source: trunk/third/moira/util/rsaref/r_dh.c @ 23095

Revision 23095, 4.8 KB checked in by ghudson, 16 years ago (diff)
Import the moira package from SIPB Debathena.
RevLine 
[23095]1/* R_DH.C - Diffie-Hellman routines for RSAREF
2 */
3
4/* Copyright (C) RSA Laboratories, a division of RSA Data Security,
5     Inc., created 1993. All rights reserved.
6 */
7
8#include "global.h"
9#include "rsaref.h"
10#include "r_random.h"
11#include "nn.h"
12#include "prime.h"
13
14/* Generates Diffie-Hellman parameters.
15 */
16int R_GenerateDHParams (params, primeBits, subPrimeBits, randomStruct)
17R_DH_PARAMS *params;                       /* new Diffie-Hellman parameters */
18unsigned int primeBits;                          /* length of prime in bits */
19unsigned int subPrimeBits;                    /* length of subprime in bits */
20R_RANDOM_STRUCT *randomStruct;                          /* random structure */
21{
22  int status;
23  NN_DIGIT g[MAX_NN_DIGITS], p[MAX_NN_DIGITS], q[MAX_NN_DIGITS],
24    t[MAX_NN_DIGITS], u[MAX_NN_DIGITS], v[MAX_NN_DIGITS];
25  unsigned int pDigits;
26
27  pDigits = (primeBits + NN_DIGIT_BITS - 1) / NN_DIGIT_BITS;
28 
29  /* Generate subprime q between 2^(subPrimeBits-1) and
30       2^subPrimeBits-1, searching in steps of 2.
31   */
32  NN_Assign2Exp (t, subPrimeBits-1, pDigits);
33  NN_Assign (u, t, pDigits);
34  NN_ASSIGN_DIGIT (v, 1, pDigits);
35  NN_Sub (v, t, v, pDigits);
36  NN_Add (u, u, v, pDigits);
37  NN_ASSIGN_DIGIT (v, 2, pDigits);
38  if (status = GeneratePrime (q, t, u, v, pDigits, randomStruct))
39    return (status);
40 
41  /* Generate prime p between 2^(primeBits-1) and 2^primeBits-1,
42       searching in steps of 2*q.
43   */
44  NN_Assign2Exp (t, primeBits-1, pDigits);
45  NN_Assign (u, t, pDigits);
46  NN_ASSIGN_DIGIT (v, 1, pDigits);
47  NN_Sub (v, t, v, pDigits);
48  NN_Add (u, u, v, pDigits);
49  NN_LShift (v, q, 1, pDigits);
50  if (status = GeneratePrime (p, t, u, v, pDigits, randomStruct))
51    return (status);
52 
53  /* Generate generator g for subgroup as 2^((p-1)/q) mod p.
54   */
55  NN_ASSIGN_DIGIT (g, 2, pDigits);
56  NN_Div (t, u, p, pDigits, q, pDigits);
57  NN_ModExp (g, g, t, pDigits, p, pDigits);
58
59  params->generatorLen = params->primeLen = DH_PRIME_LEN (primeBits);
60  NN_Encode (params->prime, params->primeLen, p, pDigits);
61  NN_Encode (params->generator, params->generatorLen, g, pDigits);
62
63  return (0);
64}
65
66/* Sets up Diffie-Hellman key agreement. Public value has same length
67   as prime.
68 */
69int R_SetupDHAgreement
70  (publicValue, privateValue, privateValueLen, params, randomStruct)
71unsigned char *publicValue;                             /* new public value */
72unsigned char *privateValue;                           /* new private value */
73unsigned int privateValueLen;                    /* length of private value */
74R_DH_PARAMS *params;                           /* Diffie-Hellman parameters */
75R_RANDOM_STRUCT *randomStruct;                          /* random structure */
76{
77  int status;
78  NN_DIGIT g[MAX_NN_DIGITS], p[MAX_NN_DIGITS], x[MAX_NN_DIGITS],
79    y[MAX_NN_DIGITS];
80  unsigned int pDigits, xDigits;
81
82  NN_Decode (p, MAX_NN_DIGITS, params->prime, params->primeLen);
83  pDigits = NN_Digits (p, MAX_NN_DIGITS);
84  NN_Decode (g, pDigits, params->generator, params->generatorLen);
85
86  /* Generate private value.
87   */
88  if (status = R_GenerateBytes (privateValue, privateValueLen, randomStruct))
89    return (status);
90  NN_Decode (x, pDigits, privateValue, privateValueLen);
91  xDigits = NN_Digits (x, pDigits);
92 
93  /* Compute y = g^x mod p.
94   */
95  NN_ModExp (y, g, x, xDigits, p, pDigits);
96
97  NN_Encode (publicValue, params->primeLen, y, pDigits);
98 
99  /* Zeroize sensitive information.
100   */
101  R_memset ((POINTER)x, 0, sizeof (x));
102
103  return (0);
104}
105
106/* Computes agreed key from the other party's public value, a private
107   value, and Diffie-Hellman parameters. Other public value and
108   agreed-upon key have same length as prime.
109
110   Requires otherPublicValue < prime.
111 */
112int R_ComputeDHAgreedKey
113  (agreedKey, otherPublicValue, privateValue, privateValueLen, params)
114unsigned char *agreedKey;                                 /* new agreed key */
115unsigned char *otherPublicValue;                    /* other's public value */
116unsigned char *privateValue;                               /* private value */
117unsigned int privateValueLen;                    /* length of private value */
118R_DH_PARAMS *params;                           /* Diffie-Hellman parameters */
119{
120  NN_DIGIT p[MAX_NN_DIGITS], x[MAX_NN_DIGITS], y[MAX_NN_DIGITS],
121    z[MAX_NN_DIGITS];
122  unsigned int pDigits, xDigits;
123
124  NN_Decode (p, MAX_NN_DIGITS, params->prime, params->primeLen);
125  pDigits = NN_Digits (p, MAX_NN_DIGITS);
126  NN_Decode (x, pDigits, privateValue, privateValueLen);
127  xDigits = NN_Digits (x, pDigits);
128  NN_Decode (y, pDigits, otherPublicValue, params->primeLen);
129
130  if (NN_Cmp (y, p, pDigits) >= 0)
131    return (RE_DATA);
132 
133  /* Compute z = y^x mod p.
134   */
135  NN_ModExp (z, y, x, xDigits, p, pDigits);
136
137  NN_Encode (agreedKey, params->primeLen, z, pDigits);
138 
139  /* Zeroize sensitive information.
140   */
141  R_memset ((POINTER)x, 0, sizeof (x));
142  R_memset ((POINTER)z, 0, sizeof (z));
143
144  return (0);
145}
Note: See TracBrowser for help on using the repository browser.