Mercurial > dropbear

annotate libtomcrypt/src/pk/pkcs1/pkcs_1_i2osp.c @ 409:0e69e948caba

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Add comments about requiring keysize <= 2*SHA1_HASH_SIZE
author Matt Johnston <matt@ucc.asn.au>
date Sun, 04 Feb 2007 10:31:48 +0000
parents 1b9e69c058d2
children 0cbe8f6dbf9e
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1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
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2 *
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3 * LibTomCrypt is a library that provides various cryptographic
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4 * algorithms in a highly modular and flexible manner.
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5 *
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6 * The library is free for all purposes without any express
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7 * guarantee it works.
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8 *
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9 * Tom St Denis, [email protected], http://libtomcrypt.org
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10 */
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11 #include "tomcrypt.h"
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12
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13 /**
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14 @file pkcs_1_i2osp.c
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15 Integer to Octet I2OSP, Tom St Denis
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16 */
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17
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18 #ifdef PKCS_1
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19
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20 /* always stores the same # of bytes, pads with leading zero bytes
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21 as required
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22 */
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23
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24 /**
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25 PKCS #1 Integer to binary
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26 @param n The integer to store
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27 @param modulus_len The length of the RSA modulus
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28 @param out [out] The destination for the integer
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29 @return CRYPT_OK if successful
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30 */
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31 int pkcs_1_i2osp(mp_int *n, unsigned long modulus_len, unsigned char *out)
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32 {
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33 int err;
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34 unsigned long size;
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36 size = mp_unsigned_bin_size(n);
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38 if (size > modulus_len) {
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39 return CRYPT_BUFFER_OVERFLOW;
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40 }
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42 /* store it */
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43 zeromem(out, modulus_len);
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44 if ((err = mp_to_unsigned_bin(n, out+(modulus_len-size))) != MP_OKAY) {
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45 return mpi_to_ltc_error(err);
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46 }
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47 return CRYPT_OK;
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48 }
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50 #endif /* PKCS_1 */
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53 /* $Source: /cvs/libtom/libtomcrypt/src/pk/pkcs1/pkcs_1_i2osp.c,v $ */
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54 /* $Revision: 1.3 $ */
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55 /* $Date: 2005/05/05 14:35:59 $ */