checking in all the old panacean stuff
This commit is contained in:
838
puttysrc/SSHRSA.C
Normal file
838
puttysrc/SSHRSA.C
Normal file
@@ -0,0 +1,838 @@
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/*
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* RSA implementation for PuTTY.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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#include "ssh.h"
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#include "misc.h"
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int makekey(unsigned char *data, int len, struct RSAKey *result,
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unsigned char **keystr, int order)
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{
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unsigned char *p = data;
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int i, n;
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if (len < 4)
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return -1;
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if (result) {
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result->bits = 0;
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for (i = 0; i < 4; i++)
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result->bits = (result->bits << 8) + *p++;
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} else
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p += 4;
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len -= 4;
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/*
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* order=0 means exponent then modulus (the keys sent by the
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* server). order=1 means modulus then exponent (the keys
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* stored in a keyfile).
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*/
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if (order == 0) {
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n = ssh1_read_bignum(p, len, result ? &result->exponent : NULL);
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if (n < 0) return -1;
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p += n;
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len -= n;
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}
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n = ssh1_read_bignum(p, len, result ? &result->modulus : NULL);
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if (n < 0 || (result && bignum_bitcount(result->modulus) == 0)) return -1;
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if (result)
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result->bytes = n - 2;
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if (keystr)
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*keystr = p + 2;
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p += n;
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len -= n;
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if (order == 1) {
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n = ssh1_read_bignum(p, len, result ? &result->exponent : NULL);
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if (n < 0) return -1;
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p += n;
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len -= n;
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}
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return p - data;
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}
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int makeprivate(unsigned char *data, int len, struct RSAKey *result)
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{
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return ssh1_read_bignum(data, len, &result->private_exponent);
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}
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int rsaencrypt(unsigned char *data, int length, struct RSAKey *key)
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{
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Bignum b1, b2;
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int i;
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unsigned char *p;
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if (key->bytes < length + 4)
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return 0; /* RSA key too short! */
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memmove(data + key->bytes - length, data, length);
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data[0] = 0;
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data[1] = 2;
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for (i = 2; i < key->bytes - length - 1; i++) {
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do {
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data[i] = random_byte();
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} while (data[i] == 0);
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}
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data[key->bytes - length - 1] = 0;
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b1 = bignum_from_bytes(data, key->bytes);
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b2 = modpow(b1, key->exponent, key->modulus);
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p = data;
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for (i = key->bytes; i--;) {
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*p++ = bignum_byte(b2, i);
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}
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freebn(b1);
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freebn(b2);
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return 1;
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}
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static void sha512_mpint(SHA512_State * s, Bignum b)
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{
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unsigned char lenbuf[4];
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int len;
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len = (bignum_bitcount(b) + 8) / 8;
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PUT_32BIT(lenbuf, len);
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SHA512_Bytes(s, lenbuf, 4);
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while (len-- > 0) {
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lenbuf[0] = bignum_byte(b, len);
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SHA512_Bytes(s, lenbuf, 1);
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}
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memset(lenbuf, 0, sizeof(lenbuf));
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}
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/*
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* This function is a wrapper on modpow(). It has the same effect
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* as modpow(), but employs RSA blinding to protect against timing
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* attacks.
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*/
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static Bignum rsa_privkey_op(Bignum input, struct RSAKey *key)
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{
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Bignum random, random_encrypted, random_inverse;
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Bignum input_blinded, ret_blinded;
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Bignum ret;
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SHA512_State ss;
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unsigned char digest512[64];
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int digestused = lenof(digest512);
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int hashseq = 0;
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/*
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* Start by inventing a random number chosen uniformly from the
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* range 2..modulus-1. (We do this by preparing a random number
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* of the right length and retrying if it's greater than the
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* modulus, to prevent any potential Bleichenbacher-like
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* attacks making use of the uneven distribution within the
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* range that would arise from just reducing our number mod n.
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* There are timing implications to the potential retries, of
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* course, but all they tell you is the modulus, which you
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* already knew.)
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*
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* To preserve determinism and avoid Pageant needing to share
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* the random number pool, we actually generate this `random'
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* number by hashing stuff with the private key.
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*/
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while (1) {
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int bits, byte, bitsleft, v;
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random = copybn(key->modulus);
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/*
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* Find the topmost set bit. (This function will return its
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* index plus one.) Then we'll set all bits from that one
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* downwards randomly.
