/* * RSA implementation just sufficient for ssh client-side * initialisation step * * Rewritten for more speed by Joris van Rantwijk, Jun 1999. */ #include #include #include #if defined TESTMODE || defined RSADEBUG #ifndef DLVL #define DLVL 10000 #endif #define debug(x) bndebug(#x,x) static int level = 0; static void bndebug(char *name, Bignum b) { int i; int w = 50-level-strlen(name)-5*b[0]; if (level >= DLVL) return; if (w < 0) w = 0; dprintf("%*s%s%*s", level, "", name, w, ""); for (i=b[0]; i>0; i--) dprintf(" %04x", b[i]); dprintf("\n"); } #define dmsg(x) do {if(levelbits = 0; for (i=0; i<4; i++) result->bits = (result->bits << 8) + *p++; for (j=0; j<2; j++) { w = 0; for (i=0; i<2; i++) w = (w << 8) + *p++; result->bytes = b = (w+7)/8; /* bits -> bytes */ w = (w+15)/16; /* bits -> words */ bn[j] = newbn(w); if (keystr) *keystr = p; /* point at key string, second time */ for (i=1; i<=w; i++) bn[j][i] = 0; for (i=b; i-- ;) { unsigned char byte = *p++; if (i & 1) bn[j][1+i/2] |= byte<<8; else bn[j][1+i/2] |= byte; } debug(bn[j]); } result->exponent = bn[0]; result->modulus = bn[1]; return p - data; } void rsaencrypt(unsigned char *data, int length, struct RSAKey *key) { Bignum b1, b2; int w, i; unsigned char *p; debug(key->exponent); memmove(data+key->bytes-length, data, length); data[0] = 0; data[1] = 2; for (i = 2; i < key->bytes-length-1; i++) { do { data[i] = random_byte(); } while (data[i] == 0); } data[key->bytes-length-1] = 0; w = (key->bytes+1)/2; b1 = newbn(w); b2 = newbn(w); p = data; for (i=1; i<=w; i++) b1[i] = 0; for (i=key->bytes; i-- ;) { unsigned char byte = *p++; if (i & 1) b1[1+i/2] |= byte<<8; else b1[1+i/2] |= byte; } debug(b1); modpow(b1, key->exponent, key->modulus, b2); debug(b2); p = data; for (i=key->bytes; i-- ;) { unsigned char b; if (i & 1) b = b2[1+i/2] >> 8; else b = b2[1+i/2] & 0xFF; *p++ = b; } freebn(b1); freebn(b2); } int rsastr_len(struct RSAKey *key) { Bignum md, ex; md = key->modulus; ex = key->exponent; return 4 * (ex[0]+md[0]) + 10; } void rsastr_fmt(char *str, struct RSAKey *key) { Bignum md, ex; int len = 0, i; md = key->modulus; ex = key->exponent; for (i=1; i<=ex[0]; i++) { sprintf(str+len, "%04x", ex[i]); len += strlen(str+len); } str[len++] = '/'; for (i=1; i<=md[0]; i++) { sprintf(str+len, "%04x", md[i]); len += strlen(str+len); } str[len] = '\0'; } #ifdef TESTMODE #ifndef NODDY #define p1 10007 #define p2 10069 #define p3 10177 #else #define p1 3 #define p2 7 #define p3 13 #endif unsigned short P1[2] = { 1, p1 }; unsigned short P2[2] = { 1, p2 }; unsigned short P3[2] = { 1, p3 }; unsigned short bigmod[5] = { 4, 0, 0, 0, 32768U }; unsigned short mod[5] = { 4, 0, 0, 0, 0 }; unsigned short a[5] = { 4, 0, 0, 0, 0 }; unsigned short b[5] = { 4, 0, 0, 0, 0 }; unsigned short c[5] = { 4, 0, 0, 0, 0 }; unsigned short One[2] = { 1, 1 }; unsigned short Two[2] = { 1, 2 }; int main(void) { modmult(P1, P2, bigmod, a); debug(a); modmult(a, P3, bigmod, mod); debug(mod); sub(P1, One, a); debug(a); sub(P2, One, b); debug(b); modmult(a, b, bigmod, c); debug(c); sub(P3, One, a); debug(a); modmult(a, c, bigmod, b); debug(b); modpow(Two, b, mod, a); debug(a); return 0; } #endif