2 * Copyright (C) 2005-2008 Martin Willi
3 * Copyright (C) 2005 Jan Hutter
4 * Hochschule fuer Technik Rapperswil
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License as published by the
8 * Free Software Foundation; either version 2 of the License, or (at your
9 * option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
11 * This program is distributed in the hope that it will be useful, but
12 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
24 #include "gmp_rsa_private_key.h"
25 #include "gmp_rsa_public_key.h"
29 #include <asn1/asn1.h>
30 #include <asn1/asn1_parser.h>
33 * Public exponent to use for key generation.
35 #define PUBLIC_EXPONENT 0x10001
37 typedef struct private_gmp_rsa_private_key_t private_gmp_rsa_private_key_t
;
40 * Private data of a gmp_rsa_private_key_t object.
42 struct private_gmp_rsa_private_key_t
{
44 * Public interface for this signer.
46 gmp_rsa_private_key_t
public;
49 * Version of key, as encoded in PKCS#1
89 * Private coefficient.
99 * Keyid formed as a SHA-1 hash of a publicKey object
101 identification_t
* keyid
;
104 * Keyid formed as a SHA-1 hash of a publicKeyInfo object
106 identification_t
* keyid_info
;
115 * shared functions, implemented in gmp_rsa_public_key.c
117 bool gmp_rsa_public_key_build_id(mpz_t n
, mpz_t e
, identification_t
**keyid
,
118 identification_t
**keyid_info
);
119 gmp_rsa_public_key_t
*gmp_rsa_public_key_create_from_n_e(mpz_t n
, mpz_t e
);
122 * Auxiliary function overwriting private key material with zero bytes
124 static void mpz_clear_randomized(mpz_t z
)
126 size_t len
= mpz_size(z
) * GMP_LIMB_BITS
/ BITS_PER_BYTE
;
127 u_int8_t
*random
= alloca(len
);
129 memset(random
, 0, len
);
130 /* overwrite mpz_t with zero bytes before clearing it */
131 mpz_import(z
, len
, 1, 1, 1, 0, random
);
136 * Create a mpz prime of at least prime_size
138 static status_t
compute_prime(private_gmp_rsa_private_key_t
*this,
139 size_t prime_size
, mpz_t
*prime
)
142 chunk_t random_bytes
;
144 rng
= lib
->crypto
->create_rng(lib
->crypto
, RNG_REAL
);
147 DBG1("no RNG of quality %N found", rng_quality_names
, RNG_REAL
);
154 rng
->allocate_bytes(rng
, prime_size
, &random_bytes
);
155 /* make sure most significant bit is set */
156 random_bytes
.ptr
[0] = random_bytes
.ptr
[0] | 0x80;
158 mpz_import(*prime
, random_bytes
.len
, 1, 1, 1, 0, random_bytes
.ptr
);
159 mpz_nextprime (*prime
, *prime
);
160 chunk_clear(&random_bytes
);
162 /* check if it isn't too large */
163 while (((mpz_sizeinbase(*prime
, 2) + 7) / 8) > prime_size
);
170 * PKCS#1 RSADP function
172 static chunk_t
rsadp(private_gmp_rsa_private_key_t
*this, chunk_t data
)
180 mpz_import(t1
, data
.len
, 1, 1, 1, 0, data
.ptr
);
182 mpz_powm(t2
, t1
, this->exp1
, this->p
); /* m1 = c^dP mod p */
183 mpz_powm(t1
, t1
, this->exp2
, this->q
); /* m2 = c^dQ mod Q */
184 mpz_sub(t2
, t2
, t1
); /* h = qInv (m1 - m2) mod p */
185 mpz_mod(t2
, t2
, this->p
);
186 mpz_mul(t2
, t2
, this->coeff
);
187 mpz_mod(t2
, t2
, this->p
);
189 mpz_mul(t2
, t2
, this->q
); /* m = m2 + h q */
192 decrypted
.len
= this->k
;
193 decrypted
.ptr
= mpz_export(NULL
, NULL
, 1, decrypted
.len
, 1, 0, t1
);
195 mpz_clear_randomized(t1
);
196 mpz_clear_randomized(t2
);
202 * PKCS#1 RSASP1 function
204 static chunk_t
rsasp1(private_gmp_rsa_private_key_t
*this, chunk_t data
)
206 return rsadp(this, data
);
210 * Implementation of gmp_rsa_private_key_t.build_emsa_pkcs1_signature.