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*/
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bits = bignum_bitcount(random);
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byte = 0;
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bitsleft = 0;
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while (bits--) {
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if (bitsleft <= 0) {
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bitsleft = 8;
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/*
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* Conceptually the following few lines are equivalent to
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* byte = random_byte();
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*/
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if (digestused >= lenof(digest512)) {
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unsigned char seqbuf[4];
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PUT_32BIT(seqbuf, hashseq);
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SHA512_Init(&ss);
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SHA512_Bytes(&ss, "RSA deterministic blinding", 26);
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SHA512_Bytes(&ss, seqbuf, sizeof(seqbuf));
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sha512_mpint(&ss, key->private_exponent);
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SHA512_Final(&ss, digest512);
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hashseq++;
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/*
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* Now hash that digest plus the signature
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* input.
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*/
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SHA512_Init(&ss);
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SHA512_Bytes(&ss, digest512, sizeof(digest512));
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sha512_mpint(&ss, input);
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SHA512_Final(&ss, digest512);
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digestused = 0;
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}
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byte = digest512[digestused++];
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}
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v = byte & 1;
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byte >>= 1;
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bitsleft--;
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bignum_set_bit(random, bits, v);
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}
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/*
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* Now check that this number is strictly greater than
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* zero, and strictly less than modulus.
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*/
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if (bignum_cmp(random, Zero) <= 0 ||
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bignum_cmp(random, key->modulus) >= 0) {
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freebn(random);
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continue;
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} else {
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break;
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}
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}
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/*
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* RSA blinding relies on the fact that (xy)^d mod n is equal
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* to (x^d mod n) * (y^d mod n) mod n. We invent a random pair
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* y and y^d; then we multiply x by y, raise to the power d mod
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* n as usual, and divide by y^d to recover x^d. Thus an
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* attacker can't correlate the timing of the modpow with the
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* input, because they don't know anything about the number
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* that was input to the actual modpow.
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*
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* The clever bit is that we don't have to do a huge modpow to
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* get y and y^d; we will use the number we just invented as
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* _y^d_, and use the _public_ exponent to compute (y^d)^e = y
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* from it, which is much faster to do.
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*/
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random_encrypted = modpow(random, key->exponent, key->modulus);
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random_inverse = modinv(random, key->modulus);
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input_blinded = modmul(input, random_encrypted, key->modulus);
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ret_blinded = modpow(input_blinded, key->private_exponent, key->modulus);
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ret = modmul(ret_blinded, random_inverse, key->modulus);
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freebn(ret_blinded);
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freebn(input_blinded);
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freebn(random_inverse);
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freebn(random_encrypted);
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freebn(random);
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return ret;
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}
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Bignum rsadecrypt(Bignum input, struct RSAKey *key)
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{
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return rsa_privkey_op(input, key);
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}
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int rsastr_len(struct RSAKey *key)
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{
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Bignum md, ex;
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int mdlen, exlen;
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md = key->modulus;
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ex = key->exponent;
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mdlen = (bignum_bitcount(md) + 15) / 16;
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exlen = (bignum_bitcount(ex) + 15) / 16;
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return 4 * (mdlen + exlen) + 20;
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}
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void rsastr_fmt(char *str, struct RSAKey *key)
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{
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Bignum md, ex;
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int len = 0, i, nibbles;
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static const char hex[] = "0123456789abcdef";
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md = key->modulus;
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ex = key->exponent;
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len += sprintf(str + len, "0x");
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nibbles = (3 + bignum_bitcount(ex)) / 4;
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if (nibbles < 1)
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nibbles = 1;
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for (i = nibbles; i--;)
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str[len++] = hex[(bignum_byte(ex, i / 2) >> (4 * (i % 2))) & 0xF];
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len += sprintf(str + len, ",0x");
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nibbles = (3 + bignum_bitcount(md)) / 4;
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if (nibbles < 1)
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nibbles = 1;
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for (i = nibbles; i--;)
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str[len++] = hex[(bignum_byte(md, i / 2) >> (4 * (i % 2))) & 0xF];
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str[len] = '\0';
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}
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/*
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* Generate a fingerprint string for the key. Compatible with the
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* OpenSSH fingerprint code.
