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/*
* Copyright (c) 2007, Cameron Rich
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* * Neither the name of the axTLS project nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
* Implements the RSA public encryption algorithm. Uses the bigint library to
* perform its calculations.
*/
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <stdlib.h>
#include "crypto.h"
void RSA_priv_key_new(RSA_CTX **ctx,
const uint8_t *modulus, int mod_len,
const uint8_t *pub_exp, int pub_len,
const uint8_t *priv_exp, int priv_len
#if CONFIG_BIGINT_CRT
, const uint8_t *p, int p_len,
const uint8_t *q, int q_len,
const uint8_t *dP, int dP_len,
const uint8_t *dQ, int dQ_len,
const uint8_t *qInv, int qInv_len
#endif
)
{
RSA_CTX *rsa_ctx;
BI_CTX *bi_ctx;
RSA_pub_key_new(ctx, modulus, mod_len, pub_exp, pub_len);
rsa_ctx = *ctx;
bi_ctx = rsa_ctx->bi_ctx;
rsa_ctx->d = bi_import(bi_ctx, priv_exp, priv_len);
bi_permanent(rsa_ctx->d);
#ifdef CONFIG_BIGINT_CRT
rsa_ctx->p = bi_import(bi_ctx, p, p_len);
rsa_ctx->q = bi_import(bi_ctx, q, q_len);
rsa_ctx->dP = bi_import(bi_ctx, dP, dP_len);
rsa_ctx->dQ = bi_import(bi_ctx, dQ, dQ_len);
rsa_ctx->qInv = bi_import(bi_ctx, qInv, qInv_len);
bi_permanent(rsa_ctx->dP);
bi_permanent(rsa_ctx->dQ);
bi_permanent(rsa_ctx->qInv);
bi_set_mod(bi_ctx, rsa_ctx->p, BIGINT_P_OFFSET);
bi_set_mod(bi_ctx, rsa_ctx->q, BIGINT_Q_OFFSET);
#endif
}
void RSA_pub_key_new(RSA_CTX **ctx,
const uint8_t *modulus, int mod_len,
const uint8_t *pub_exp, int pub_len)
{
RSA_CTX *rsa_ctx;
BI_CTX *bi_ctx;
if (*ctx) /* if we load multiple certs, dump the old one */
RSA_free(*ctx);
bi_ctx = bi_initialize();
*ctx = (RSA_CTX *)calloc(1, sizeof(RSA_CTX));
rsa_ctx = *ctx;
rsa_ctx->bi_ctx = bi_ctx;
rsa_ctx->num_octets = (mod_len & 0xFFF0);
rsa_ctx->m = bi_import(bi_ctx, modulus, mod_len);
bi_set_mod(bi_ctx, rsa_ctx->m, BIGINT_M_OFFSET);
rsa_ctx->e = bi_import(bi_ctx, pub_exp, pub_len);
bi_permanent(rsa_ctx->e);
}
/**
* Free up any RSA context resources.
*/
void RSA_free(RSA_CTX *rsa_ctx)
{
BI_CTX *bi_ctx;
if (rsa_ctx == NULL) /* deal with ptrs that are null */
return;
bi_ctx = rsa_ctx->bi_ctx;
bi_depermanent(rsa_ctx->e);
bi_free(bi_ctx, rsa_ctx->e);
bi_free_mod(rsa_ctx->bi_ctx, BIGINT_M_OFFSET);
if (rsa_ctx->d)
{
bi_depermanent(rsa_ctx->d);
bi_free(bi_ctx, rsa_ctx->d);
#ifdef CONFIG_BIGINT_CRT
bi_depermanent(rsa_ctx->dP);
bi_depermanent(rsa_ctx->dQ);
bi_depermanent(rsa_ctx->qInv);
bi_free(bi_ctx, rsa_ctx->dP);
bi_free(bi_ctx, rsa_ctx->dQ);
bi_free(bi_ctx, rsa_ctx->qInv);
bi_free_mod(rsa_ctx->bi_ctx, BIGINT_P_OFFSET);
bi_free_mod(rsa_ctx->bi_ctx, BIGINT_Q_OFFSET);
#endif
}
bi_terminate(bi_ctx);
free(rsa_ctx);
}
/**
* @brief Use PKCS1.5 for decryption/verification.
* @param ctx [in] The context
* @param in_data [in] The data to encrypt (must be < modulus size-11)
* @param out_data [out] The encrypted data.
* @param is_decryption [in] Decryption or verify operation.
* @return The number of bytes that were originally encrypted. -1 on error.
