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
22 #include "gmp_rsa_private_key.h"
23 #include "gmp_rsa_public_key.h"
27 #include <asn1/asn1.h>
28 #include <asn1/asn1_parser.h>
31 * Public exponent to use for key generation.
33 #define PUBLIC_EXPONENT 0x10001
35 typedef struct private_gmp_rsa_private_key_t private_gmp_rsa_private_key_t
;
38 * Private data of a gmp_rsa_private_key_t object.
40 struct private_gmp_rsa_private_key_t
{
42 * Public interface for this signer.
44 gmp_rsa_private_key_t
public;
47 * Version of key, as encoded in PKCS#1
87 * Private coefficient.
97 * Keyid formed as a SHA-1 hash of a publicKey object
99 identification_t
* keyid
;
102 * Keyid formed as a SHA-1 hash of a publicKeyInfo object
104 identification_t
* keyid_info
;
113 * shared functions, implemented in gmp_rsa_public_key.c
115 bool gmp_rsa_public_key_build_id(mpz_t n
, mpz_t e
, identification_t
**keyid
,
116 identification_t
**keyid_info
);
117 gmp_rsa_public_key_t
*gmp_rsa_public_key_create_from_n_e(mpz_t n
, mpz_t e
);
120 * Auxiliary function overwriting private key material with zero bytes
122 static void mpz_clear_randomized(mpz_t z
)
124 size_t len
= mpz_size(z
) * GMP_LIMB_BITS
/ BITS_PER_BYTE
;
125 u_int8_t
*random
= alloca(len
);
127 memset(random
, 0, len
);
128 /* overwrite mpz_t with zero bytes before clearing it */
129 mpz_import(z
, len
, 1, 1, 1, 0, random
);
134 * Create a mpz prime of at least prime_size
136 static status_t
compute_prime(private_gmp_rsa_private_key_t
*this,
137 size_t prime_size
, mpz_t
*prime
)
140 chunk_t random_bytes
;
142 rng
= lib
->crypto
->create_rng(lib
->crypto
, RNG_TRUE
);
145 DBG1("no RNG of quality %N found", rng_quality_names
, RNG_TRUE
);
152 rng
->allocate_bytes(rng
, prime_size
, &random_bytes
);
153 /* make sure most significant bit is set */
154 random_bytes
.ptr
[0] = random_bytes
.ptr
[0] | 0x80;
156 mpz_import(*prime
, random_bytes
.len
, 1, 1, 1, 0, random_bytes
.ptr
);
157 mpz_nextprime (*prime
, *prime
);
158 chunk_clear(&random_bytes
);
160 /* check if it isn't too large */
161 while (((mpz_sizeinbase(*prime
, 2) + 7) / 8) > prime_size
);
168 * PKCS#1 RSADP function
170 static chunk_t
rsadp(private_gmp_rsa_private_key_t
*this, chunk_t data
)
178 mpz_import(t1
, data
.len
, 1, 1, 1, 0, data
.ptr
);
180 mpz_powm(t2
, t1
, this->exp1
, this->p
); /* m1 = c^dP mod p */
181 mpz_powm(t1
, t1
, this->exp2
, this->q
); /* m2 = c^dQ mod Q */
182 mpz_sub(t2
, t2
, t1
); /* h = qInv (m1 - m2) mod p */
183 mpz_mod(t2
, t2
, this->p
);
184 mpz_mul(t2
, t2
, this->coeff
);
185 mpz_mod(t2
, t2
, this->p
);
187 mpz_mul(t2
, t2
, this->q
); /* m = m2 + h q */
190 decrypted
.len
= this->k
;
191 decrypted
.ptr
= mpz_export(NULL
, NULL
, 1, decrypted
.len
, 1, 0, t1
);
192 if (decrypted
.ptr
== NULL
)
197 mpz_clear_randomized(t1
);
198 mpz_clear_randomized(t2
);
204 * PKCS#1 RSASP1 function
206 static chunk_t
rsasp1(private_gmp_rsa_private_key_t
*this, chunk_t data
)
208 return rsadp(this, data
);
212 * Implementation of gmp_rsa_private_key_t.build_emsa_pkcs1_signature.
