#include <stdio.h>
#include <stdlib.h>
#include <string.h>
+#include <assert.h>
#include "ssh.h"
int makekey(unsigned char *data, struct RSAKey *result,
- unsigned char **keystr, int order) {
+ unsigned char **keystr, int order)
+{
unsigned char *p = data;
int i;
if (result) {
- result->bits = 0;
- for (i=0; i<4; i++)
- result->bits = (result->bits << 8) + *p++;
+ result->bits = 0;
+ for (i = 0; i < 4; i++)
+ result->bits = (result->bits << 8) + *p++;
} else
- p += 4;
+ p += 4;
/*
* order=0 means exponent then modulus (the keys sent by the
*/
if (order == 0)
- p += ssh1_read_bignum(p, result ? &result->exponent : NULL);
+ p += ssh1_read_bignum(p, result ? &result->exponent : NULL);
if (result)
- result->bytes = (((p[0] << 8) + p[1]) + 7) / 8;
- if (keystr) *keystr = p+2;
+ result->bytes = (((p[0] << 8) + p[1]) + 7) / 8;
+ 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 += ssh1_read_bignum(p, result ? &result->exponent : NULL);
return p - data;
}
-int makeprivate(unsigned char *data, struct RSAKey *result) {
+int makeprivate(unsigned char *data, struct RSAKey *result)
+{
return ssh1_read_bignum(data, &result->private_exponent);
}
-void rsaencrypt(unsigned char *data, int length, struct RSAKey *key) {
+void rsaencrypt(unsigned char *data, int length, struct RSAKey *key)
+{
Bignum b1, b2;
- int w, i;
+ int i;
unsigned char *p;
- memmove(data+key->bytes-length, data, length);
+ memmove(data + key->bytes - length, data, length);
data[0] = 0;
data[1] = 2;
- for (i = 2; i < key->bytes-length-1; i++) {
+ 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);
+ data[key->bytes - length - 1] = 0;
- 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;
- }
+ b1 = bignum_from_bytes(data, key->bytes);
b2 = modpow(b1, key->exponent, key->modulus);
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;
+ for (i = key->bytes; i--;) {
+ *p++ = bignum_byte(b2, i);
}
freebn(b1);
freebn(b2);
}
-Bignum rsadecrypt(Bignum input, struct RSAKey *key) {
+Bignum rsadecrypt(Bignum input, struct RSAKey *key)
+{
Bignum ret;
ret = modpow(input, key->private_exponent, key->modulus);
return ret;
}
-int rsastr_len(struct RSAKey *key) {
+int rsastr_len(struct RSAKey *key)
+{
Bignum md, ex;
+ int mdlen, exlen;
md = key->modulus;
ex = key->exponent;
- return 4 * (ex[0]+md[0]) + 20;
+ mdlen = (bignum_bitcount(md) + 15) / 16;
+ exlen = (bignum_bitcount(ex) + 15) / 16;
+ return 4 * (mdlen + exlen) + 20;
}
-void rsastr_fmt(char *str, struct RSAKey *key) {
+void rsastr_fmt(char *str, struct RSAKey *key)
+{
Bignum md, ex;
int len = 0, i, nibbles;
static const char hex[] = "0123456789abcdef";
md = key->modulus;
ex = key->exponent;
- len += sprintf(str+len, "0x");
+ len += sprintf(str + len, "0x");
- nibbles = (3 + ssh1_bignum_bitcount(ex))/4; if (nibbles<1) nibbles=1;
- for (i=nibbles; i-- ;)
- str[len++] = hex[(bignum_byte(ex, i/2) >> (4*(i%2))) & 0xF];
+ nibbles = (3 + bignum_bitcount(ex)) / 4;
+ if (nibbles < 1)
+ nibbles = 1;
+ for (i = nibbles; i--;)
+ str[len++] = hex[(bignum_byte(ex, i / 2) >> (4 * (i % 2))) & 0xF];
- len += sprintf(str+len, ",0x");
+ len += sprintf(str + len, ",0x");
- nibbles = (3 + ssh1_bignum_bitcount(md))/4; if (nibbles<1) nibbles=1;
- for (i=nibbles; i-- ;)
- str[len++] = hex[(bignum_byte(md, i/2) >> (4*(i%2))) & 0xF];
+ nibbles = (3 + bignum_bitcount(md)) / 4;
+ if (nibbles < 1)
+ nibbles = 1;
+ for (i = nibbles; i--;)
+ str[len++] = hex[(bignum_byte(md, i / 2) >> (4 * (i % 2))) & 0xF];
str[len] = '\0';
}
* Generate a fingerprint string for the key. Compatible with the
* OpenSSH fingerprint code.