212 static bool build_emsa_pkcs1_signature(private_gmp_rsa_private_key_t
*this,
213 hash_algorithm_t hash_algorithm
,
214 chunk_t data
, chunk_t
*signature
)
217 chunk_t em
, digestInfo
, hash
;
218 int hash_oid
= hasher_algorithm_to_oid(hash_algorithm
);
220 if (hash_oid
== OID_UNKNOWN
)
226 hasher
= lib
->crypto
->create_hasher(lib
->crypto
, hash_algorithm
);
233 hasher
->allocate_hash(hasher
, data
, &hash
);
234 hasher
->destroy(hasher
);
236 /* build DER-encoded digestInfo */
237 digestInfo
= asn1_wrap(ASN1_SEQUENCE
, "cm",
238 asn1_algorithmIdentifier(hash_oid
),
239 asn1_simple_object(ASN1_OCTET_STRING
, hash
)
243 /* build chunk to rsa-decrypt:
244 * EM = 0x00 || 0x01 || PS || 0x00 || T.
245 * PS = 0xFF padding, with length to fill em
249 em
.ptr
= malloc(em
.len
);
251 /* fill em with padding */
252 memset(em
.ptr
, 0xFF, em
.len
);
253 /* set magic bytes */
256 *(em
.ptr
+ em
.len
- digestInfo
.len
- 1) = 0x00;
257 /* set DER-encoded hash */
258 memcpy(em
.ptr
+ em
.len
- digestInfo
.len
, digestInfo
.ptr
, digestInfo
.len
);
260 /* build signature */
261 *signature
= rsasp1(this, em
);
263 free(digestInfo
.ptr
);
270 * Implementation of gmp_rsa_private_key.destroy.
272 static key_type_t
get_type(private_gmp_rsa_private_key_t
*this)
278 * Implementation of gmp_rsa_private_key.destroy.
280 static bool sign(private_gmp_rsa_private_key_t
*this, signature_scheme_t scheme
,
281 chunk_t data
, chunk_t
*signature
)
286 /* default is EMSA-PKCS1 using SHA1 */
287 case SIGN_RSA_EMSA_PKCS1_SHA1
:
288 return build_emsa_pkcs1_signature(this, HASH_SHA1
, data
, signature
);
289 case SIGN_RSA_EMSA_PKCS1_SHA256
:
290 return build_emsa_pkcs1_signature(this, HASH_SHA256
, data
, signature
);
291 case SIGN_RSA_EMSA_PKCS1_SHA384
:
292 return build_emsa_pkcs1_signature(this, HASH_SHA384
, data
, signature
);
293 case SIGN_RSA_EMSA_PKCS1_SHA512
:
294 return build_emsa_pkcs1_signature(this, HASH_SHA512
, data
, signature
);
295 case SIGN_RSA_EMSA_PKCS1_MD5
:
296 return build_emsa_pkcs1_signature(this, HASH_MD5
, data
, signature
);
298 DBG1("signature scheme %N not supported in RSA",
299 signature_scheme_names
, scheme
);
305 * Implementation of gmp_rsa_private_key.destroy.
307 static bool decrypt(private_gmp_rsa_private_key_t
*this,
308 chunk_t crypto
, chunk_t
*plain
)
310 DBG1("RSA private key decryption not implemented");
315 * Implementation of gmp_rsa_private_key.destroy.
317 static size_t get_keysize(private_gmp_rsa_private_key_t
*this)
323 * Implementation of gmp_rsa_private_key.destroy.