214 static bool build_emsa_pkcs1_signature(private_gmp_rsa_private_key_t
*this,
215 hash_algorithm_t hash_algorithm
,
216 chunk_t data
, chunk_t
*signature
)
219 chunk_t em
, digestInfo
, hash
;
220 int hash_oid
= hasher_algorithm_to_oid(hash_algorithm
);
222 if (hash_oid
== OID_UNKNOWN
)
228 hasher
= lib
->crypto
->create_hasher(lib
->crypto
, hash_algorithm
);
235 hasher
->allocate_hash(hasher
, data
, &hash
);
236 hasher
->destroy(hasher
);
238 /* build DER-encoded digestInfo */
239 digestInfo
= asn1_wrap(ASN1_SEQUENCE
, "cm",
240 asn1_algorithmIdentifier(hash_oid
),
241 asn1_simple_object(ASN1_OCTET_STRING
, hash
)
245 /* build chunk to rsa-decrypt:
246 * EM = 0x00 || 0x01 || PS || 0x00 || T.
247 * PS = 0xFF padding, with length to fill em
251 em
.ptr
= malloc(em
.len
);
253 /* fill em with padding */
254 memset(em
.ptr
, 0xFF, em
.len
);
255 /* set magic bytes */
258 *(em
.ptr
+ em
.len
- digestInfo
.len
- 1) = 0x00;
259 /* set DER-encoded hash */
260 memcpy(em
.ptr
+ em
.len
- digestInfo
.len
, digestInfo
.ptr
, digestInfo
.len
);
262 /* build signature */
263 *signature
= rsasp1(this, em
);
265 free(digestInfo
.ptr
);
272 * Implementation of gmp_rsa_private_key.destroy.
274 static key_type_t
get_type(private_gmp_rsa_private_key_t
*this)
280 * Implementation of gmp_rsa_private_key.destroy.
282 static bool sign(private_gmp_rsa_private_key_t
*this, signature_scheme_t scheme
,
283 chunk_t data
, chunk_t
*signature
)
288 /* default is EMSA-PKCS1 using SHA1 */
289 case SIGN_RSA_EMSA_PKCS1_SHA1
:
290 return build_emsa_pkcs1_signature(this, HASH_SHA1
, data
, signature
);
291 case SIGN_RSA_EMSA_PKCS1_SHA256
:
292 return build_emsa_pkcs1_signature(this, HASH_SHA256
, data
, signature
);
293 case SIGN_RSA_EMSA_PKCS1_SHA384
:
294 return build_emsa_pkcs1_signature(this, HASH_SHA384
, data
, signature
);
295 case SIGN_RSA_EMSA_PKCS1_SHA512
:
296 return build_emsa_pkcs1_signature(this, HASH_SHA512
, data
, signature
);
297 case SIGN_RSA_EMSA_PKCS1_MD5
:
298 return build_emsa_pkcs1_signature(this, HASH_MD5
, data
, signature
);
300 DBG1("signature scheme %N not supported in RSA",
301 signature_scheme_names
, scheme
);
307 * Implementation of gmp_rsa_private_key.destroy.
309 static bool decrypt(private_gmp_rsa_private_key_t
*this,
310 chunk_t crypto
, chunk_t
*plain
)
312 DBG1("RSA private key decryption not implemented");
317 * Implementation of gmp_rsa_private_key.destroy.
319 static size_t get_keysize(private_gmp_rsa_private_key_t
*this)
325 * Implementation of gmp_rsa_private_key.destroy.
327 static identification_t
* get_id(private_gmp_rsa_private_key_t
*this,
332 case ID_PUBKEY_INFO_SHA1
:
333 return this->keyid_info
;
342 * Implementation of gmp_rsa_private_key.get_public_key.
