285 lines
8.7 KiB
C
285 lines
8.7 KiB
C
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/*
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* Copyright (c) 2007-2014, Cameron Rich
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*
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* * Neither the name of the axTLS project nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/**
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* Implements the RSA public encryption algorithm. Uses the bigint library to
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* perform its calculations.
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*/
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#include <stdio.h>
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#include <string.h>
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#include <time.h>
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#include <stdlib.h>
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#include "os_port.h"
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#include "crypto.h"
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void RSA_priv_key_new(RSA_CTX **ctx,
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const uint8_t *modulus, int mod_len,
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const uint8_t *pub_exp, int pub_len,
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const uint8_t *priv_exp, int priv_len
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#if CONFIG_BIGINT_CRT
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, const uint8_t *p, int p_len,
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const uint8_t *q, int q_len,
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const uint8_t *dP, int dP_len,
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const uint8_t *dQ, int dQ_len,
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const uint8_t *qInv, int qInv_len
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#endif
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)
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{
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RSA_CTX *rsa_ctx;
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BI_CTX *bi_ctx;
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RSA_pub_key_new(ctx, modulus, mod_len, pub_exp, pub_len);
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rsa_ctx = *ctx;
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bi_ctx = rsa_ctx->bi_ctx;
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rsa_ctx->d = bi_import(bi_ctx, priv_exp, priv_len);
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bi_permanent(rsa_ctx->d);
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#ifdef CONFIG_BIGINT_CRT
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rsa_ctx->p = bi_import(bi_ctx, p, p_len);
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rsa_ctx->q = bi_import(bi_ctx, q, q_len);
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rsa_ctx->dP = bi_import(bi_ctx, dP, dP_len);
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rsa_ctx->dQ = bi_import(bi_ctx, dQ, dQ_len);
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rsa_ctx->qInv = bi_import(bi_ctx, qInv, qInv_len);
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bi_permanent(rsa_ctx->dP);
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bi_permanent(rsa_ctx->dQ);
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bi_permanent(rsa_ctx->qInv);
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bi_set_mod(bi_ctx, rsa_ctx->p, BIGINT_P_OFFSET);
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bi_set_mod(bi_ctx, rsa_ctx->q, BIGINT_Q_OFFSET);
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#endif
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}
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void RSA_pub_key_new(RSA_CTX **ctx,
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const uint8_t *modulus, int mod_len,
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const uint8_t *pub_exp, int pub_len)
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{
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RSA_CTX *rsa_ctx;
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BI_CTX *bi_ctx;
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if (*ctx) /* if we load multiple certs, dump the old one */
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RSA_free(*ctx);
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bi_ctx = bi_initialize();
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*ctx = (RSA_CTX *)calloc(1, sizeof(RSA_CTX));
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rsa_ctx = *ctx;
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rsa_ctx->bi_ctx = bi_ctx;
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rsa_ctx->num_octets = mod_len;
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rsa_ctx->m = bi_import(bi_ctx, modulus, mod_len);
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bi_set_mod(bi_ctx, rsa_ctx->m, BIGINT_M_OFFSET);
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rsa_ctx->e = bi_import(bi_ctx, pub_exp, pub_len);
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bi_permanent(rsa_ctx->e);
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}
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/**
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* Free up any RSA context resources.
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*/
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void RSA_free(RSA_CTX *rsa_ctx)
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{
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BI_CTX *bi_ctx;
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if (rsa_ctx == NULL) /* deal with ptrs that are null */
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return;
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bi_ctx = rsa_ctx->bi_ctx;
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bi_depermanent(rsa_ctx->e);
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bi_free(bi_ctx, rsa_ctx->e);
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bi_free_mod(rsa_ctx->bi_ctx, BIGINT_M_OFFSET);
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if (rsa_ctx->d)
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{
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bi_depermanent(rsa_ctx->d);
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bi_free(bi_ctx, rsa_ctx->d);
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#ifdef CONFIG_BIGINT_CRT
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bi_depermanent(rsa_ctx->dP);
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bi_depermanent(rsa_ctx->dQ);
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bi_depermanent(rsa_ctx->qInv);
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bi_free(bi_ctx, rsa_ctx->dP);
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bi_free(bi_ctx, rsa_ctx->dQ);
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bi_free(bi_ctx, rsa_ctx->qInv);
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bi_free_mod(rsa_ctx->bi_ctx, BIGINT_P_OFFSET);
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bi_free_mod(rsa_ctx->bi_ctx, BIGINT_Q_OFFSET);
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#endif
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}
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bi_terminate(bi_ctx);
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free(rsa_ctx);
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}
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/**
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* @brief Use PKCS1.5 for decryption/verification.
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* @param ctx [in] The context
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* @param in_data [in] The data to decrypt (must be < modulus size-11)
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* @param out_data [out] The decrypted data.
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* @param out_len [int] The size of the decrypted buffer in bytes
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* @param is_decryption [in] Decryption or verify operation.
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* @return The number of bytes that were originally encrypted. -1 on error.