* @see http://www.rsasecurity.com/rsalabs/node.asp?id=2125
*/
int RSA_decrypt(const RSA_CTX *ctx, const uint8_t *in_data,
uint8_t *out_data, int is_decryption)
{
const int byte_size = ctx->num_octets;
int i, size;
bigint *decrypted_bi, *dat_bi;
uint8_t *block = (uint8_t *)alloca(byte_size);
memset(out_data, 0, byte_size); /* initialise */
/* decrypt */
dat_bi = bi_import(ctx->bi_ctx, in_data, byte_size);
#ifdef CONFIG_SSL_CERT_VERIFICATION
decrypted_bi = is_decryption ? /* decrypt or verify? */
RSA_private(ctx, dat_bi) : RSA_public(ctx, dat_bi);
#else /* always a decryption */
decrypted_bi = RSA_private(ctx, dat_bi);
#endif
/* convert to a normal block */
bi_export(ctx->bi_ctx, decrypted_bi, block, byte_size);
i = 10; /* start at the first possible non-padded byte */
#ifdef CONFIG_SSL_CERT_VERIFICATION
if (is_decryption == 0) /* PKCS1.5 signing pads with "0xff"s */
{
while (block[i++] == 0xff && i < byte_size);
if (block[i-2] != 0xff)
i = byte_size; /*ensure size is 0 */
}
else /* PKCS1.5 encryption padding is random */
#endif
{
while (block[i++] && i < byte_size);
}
size = byte_size - i;
/* get only the bit we want */
if (size > 0)
memcpy(out_data, &block[i], size);
return size ? size : -1;
}
/**
* Performs m = c^d mod n
*/
bigint *RSA_private(const RSA_CTX *c, bigint *bi_msg)
{
#ifdef CONFIG_BIGINT_CRT
return bi_crt(c->bi_ctx, bi_msg, c->dP, c->dQ, c->p, c->q, c->qInv);
#else
BI_CTX *ctx = c->bi_ctx;
ctx->mod_offset = BIGINT_M_OFFSET;
return bi_mod_power(ctx, bi_msg, c->d);
#endif
}
#ifdef CONFIG_SSL_FULL_MODE
/**
* Used for diagnostics.
*/
void RSA_print(const RSA_CTX *rsa_ctx)
{
if (rsa_ctx == NULL)
return;
printf("----------------- RSA DEBUG ----------------\n");
printf("Size:\t%d\n", rsa_ctx->num_octets);
bi_print("Modulus", rsa_ctx->m);
bi_print("Public Key", rsa_ctx->e);
bi_print("Private Key", rsa_ctx->d);
}
#endif
#if defined(CONFIG_SSL_CERT_VERIFICATION) || defined(CONFIG_SSL_GENERATE_X509_CERT)
/**
* Performs c = m^e mod n
*/
bigint *RSA_public(const RSA_CTX * c, bigint *bi_msg)
{
c->bi_ctx->mod_offset = BIGINT_M_OFFSET;
return bi_mod_power(c->bi_ctx, bi_msg, c->e);
}
/**
* Use PKCS1.5 for encryption/signing.
* see http://www.rsasecurity.com/rsalabs/node.asp?id=2125
*/
int RSA_encrypt(const RSA_CTX *ctx, const uint8_t *in_data, uint16_t in_len,
uint8_t *out_data, int is_signing)
{
int byte_size = ctx->num_octets;
int num_pads_needed = byte_size-in_len-3;
bigint *dat_bi, *encrypt_bi;
/* note: in_len+11 must be > byte_size */
out_data[0] = 0; /* ensure encryption block is < modulus */
if (is_signing)
{
out_data[1] = 1; /* PKCS1.5 signing pads with "0xff"'s */
memset(&out_data[2], 0xff, num_pads_needed);
}
else /* randomize the encryption padding with non-zero bytes */
{
out_data[1] = 2;
get_random_NZ(num_pads_needed, &out_data[2]);
}
out_data[2+num_pads_needed] = 0;
memcpy(&out_data[3+num_pads_needed], in_data, in_len);
/* now encrypt it */
dat_bi = bi_import(ctx->bi_ctx, out_data, byte_size);
encrypt_bi = is_signing ? RSA_private(ctx, dat_bi) :
RSA_public(ctx, dat_bi);
bi_export(ctx->bi_ctx, encrypt_bi, out_data, byte_size);
/* save a few bytes of memory */
bi_clear_cache(ctx->bi_ctx);
return byte_size;
}
#endif /* CONFIG_SSL_CERT_VERIFICATION */
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