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rsa.h 11.99 KiB
/* rsa.h
*
* The RSA publickey algorithm.
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2001, 2002 Niels Möller
*
* The nettle library 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.
*
* The nettle library 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 the nettle library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02111-1301, USA.
*/
#ifndef NETTLE_RSA_H_INCLUDED
#define NETTLE_RSA_H_INCLUDED
#include <gmp.h>
#include "nettle-types.h"
#include "md5.h"
#include "sha.h"
#ifdef __cplusplus
extern "C" {
#endif
/* Name mangling */
#define rsa_public_key_init nettle_rsa_public_key_init
#define rsa_public_key_clear nettle_rsa_public_key_clear
#define rsa_public_key_prepare nettle_rsa_public_key_prepare
#define rsa_private_key_init nettle_rsa_private_key_init
#define rsa_private_key_clear nettle_rsa_private_key_clear
#define rsa_private_key_prepare nettle_rsa_private_key_prepare
#define rsa_pkcs1_verify nettle_rsa_pkcs1_verify
#define rsa_pkcs1_sign nettle_rsa_pkcs1_sign
#define rsa_pkcs1_sign_tr nettle_rsa_pkcs1_sign_tr
#define rsa_md5_sign nettle_rsa_md5_sign
#define rsa_md5_verify nettle_rsa_md5_verify
#define rsa_sha1_sign nettle_rsa_sha1_sign
#define rsa_sha1_verify nettle_rsa_sha1_verify
#define rsa_sha256_sign nettle_rsa_sha256_sign
#define rsa_sha256_verify nettle_rsa_sha256_verify
#define rsa_sha512_sign nettle_rsa_sha512_sign
#define rsa_sha512_verify nettle_rsa_sha512_verify
#define rsa_md5_sign_digest nettle_rsa_md5_sign_digest
#define rsa_md5_verify_digest nettle_rsa_md5_verify_digest
#define rsa_sha1_sign_digest nettle_rsa_sha1_sign_digest
#define rsa_sha1_verify_digest nettle_rsa_sha1_verify_digest
#define rsa_sha256_sign_digest nettle_rsa_sha256_sign_digest
#define rsa_sha256_verify_digest nettle_rsa_sha256_verify_digest
#define rsa_sha512_sign_digest nettle_rsa_sha512_sign_digest
#define rsa_sha512_verify_digest nettle_rsa_sha512_verify_digest
#define rsa_encrypt nettle_rsa_encrypt
#define rsa_decrypt nettle_rsa_decrypt
#define rsa_decrypt_tr nettle_rsa_decrypt_tr
#define rsa_compute_root nettle_rsa_compute_root
#define rsa_generate_keypair nettle_rsa_generate_keypair
#define rsa_keypair_to_sexp nettle_rsa_keypair_to_sexp#define rsa_keypair_from_sexp_alist nettle_rsa_keypair_from_sexp_alist
#define rsa_keypair_from_sexp nettle_rsa_keypair_from_sexp
#define rsa_public_key_from_der_iterator nettle_rsa_public_key_from_der_iterator
#define rsa_private_key_from_der_iterator nettle_rsa_private_key_from_der_iterator
#define rsa_keypair_from_der nettle_rsa_keypair_from_der
#define rsa_keypair_to_openpgp nettle_rsa_keypair_to_openpgp
#define _rsa_verify _nettle_rsa_verify
#define _rsa_check_size _nettle_rsa_check_size
#define _rsa_blind _nettle_rsa_blind
#define _rsa_unblind _nettle_rsa_unblind
/* This limit is somewhat arbitrary. Technically, the smallest modulo
which makes sense at all is 15 = 3*5, phi(15) = 8, size 4 bits. But
for ridiculously small keys, not all odd e are possible (e.g., for
5 bits, the only possible modulo is 3*7 = 21, phi(21) = 12, and e =
3 don't work). The smallest size that makes sense with pkcs#1, and
which allows RSA encryption of one byte messages, is 12 octets, 89
bits. */
#define RSA_MINIMUM_N_OCTETS 12
#define RSA_MINIMUM_N_BITS (8*RSA_MINIMUM_N_OCTETS - 7)
struct rsa_public_key
{
/* Size of the modulo, in octets. This is also the size of all
* signatures that are created or verified with this key. */
unsigned size;
/* Modulo */
mpz_t n;
/* Public exponent */
mpz_t e;
};
struct rsa_private_key
{
unsigned size;
/* d is filled in by the key generation function; otherwise it's
* completely unused. */
mpz_t d;
/* The two factors */
mpz_t p; mpz_t q;
/* d % (p-1), i.e. a e = 1 (mod (p-1)) */
mpz_t a;
/* d % (q-1), i.e. b e = 1 (mod (q-1)) */
mpz_t b;
/* modular inverse of q , i.e. c q = 1 (mod p) */
mpz_t c;
};
/* Signing a message works as follows:
*
* Store the private key in a rsa_private_key struct.