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*/
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void rsa_fingerprint(char *str, int len, struct RSAKey *key)
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{
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struct MD5Context md5c;
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unsigned char digest[16];
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char buffer[16 * 3 + 40];
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int numlen, slen, i;
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MD5Init(&md5c);
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numlen = ssh1_bignum_length(key->modulus) - 2;
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for (i = numlen; i--;) {
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unsigned char c = bignum_byte(key->modulus, i);
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MD5Update(&md5c, &c, 1);
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}
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numlen = ssh1_bignum_length(key->exponent) - 2;
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for (i = numlen; i--;) {
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unsigned char c = bignum_byte(key->exponent, i);
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MD5Update(&md5c, &c, 1);
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}
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MD5Final(digest, &md5c);
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sprintf(buffer, "%d ", bignum_bitcount(key->modulus));
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for (i = 0; i < 16; i++)
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sprintf(buffer + strlen(buffer), "%s%02x", i ? ":" : "",
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digest[i]);
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strncpy(str, buffer, len);
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str[len - 1] = '\0';
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slen = strlen(str);
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if (key->comment && slen < len - 1) {
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str[slen] = ' ';
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strncpy(str + slen + 1, key->comment, len - slen - 1);
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str[len - 1] = '\0';
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}
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}
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/*
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* Verify that the public data in an RSA key matches the private
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* data. We also check the private data itself: we ensure that p >
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* q and that iqmp really is the inverse of q mod p.
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*/
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int rsa_verify(struct RSAKey *key)
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{
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Bignum n, ed, pm1, qm1;
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int cmp;
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/* n must equal pq. */
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n = bigmul(key->p, key->q);
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cmp = bignum_cmp(n, key->modulus);
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freebn(n);
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if (cmp != 0)
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return 0;
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/* e * d must be congruent to 1, modulo (p-1) and modulo (q-1). */
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pm1 = copybn(key->p);
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decbn(pm1);
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ed = modmul(key->exponent, key->private_exponent, pm1);
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cmp = bignum_cmp(ed, One);
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sfree(ed);
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if (cmp != 0)
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return 0;
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qm1 = copybn(key->q);
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decbn(qm1);
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ed = modmul(key->exponent, key->private_exponent, qm1);
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cmp = bignum_cmp(ed, One);
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sfree(ed);
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if (cmp != 0)
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return 0;
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/*
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* Ensure p > q.
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*/
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if (bignum_cmp(key->p, key->q) <= 0)
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return 0;
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/*
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* Ensure iqmp * q is congruent to 1, modulo p.
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*/
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n = modmul(key->iqmp, key->q, key->p);
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cmp = bignum_cmp(n, One);
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sfree(n);
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if (cmp != 0)
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return 0;
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return 1;
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}
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/* Public key blob as used by Pageant: exponent before modulus. */
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unsigned char *rsa_public_blob(struct RSAKey *key, int *len)
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{
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int length, pos;
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unsigned char *ret;
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length = (ssh1_bignum_length(key->modulus) +
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ssh1_bignum_length(key->exponent) + 4);
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ret = snewn(length, unsigned char);
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PUT_32BIT(ret, bignum_bitcount(key->modulus));
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pos = 4;
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pos += ssh1_write_bignum(ret + pos, key->exponent);
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pos += ssh1_write_bignum(ret + pos, key->modulus);
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*len = length;
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return ret;
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}
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/* Given a public blob, determine its length. */
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int rsa_public_blob_len(void *data, int maxlen)
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{
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unsigned char *p = (unsigned char *)data;
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int n;
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if (maxlen < 4)
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return -1;
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p += 4; /* length word */
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maxlen -= 4;
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n = ssh1_read_bignum(p, maxlen, NULL); /* exponent */
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if (n < 0)
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return -1;
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p += n;
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n = ssh1_read_bignum(p, maxlen, NULL); /* modulus */
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if (n < 0)
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return -1;
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p += n;
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return p - (unsigned char *)data;
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}
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void freersakey(struct RSAKey *key)
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{
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if (key->modulus)
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freebn(key->modulus);
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if (key->exponent)
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freebn(key->exponent);
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if (key->private_exponent)
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freebn(key->private_exponent);
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if (key->comment)
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sfree(key->comment);
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}
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/* ----------------------------------------------------------------------
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* Implementation of the ssh-rsa signing key type.