*/
-void rsa_fingerprint(char *str, int len, struct RSAKey *key) {
+void rsa_fingerprint(char *str, int len, struct RSAKey *key)
+{
struct MD5Context md5c;
unsigned char digest[16];
- char buffer[16*3+40];
+ char buffer[16 * 3 + 40];
int numlen, slen, i;
MD5Init(&md5c);
numlen = ssh1_bignum_length(key->modulus) - 2;
- for (i = numlen; i-- ;) {
- unsigned char c = bignum_byte(key->modulus, i);
- MD5Update(&md5c, &c, 1);
+ for (i = numlen; i--;) {
+ unsigned char c = bignum_byte(key->modulus, i);
+ MD5Update(&md5c, &c, 1);
}
numlen = ssh1_bignum_length(key->exponent) - 2;
- for (i = numlen; i-- ;) {
- unsigned char c = bignum_byte(key->exponent, i);
- MD5Update(&md5c, &c, 1);
+ for (i = numlen; i--;) {
+ unsigned char c = bignum_byte(key->exponent, i);
+ MD5Update(&md5c, &c, 1);
}
MD5Final(digest, &md5c);
- sprintf(buffer, "%d ", ssh1_bignum_bitcount(key->modulus));
+ sprintf(buffer, "%d ", bignum_bitcount(key->modulus));
for (i = 0; i < 16; i++)
- sprintf(buffer+strlen(buffer), "%s%02x", i?":":"", digest[i]);
- strncpy(str, buffer, len); str[len-1] = '\0';
+ sprintf(buffer + strlen(buffer), "%s%02x", i ? ":" : "",
+ digest[i]);
+ strncpy(str, buffer, len);
+ str[len - 1] = '\0';
slen = strlen(str);
- if (key->comment && slen < len-1) {
- str[slen] = ' ';
- strncpy(str+slen+1, key->comment, len-slen-1);
- str[len-1] = '\0';
+ if (key->comment && slen < len - 1) {
+ str[slen] = ' ';
+ strncpy(str + slen + 1, key->comment, len - slen - 1);
+ str[len - 1] = '\0';
+ }
+}
+
+/*
+ * Verify that the public data in an RSA key matches the private
+ * data. We also check the private data itself: we ensure that p >
+ * q and that iqmp really is the inverse of q mod p.
+ */
+int rsa_verify(struct RSAKey *key)
+{
+ Bignum n, ed, pm1, qm1;
+ int cmp;
+
+ /* n must equal pq. */
+ n = bigmul(key->p, key->q);
+ cmp = bignum_cmp(n, key->modulus);
+ freebn(n);
+ if (cmp != 0)
+ return 0;
+
+ /* e * d must be congruent to 1, modulo (p-1) and modulo (q-1). */
+ pm1 = copybn(key->p);
+ decbn(pm1);
+ ed = modmul(key->exponent, key->private_exponent, pm1);
+ cmp = bignum_cmp(ed, One);
+ sfree(ed);
+ if (cmp != 0)
+ return 0;
+
+ qm1 = copybn(key->q);
+ decbn(qm1);
+ ed = modmul(key->exponent, key->private_exponent, qm1);
+ cmp = bignum_cmp(ed, One);
+ sfree(ed);
+ if (cmp != 0)
+ return 0;
+
+ /*
+ * Ensure p > q.
