| 1 | /* |
| 2 | * RSA implementation just sufficient for ssh client-side |
| 3 | * initialisation step |
| 4 | * |
| 5 | * Rewritten for more speed by Joris van Rantwijk, Jun 1999. |
| 6 | */ |
| 7 | |
| 8 | #include <stdio.h> |
| 9 | #include <stdlib.h> |
| 10 | #include <string.h> |
| 11 | |
| 12 | #if defined TESTMODE || defined RSADEBUG |
| 13 | #ifndef DLVL |
| 14 | #define DLVL 10000 |
| 15 | #endif |
| 16 | #define debug(x) bndebug(#x,x) |
| 17 | static int level = 0; |
| 18 | static void bndebug(char *name, Bignum b) { |
| 19 | int i; |
| 20 | int w = 50-level-strlen(name)-5*b[0]; |
| 21 | if (level >= DLVL) |
| 22 | return; |
| 23 | if (w < 0) w = 0; |
| 24 | dprintf("%*s%s%*s", level, "", name, w, ""); |
| 25 | for (i=b[0]; i>0; i--) |
| 26 | dprintf(" %04x", b[i]); |
| 27 | dprintf("\n"); |
| 28 | } |
| 29 | #define dmsg(x) do {if(level<DLVL){dprintf("%*s",level,"");printf x;}} while(0) |
| 30 | #define enter(x) do { dmsg(x); level += 4; } while(0) |
| 31 | #define leave(x) do { level -= 4; dmsg(x); } while(0) |
| 32 | #else |
| 33 | #define debug(x) |
| 34 | #define dmsg(x) |
| 35 | #define enter(x) |
| 36 | #define leave(x) |
| 37 | #endif |
| 38 | |
| 39 | #include "ssh.h" |
| 40 | |
| 41 | int makekey(unsigned char *data, struct RSAKey *result, |
| 42 | unsigned char **keystr, int order) { |
| 43 | unsigned char *p = data; |
| 44 | int i; |
| 45 | |
| 46 | result->bits = 0; |
| 47 | for (i=0; i<4; i++) |
| 48 | result->bits = (result->bits << 8) + *p++; |
| 49 | |
| 50 | /* |
| 51 | * order=0 means exponent then modulus (the keys sent by the |
| 52 | * server). order=1 means modulus then exponent (the keys |
| 53 | * stored in a keyfile). |
| 54 | */ |
| 55 | |
| 56 | if (order == 0) |
| 57 | p += ssh1_read_bignum(p, &result->exponent); |
| 58 | result->bytes = (((p[0] << 8) + p[1]) + 7) / 8; |
| 59 | if (keystr) *keystr = p+2; |
| 60 | p += ssh1_read_bignum(p, &result->modulus); |
| 61 | if (order == 1) |
| 62 | p += ssh1_read_bignum(p, &result->exponent); |
| 63 | |
| 64 | return p - data; |
| 65 | } |
| 66 | |
| 67 | int makeprivate(unsigned char *data, struct RSAKey *result) { |
| 68 | return ssh1_read_bignum(data, &result->private_exponent); |
| 69 | } |
| 70 | |
| 71 | void rsaencrypt(unsigned char *data, int length, struct RSAKey *key) { |
| 72 | Bignum b1, b2; |
| 73 | int w, i; |
| 74 | unsigned char *p; |
| 75 | |
| 76 | debug(key->exponent); |
| 77 | |
| 78 | memmove(data+key->bytes-length, data, length); |
| 79 | data[0] = 0; |
| 80 | data[1] = 2; |
| 81 | |
| 82 | for (i = 2; i < key->bytes-length-1; i++) { |
| 83 | do { |
| 84 | data[i] = random_byte(); |
| 85 | } while (data[i] == 0); |
| 86 | } |
| 87 | data[key->bytes-length-1] = 0; |
| 88 | |
| 89 | w = (key->bytes+1)/2; |
| 90 | |
| 91 | b1 = newbn(w); |
| 92 | b2 = newbn(w); |
| 93 | |
| 94 | p = data; |
