#include "ssh.h"
#include "misc.h"
-#define GET_32BIT(cp) \
- (((unsigned long)(unsigned char)(cp)[0] << 24) | \
- ((unsigned long)(unsigned char)(cp)[1] << 16) | \
- ((unsigned long)(unsigned char)(cp)[2] << 8) | \
- ((unsigned long)(unsigned char)(cp)[3]))
-
-#define PUT_32BIT(cp, value) { \
- (cp)[0] = (unsigned char)((value) >> 24); \
- (cp)[1] = (unsigned char)((value) >> 16); \
- (cp)[2] = (unsigned char)((value) >> 8); \
- (cp)[3] = (unsigned char)(value); }
-
-int makekey(unsigned char *data, struct RSAKey *result,
+int makekey(unsigned char *data, int len, struct RSAKey *result,
unsigned char **keystr, int order)
{
unsigned char *p = data;
- int i;
+ int i, n;
+
+ if (len < 4)
+ return -1;
if (result) {
result->bits = 0;
} else
p += 4;
+ len -= 4;
+
/*
* order=0 means exponent then modulus (the keys sent by the
* server). order=1 means modulus then exponent (the keys
* stored in a keyfile).
*/
- if (order == 0)
- p += ssh1_read_bignum(p, result ? &result->exponent : NULL);
+ if (order == 0) {
+ n = ssh1_read_bignum(p, len, result ? &result->exponent : NULL);
+ if (n < 0) return -1;
+ p += n;
+ len -= n;
+ }
+
+ n = ssh1_read_bignum(p, len, result ? &result->modulus : NULL);
+ if (n < 0 || (result && bignum_bitcount(result->modulus) == 0)) return -1;
if (result)
- result->bytes = (((p[0] << 8) + p[1]) + 7) / 8;
+ result->bytes = n - 2;
if (keystr)
*keystr = p + 2;
- p += ssh1_read_bignum(p, result ? &result->modulus : NULL);
- if (order == 1)
- p += ssh1_read_bignum(p, result ? &result->exponent : NULL);
-
+ p += n;
+ len -= n;
+
+ if (order == 1) {
+ n = ssh1_read_bignum(p, len, result ? &result->exponent : NULL);
+ if (n < 0) return -1;
+ p += n;
+ len -= n;
+ }
return p - data;
}
-int makeprivate(unsigned char *data, struct RSAKey *result)
+int makeprivate(unsigned char *data, int len, struct RSAKey *result)
{
- return ssh1_read_bignum(data, &result->private_exponent);
+ return ssh1_read_bignum(data, len, &result->private_exponent);
}
-void rsaencrypt(unsigned char *data, int length, struct RSAKey *key)
+int rsaencrypt(unsigned char *data, int length, struct RSAKey *key)
{
Bignum b1, b2;
int i;
unsigned char *p;
+ if (key->bytes < length + 4)
+ return 0; /* RSA key too short! */
+
memmove(data + key->bytes - length, data, length);
data[0] = 0;
data[1] = 2;
freebn(b1);
freebn(b2);
+
+ return 1;
}
static void sha512_mpint(SHA512_State * s, Bignum b)
/*
* Ensure p > q.
+ *
+ * I have seen key blobs in the wild which were generated with
+ * p < q, so instead of rejecting the key in this case we
+ * should instead flip them round into the canonical order of
+ * p > q. This also involves regenerating iqmp.
*/
- if (bignum_cmp(key->p, key->q) <= 0)
- return 0;
+ if (bignum_cmp(key->p, key->q) <= 0) {
+ Bignum tmp = key->p;
+ key->p = key->q;
+ key->q = tmp;
+
+ freebn(key->iqmp);
+ key->iqmp = modinv(key->q, key->p);
+ }
/*
* Ensure iqmp * q is congruent to 1, modulo p.
