Preliminary support for RSA user authentication in SSH2! Most of the

[sgt/putty] / sshmd5.c

diff --git a/sshmd5.c b/sshmd5.c
index 43c274c..2b0d5f5 100644 (file)
--- a/sshmd5.c
+++ b/sshmd5.c
@@ -19,10 +19,6 @@
 #define subround(f,w,x,y,z,k,s,ti) \
        w = x + rol(w + f(x,y,z) + block[k] + ti, s)
 
-typedef struct {
-    uint32 h[4];
-} MD5_Core_State;
-
 void MD5_Core_Init(MD5_Core_State *s) {
     s->h[0] = 0x67452301;
     s->h[1] = 0xefcdab89;
@@ -162,7 +158,7 @@ void MD5Update(struct MD5Context *s, unsigned char const *p,
 
 void MD5Final(unsigned char output[16], struct MD5Context *s) {
     int i;
-    int pad;
+    unsigned pad;
     unsigned char c[64];
     uint32 lenhi, lenlo;
 
@@ -176,7 +172,7 @@ void MD5Final(unsigned char output[16], struct MD5Context *s) {
 
     memset(c, 0, pad);
     c[0] = 0x80;
-    MD5_Bytes(s, &c, pad);
+    MD5Update(s, c, pad);
 
     c[7] = (lenhi >> 24) & 0xFF;
     c[6] = (lenhi >> 16) & 0xFF;
@@ -187,7 +183,7 @@ void MD5Final(unsigned char output[16], struct MD5Context *s) {
     c[1] = (lenlo >>  8) & 0xFF;
     c[0] = (lenlo >>  0) & 0xFF;
 
-    MD5_Bytes(s, &c, 8);
+    MD5Update(s, c, 8);
 
     for (i = 0; i < 4; i++) {
         output[4*i+3] = (s->core.h[i] >> 24) & 0xFF;
@@ -196,3 +192,77 @@ void MD5Final(unsigned char output[16], struct MD5Context *s) {
         output[4*i+0] = (s->core.h[i] >>  0) & 0xFF;
     }
 }
+
+/* ----------------------------------------------------------------------
+ * The above is the MD5 algorithm itself. Now we implement the
+ * HMAC wrapper on it.
+ */
+
+static struct MD5Context md5_cs_mac_s1, md5_cs_mac_s2;
+static struct MD5Context md5_sc_mac_s1, md5_sc_mac_s2;
+
+static void md5_key(struct MD5Context *s1, struct MD5Context *s2,
+                    unsigned char *key, int len) {
+    unsigned char foo[64];
+    int i;
+
+    memset(foo, 0x36, 64);
+    for (i = 0; i < len && i < 64; i++)
+        foo[i] ^= key[i];
+    MD5Init(s1);
+    MD5Update(s1, foo, 64);
+
+    memset(foo, 0x5C, 64);
+    for (i = 0; i < len && i < 64; i++)
+        foo[i] ^= key[i];
+    MD5Init(s2);
+    MD5Update(s2, foo, 64);
+
+    memset(foo, 0, 64);                /* burn the evidence */
+}
+
+static void md5_cskey(unsigned char *key) {
+    md5_key(&md5_cs_mac_s1, &md5_cs_mac_s2, key, 16);
+}
+
+static void md5_sckey(unsigned char *key) {
+    md5_key(&md5_sc_mac_s1, &md5_sc_mac_s2, key, 16);
+}
+
+static void md5_do_hmac(struct MD5Context *s1, struct MD5Context *s2,
+                         unsigned char *blk, int len, unsigned long seq,
+                         unsigned char *hmac) {
+    struct MD5Context s;
+    unsigned char intermediate[16];
+
+    intermediate[0] = (unsigned char)((seq >> 24) & 0xFF);
+    intermediate[1] = (unsigned char)((seq >> 16) & 0xFF);
+    intermediate[2] = (unsigned char)((seq >>  8) & 0xFF);
+    intermediate[3] = (unsigned char)((seq      ) & 0xFF);
+
+    s = *s1;                           /* structure copy */
+    MD5Update(&s, intermediate, 4);
+    MD5Update(&s, blk, len);
+    MD5Final(intermediate, &s);
+    s = *s2;                           /* structure copy */
+    MD5Update(&s, intermediate, 16);
+    MD5Final(hmac, &s);
+}
+
+static void md5_generate(unsigned char *blk, int len, unsigned long seq) {
+    md5_do_hmac(&md5_cs_mac_s1, &md5_cs_mac_s2, blk, len, seq, blk+len);
+}
+
+static int md5_verify(unsigned char *blk, int len, unsigned long seq) {
+    unsigned char correct[16];
+    md5_do_hmac(&md5_sc_mac_s1, &md5_sc_mac_s2, blk, len, seq, correct);
+    return !memcmp(correct, blk+len, 16);
+}
+
+const struct ssh_mac ssh_md5 = {
+    md5_cskey, md5_sckey,
+    md5_generate,
+    md5_verify,
+    "hmac-md5",
+    16
+};