| 95 | for (i=1; i<=w; i++) |
| 96 | b1[i] = 0; |
| 97 | for (i=key->bytes; i-- ;) { |
| 98 | unsigned char byte = *p++; |
| 99 | if (i & 1) |
| 100 | b1[1+i/2] |= byte<<8; |
| 101 | else |
| 102 | b1[1+i/2] |= byte; |
| 103 | } |
| 104 | |
| 105 | debug(b1); |
| 106 | |
| 107 | modpow(b1, key->exponent, key->modulus, b2); |
| 108 | |
| 109 | debug(b2); |
| 110 | |
| 111 | p = data; |
| 112 | for (i=key->bytes; i-- ;) { |
| 113 | unsigned char b; |
| 114 | if (i & 1) |
| 115 | b = b2[1+i/2] >> 8; |
| 116 | else |
| 117 | b = b2[1+i/2] & 0xFF; |
| 118 | *p++ = b; |
| 119 | } |
| 120 | |
| 121 | freebn(b1); |
| 122 | freebn(b2); |
| 123 | } |
| 124 | |
| 125 | Bignum rsadecrypt(Bignum input, struct RSAKey *key) { |
| 126 | Bignum ret; |
| 127 | ret = newbn(key->modulus[0]); |
| 128 | modpow(input, key->private_exponent, key->modulus, ret); |
| 129 | return ret; |
| 130 | } |
| 131 | |
| 132 | int rsastr_len(struct RSAKey *key) { |
| 133 | Bignum md, ex; |
| 134 | |
| 135 | md = key->modulus; |
| 136 | ex = key->exponent; |
| 137 | return 4 * (ex[0]+md[0]) + 10; |
| 138 | } |
| 139 | |
| 140 | void rsastr_fmt(char *str, struct RSAKey *key) { |
| 141 | Bignum md, ex; |
| 142 | int len = 0, i; |
| 143 | |
| 144 | md = key->modulus; |
| 145 | ex = key->exponent; |
| 146 | |
| 147 | for (i=1; i<=ex[0]; i++) { |
| 148 | sprintf(str+len, "%04x", ex[i]); |
| 149 | len += strlen(str+len); |
| 150 | } |
| 151 | str[len++] = '/'; |
| 152 | for (i=1; i<=md[0]; i++) { |
| 153 | sprintf(str+len, "%04x", md[i]); |
| 154 | len += strlen(str+len); |
| 155 | } |
| 156 | str[len] = '\0'; |
| 157 | } |
| 158 | |
| 159 | #ifdef TESTMODE |
| 160 | |
| 161 | #ifndef NODDY |
| 162 | #define p1 10007 |
| 163 | #define p2 10069 |
| 164 | #define p3 10177 |
| 165 | #else |
| 166 | #define p1 3 |
| 167 | #define p2 7 |
| 168 | #define p3 13 |
| 169 | #endif |
| 170 | |
| 171 | unsigned short P1[2] = { 1, p1 }; |
| 172 | unsigned short P2[2] = { 1, p2 }; |
| 173 | unsigned short P3[2] = { 1, p3 }; |
| 174 | unsigned short bigmod[5] = { 4, 0, 0, 0, 32768U }; |
| 175 | unsigned short mod[5] = { 4, 0, 0, 0, 0 }; |
| 176 | unsigned short a[5] = { 4, 0, 0, 0, 0 }; |
| 177 | unsigned short b[5] = { 4, 0, 0, 0, 0 }; |
| 178 | unsigned short c[5] = { 4, 0, 0, 0, 0 }; |
| 179 | unsigned short One[2] = { 1, 1 }; |
| 180 | unsigned short Two[2] = { 1, 2 }; |
| 181 | |
| 182 | int main(void) { |
| 183 | modmult(P1, P2, bigmod, a); debug(a); |
| 184 | modmult(a, P3, bigmod, mod); debug(mod); |
| 185 | |
| 186 | sub(P1, One, a); debug(a); |
| 187 | sub(P2, One, b); debug(b); |
| 188 | modmult(a, b, bigmod, c); debug(c); |
| 189 | sub(P3, One, a); debug(a); |
| 190 | modmult(a, c, bigmod, b); debug(b); |
| 191 | |
| 192 | modpow(Two, b, mod, a); debug(a); |
| 193 | |
| 194 | return 0; |
| 195 | } |
| 196 | |
| 197 | #endif |