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*/
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static void getstring(char **data, int *datalen, char **p, int *length)
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{
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*p = NULL;
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if (*datalen < 4)
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return;
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*length = GET_32BIT(*data);
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*datalen -= 4;
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*data += 4;
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if (*datalen < *length)
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return;
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*p = *data;
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*data += *length;
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*datalen -= *length;
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}
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static Bignum getmp(char **data, int *datalen)
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{
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char *p;
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int length;
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Bignum b;
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getstring(data, datalen, &p, &length);
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if (!p)
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return NULL;
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b = bignum_from_bytes((unsigned char *)p, length);
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return b;
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}
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static void *rsa2_newkey(char *data, int len)
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{
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char *p;
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int slen;
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struct RSAKey *rsa;
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rsa = snew(struct RSAKey);
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if (!rsa)
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return NULL;
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getstring(&data, &len, &p, &slen);
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if (!p || slen != 7 || memcmp(p, "ssh-rsa", 7)) {
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sfree(rsa);
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return NULL;
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}
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rsa->exponent = getmp(&data, &len);
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rsa->modulus = getmp(&data, &len);
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rsa->private_exponent = NULL;
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rsa->comment = NULL;
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return rsa;
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}
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static void rsa2_freekey(void *key)
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{
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struct RSAKey *rsa = (struct RSAKey *) key;
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freersakey(rsa);
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sfree(rsa);
|
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}
|
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static char *rsa2_fmtkey(void *key)
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{
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struct RSAKey *rsa = (struct RSAKey *) key;
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char *p;
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int len;
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len = rsastr_len(rsa);
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p = snewn(len, char);
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rsastr_fmt(p, rsa);
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return p;
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}
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||||
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static unsigned char *rsa2_public_blob(void *key, int *len)
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{
|
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struct RSAKey *rsa = (struct RSAKey *) key;
|
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int elen, mlen, bloblen;
|
||||
int i;
|
||||
unsigned char *blob, *p;
|
||||
|
||||
elen = (bignum_bitcount(rsa->exponent) + 8) / 8;
|
||||
mlen = (bignum_bitcount(rsa->modulus) + 8) / 8;
|
||||
|
||||
/*
|
||||
* string "ssh-rsa", mpint exp, mpint mod. Total 19+elen+mlen.
|
||||
* (three length fields, 12+7=19).
|
||||
*/
|
||||
bloblen = 19 + elen + mlen;
|
||||
blob = snewn(bloblen, unsigned char);
|
||||
p = blob;
|
||||
PUT_32BIT(p, 7);
|
||||
p += 4;
|
||||
memcpy(p, "ssh-rsa", 7);
|
||||
p += 7;
|
||||
PUT_32BIT(p, elen);
|
||||
p += 4;
|
||||
for (i = elen; i--;)
|
||||
*p++ = bignum_byte(rsa->exponent, i);
|
||||
PUT_32BIT(p, mlen);
|
||||
p += 4;
|
||||
for (i = mlen; i--;)
|
||||
*p++ = bignum_byte(rsa->modulus, i);
|
||||
assert(p == blob + bloblen);
|
||||
*len = bloblen;
|
||||
return blob;
|
||||
}
|
||||
|
||||
static unsigned char *rsa2_private_blob(void *key, int *len)
|
||||
{
|
||||
struct RSAKey *rsa = (struct RSAKey *) key;
|
||||
int dlen, plen, qlen, ulen, bloblen;
|
||||
int i;
|
||||
unsigned char *blob, *p;
|
||||
|
||||
dlen = (bignum_bitcount(rsa->private_exponent) + 8) / 8;
|
||||
plen = (bignum_bitcount(rsa->p) + 8) / 8;
|
||||
qlen = (bignum_bitcount(rsa->q) + 8) / 8;
|
||||
ulen = (bignum_bitcount(rsa->iqmp) + 8) / 8;
|
||||
|
||||
/*
|
||||
* mpint private_exp, mpint p, mpint q, mpint iqmp. Total 16 +
|
||||
* sum of lengths.