344 static gmp_rsa_public_key_t
* get_public_key(private_gmp_rsa_private_key_t
*this)
346 return gmp_rsa_public_key_create_from_n_e(this->n
, this->e
);
350 * Implementation of gmp_rsa_private_key.destroy.
352 static bool belongs_to(private_gmp_rsa_private_key_t
*this, public_key_t
*public)
354 identification_t
*keyid
;
356 if (public->get_type(public) != KEY_RSA
)
360 keyid
= public->get_id(public, ID_PUBKEY_SHA1
);
361 if (keyid
&& keyid
->equals(keyid
, this->keyid
))
365 keyid
= public->get_id(public, ID_PUBKEY_INFO_SHA1
);
366 if (keyid
&& keyid
->equals(keyid
, this->keyid_info
))
374 * convert a MP integer into a DER coded ASN.1 object
376 chunk_t
gmp_mpz_to_asn1(const mpz_t value
)
380 n
.len
= 1 + mpz_sizeinbase(value
, 2) / 8; /* size in bytes */
381 n
.ptr
= mpz_export(NULL
, NULL
, 1, n
.len
, 1, 0, value
);
383 { /* if we have zero in "value", gmp returns NULL */
386 return asn1_wrap(ASN1_INTEGER
, "m", n
);
390 * Implementation of private_key_t.get_encoding.
392 static chunk_t
get_encoding(private_gmp_rsa_private_key_t
*this)
394 return asn1_wrap(ASN1_SEQUENCE
, "cmmmmmmmm",
396 gmp_mpz_to_asn1(this->n
),
397 gmp_mpz_to_asn1(this->e
),
398 gmp_mpz_to_asn1(this->d
),
399 gmp_mpz_to_asn1(this->p
),
400 gmp_mpz_to_asn1(this->q
),
401 gmp_mpz_to_asn1(this->exp1
),
402 gmp_mpz_to_asn1(this->exp2
),
403 gmp_mpz_to_asn1(this->coeff
));
407 * Implementation of gmp_rsa_private_key.destroy.
409 static private_gmp_rsa_private_key_t
* get_ref(private_gmp_rsa_private_key_t
*this)
417 * Implementation of gmp_rsa_private_key.destroy.
419 static void destroy(private_gmp_rsa_private_key_t
*this)
421 if (ref_put(&this->ref
))
423 mpz_clear_randomized(this->n
);
424 mpz_clear_randomized(this->e
);
425 mpz_clear_randomized(this->p
);
426 mpz_clear_randomized(this->q
);
427 mpz_clear_randomized(this->d
);
428 mpz_clear_randomized(this->exp1
);
429 mpz_clear_randomized(this->exp2
);
430 mpz_clear_randomized(this->coeff
);
431 DESTROY_IF(this->keyid
);
432 DESTROY_IF(this->keyid_info
);
438 * Check the loaded key if it is valid and usable
440 static status_t
check(private_gmp_rsa_private_key_t
*this)
443 status_t status
= SUCCESS
;
445 /* PKCS#1 1.5 section 6 requires modulus to have at least 12 octets.
446 * We actually require more (for security).