325 static identification_t
* get_id(private_gmp_rsa_private_key_t
*this,
330 case ID_PUBKEY_INFO_SHA1
:
331 return this->keyid_info
;
340 * Implementation of gmp_rsa_private_key.destroy.
342 static gmp_rsa_public_key_t
* get_public_key(private_gmp_rsa_private_key_t
*this)
344 return gmp_rsa_public_key_create_from_n_e(this->n
, this->e
);
348 * Implementation of gmp_rsa_private_key.destroy.
350 static bool belongs_to(private_gmp_rsa_private_key_t
*this, public_key_t
*public)
352 identification_t
*keyid
;
354 if (public->get_type(public) != KEY_RSA
)
358 keyid
= public->get_id(public, ID_PUBKEY_SHA1
);
359 if (keyid
&& keyid
->equals(keyid
, this->keyid
))
363 keyid
= public->get_id(public, ID_PUBKEY_INFO_SHA1
);
364 if (keyid
&& keyid
->equals(keyid
, this->keyid_info
))
372 * convert a MP integer into a DER coded ASN.1 object
374 chunk_t
gmp_mpz_to_asn1(const mpz_t value
)
376 size_t bits
= mpz_sizeinbase(value
, 2); /* size in bits */
379 n
.len
= 1 + bits
/ 8; /* size in bytes */
380 n
.ptr
= mpz_export(NULL
, NULL
, 1, n
.len
, 1, 0, value
);
382 return asn1_wrap(ASN1_INTEGER
, "m", n
);
386 * Implementation of private_key_t.get_encoding.
388 static chunk_t
get_encoding(private_gmp_rsa_private_key_t
*this)
390 return asn1_wrap(ASN1_SEQUENCE
, "cmmmmmmmm",
392 gmp_mpz_to_asn1(this->n
),
393 gmp_mpz_to_asn1(this->e
),
394 gmp_mpz_to_asn1(this->d
),
395 gmp_mpz_to_asn1(this->p
),
396 gmp_mpz_to_asn1(this->q
),
397 gmp_mpz_to_asn1(this->exp1
),
398 gmp_mpz_to_asn1(this->exp2
),
399 gmp_mpz_to_asn1(this->coeff
));
403 * Implementation of gmp_rsa_private_key.destroy.
405 static private_gmp_rsa_private_key_t
* get_ref(private_gmp_rsa_private_key_t
*this)
413 * Implementation of gmp_rsa_private_key.destroy.
415 static void destroy(private_gmp_rsa_private_key_t
*this)
417 if (ref_put(&this->ref
))
419 mpz_clear_randomized(this->n
);
420 mpz_clear_randomized(this->e
);
421 mpz_clear_randomized(this->p
);
422 mpz_clear_randomized(this->q
);
423 mpz_clear_randomized(this->d
);
424 mpz_clear_randomized(this->exp1
);
425 mpz_clear_randomized(this->exp2
);
426 mpz_clear_randomized(this->coeff
);
427 DESTROY_IF(this->keyid
);
428 DESTROY_IF(this->keyid_info
);
434 * Check the loaded key if it is valid and usable
436 static status_t
check(private_gmp_rsa_private_key_t
*this)
439 status_t status
= SUCCESS
;
441 /* PKCS#1 1.5 section 6 requires modulus to have at least 12 octets.
442 * We actually require more (for security).