|
||||
*/
|
||||
bloblen = 16 + dlen + plen + qlen + ulen;
|
||||
blob = snewn(bloblen, unsigned char);
|
||||
p = blob;
|
||||
PUT_32BIT(p, dlen);
|
||||
p += 4;
|
||||
for (i = dlen; i--;)
|
||||
*p++ = bignum_byte(rsa->private_exponent, i);
|
||||
PUT_32BIT(p, plen);
|
||||
p += 4;
|
||||
for (i = plen; i--;)
|
||||
*p++ = bignum_byte(rsa->p, i);
|
||||
PUT_32BIT(p, qlen);
|
||||
p += 4;
|
||||
for (i = qlen; i--;)
|
||||
*p++ = bignum_byte(rsa->q, i);
|
||||
PUT_32BIT(p, ulen);
|
||||
p += 4;
|
||||
for (i = ulen; i--;)
|
||||
*p++ = bignum_byte(rsa->iqmp, i);
|
||||
assert(p == blob + bloblen);
|
||||
*len = bloblen;
|
||||
return blob;
|
||||
}
|
||||
|
||||
static void *rsa2_createkey(unsigned char *pub_blob, int pub_len,
|
||||
unsigned char *priv_blob, int priv_len)
|
||||
{
|
||||
struct RSAKey *rsa;
|
||||
char *pb = (char *) priv_blob;
|
||||
|
||||
rsa = rsa2_newkey((char *) pub_blob, pub_len);
|
||||
rsa->private_exponent = getmp(&pb, &priv_len);
|
||||
rsa->p = getmp(&pb, &priv_len);
|
||||
rsa->q = getmp(&pb, &priv_len);
|
||||
rsa->iqmp = getmp(&pb, &priv_len);
|
||||
|
||||
if (!rsa_verify(rsa)) {
|
||||
rsa2_freekey(rsa);
|
||||
return NULL;
|
||||
}
|
||||
|
||||
return rsa;
|
||||
}
|
||||
|
||||
static void *rsa2_openssh_createkey(unsigned char **blob, int *len)
|
||||
{
|
||||
char **b = (char **) blob;
|
||||
struct RSAKey *rsa;
|
||||
|
||||
rsa = snew(struct RSAKey);
|
||||
if (!rsa)
|
||||
return NULL;
|
||||
rsa->comment = NULL;
|
||||
|
||||
rsa->modulus = getmp(b, len);
|
||||
rsa->exponent = getmp(b, len);
|
||||
rsa->private_exponent = getmp(b, len);
|
||||
rsa->iqmp = getmp(b, len);
|
||||
rsa->p = getmp(b, len);
|
||||
rsa->q = getmp(b, len);
|
||||
|
||||
if (!rsa->modulus || !rsa->exponent || !rsa->private_exponent ||
|
||||
!rsa->iqmp || !rsa->p || !rsa->q) {
|
||||
sfree(rsa->modulus);
|
||||
sfree(rsa->exponent);
|
||||
sfree(rsa->private_exponent);
|
||||
sfree(rsa->iqmp);
|
||||
sfree(rsa->p);
|
||||
sfree(rsa->q);
|
||||
sfree(rsa);
|
||||
return NULL;
|
||||
}
|
||||
|
||||
return rsa;
|
||||
}
|
||||
|
||||
static int rsa2_openssh_fmtkey(void *key, unsigned char *blob, int len)
|
||||
{
|
||||
struct RSAKey *rsa = (struct RSAKey *) key;
|
||||
int bloblen, i;
|
||||
|
||||
bloblen =
|
||||
ssh2_bignum_length(rsa->modulus) +
|
||||
ssh2_bignum_length(rsa->exponent) +
|
||||
ssh2_bignum_length(rsa->private_exponent) +
|
||||
ssh2_bignum_length(rsa->iqmp) +
|
||||
ssh2_bignum_length(rsa->p) + ssh2_bignum_length(rsa->q);
|
||||
|
||||
if (bloblen > len)
|
||||
return bloblen;
|
||||
|
||||
bloblen = 0;
|
||||
#define ENC(x) \
|
||||
PUT_32BIT(blob+bloblen, ssh2_bignum_length((x))-4); bloblen += 4; \
|
||||
for (i = ssh2_bignum_length((x))-4; i-- ;) blob[bloblen++]=bignum_byte((x),i);
|
||||
ENC(rsa->modulus);
|
||||
ENC(rsa->exponent);
|
||||
ENC(rsa->private_exponent);
|
||||
ENC(rsa->iqmp);
|
||||
ENC(rsa->p);
|
||||
ENC(rsa->q);
|
||||
|
||||
return bloblen;
|
||||
