2 * Copyright (c) 2013, Google Inc.
4 * SPDX-License-Identifier: GPL-2.0+
12 #include <openssl/rsa.h>
13 #include <openssl/pem.h>
14 #include <openssl/err.h>
15 #include <openssl/ssl.h>
16 #include <openssl/evp.h>
18 #if OPENSSL_VERSION_NUMBER >= 0x10000000L
19 #define HAVE_ERR_REMOVE_THREAD_STATE
22 static int rsa_err(const char *msg)
24 unsigned long sslErr = ERR_get_error();
26 fprintf(stderr, "%s", msg);
27 fprintf(stderr, ": %s\n",
28 ERR_error_string(sslErr, 0));
34 * rsa_get_pub_key() - read a public key from a .crt file
36 * @keydir: Directory containins the key
37 * @name Name of key file (will have a .crt extension)
38 * @rsap Returns RSA object, or NULL on failure
39 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
41 static int rsa_get_pub_key(const char *keydir, const char *name, RSA **rsap)
51 snprintf(path, sizeof(path), "%s/%s.crt", keydir, name);
54 fprintf(stderr, "Couldn't open RSA certificate: '%s': %s\n",
55 path, strerror(errno));
59 /* Read the certificate */
61 if (!PEM_read_X509(f, &cert, NULL, NULL)) {
62 rsa_err("Couldn't read certificate");
67 /* Get the public key from the certificate. */
68 key = X509_get_pubkey(cert);
70 rsa_err("Couldn't read public key\n");
75 /* Convert to a RSA_style key. */
76 rsa = EVP_PKEY_get1_RSA(key);
78 rsa_err("Couldn't convert to a RSA style key");
99 * rsa_get_priv_key() - read a private key from a .key file
101 * @keydir: Directory containins the key
102 * @name Name of key file (will have a .key extension)
103 * @rsap Returns RSA object, or NULL on failure
104 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
106 static int rsa_get_priv_key(const char *keydir, const char *name, RSA **rsap)
113 snprintf(path, sizeof(path), "%s/%s.key", keydir, name);
114 f = fopen(path, "r");
116 fprintf(stderr, "Couldn't open RSA private key: '%s': %s\n",
117 path, strerror(errno));
121 rsa = PEM_read_RSAPrivateKey(f, 0, NULL, path);
123 rsa_err("Failure reading private key");
133 static int rsa_init(void)
137 ret = SSL_library_init();
139 fprintf(stderr, "Failure to init SSL library\n");
142 SSL_load_error_strings();
144 OpenSSL_add_all_algorithms();
145 OpenSSL_add_all_digests();
146 OpenSSL_add_all_ciphers();
151 static void rsa_remove(void)
153 CRYPTO_cleanup_all_ex_data();
155 #ifdef HAVE_ERR_REMOVE_THREAD_STATE
156 ERR_remove_thread_state(NULL);
163 static int rsa_sign_with_key(RSA *rsa, struct checksum_algo *checksum_algo,
164 const struct image_region region[], int region_count,
165 uint8_t **sigp, uint *sig_size)
173 key = EVP_PKEY_new();
175 return rsa_err("EVP_PKEY object creation failed");
177 if (!EVP_PKEY_set1_RSA(key, rsa)) {
178 ret = rsa_err("EVP key setup failed");
182 size = EVP_PKEY_size(key);
185 fprintf(stderr, "Out of memory for signature (%d bytes)\n",
191 context = EVP_MD_CTX_create();
193 ret = rsa_err("EVP context creation failed");
196 EVP_MD_CTX_init(context);
197 if (!EVP_SignInit(context, checksum_algo->calculate_sign())) {
198 ret = rsa_err("Signer setup failed");
202 for (i = 0; i < region_count; i++) {
203 if (!EVP_SignUpdate(context, region[i].data, region[i].size)) {
204 ret = rsa_err("Signing data failed");
209 if (!EVP_SignFinal(context, sig, sig_size, key)) {
210 ret = rsa_err("Could not obtain signature");
213 EVP_MD_CTX_cleanup(context);
214 EVP_MD_CTX_destroy(context);
217 debug("Got signature: %d bytes, expected %d\n", *sig_size, size);
224 EVP_MD_CTX_destroy(context);
233 int rsa_sign(struct image_sign_info *info,
234 const struct image_region region[], int region_count,
235 uint8_t **sigp, uint *sig_len)
244 ret = rsa_get_priv_key(info->keydir, info->keyname, &rsa);
247 ret = rsa_sign_with_key(rsa, info->algo->checksum, region,
248 region_count, sigp, sig_len);
265 * rsa_get_exponent(): - Get the public exponent from an RSA key
267 static int rsa_get_exponent(RSA *key, uint64_t *e)
279 if (BN_num_bits(key->e) > 64)
282 *e = BN_get_word(key->e);