446 DBG1("key shorter than 512 bits");
450 /* we picked a max modulus size to simplify buffer allocation */
451 if (this->k
> 8192/8)
453 DBG1("key larger thant 8192 bits");
461 /* check that n == p * q */
462 mpz_mul(u
, this->p
, this->q
);
463 if (mpz_cmp(u
, this->n
) != 0)
468 /* check that e divides neither p-1 nor q-1 */
469 mpz_sub_ui(t
, this->p
, 1);
470 mpz_mod(t
, t
, this->e
);
471 if (mpz_cmp_ui(t
, 0) == 0)
476 mpz_sub_ui(t
, this->q
, 1);
477 mpz_mod(t
, t
, this->e
);
478 if (mpz_cmp_ui(t
, 0) == 0)
483 /* check that d is e^-1 (mod lcm(p-1, q-1)) */
484 /* see PKCS#1v2, aka RFC 2437, for the "lcm" */
485 mpz_sub_ui(q1
, this->q
, 1);
486 mpz_sub_ui(u
, this->p
, 1);
487 mpz_gcd(t
, u
, q1
); /* t := gcd(p-1, q-1) */
488 mpz_mul(u
, u
, q1
); /* u := (p-1) * (q-1) */
489 mpz_divexact(u
, u
, t
); /* u := lcm(p-1, q-1) */
491 mpz_mul(t
, this->d
, this->e
);
493 if (mpz_cmp_ui(t
, 1) != 0)
498 /* check that exp1 is d mod (p-1) */
499 mpz_sub_ui(u
, this->p
, 1);
500 mpz_mod(t
, this->d
, u
);
501 if (mpz_cmp(t
, this->exp1
) != 0)
506 /* check that exp2 is d mod (q-1) */
507 mpz_sub_ui(u
, this->q
, 1);
508 mpz_mod(t
, this->d
, u
);
509 if (mpz_cmp(t
, this->exp2
) != 0)
514 /* check that coeff is (q^-1) mod p */
515 mpz_mul(t
, this->coeff
, this->q
);
516 mpz_mod(t
, t
, this->p
);
517 if (mpz_cmp_ui(t
, 1) != 0)
522 mpz_clear_randomized(t
);
523 mpz_clear_randomized(u
);
524 mpz_clear_randomized(q1
);
525 if (status
!= SUCCESS
)
527 DBG1("key integrity tests failed");
533 * Internal generic constructor
535 static private_gmp_rsa_private_key_t
*gmp_rsa_private_key_create_empty(void)
537 private_gmp_rsa_private_key_t
*this = malloc_thing(private_gmp_rsa_private_key_t
);
539 this->public.interface
.get_type
= (key_type_t (*)(private_key_t
*this))get_type
;
540 this->public.interface
.sign
= (bool (*)(private_key_t
*this, signature_scheme_t scheme
, chunk_t data
, chunk_t
*signature
))sign
;
541 this->public.interface
.decrypt
= (bool (*)(private_key_t
*this, chunk_t crypto
, chunk_t
*plain
))decrypt
;
542 this->public.interface
.get_keysize
= (size_t (*) (private_key_t
*this))get_keysize
;
543 this->public.interface
.get_id
= (identification_t
* (*) (private_key_t
*this,id_type_t
))get_id
;
544 this->public.interface
.get_public_key
= (public_key_t
* (*)(private_key_t
*this))get_public_key
;
545 this->public.interface
.belongs_to
= (bool (*) (private_key_t
*this, public_key_t
*public))belongs_to
;
546 this->public.interface
.get_encoding
= (chunk_t(*)(private_key_t
*))get_encoding
;
547 this->public.interface
.get_ref
= (private_key_t
* (*)(private_key_t
*this))get_ref
;
548 this->public.interface
.destroy
= (void (*)(private_key_t
*this))destroy
;
551 this->keyid_info
= NULL
;
558 * Generate an RSA key of specified key size
560 static gmp_rsa_private_key_t