}
/* Given a public blob, determine its length. */
-int rsa_public_blob_len(void *data)
+int rsa_public_blob_len(void *data, int maxlen)
{
unsigned char *p = (unsigned char *)data;
+ int n;
+ if (maxlen < 4)
+ return -1;
p += 4; /* length word */
- p += ssh1_read_bignum(p, NULL); /* exponent */
- p += ssh1_read_bignum(p, NULL); /* modulus */
+ maxlen -= 4;
+
+ n = ssh1_read_bignum(p, maxlen, NULL); /* exponent */
+ if (n < 0)
+ return -1;
+ p += n;
+
+ n = ssh1_read_bignum(p, maxlen, NULL); /* modulus */
+ if (n < 0)
+ return -1;
+ p += n;
return p - (unsigned char *)data;
}
freebn(key->exponent);
if (key->private_exponent)
freebn(key->private_exponent);
+ if (key->p)
+ freebn(key->p);
+ if (key->q)
+ freebn(key->q);
+ if (key->iqmp)
+ freebn(key->iqmp);
if (key->comment)
sfree(key->comment);
}
rsa->exponent = getmp(&data, &len);
rsa->modulus = getmp(&data, &len);
rsa->private_exponent = NULL;
+ rsa->p = rsa->q = rsa->iqmp = NULL;
rsa->comment = NULL;
return rsa;
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;
"ssh-rsa",
"rsa2"
};
+
+void *ssh_rsakex_newkey(char *data, int len)
+{
+ return rsa2_newkey(data, len);
+}
+
+void ssh_rsakex_freekey(void *key)
+{
+ rsa2_freekey(key);
+}
+
+int ssh_rsakex_klen(void *key)
+{
+ struct RSAKey *rsa = (struct RSAKey *) key;
+
+ return bignum_bitcount(rsa->modulus);
+}
+
+static void oaep_mask(const struct ssh_hash *h, void *seed, int seedlen,
+ void *vdata, int datalen)
+{
+ unsigned char *data = (unsigned char *)vdata;
+ unsigned count = 0;
+
+ while (datalen > 0) {
+ int i, max = (datalen > h->hlen ? h->hlen : datalen);
+ void *s;
+ unsigned char counter[4], hash[SSH2_KEX_MAX_HASH_LEN];
+
+ assert(h->hlen <= SSH2_KEX_MAX_HASH_LEN);
+ PUT_32BIT(counter, count);
+ s = h->init();
+ h->bytes(s, seed, seedlen);
+ h->bytes(s, counter, 4);
+ h->final(s, hash);
+ count++;
+
+ for (i = 0; i < max; i++)
+ data[i] ^= hash[i];
+
+ data += max;
+ datalen -= max;
+ }
+}
+
+void ssh_rsakex_encrypt(const struct ssh_hash *h, unsigned char *in, int inlen,
+ unsigned char *out, int outlen,
+ void *key)
+{
+ Bignum b1, b2;
+ struct RSAKey *rsa = (struct RSAKey *) key;
+ int k, i;
+ char *p;
+ const int HLEN = h->hlen;
+
+ /*
+ * Here we encrypt using RSAES-OAEP. Essentially this means:
+ *
+ * - we have a SHA-based `mask generation function' which
+ * creates a pseudo-random stream of mask data
+ * deterministically from an input chunk of data.
+ *
+ * - we have a random chunk of data called a seed.
+ *
+ * - we use the seed to generate a mask which we XOR with our
+ * plaintext.
+ *
+ * - then we use _the masked plaintext_ to generate a mask
+ * which we XOR with the seed.
+ *
+ * - then we concatenate the masked seed and the masked
+ * plaintext, and RSA-encrypt that lot.
+ *
+ * The result is that the data input to the encryption function
+ * is random-looking and (hopefully) contains no exploitable
+ * structure such as PKCS1-v1_5 does.
+ *
+ * For a precise specification, see RFC 3447, section 7.1.1.
+ * Some of the variable names below are derived from that, so
+ * it'd probably help to read it anyway.
+ */
+
+ /* k denotes the length in octets of the RSA modulus. */
+ k = (7 + bignum_bitcount(rsa->modulus)) / 8;
+
+ /* The length of the input data must be at most k - 2hLen - 2. */
+ assert(inlen > 0 && inlen <= k - 2*HLEN - 2);
+
+ /* The length of the output data wants to be precisely k. */
+ assert(outlen == k);
+
+ /*
+ * Now perform EME-OAEP encoding. First set up all the unmasked
+ * output data.
+ */
+ /* Leading byte zero. */
+ out[0] = 0;
+ /* At position 1, the seed: HLEN bytes of random data. */
+ for (i = 0; i < HLEN; i++)
+ out[i + 1] = random_byte();
+ /* At position 1+HLEN, the data block DB, consisting of: */
+ /* The hash of the label (we only support an empty label here) */
+ h->final(h->init(), out + HLEN + 1);
+ /* A bunch of zero octets */
+ memset(out + 2*HLEN + 1, 0, outlen - (2*HLEN + 1));
+ /* A single 1 octet, followed by the input message data. */
+ out[outlen - inlen - 1] = 1;
+ memcpy(out + outlen - inlen, in, inlen);
+
+ /*
+ * Now use the seed data to mask the block DB.
+ */
+ oaep_mask(h, out+1, HLEN, out+HLEN+1, outlen-HLEN-1);
+
+ /*
+ * And now use the masked DB to mask the seed itself.
+ */
+ oaep_mask(h, out+HLEN+1, outlen-HLEN-1, out+1, HLEN);
+
+ /*
+ * Now `out' contains precisely the data we want to
+ * RSA-encrypt.
+ */
+ b1 = bignum_from_bytes(out, outlen);
+ b2 = modpow(b1, rsa->exponent, rsa->modulus);
+ p = (char *)out;
+ for (i = outlen; i--;) {
+ *p++ = bignum_byte(b2, i);
+ }
+ freebn(b1);
+ freebn(b2);
+
+ /*
+ * And we're done.
+ */
+}
+
+static const struct ssh_kex ssh_rsa_kex_sha1 = {
+ "rsa1024-sha1", NULL, KEXTYPE_RSA, NULL, NULL, 0, 0, &ssh_sha1
+};
+
+static const struct ssh_kex ssh_rsa_kex_sha256 = {
+ "rsa2048-sha256", NULL, KEXTYPE_RSA, NULL, NULL, 0, 0, &ssh_sha256
+};
+
+static const struct ssh_kex *const rsa_kex_list[] = {
+ &ssh_rsa_kex_sha256,
+ &ssh_rsa_kex_sha1
+};
+
+const struct ssh_kexes ssh_rsa_kex = {
+ sizeof(rsa_kex_list) / sizeof(*rsa_kex_list),
+ rsa_kex_list
+};
projects / u / mdw / putty / blobdiff