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comparison libtomcrypt/src/pk/katja/katja_encrypt_key.c @ 382:0cbe8f6dbf9e

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propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f) to branch 'au.asn.ucc.matt.dropbear' (head 02c413252c90e9de8e03d91e9939dde3029f5c0a)
author Matt Johnston <matt@ucc.asn.au>
date Thu, 11 Jan 2007 02:41:05 +0000
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children f849a5ca2efc
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379:b66a00272a90 382:0cbe8f6dbf9e
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, [email protected], http://libtomcrypt.com
10 */
11 #include "tomcrypt.h"
12
13 /**
14 @file katja_encrypt_key.c
15 Katja PKCS-style OAEP encryption, Tom St Denis
16 */
17
18 #ifdef MKAT
19
20 /**
21 (PKCS #1 v2.0) OAEP pad then encrypt
22 @param in The plaintext
23 @param inlen The length of the plaintext (octets)
24 @param out [out] The ciphertext
25 @param outlen [in/out] The max size and resulting size of the ciphertext
26 @param lparam The system "lparam" for the encryption
27 @param lparamlen The length of lparam (octets)
28 @param prng An active PRNG
29 @param prng_idx The index of the desired prng
30 @param hash_idx The index of the desired hash
31 @param key The Katja key to encrypt to
32 @return CRYPT_OK if successful
33 */
34 int katja_encrypt_key(const unsigned char *in, unsigned long inlen,
35 unsigned char *out, unsigned long *outlen,
36 const unsigned char *lparam, unsigned long lparamlen,
37 prng_state *prng, int prng_idx, int hash_idx, katja_key *key)
38 {
39 unsigned long modulus_bitlen, modulus_bytelen, x;
40 int err;
41
42 LTC_ARGCHK(in != NULL);
43 LTC_ARGCHK(out != NULL);
44 LTC_ARGCHK(outlen != NULL);
45 LTC_ARGCHK(key != NULL);
46
47 /* valid prng and hash ? */
48 if ((err = prng_is_valid(prng_idx)) != CRYPT_OK) {
49 return err;
50 }
51 if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) {
52 return err;
53 }
54
55 /* get modulus len in bits */
56 modulus_bitlen = mp_count_bits((key->N));
57
58 /* payload is upto pq, so we know q is 1/3rd the size of N and therefore pq is 2/3th the size */
59 modulus_bitlen = ((modulus_bitlen << 1) / 3);
60
61 /* round down to next byte */
62 modulus_bitlen -= (modulus_bitlen & 7) + 8;
63
64 /* outlen must be at least the size of the modulus */
65 modulus_bytelen = mp_unsigned_bin_size((key->N));
66 if (modulus_bytelen > *outlen) {
67 *outlen = modulus_bytelen;
68 return CRYPT_BUFFER_OVERFLOW;
69 }
70
71 /* OAEP pad the key */
72 x = *outlen;
73 if ((err = pkcs_1_oaep_encode(in, inlen, lparam,
74 lparamlen, modulus_bitlen, prng, prng_idx, hash_idx,
75 out, &x)) != CRYPT_OK) {
76 return err;
77 }
78
79 /* Katja exptmod the OAEP pad */
80 return katja_exptmod(out, x, out, outlen, PK_PUBLIC, key);
81 }
82
83 #endif /* MRSA */
84
85 /* $Source: /cvs/libtom/libtomcrypt/src/pk/katja/katja_encrypt_key.c,v $ */
86 /* $Revision: 1.5 $ */
87 /* $Date: 2006/06/16 21:53:41 $ */