}
|
||||
|
||||
static int rsa2_pubkey_bits(void *blob, int len)
|
||||
{
|
||||
struct RSAKey *rsa;
|
||||
int ret;
|
||||
|
||||
rsa = rsa2_newkey((char *) blob, len);
|
||||
ret = bignum_bitcount(rsa->modulus);
|
||||
rsa2_freekey(rsa);
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
||||
static char *rsa2_fingerprint(void *key)
|
||||
{
|
||||
struct RSAKey *rsa = (struct RSAKey *) key;
|
||||
struct MD5Context md5c;
|
||||
unsigned char digest[16], lenbuf[4];
|
||||
char buffer[16 * 3 + 40];
|
||||
char *ret;
|
||||
int numlen, i;
|
||||
|
||||
MD5Init(&md5c);
|
||||
MD5Update(&md5c, (unsigned char *)"\0\0\0\7ssh-rsa", 11);
|
||||
|
||||
#define ADD_BIGNUM(bignum) \
|
||||
numlen = (bignum_bitcount(bignum)+8)/8; \
|
||||
PUT_32BIT(lenbuf, numlen); MD5Update(&md5c, lenbuf, 4); \
|
||||
for (i = numlen; i-- ;) { \
|
||||
unsigned char c = bignum_byte(bignum, i); \
|
||||
MD5Update(&md5c, &c, 1); \
|
||||
}
|
||||
ADD_BIGNUM(rsa->exponent);
|
||||
ADD_BIGNUM(rsa->modulus);
|
||||
#undef ADD_BIGNUM
|
||||
|
||||
MD5Final(digest, &md5c);
|
||||
|
||||
sprintf(buffer, "ssh-rsa %d ", bignum_bitcount(rsa->modulus));
|
||||
for (i = 0; i < 16; i++)
|
||||
sprintf(buffer + strlen(buffer), "%s%02x", i ? ":" : "",
|
||||
digest[i]);
|
||||
ret = snewn(strlen(buffer) + 1, char);
|
||||
if (ret)
|
||||
strcpy(ret, buffer);
|
||||
return ret;
|
||||
}
|
||||
|
||||
/*
|
||||
* This is the magic ASN.1/DER prefix that goes in the decoded
|
||||
* signature, between the string of FFs and the actual SHA hash
|
||||
* value. The meaning of it is:
|
||||
*
|
||||
* 00 -- this marks the end of the FFs; not part of the ASN.1 bit itself
|
||||
*
|
||||
* 30 21 -- a constructed SEQUENCE of length 0x21
|
||||
* 30 09 -- a constructed sub-SEQUENCE of length 9
|
||||
* 06 05 -- an object identifier, length 5
|
||||
* 2B 0E 03 02 1A -- object id { 1 3 14 3 2 26 }
|
||||
* (the 1,3 comes from 0x2B = 43 = 40*1+3)
|
||||
* 05 00 -- NULL
|
||||
* 04 14 -- a primitive OCTET STRING of length 0x14
|
||||
* [0x14 bytes of hash data follows]
|
||||
*
|
||||
* The object id in the middle there is listed as `id-sha1' in
|
||||
* ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1d2.asn (the
|
||||
* ASN module for PKCS #1) and its expanded form is as follows:
|
||||
*
|
||||
* id-sha1 OBJECT IDENTIFIER ::= {
|
||||
* iso(1) identified-organization(3) oiw(14) secsig(3)
|
||||
* algorithms(2) 26 }
|
||||
*/
|
||||
static const unsigned char asn1_weird_stuff[] = {
|
||||
0x00, 0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2B,
|
||||
0x0E, 0x03, 0x02, 0x1A, 0x05, 0x00, 0x04, 0x14,
|
||||
};
|
||||
|
||||
#define ASN1_LEN ( (int) sizeof(asn1_weird_stuff) )
|
||||
|
||||
static int rsa2_verifysig(void *key, char *sig, int siglen,
|
||||
char *data, int datalen)
|
||||
{
|
||||
struct RSAKey *rsa = (struct RSAKey *) key;
|
||||
Bignum in, out;
|
||||
char *p;
|
||||
int slen;
|
||||
int bytes, i, j, ret;
|
||||
unsigned char hash[20];