*
* Call rsa_private_key_prepare. This initializes the size attribute
* to the length of a signature.
*
* Initialize a hashing context, by callling
* md5_init
*
* Hash the message by calling
* md5_update
*
* Create the signature by calling * rsa_md5_sign
*
* The signature is represented as a mpz_t bignum. This call also
* resets the hashing context.
*
* When done with the key and signature, don't forget to call
* mpz_clear.
*/
/* Calls mpz_init to initialize bignum storage. */
void
rsa_public_key_init(struct rsa_public_key *key);
/* Calls mpz_clear to deallocate bignum storage. */
void
rsa_public_key_clear(struct rsa_public_key *key);
int
rsa_public_key_prepare(struct rsa_public_key *key);
/* Calls mpz_init to initialize bignum storage. */
void
rsa_private_key_init(struct rsa_private_key *key);
/* Calls mpz_clear to deallocate bignum storage. */
void
rsa_private_key_clear(struct rsa_private_key *key);
int
rsa_private_key_prepare(struct rsa_private_key *key);
/* PKCS#1 style signatures */
int
rsa_pkcs1_sign(const struct rsa_private_key *key,
unsigned length, const uint8_t *digest_info,
mpz_t s);
int
rsa_pkcs1_sign_tr(const struct rsa_public_key *pub,
const struct rsa_private_key *key,
void *random_ctx, nettle_random_func *random,
unsigned length, const uint8_t *digest_info,
mpz_t s);
int
rsa_pkcs1_verify(const struct rsa_public_key *key,
unsigned length, const uint8_t *digest_info,
const mpz_t signature);
int
rsa_md5_sign(const struct rsa_private_key *key,
struct md5_ctx *hash,
mpz_t signature);
int
rsa_md5_verify(const struct rsa_public_key *key,
struct md5_ctx *hash,
const mpz_t signature);
int
rsa_sha1_sign(const struct rsa_private_key *key,
struct sha1_ctx *hash,
mpz_t signature);
int
rsa_sha1_verify(const struct rsa_public_key *key,
struct sha1_ctx *hash,
const mpz_t signature);
int
rsa_sha256_sign(const struct rsa_private_key *key,
struct sha256_ctx *hash,
mpz_t signature);
int
rsa_sha256_verify(const struct rsa_public_key *key,
struct sha256_ctx *hash,
const mpz_t signature);
int
rsa_sha512_sign(const struct rsa_private_key *key,
struct sha512_ctx *hash,
mpz_t signature);
int
rsa_sha512_verify(const struct rsa_public_key *key,
struct sha512_ctx *hash,
const mpz_t signature);
/* Variants taking the digest as argument. */
int
rsa_md5_sign_digest(const struct rsa_private_key *key,
const uint8_t *digest,
mpz_t s);
int
rsa_md5_verify_digest(const struct rsa_public_key *key,
const uint8_t *digest,
const mpz_t signature);
int
rsa_sha1_sign_digest(const struct rsa_private_key *key,
const uint8_t *digest,
mpz_t s);
int
rsa_sha1_verify_digest(const struct rsa_public_key *key,
const uint8_t *digest,
const mpz_t signature);
int
rsa_sha256_sign_digest(const struct rsa_private_key *key,
const uint8_t *digest,
mpz_t s);
int
rsa_sha256_verify_digest(const struct rsa_public_key *key,
const uint8_t *digest,
const mpz_t signature);
int
rsa_sha512_sign_digest(const struct rsa_private_key *key,
const uint8_t *digest,
mpz_t s);
int
rsa_sha512_verify_digest(const struct rsa_public_key *key,
const uint8_t *digest,
const mpz_t signature);
/* RSA encryption, using PKCS#1 */
/* These functions uses the v1.5 padding. What should the v2 (OAEP)
* functions be called? */
/* Returns 1 on success, 0 on failure, which happens if the
* message is too long for the key. */
int
rsa_encrypt(const struct rsa_public_key *key, /* For padding */
void *random_ctx, nettle_random_func *random,
unsigned length, const uint8_t *cleartext,
mpz_t cipher);
