1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
2 *
3 * LibTomCrypt is a library that provides various cryptographic
4 * algorithms in a highly modular and flexible manner.
5 *
6 * The library is free for all purposes without any express
7 * guarantee it works.
8 *
9 * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com
10 */
11 #include "tomcrypt.h"
12
13 /**
14 @file pkcs_1_i2osp.c
15 Integer to Octet I2OSP, Tom St Denis
16 */
17
18 #ifdef PKCS_1
19
20 /* always stores the same # of bytes, pads with leading zero bytes
21 as required
22 */
23
24 /**
25 PKCS #1 Integer to binary
26 @param n The integer to store
27 @param modulus_len The length of the RSA modulus
28 @param out [out] The destination for the integer
29 @return CRYPT_OK if successful
30 */
pkcs_1_i2osp(void * n,unsigned long modulus_len,unsigned char * out)31 int pkcs_1_i2osp(void *n, unsigned long modulus_len, unsigned char *out)
32 {
33 unsigned long size;
34
35 size = mp_unsigned_bin_size(n);
36
37 if (size > modulus_len) {
38 return CRYPT_BUFFER_OVERFLOW;
39 }
40
41 /* store it */
42 zeromem(out, modulus_len);
43 return mp_to_unsigned_bin(n, out+(modulus_len-size));
44 }
45
46 #endif /* PKCS_1 */
47
48
49 /* $Source: /cvs/libtom/libtomcrypt/src/pk/pkcs1/pkcs_1_i2osp.c,v $ */
50 /* $Revision: 1.5 $ */
51 /* $Date: 2006/03/31 14:15:35 $ */
52