284 if (BN_num_bits(key->e) < 33) {
289 bn_te = BN_dup(key->e);
293 if (!BN_rshift(bn_te, bn_te, 32))
296 if (!BN_mask_bits(bn_te, 32))
299 te = BN_get_word(bn_te);
312 * rsa_get_params(): - Get the important parameters of an RSA public key
314 int rsa_get_params(RSA *key, uint64_t *exponent, uint32_t *n0_invp,
315 BIGNUM **modulusp, BIGNUM **r_squaredp)
317 BIGNUM *big1, *big2, *big32, *big2_32;
318 BIGNUM *n, *r, *r_squared, *tmp;
319 BN_CTX *bn_ctx = BN_CTX_new();
322 /* Initialize BIGNUMs */
327 r_squared = BN_new();
331 if (!big1 || !big2 || !big32 || !r || !r_squared || !tmp || !big2_32 ||
333 fprintf(stderr, "Out of memory (bignum)\n");
337 if (0 != rsa_get_exponent(key, exponent))
340 if (!BN_copy(n, key->n) || !BN_set_word(big1, 1L) ||
341 !BN_set_word(big2, 2L) || !BN_set_word(big32, 32L))
345 if (!BN_exp(big2_32, big2, big32, bn_ctx))
348 /* Calculate n0_inv = -1 / n[0] mod 2^32 */
349 if (!BN_mod_inverse(tmp, n, big2_32, bn_ctx) ||
350 !BN_sub(tmp, big2_32, tmp))
352 *n0_invp = BN_get_word(tmp);
354 /* Calculate R = 2^(# of key bits) */
355 if (!BN_set_word(tmp, BN_num_bits(n)) ||
356 !BN_exp(r, big2, tmp, bn_ctx))
359 /* Calculate r_squared = R^2 mod n */
360 if (!BN_copy(r_squared, r) ||
361 !BN_mul(tmp, r_squared, r, bn_ctx) ||
362 !BN_mod(r_squared, tmp, n, bn_ctx))
366 *r_squaredp = r_squared;
375 fprintf(stderr, "Bignum operations failed\n");
382 static int fdt_add_bignum(void *blob, int noffset, const char *prop_name,
383 BIGNUM *num, int num_bits)
385 int nwords = num_bits / 32;
388 BIGNUM *tmp, *big2, *big32, *big2_32;
396 if (!tmp || !big2 || !big32 || !big2_32) {
397 fprintf(stderr, "Out of memory (bignum)\n");
402 fprintf(stderr, "Out of memory (bignum context)\n");
405 BN_set_word(big2, 2L);
406 BN_set_word(big32, 32L);
407 BN_exp(big2_32, big2, big32, ctx); /* B = 2^32 */
409 size = nwords * sizeof(uint32_t);
412 fprintf(stderr, "Out of memory (%d bytes)\n", size);
416 /* Write out modulus as big endian array of integers */
417 for (ptr = buf + nwords - 1; ptr >= buf; ptr--) {
418 BN_mod(tmp, num, big2_32, ctx); /* n = N mod B */
419 *ptr = cpu_to_fdt32(BN_get_word(tmp));
420 BN_rshift(num, num, 32); /* N = N/B */
423 ret = fdt_setprop(blob, noffset, prop_name, buf, size);
425 fprintf(stderr, "Failed to write public key to FIT\n");
437 int rsa_add_verify_data(struct image_sign_info *info, void *keydest)
439 BIGNUM *modulus, *r_squared;
448 debug("%s: Getting verification data\n", __func__);
449 ret = rsa_get_pub_key(info->keydir, info->keyname, &rsa);
452 ret = rsa_get_params(rsa, &exponent, &n0_inv, &modulus, &r_squared);
455 bits = BN_num_bits(modulus);
456 parent = fdt_subnode_offset(keydest, 0, FIT_SIG_NODENAME);
457 if (parent == -FDT_ERR_NOTFOUND) {
458 parent = fdt_add_subnode(keydest, 0, FIT_SIG_NODENAME);
461 if (ret != -FDT_ERR_NOSPACE) {
462 fprintf(stderr, "Couldn't create signature node: %s\n",
463 fdt_strerror(parent));
470 /* Either create or overwrite the named key node */
471 snprintf(name, sizeof(name), "key-%s", info->keyname);
472 node = fdt_subnode_offset(keydest, parent, name);
473 if (node == -FDT_ERR_NOTFOUND) {
474 node = fdt_add_subnode(keydest, parent, name);
477 if (ret != -FDT_ERR_NOSPACE) {
478 fprintf(stderr, "Could not create key subnode: %s\n",
482 } else if (node < 0) {
483 fprintf(stderr, "Cannot select keys parent: %s\n",
489 ret = fdt_setprop_string(keydest, node, "key-name-hint",
493 ret = fdt_setprop_u32(keydest, node, "rsa,num-bits", bits);
495 ret = fdt_setprop_u32(keydest, node, "rsa,n0-inverse", n0_inv);
497 ret = fdt_setprop_u64(keydest, node, "rsa,exponent", exponent);
500 ret = fdt_add_bignum(keydest, node, "rsa,modulus", modulus,
504 ret = fdt_add_bignum(keydest, node, "rsa,r-squared", r_squared,
508 ret = fdt_setprop_string(keydest, node, FIT_ALGO_PROP,
511 if (info->require_keys) {
512 ret = fdt_setprop_string(keydest, node, "required",
519 return ret == -FDT_ERR_NOSPACE ? -ENOSPC : -EIO;