450 DBG1("key shorter than 512 bits");
454 /* we picked a max modulus size to simplify buffer allocation */
455 if (this->k
> 8192/8)
457 DBG1("key larger than 8192 bits");
465 /* check that n == p * q */
466 mpz_mul(u
, this->p
, this->q
);
467 if (mpz_cmp(u
, this->n
) != 0)
472 /* check that e divides neither p-1 nor q-1 */
473 mpz_sub_ui(t
, this->p
, 1);
474 mpz_mod(t
, t
, this->e
);
475 if (mpz_cmp_ui(t
, 0) == 0)
480 mpz_sub_ui(t
, this->q
, 1);
481 mpz_mod(t
, t
, this->e
);
482 if (mpz_cmp_ui(t
, 0) == 0)
487 /* check that d is e^-1 (mod lcm(p-1, q-1)) */
488 /* see PKCS#1v2, aka RFC 2437, for the "lcm" */
489 mpz_sub_ui(q1
, this->q
, 1);
490 mpz_sub_ui(u
, this->p
, 1);
491 mpz_gcd(t
, u
, q1
); /* t := gcd(p-1, q-1) */
492 mpz_mul(u
, u
, q1
); /* u := (p-1) * (q-1) */
493 mpz_divexact(u
, u
, t
); /* u := lcm(p-1, q-1) */
495 mpz_mul(t
, this->d
, this->e
);
497 if (mpz_cmp_ui(t
, 1) != 0)
502 /* check that exp1 is d mod (p-1) */
503 mpz_sub_ui(u
, this->p
, 1);
504 mpz_mod(t
, this->d
, u
);
505 if (mpz_cmp(t
, this->exp1
) != 0)
510 /* check that exp2 is d mod (q-1) */
511 mpz_sub_ui(u
, this->q
, 1);
512 mpz_mod(t
, this->d
, u
);
513 if (mpz_cmp(t
, this->exp2
) != 0)
518 /* check that coeff is (q^-1) mod p */
519 mpz_mul(t
, this->coeff
, this->q
);
520 mpz_mod(t
, t
, this->p
);
521 if (mpz_cmp_ui(t
, 1) != 0)
526 mpz_clear_randomized(t
);
527 mpz_clear_randomized(u
);
528 mpz_clear_randomized(q1
);
529 if (status
!= SUCCESS
)
531 DBG1("key integrity tests failed");
537 * Internal generic constructor
539 static private_gmp_rsa_private_key_t
*gmp_rsa_private_key_create_empty(void)
541 private_gmp_rsa_private_key_t
*this = malloc_thing(private_gmp_rsa_private_key_t
);
543 this->public.interface
.get_type
= (key_type_t (*)(private_key_t
*this))get_type
;
544 this->public.interface
.sign
= (bool (*)(private_key_t
*this, signature_scheme_t scheme
, chunk_t data
, chunk_t
*signature
))sign
;
545 this->public.interface
.decrypt
= (bool (*)(private_key_t
*this, chunk_t crypto
, chunk_t
*plain
))decrypt
;
546 this->public.interface
.get_keysize
= (size_t (*) (private_key_t
*this))get_keysize
;
547 this->public.interface
.get_id
= (identification_t
* (*) (private_key_t
*this,id_type_t
))get_id
;
548 this->public.interface
.get_public_key
= (public_key_t
* (*)(private_key_t
*this))get_public_key
;
549 this->public.interface
.belongs_to
= (bool (*) (private_key_t
*this, public_key_t
*public))belongs_to
;
550 this->public.interface
.get_encoding
= (chunk_t(*)(private_key_t
*))get_encoding
;
551 this->public.interface
.get_ref
= (private_key_t
* (*)(private_key_t
*this))get_ref
;
552 this->public.interface
.destroy
= (void (*)(private_key_t
*this))destroy
;
555 this->keyid_info
= NULL
;
562 * Generate an RSA key of specified key size
564 static gmp_rsa_private_key_t