*generate(size_t key_size
)
562 mpz_t p
, q
, n
, e
, d
, exp1
, exp2
, coeff
;
564 private_gmp_rsa_private_key_t
*this = gmp_rsa_private_key_create_empty();
566 key_size
= key_size
/ 8;
568 /* Get values of primes p and q */
569 if (compute_prime(this, key_size
/2, &p
) != SUCCESS
)
574 if (compute_prime(this, key_size
/2, &q
) != SUCCESS
)
588 /* Swapping Primes so p is larger then q */
589 if (mpz_cmp(p
, q
) < 0)
594 mpz_mul(n
, p
, q
); /* n = p*q */
595 mpz_init_set_ui(e
, PUBLIC_EXPONENT
); /* assign public exponent */
596 mpz_init_set(m
, p
); /* m = p */
597 mpz_sub_ui(m
, m
, 1); /* m = m -1 */
598 mpz_init_set(q1
, q
); /* q1 = q */
599 mpz_sub_ui(q1
, q1
, 1); /* q1 = q1 -1 */
600 mpz_gcd(t
, m
, q1
); /* t = gcd(p-1, q-1) */
601 mpz_mul(m
, m
, q1
); /* m = (p-1)*(q-1) */
602 mpz_divexact(m
, m
, t
); /* m = m / t */
603 mpz_gcd(t
, m
, e
); /* t = gcd(m, e) */
605 mpz_invert(d
, e
, m
); /* e has an inverse mod m */
606 if (mpz_cmp_ui(d
, 0) < 0) /* make sure d is positive */
610 mpz_sub_ui(t
, p
, 1); /* t = p-1 */
611 mpz_mod(exp1
, d
, t
); /* exp1 = d mod p-1 */
612 mpz_sub_ui(t
, q
, 1); /* t = q-1 */
613 mpz_mod(exp2
, d
, t
); /* exp2 = d mod q-1 */
615 mpz_invert(coeff
, q
, p
); /* coeff = q^-1 mod p */
616 if (mpz_cmp_ui(coeff
, 0) < 0) /* make coeff d is positive */
618 mpz_add(coeff
, coeff
, p
);
621 mpz_clear_randomized(q1
);
622 mpz_clear_randomized(m
);
623 mpz_clear_randomized(t
);
631 *(this->exp1
) = *exp1
;
632 *(this->exp2
) = *exp2
;
633 *(this->coeff
) = *coeff
;
635 /* set key size in bytes */
638 return &this->public;
642 * ASN.1 definition of a PKCS#1 RSA private key
644 static const asn1Object_t privkeyObjects
[] = {
645 { 0, "RSAPrivateKey", ASN1_SEQUENCE
, ASN1_NONE
}, /* 0 */
646 { 1, "version", ASN1_INTEGER
, ASN1_BODY
}, /* 1 */
647 { 1, "modulus", ASN1_INTEGER
, ASN1_BODY
}, /* 2 */
648 { 1, "publicExponent", ASN1_INTEGER
, ASN1_BODY
}, /* 3 */
649 { 1, "privateExponent", ASN1_INTEGER
, ASN1_BODY
}, /* 4 */
650 { 1, "prime1", ASN1_INTEGER
, ASN1_BODY
}, /* 5 */
651 { 1, "prime2", ASN1_INTEGER
, ASN1_BODY
}, /* 6 */
652 { 1, "exponent1", ASN1_INTEGER
, ASN1_BODY
}, /* 7 */
653 { 1, "exponent2", ASN1_INTEGER
, ASN1_BODY
}, /* 8 */
654 { 1, "coefficient", ASN1_INTEGER
, ASN1_BODY
}, /* 9 */
655 { 1, "otherPrimeInfos", ASN1_SEQUENCE
, ASN1_OPT
|
656 ASN1_LOOP
}, /* 10 */
657 { 2, "otherPrimeInfo", ASN1_SEQUENCE
, ASN1_NONE
}, /* 11 */
658 { 3, "prime", ASN1_INTEGER
, ASN1_BODY
}, /* 12 */
659 { 3, "exponent", ASN1_INTEGER
, ASN1_BODY
}, /* 13 */
660 { 3, "coefficient", ASN1_INTEGER
, ASN1_BODY
}, /* 14 */
661 { 1, "end opt or loop", ASN1_EOC
, ASN1_END
}, /* 15 */
662 { 0, "exit", ASN1_EOC
, ASN1_EXIT
}
664 #define PRIV_KEY_VERSION 1
665 #define PRIV_KEY_MODULUS 2
666 #define PRIV_KEY_PUB_EXP 3
667 #define PRIV_KEY_PRIV_EXP 4
668 #define PRIV_KEY_PRIME1 5