+ */
+ if (bignum_cmp(key->p, key->q) <= 0)
+ return 0;
+
+ /*
+ * Ensure iqmp * q is congruent to 1, modulo p.
+ */
+ n = modmul(key->iqmp, key->q, key->p);
+ cmp = bignum_cmp(n, One);
+ sfree(n);
+ if (cmp != 0)
+ return 0;
+
+ return 1;
+}
+
+void freersakey(struct RSAKey *key)
+{
+ if (key->modulus)
+ freebn(key->modulus);
+ if (key->exponent)
+ freebn(key->exponent);
+ if (key->private_exponent)
+ freebn(key->private_exponent);
+ if (key->comment)
+ sfree(key->comment);
+}
+
+/* ----------------------------------------------------------------------
+ * Implementation of the ssh-rsa signing key type.
+ */
+
+#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); }
+
+static void getstring(char **data, int *datalen, char **p, int *length)
+{
+ *p = NULL;
+ if (*datalen < 4)
+ return;
+ *length = GET_32BIT(*data);
+ *datalen -= 4;
+ *data += 4;
+ if (*datalen < *length)
+ return;
+ *p = *data;
+ *data += *length;
+ *datalen -= *length;
+}
+static Bignum getmp(char **data, int *datalen)
+{
+ char *p;
+ int length;
+ Bignum b;
+
+ getstring(data, datalen, &p, &length);
+ if (!p)
+ return NULL;
+ b = bignum_from_bytes(p, length);
+ return b;
+}
+
+static void *rsa2_newkey(char *data, int len)
+{
+ char *p;
+ int slen;
+ struct RSAKey *rsa;
+
+ rsa = smalloc(sizeof(struct RSAKey));
+ if (!rsa)
+ return NULL;
+ getstring(&data, &len, &p, &slen);
+
+ if (!p || slen != 7 || memcmp(p, "ssh-rsa", 7)) {
+ sfree(rsa);
+ return NULL;
+ }
+ rsa->exponent = getmp(&data, &len);
+ rsa->modulus = getmp(&data, &len);
+ rsa->private_exponent = NULL;
+ rsa->comment = NULL;
+
+ return rsa;
+}
+
+static void rsa2_freekey(void *key)
+{
+ struct RSAKey *rsa = (struct RSAKey *) key;
+ freersakey(rsa);
+ sfree(rsa);
+}
+
+static char *rsa2_fmtkey(void *key)
+{
+ struct RSAKey *rsa = (struct RSAKey *) key;
+ char *p;
+ int len;
+
+ len = rsastr_len(rsa);
+ p = smalloc(len);
+ rsastr_fmt(p, rsa);
+ return p;
+}
+
+static unsigned char *rsa2_public_blob(void *key, int *len)
+{
+ struct RSAKey *rsa = (struct RSAKey *) key;
+ 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 = smalloc(bloblen);
+ 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 = smalloc(bloblen);
+ 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 = smalloc(sizeof(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 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, "\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 = smalloc(strlen(buffer) + 1);
+ 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 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) / 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;
+ }
+
+ return ret;
}
-void freersakey(struct RSAKey *key) {
- if (key->modulus) freebn(key->modulus);
- if (key->exponent) freebn(key->exponent);
- if (key->private_exponent) freebn(key->private_exponent);
- if (key->comment) free(key->comment);
+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;
+ bytes = smalloc(nbytes);
+
+ 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 = modpow(in, rsa->private_exponent, rsa->modulus);
+ freebn(in);
+
+ nbytes = (bignum_bitcount(out) + 7) / 8;
+ bytes = smalloc(4 + 7 + 4 + nbytes);
+ 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_fingerprint,
+ rsa2_verifysig,
+ rsa2_sign,
+ "ssh-rsa",
+ "rsa2"
+};
projects / u / mdw / putty / blobdiff