*generate(size_t key_size
)
566 mpz_t p
, q
, n
, e
, d
, exp1
, exp2
, coeff
;
568 private_gmp_rsa_private_key_t
*this = gmp_rsa_private_key_create_empty();
570 key_size
= key_size
/ 8;
572 /* Get values of primes p and q */
573 if (compute_prime(this, key_size
/2, &p
) != SUCCESS
)
578 if (compute_prime(this, key_size
/2, &q
) != SUCCESS
)
592 /* Swapping Primes so p is larger then q */
593 if (mpz_cmp(p
, q
) < 0)
598 mpz_mul(n
, p
, q
); /* n = p*q */
599 mpz_init_set_ui(e
, PUBLIC_EXPONENT
); /* assign public exponent */
600 mpz_init_set(m
, p
); /* m = p */
601 mpz_sub_ui(m
, m
, 1); /* m = m -1 */
602 mpz_init_set(q1
, q
); /* q1 = q */
603 mpz_sub_ui(q1
, q1
, 1); /* q1 = q1 -1 */
604 mpz_gcd(t
, m
, q1
); /* t = gcd(p-1, q-1) */
605 mpz_mul(m
, m
, q1
); /* m = (p-1)*(q-1) */
606 mpz_divexact(m
, m
, t
); /* m = m / t */
607 mpz_gcd(t
, m
, e
); /* t = gcd(m, e) */
609 mpz_invert(d
, e
, m
); /* e has an inverse mod m */
610 if (mpz_cmp_ui(d
, 0) < 0) /* make sure d is positive */
614 mpz_sub_ui(t
, p
, 1); /* t = p-1 */
615 mpz_mod(exp1
, d
, t
); /* exp1 = d mod p-1 */
616 mpz_sub_ui(t
, q
, 1); /* t = q-1 */
617 mpz_mod(exp2
, d
, t
); /* exp2 = d mod q-1 */
619 mpz_invert(coeff
, q
, p
); /* coeff = q^-1 mod p */
620 if (mpz_cmp_ui(coeff
, 0) < 0) /* make coeff d is positive */
622 mpz_add(coeff
, coeff
, p
);
625 mpz_clear_randomized(q1
);
626 mpz_clear_randomized(m
);
627 mpz_clear_randomized(t
);
635 *(this->exp1
) = *exp1
;
636 *(this->exp2
) = *exp2
;
637 *(this->coeff
) = *coeff
;
639 /* set key size in bytes */
642 return &this->public;
646 * ASN.1 definition of a PKCS#1 RSA private key
648 static const asn1Object_t privkeyObjects
[] = {
649 { 0, "RSAPrivateKey", ASN1_SEQUENCE
, ASN1_NONE
}, /* 0 */
650 { 1, "version", ASN1_INTEGER
, ASN1_BODY
}, /* 1 */
651 { 1, "modulus", ASN1_INTEGER
, ASN1_BODY
}, /* 2 */
652 { 1, "publicExponent", ASN1_INTEGER
, ASN1_BODY
}, /* 3 */
653 { 1, "privateExponent", ASN1_INTEGER
, ASN1_BODY
}, /* 4 */
654 { 1, "prime1", ASN1_INTEGER
, ASN1_BODY
}, /* 5 */
655 { 1, "prime2", ASN1_INTEGER
, ASN1_BODY
}, /* 6 */
656 { 1, "exponent1", ASN1_INTEGER
, ASN1_BODY
}, /* 7 */
657 { 1, "exponent2", ASN1_INTEGER
, ASN1_BODY
}, /* 8 */
658 { 1, "coefficient", ASN1_INTEGER
, ASN1_BODY
}, /* 9 */
659 { 1, "otherPrimeInfos", ASN1_SEQUENCE
, ASN1_OPT
|
660 ASN1_LOOP
}, /* 10 */
661 { 2, "otherPrimeInfo", ASN1_SEQUENCE
, ASN1_NONE
}, /* 11 */
662 { 3, "prime", ASN1_INTEGER
, ASN1_BODY
}, /* 12 */
663 { 3, "exponent", ASN1_INTEGER
, ASN1_BODY
}, /* 13 */
664 { 3, "coefficient", ASN1_INTEGER
, ASN1_BODY
}, /* 14 */
665 { 1, "end opt or loop", ASN1_EOC
, ASN1_END
}, /* 15 */
666 { 0, "exit", ASN1_EOC
, ASN1_EXIT
}
668 #define PRIV_KEY_VERSION 1
669 #define PRIV_KEY_MODULUS 2
670 #define PRIV_KEY_PUB_EXP 3
671 #define PRIV_KEY_PRIV_EXP 4