669 #define PRIV_KEY_PRIME2 6
670 #define PRIV_KEY_EXP1 7
671 #define PRIV_KEY_EXP2 8
672 #define PRIV_KEY_COEFF 9
675 * load private key from a ASN1 encoded blob
677 static gmp_rsa_private_key_t
*load(chunk_t blob
)
679 asn1_parser_t
*parser
;
682 bool success
= FALSE
;
684 private_gmp_rsa_private_key_t
*this = gmp_rsa_private_key_create_empty();
691 mpz_init(this->exp1
);
692 mpz_init(this->exp2
);
693 mpz_init(this->coeff
);
695 parser
= asn1_parser_create(privkeyObjects
, blob
);
696 parser
->set_flags(parser
, FALSE
, TRUE
);
698 while (parser
->iterate(parser
, &objectID
, &object
))
702 case PRIV_KEY_VERSION
:
703 if (object
.len
> 0 && *object
.ptr
!= 0)
708 case PRIV_KEY_MODULUS
:
709 mpz_import(this->n
, object
.len
, 1, 1, 1, 0, object
.ptr
);
711 case PRIV_KEY_PUB_EXP
:
712 mpz_import(this->e
, object
.len
, 1, 1, 1, 0, object
.ptr
);
714 case PRIV_KEY_PRIV_EXP
:
715 mpz_import(this->d
, object
.len
, 1, 1, 1, 0, object
.ptr
);
717 case PRIV_KEY_PRIME1
:
718 mpz_import(this->p
, object
.len
, 1, 1, 1, 0, object
.ptr
);
720 case PRIV_KEY_PRIME2
:
721 mpz_import(this->q
, object
.len
, 1, 1, 1, 0, object
.ptr
);
724 mpz_import(this->exp1
, object
.len
, 1, 1, 1, 0, object
.ptr
);
727 mpz_import(this->exp2
, object
.len
, 1, 1, 1, 0, object
.ptr
);
730 mpz_import(this->coeff
, object
.len
, 1, 1, 1, 0, object
.ptr
);
734 success
= parser
->success(parser
);
737 parser
->destroy(parser
);
746 this->k
= (mpz_sizeinbase(this->n
, 2) + 7) / BITS_PER_BYTE
;
748 if (!gmp_rsa_public_key_build_id(this->n
, this->e
,
749 &this->keyid
, &this->keyid_info
))
755 if (check(this) != SUCCESS
)
760 return &this->public;
763 typedef struct private_builder_t private_builder_t
;
765 * Builder implementation for key loading/generation
767 struct private_builder_t
{
768 /** implements the builder interface */
770 /** loaded/generated private key */
771 gmp_rsa_private_key_t
*key
;
775 * Implementation of builder_t.build
777 static gmp_rsa_private_key_t
*build(private_builder_t
*this)
779 gmp_rsa_private_key_t
*key
= this->key
;
786 * Implementation of builder_t.add
788 static void add(private_builder_t
*this, builder_part_t part
, ...)
794 DBG1("ignoring surplus build part %N", builder_part_names
, part
);
800 case BUILD_BLOB_ASN1_DER
:
802 va_start(args
, part
);
803 this->key
= load(va_arg(args
, chunk_t
));
809 va_start(args
, part
);
810 this->key
= generate(va_arg(args
, u_int
));
815 DBG1("ignoring unsupported build part %N", builder_part_names
, part
);
821 * Builder construction function
823 builder_t
*gmp_rsa_private_key_builder(key_type_t type
)
825 private_builder_t
*this;
832 this = malloc_thing(private_builder_t
);
835 this->public.add
= (void(*)(builder_t
*this, builder_part_t part
, ...))add
;
836 this->public.build
= (void*(*)(builder_t
*this))build
;
838 return &this->public;