_sexp_nth_mpi (tmplist, 1, GCRYMPI_FMT_USG); + else + decr_plaintext = gcry_sexp_nth_mpi (decr, 0, GCRYMPI_FMT_USG); + if (!decr_plaintext) + { + errtxt = "decrypt returned no plaintext"; + goto leave; + } + + /* Check that the decrypted plaintext matches the original plaintext. */ + if (gcry_mpi_cmp (plaintext, decr_plaintext)) + { + errtxt = "mismatch"; + goto leave; + } + + leave: + gcry_sexp_release (tmplist); + gcry_mpi_release (decr_plaintext); + gcry_sexp_release (decr); + gcry_mpi_release (ciphertext); + gcry_sexp_release (encr); + gcry_sexp_release (plain); + gcry_mpi_release (plaintext); + return errtxt; +} + + +static gpg_err_code_t +selftests_rsa (selftest_report_func_t report) +{ + const char *what; + const char *errtxt; + gcry_error_t err; + gcry_sexp_t skey = NULL; + gcry_sexp_t pkey = NULL; + + /* Convert the S-expressions into the internal representation. */ + what = "convert"; + err = gcry_sexp_sscan (&skey, NULL, + sample_secret_key, strlen (sample_secret_key)); + if (!err) + err = gcry_sexp_sscan (&pkey, NULL, + sample_public_key, strlen (sample_public_key)); + if (err) + { + errtxt = gcry_strerror (err); + goto failed; + } + + what = "key consistency"; + err = gcry_pk_testkey (skey); + if (err) + { + errtxt = gcry_strerror (err); + goto failed; + } + + what = "sign"; + errtxt = selftest_sign_1024 (pkey, skey); + if (errtxt) + goto failed; + + what = "encrypt"; + errtxt = selftest_encr_1024 (pkey, skey); + if (errtxt) + goto failed; + + gcry_sexp_release (pkey); + gcry_sexp_release (skey); + return 0; /* Succeeded. */ + + failed: + gcry_sexp_release (pkey); + gcry_sexp_release (skey); + if (report) + report ("pubkey", GCRY_PK_RSA, what, errtxt); + return GPG_ERR_SELFTEST_FAILED; +} + + +/* Run a full self-test for ALGO and return 0 on success. */ +static gpg_err_code_t +run_selftests (int algo, int extended, selftest_report_func_t report) +{ + gpg_err_code_t ec; + + (void)extended; + + switch (algo) + { + case GCRY_PK_RSA: + ec = selftests_rsa (report); + break; + default: + ec = GPG_ERR_PUBKEY_ALGO; + break; + + } + return ec; +} + + + + +static const char *rsa_names[] = + { + "rsa", + "openpgp-rsa", + "oid.1.2.840.113549.1.1.1", + NULL, + }; + +gcry_pk_spec_t _gcry_pubkey_spec_rsa = + { + "RSA", rsa_names, + "ne", "nedpqu", "a", "s", "n", + GCRY_PK_USAGE_SIGN | GCRY_PK_USAGE_ENCR, + rsa_generate, + rsa_check_secret_key, + rsa_encrypt, + rsa_decrypt, + rsa_sign, + rsa_verify, + rsa_get_nbits, + }; +pk_extra_spec_t _gcry_pubkey_extraspec_rsa = + { + run_selftests, + rsa_generate_ext, + compute_keygrip + }; |