672 #define PRIV_KEY_PRIME1 5
673 #define PRIV_KEY_PRIME2 6
674 #define PRIV_KEY_EXP1 7
675 #define PRIV_KEY_EXP2 8
676 #define PRIV_KEY_COEFF 9
679 * load private key from a ASN1 encoded blob
681 static gmp_rsa_private_key_t
*load(chunk_t blob
)
683 asn1_parser_t
*parser
;
686 bool success
= FALSE
;
688 private_gmp_rsa_private_key_t
*this = gmp_rsa_private_key_create_empty();
695 mpz_init(this->exp1
);
696 mpz_init(this->exp2
);
697 mpz_init(this->coeff
);
699 parser
= asn1_parser_create(privkeyObjects
, blob
);
700 parser
->set_flags(parser
, FALSE
, TRUE
);
702 while (parser
->iterate(parser
, &objectID
, &object
))
706 case PRIV_KEY_VERSION
:
707 if (object
.len
> 0 && *object
.ptr
!= 0)
712 case PRIV_KEY_MODULUS
:
713 mpz_import(this->n
, object
.len
, 1, 1, 1, 0, object
.ptr
);
715 case PRIV_KEY_PUB_EXP
:
716 mpz_import(this->e
, object
.len
, 1, 1, 1, 0, object
.ptr
);
718 case PRIV_KEY_PRIV_EXP
:
719 mpz_import(this->d
, object
.len
, 1, 1, 1, 0, object
.ptr
);
721 case PRIV_KEY_PRIME1
:
722 mpz_import(this->p
, object
.len
, 1, 1, 1, 0, object
.ptr
);
724 case PRIV_KEY_PRIME2
:
725 mpz_import(this->q
, object
.len
, 1, 1, 1, 0, object
.ptr
);
728 mpz_import(this->exp1
, object
.len
, 1, 1, 1, 0, object
.ptr
);
731 mpz_import(this->exp2
, object
.len
, 1, 1, 1, 0, object
.ptr
);
734 mpz_import(this->coeff
, object
.len
, 1, 1, 1, 0, object
.ptr
);
738 success
= parser
->success(parser
);
741 parser
->destroy(parser
);
750 this->k
= (mpz_sizeinbase(this->n
, 2) + 7) / BITS_PER_BYTE
;
752 if (!gmp_rsa_public_key_build_id(this->n
, this->e
,
753 &this->keyid
, &this->keyid_info
))
759 if (check(this) != SUCCESS
)
764 return &this->public;
767 typedef struct private_builder_t private_builder_t
;
769 * Builder implementation for key loading/generation
771 struct private_builder_t
{
772 /** implements the builder interface */
774 /** loaded/generated private key */
775 gmp_rsa_private_key_t
*key
;
779 * Implementation of builder_t.build
781 static gmp_rsa_private_key_t
*build(private_builder_t
*this)
783 gmp_rsa_private_key_t
*key
= this->key
;
790 * Implementation of builder_t.add
792 static void add(private_builder_t
*this, builder_part_t part
, ...)
801 case BUILD_BLOB_ASN1_DER
:
803 va_start(args
, part
);
804 chunk
= va_arg(args
, chunk_t
);
805 this->key
= load(chunk_clone(chunk
));
811 va_start(args
, part
);
812 this->key
= generate(va_arg(args
, u_int
));
822 destroy((private_gmp_rsa_private_key_t
*)this->key
);
824 builder_cancel(&this->public);
828 * Builder construction function
830 builder_t
*gmp_rsa_private_key_builder(key_type_t type
)
832 private_builder_t
*this;
839 this = malloc_thing(private_builder_t
);
842 this->public.add
= (void(*)(builder_t
*this, builder_part_t part
, ...))add
;
843 this->public.build
= (void*(*)(builder_t
*this))build
;
845 return &this->public;