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Rewrite SSH-1 RSA handling functions using BinarySource.

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The SSH-1 RSA key reading functions now have BinarySource-shaped get_*
forms, although for the moment I'm still supporting the old API as a
wrapper on the new one, because I haven't switched over the client
code yet. Also, rsa_public_blob_len uses the new system internally,
although its API is unchanged.
This commit is contained in:
Simon Tatham 2018-05-27 21:51:36 +01:00
parent 005ca6b257
commit 7d8312e71f
3 changed files with 82 additions and 51 deletions
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4
marshal.h
View File

@ -243,6 +243,10 @@ struct BinarySource {
BinarySource_get_mp_ssh1(BinarySource_UPCAST(src))
#define get_mp_ssh2(src) \
BinarySource_get_mp_ssh2(BinarySource_UPCAST(src))
#define get_rsa_ssh1_pub(src, rsa, keystr, order) \
BinarySource_get_rsa_ssh1_pub(BinarySource_UPCAST(src), rsa, keystr, order)
#define get_rsa_ssh1_priv(src, rsa) \
BinarySource_get_rsa_ssh1_priv(BinarySource_UPCAST(src), rsa)
#define get_err(src) (BinarySource_UPCAST(src)->err)
#define get_avail(src) (BinarySource_UPCAST(src)->len - \

5
ssh.h
View File

@ -182,8 +182,13 @@ typedef enum { RSA_SSH1_EXPONENT_FIRST, RSA_SSH1_MODULUS_FIRST } RsaSsh1Order;
int rsa_ssh1_readpub(const unsigned char *data, int len, struct RSAKey *result,
const unsigned char **keystr, RsaSsh1Order order);
void BinarySource_get_rsa_ssh1_pub(
BinarySource *src, struct RSAKey *result,
ptrlen *keystr, RsaSsh1Order order);
int rsa_ssh1_readpriv(const unsigned char *data, int len,
struct RSAKey *result);
void BinarySource_get_rsa_ssh1_priv(
BinarySource *src, struct RSAKey *rsa);
int rsa_ssh1_encrypt(unsigned char *data, int length, struct RSAKey *key);
Bignum rsa_ssh1_decrypt(Bignum input, struct RSAKey *key);
void rsasanitise(struct RSAKey *key);

124
sshrsa.c
View File

@ -10,53 +10,79 @@
#include "ssh.h"
#include "misc.h"
void BinarySource_get_rsa_ssh1_pub(
BinarySource *src, struct RSAKey *rsa, ptrlen *keystr, RsaSsh1Order order)
{
const unsigned char *start, *end;
unsigned bits;
Bignum e, m;
bits = get_uint32(src);
if (order == RSA_SSH1_EXPONENT_FIRST) {
e = get_mp_ssh1(src);
start = get_ptr(src);
m = get_mp_ssh1(src);
end = get_ptr(src);
} else {
start = get_ptr(src);
m = get_mp_ssh1(src);
end = get_ptr(src);
e = get_mp_ssh1(src);
}
if (keystr) {
start += (end-start >= 2 ? 2 : end-start);
keystr->ptr = start;
keystr->len = end - start;
}
if (rsa) {
rsa->bits = bits;
rsa->exponent = e;
rsa->modulus = m;
rsa->bytes = (bignum_bitcount(m) + 7) / 8;
} else {
freebn(e);
freebn(m);
}
}
int rsa_ssh1_readpub(const unsigned char *data, int len, struct RSAKey *result,
const unsigned char **keystr, RsaSsh1Order order)
{
const unsigned char *p = data;
int i, n;
BinarySource src;
ptrlen key_pl;
if (len < 4)
return -1;
BinarySource_BARE_INIT(&src, data, len);
get_rsa_ssh1_pub(&src, result, &key_pl, order);
if (result) {
result->bits = 0;
for (i = 0; i < 4; i++)
result->bits = (result->bits << 8) + *p++;
} else
p += 4;
len -= 4;
if (order == RSA_SSH1_EXPONENT_FIRST) {
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 = n - 2;
if (keystr)
*keystr = p + 2;
p += n;
len -= n;
*keystr = key_pl.ptr;
if (order == RSA_SSH1_MODULUS_FIRST) {
n = ssh1_read_bignum(p, len, result ? &result->exponent : NULL);
if (n < 0) return -1;
p += n;
len -= n;
}
return p - data;
if (get_err(&src))
return -1;
else
return key_pl.len;
}
void BinarySource_get_rsa_ssh1_priv(
BinarySource *src, struct RSAKey *rsa)
{
rsa->private_exponent = get_mp_ssh1(src);
}
int rsa_ssh1_readpriv(const unsigned char *data, int len,
struct RSAKey *result)
{
return ssh1_read_bignum(data, len, &result->private_exponent);
BinarySource src;
BinarySource_BARE_INIT(&src, data, len);
get_rsa_ssh1_priv(&src, result);
if (get_err(&src))
return -1;
else
return src.pos;
}
int rsa_ssh1_encrypt(unsigned char *data, int length, struct RSAKey *key)
@ -455,25 +481,21 @@ void rsa_ssh1_public_blob(BinarySink *bs, struct RSAKey *key,
/* Given a public blob, determine its length. */
int rsa_public_blob_len(void *data, int maxlen)
{
unsigned char *p = (unsigned char *)data;
int n;
BinarySource src[1];
if (maxlen < 4)
BinarySource_BARE_INIT(src, data, maxlen);
/* Expect a length word, then exponent and modulus. (It doesn't
* even matter which order.) */
get_uint32(src);
freebn(get_mp_ssh1(src));
freebn(get_mp_ssh1(src));
if (get_err(src))
return -1;
p += 4; /* length word */
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;
/* Return the number of bytes consumed. */
return src->pos;
}
void freersakey(struct RSAKey *key)