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* @see http://www.rsasecurity.com/rsalabs/node.asp?id=2125
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*/
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int RSA_decrypt(const RSA_CTX *ctx, const uint8_t *in_data,
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uint8_t *out_data, int out_len, int is_decryption)
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{
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const int byte_size = ctx->num_octets;
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int i = 0, size;
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bigint *decrypted_bi, *dat_bi;
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uint8_t *block = (uint8_t *)alloca(byte_size);
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int pad_count = 0;
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if (out_len < byte_size) /* check output has enough size */
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return -1;
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memset(out_data, 0, out_len); /* initialise */
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/* decrypt */
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dat_bi = bi_import(ctx->bi_ctx, in_data, byte_size);
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#ifdef CONFIG_SSL_CERT_VERIFICATION
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decrypted_bi = is_decryption ? /* decrypt or verify? */
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RSA_private(ctx, dat_bi) : RSA_public(ctx, dat_bi);
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#else /* always a decryption */
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decrypted_bi = RSA_private(ctx, dat_bi);
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#endif
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/* convert to a normal block */
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bi_export(ctx->bi_ctx, decrypted_bi, block, byte_size);
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if (block[i++] != 0) /* leading 0? */
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return -1;
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#ifdef CONFIG_SSL_CERT_VERIFICATION
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if (is_decryption == 0) /* PKCS1.5 signing pads with "0xff"s */
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{
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if (block[i++] != 0x01) /* BT correct? */
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return -1;
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while (block[i++] == 0xff && i < byte_size)
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pad_count++;
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}
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else /* PKCS1.5 encryption padding is random */
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#endif
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{
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if (block[i++] != 0x02) /* BT correct? */
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return -1;
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while (block[i++] && i < byte_size)
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pad_count++;
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}
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/* check separator byte 0x00 - and padding must be 8 or more bytes */
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if (i == byte_size || pad_count < 8)
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return -1;
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size = byte_size - i;
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/* get only the bit we want */
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memcpy(out_data, &block[i], size);
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return size;
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}
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/**
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* Performs m = c^d mod n
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*/
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bigint *RSA_private(const RSA_CTX *c, bigint *bi_msg)
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{
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#ifdef CONFIG_BIGINT_CRT
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return bi_crt(c->bi_ctx, bi_msg, c->dP, c->dQ, c->p, c->q, c->qInv);
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#else
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BI_CTX *ctx = c->bi_ctx;
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ctx->mod_offset = BIGINT_M_OFFSET;
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return bi_mod_power(ctx, bi_msg, c->d);
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#endif
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}
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#ifdef CONFIG_SSL_FULL_MODE
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/**
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* Used for diagnostics.
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*/
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void RSA_print(const RSA_CTX *rsa_ctx)
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{
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if (rsa_ctx == NULL)
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return;
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printf("----------------- RSA DEBUG ----------------\n");
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printf("Size:\t%d\n", rsa_ctx->num_octets);
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bi_print("Modulus", rsa_ctx->m);
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bi_print("Public Key", rsa_ctx->e);
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bi_print("Private Key", rsa_ctx->d);
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}
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#endif
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#if defined(CONFIG_SSL_CERT_VERIFICATION) || defined(CONFIG_SSL_GENERATE_X509_CERT)
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/**
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* Performs c = m^e mod n
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*/
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bigint *RSA_public(const RSA_CTX * c, bigint *bi_msg)
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{
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c->bi_ctx->mod_offset = BIGINT_M_OFFSET;
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return bi_mod_power(c->bi_ctx, bi_msg, c->e);
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}
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/**
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* Use PKCS1.5 for encryption/signing.
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* see http://www.rsasecurity.com/rsalabs/node.asp?id=2125
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*/
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int RSA_encrypt(const RSA_CTX *ctx, const uint8_t *in_data, uint16_t in_len,
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uint8_t *out_data, int is_signing)
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{
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int byte_size = ctx->num_octets;
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int num_pads_needed = byte_size-in_len-3;
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bigint *dat_bi, *encrypt_bi;
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/* note: in_len+11 must be > byte_size */
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out_data[0] = 0; /* ensure encryption block is < modulus */
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if (is_signing)
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{
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out_data[1] = 1; /* PKCS1.5 signing pads with "0xff"'s */
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memset(&out_data[2], 0xff, num_pads_needed);
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}
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else /* randomize the encryption padding with non-zero bytes */
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{
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out_data[1] = 2;
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if (get_random_NZ(num_pads_needed, &out_data[2]) < 0)
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return -1;
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}
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out_data[2+num_pads_needed] = 0;
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memcpy(&out_data[3+num_pads_needed], in_data, in_len);
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/* now encrypt it */
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dat_bi = bi_import(ctx->bi_ctx, out_data, byte_size);
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encrypt_bi = is_signing ? RSA_private(ctx, dat_bi) :
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RSA_public(ctx, dat_bi);
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bi_export(ctx->bi_ctx, encrypt_bi, out_data, byte_size);
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/* save a few bytes of memory */
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bi_clear_cache(ctx->bi_ctx);
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return byte_size;
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}
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#endif /* CONFIG_SSL_CERT_VERIFICATION */
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