|
||||
|
||||
getstring(&sig, &siglen, &p, &slen);
|
||||
if (!p || slen != 7 || memcmp(p, "ssh-rsa", 7)) {
|
||||
return 0;
|
||||
}
|
||||
in = getmp(&sig, &siglen);
|
||||
out = modpow(in, rsa->exponent, rsa->modulus);
|
||||
freebn(in);
|
||||
|
||||
ret = 1;
|
||||
|
||||
bytes = (bignum_bitcount(rsa->modulus)+7) / 8;
|
||||
/* Top (partial) byte should be zero. */
|
||||
if (bignum_byte(out, bytes - 1) != 0)
|
||||
ret = 0;
|
||||
/* First whole byte should be 1. */
|
||||
if (bignum_byte(out, bytes - 2) != 1)
|
||||
ret = 0;
|
||||
/* Most of the rest should be FF. */
|
||||
for (i = bytes - 3; i >= 20 + ASN1_LEN; i--) {
|
||||
if (bignum_byte(out, i) != 0xFF)
|
||||
ret = 0;
|
||||
}
|
||||
/* Then we expect to see the asn1_weird_stuff. */
|
||||
for (i = 20 + ASN1_LEN - 1, j = 0; i >= 20; i--, j++) {
|
||||
if (bignum_byte(out, i) != asn1_weird_stuff[j])
|
||||
ret = 0;
|
||||
}
|
||||
/* Finally, we expect to see the SHA-1 hash of the signed data. */
|
||||
SHA_Simple(data, datalen, hash);
|
||||
for (i = 19, j = 0; i >= 0; i--, j++) {
|
||||
if (bignum_byte(out, i) != hash[j])
|
||||
ret = 0;
|
||||
}
|
||||
freebn(out);
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
||||
static unsigned char *rsa2_sign(void *key, char *data, int datalen,
|
||||
int *siglen)
|
||||
{
|
||||
struct RSAKey *rsa = (struct RSAKey *) key;
|
||||
unsigned char *bytes;
|
||||
int nbytes;
|
||||
unsigned char hash[20];
|
||||
Bignum in, out;
|
||||
int i, j;
|
||||
|
||||
SHA_Simple(data, datalen, hash);
|
||||
|
||||
nbytes = (bignum_bitcount(rsa->modulus) - 1) / 8;
|
||||
assert(1 <= nbytes - 20 - ASN1_LEN);
|
||||
bytes = snewn(nbytes, unsigned char);
|
||||
|
||||
bytes[0] = 1;
|
||||
for (i = 1; i < nbytes - 20 - ASN1_LEN; i++)
|
||||
bytes[i] = 0xFF;
|
||||
for (i = nbytes - 20 - ASN1_LEN, j = 0; i < nbytes - 20; i++, j++)
|
||||
bytes[i] = asn1_weird_stuff[j];
|
||||
for (i = nbytes - 20, j = 0; i < nbytes; i++, j++)
|
||||
bytes[i] = hash[j];
|
||||
|
||||
in = bignum_from_bytes(bytes, nbytes);
|
||||
sfree(bytes);
|
||||
|
||||
out = rsa_privkey_op(in, rsa);
|
||||
freebn(in);
|
||||
|
||||
nbytes = (bignum_bitcount(out) + 7) / 8;
|
||||
bytes = snewn(4 + 7 + 4 + nbytes, unsigned char);
|
||||
PUT_32BIT(bytes, 7);
|
||||
memcpy(bytes + 4, "ssh-rsa", 7);
|
||||
PUT_32BIT(bytes + 4 + 7, nbytes);
|
||||
for (i = 0; i < nbytes; i++)
|
||||
bytes[4 + 7 + 4 + i] = bignum_byte(out, nbytes - 1 - i);
|
||||
freebn(out);
|
||||
|
||||
*siglen = 4 + 7 + 4 + nbytes;
|
||||
return bytes;
|
||||
}
|
||||
|
||||
const struct ssh_signkey ssh_rsa = {
|
||||
rsa2_newkey,
|
||||
rsa2_freekey,
|
||||
rsa2_fmtkey,
|
||||
rsa2_public_blob,
|
||||
rsa2_private_blob,
|
||||
rsa2_createkey,
|
||||
rsa2_openssh_createkey,
|
||||
rsa2_openssh_fmtkey,
|
||||
rsa2_pubkey_bits,
|
||||
rsa2_fingerprint,
|
||||
rsa2_verifysig,
|
||||
rsa2_sign,
|
||||
"ssh-rsa",
|
||||
"rsa2"
|
||||
};
|
||||
Reference in New Issue
Block a user