/* Message must point to a buffer of size *LENGTH. KEY->size is enough
* for all valid messages. On success, *LENGTH is updated to reflect
* the actual length of the message. Returns 1 on success, 0 on
* failure, which happens if decryption failed or if the message
* didn't fit. */
int
rsa_decrypt(const struct rsa_private_key *key,
unsigned *length, uint8_t *cleartext,
const mpz_t ciphertext);
/* Timing-resistant version, using randomized RSA blinding. */
int
rsa_decrypt_tr(const struct rsa_public_key *pub,
const struct rsa_private_key *key,
void *random_ctx, nettle_random_func *random,
unsigned *length, uint8_t *message,
const mpz_t gibberish);
/* Compute x, the e:th root of m. Calling it with x == m is allowed. */
void
rsa_compute_root(const struct rsa_private_key *key,
mpz_t x, const mpz_t m);
/* Key generation */
/* Note that the key structs must be initialized first. */
int
rsa_generate_keypair(struct rsa_public_key *pub,
struct rsa_private_key *key,
void *random_ctx, nettle_random_func *random,
void *progress_ctx, nettle_progress_func *progress,
/* Desired size of modulo, in bits */
unsigned n_size,
/* Desired size of public exponent, in bits. If
* zero, the passed in value pub->e is used. */
unsigned e_size);
#define RSA_SIGN(key, algorithm, ctx, length, data, signature) ( \
algorithm##_update(ctx, length, data), \
rsa_##algorithm##_sign(key, ctx, signature) \
)
#define RSA_VERIFY(key, algorithm, ctx, length, data, signature) ( \
algorithm##_update(ctx, length, data), \
rsa_##algorithm##_verify(key, ctx, signature) \
)
/* Keys in sexp form. */
struct nettle_buffer;
/* Generates a public-key expression if PRIV is NULL .*/
int
rsa_keypair_to_sexp(struct nettle_buffer *buffer,
const char *algorithm_name, /* NULL means "rsa" */
const struct rsa_public_key *pub,
const struct rsa_private_key *priv);
struct sexp_iterator;
int
rsa_keypair_from_sexp_alist(struct rsa_public_key *pub,
struct rsa_private_key *priv,
unsigned limit,
struct sexp_iterator *i);
/* If PRIV is NULL, expect a public-key expression. If PUB is NULL,
* expect a private key expression and ignore the parts not needed for
* the public key. */
/* Keys must be initialized before calling this function, as usual. */
int
rsa_keypair_from_sexp(struct rsa_public_key *pub,
struct rsa_private_key *priv,
unsigned limit,
unsigned length, const uint8_t *expr);
/* Keys in PKCS#1 format. */
struct asn1_der_iterator;
int
rsa_public_key_from_der_iterator(struct rsa_public_key *pub,
unsigned limit,
struct asn1_der_iterator *i);
int
rsa_private_key_from_der_iterator(struct rsa_public_key *pub,
struct rsa_private_key *priv,
unsigned limit,
struct asn1_der_iterator *i);
/* For public keys, use PRIV == NULL */
int
rsa_keypair_from_der(struct rsa_public_key *pub,
struct rsa_private_key *priv,
unsigned limit,
unsigned length, const uint8_t *data);
/* OpenPGP format. Experimental interface, subject to change. */
int
rsa_keypair_to_openpgp(struct nettle_buffer *buffer,
const struct rsa_public_key *pub,
const struct rsa_private_key *priv,
/* A single user id. NUL-terminated utf8. */
const char *userid);
/* Internal functions. */
int
_rsa_verify(const struct rsa_public_key *key,
const mpz_t m,
const mpz_t s);
unsigned
_rsa_check_size(mpz_t n);
void
_rsa_blind (const struct rsa_public_key *pub,
void *random_ctx, nettle_random_func *random,
mpz_t c, mpz_t ri);
void
_rsa_unblind (const struct rsa_public_key *pub, mpz_t c, const mpz_t ri);
#ifdef __cplusplus
}
#endif
#endif /* NETTLE_RSA_H_INCLUDED */