SHA-256 implementation, for use in future KEX algorithms, in particular

diffie-hellman-group-exchange-sha256, which the last DHGEX draft defined.
Code lifted from Simon's "crypto" directory, with changes to make it look
more like sshsh512.c.

git-svn-id: svn://svn.tartarus.org/sgt/putty@6252 cda61777-01e9-0310-a592-d414129be87e

diff --git a/Recipe b/Recipe
index a82a969..6b9f200 100644 (file)
--- a/Recipe
+++ b/Recipe
@@ -213,7 +213,7 @@ NONSSH   = telnet raw rlogin ldisc pinger
 # SSH back end (putty, plink, pscp, psftp).
 SSH      = ssh sshcrc sshdes sshmd5 sshrsa sshrand sshsha sshblowf
          + sshdh sshcrcda sshpubk sshzlib sshdss x11fwd portfwd
-         + sshaes sshsh512 sshbn wildcard pinger ssharcf
+         + sshaes sshsh256 sshsh512 sshbn wildcard pinger ssharcf
 WINSSH   = SSH winnoise winpgntc
 UXSSH    = SSH uxnoise uxagentc
 MACSSH   = SSH macnoise

diff --git a/ssh.h b/ssh.h
index 09ee167..45405d3 100644 (file)
--- a/ssh.h
+++ b/ssh.h
@@ -122,6 +122,16 @@ void SHA_Simple(void *p, int len, unsigned char *output);
 
 void hmac_sha1_simple(void *key, int keylen, void *data, int datalen,
                      unsigned char *output);
+typedef struct {
+    uint32 h[8];
+    unsigned char block[64];
+    int blkused;
+    uint32 lenhi, lenlo;
+} SHA256_State;
+void SHA256_Init(SHA256_State * s);
+void SHA256_Bytes(SHA256_State * s, const void *p, int len);
+void SHA256_Final(SHA256_State * s, unsigned char *output);
+void SHA256_Simple(const void *p, int len, unsigned char *output);
 
 typedef struct {
     uint64 h[8];
@@ -245,6 +255,7 @@ extern const struct ssh2_ciphers ssh2_aes;
 extern const struct ssh2_ciphers ssh2_blowfish;
 extern const struct ssh2_ciphers ssh2_arcfour;
 extern const struct ssh_hash ssh_sha1;
+extern const struct ssh_hash ssh_sha256;
 extern const struct ssh_kex ssh_diffiehellman_group1;
 extern const struct ssh_kex ssh_diffiehellman_group14;
 extern const struct ssh_kex ssh_diffiehellman_gex;

diff --git a/sshsh256.c b/sshsh256.c
new file mode 100644 (file)
index 0000000..70c2d7d
--- /dev/null
+++ b/sshsh256.c
@@ -0,0 +1,269 @@
+/*
+ * SHA-256 algorithm as described at
+ * 
+ *   http://csrc.nist.gov/cryptval/shs.html
+ */
+
+#include "ssh.h"
+
+/* ----------------------------------------------------------------------
+ * Core SHA256 algorithm: processes 16-word blocks into a message digest.
+ */
+
+#define ror(x,y) ( ((x) << (32-y)) | (((uint32)(x)) >> (y)) )
+#define shr(x,y) ( (((uint32)(x)) >> (y)) )
+#define Ch(x,y,z) ( ((x) & (y)) ^ (~(x) & (z)) )
+#define Maj(x,y,z) ( ((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)) )
+#define bigsigma0(x) ( ror((x),2) ^ ror((x),13) ^ ror((x),22) )
+#define bigsigma1(x) ( ror((x),6) ^ ror((x),11) ^ ror((x),25) )
+#define smallsigma0(x) ( ror((x),7) ^ ror((x),18) ^ shr((x),3) )
+#define smallsigma1(x) ( ror((x),17) ^ ror((x),19) ^ shr((x),10) )
+
+void SHA256_Core_Init(SHA256_State *s) {
+    s->h[0] = 0x6a09e667;
+    s->h[1] = 0xbb67ae85;
+    s->h[2] = 0x3c6ef372;
+    s->h[3] = 0xa54ff53a;
+    s->h[4] = 0x510e527f;
+    s->h[5] = 0x9b05688c;
+    s->h[6] = 0x1f83d9ab;
+    s->h[7] = 0x5be0cd19;
+}
+
+void SHA256_Block(SHA256_State *s, uint32 *block) {
+    uint32 w[80];
+    uint32 a,b,c,d,e,f,g,h;
+    static const int k[] = {
+        0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
+        0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
+        0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
+        0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
+        0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
+        0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
+        0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
+        0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
+        0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
+        0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
+        0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
+        0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
+        0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
+        0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
+        0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
+        0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2,
+    };
+
+    int t;
+
+    for (t = 0; t < 16; t++)
+        w[t] = block[t];
+
+    for (t = 16; t < 64; t++)
+       w[t] = smallsigma1(w[t-2]) + w[t-7] + smallsigma0(w[t-15]) + w[t-16];
+
+    a = s->h[0]; b = s->h[1]; c = s->h[2]; d = s->h[3];
+    e = s->h[4]; f = s->h[5]; g = s->h[6]; h = s->h[7];
+
+    for (t = 0; t < 64; t+=8) {
+        uint32 t1, t2;
+
+#define ROUND(j,a,b,c,d,e,f,g,h) \
+       t1 = h + bigsigma1(e) + Ch(e,f,g) + k[j] + w[j]; \
+       t2 = bigsigma0(a) + Maj(a,b,c); \
+        d = d + t1; h = t1 + t2;
+
+       ROUND(t+0, a,b,c,d,e,f,g,h);
+       ROUND(t+1, h,a,b,c,d,e,f,g);
+       ROUND(t+2, g,h,a,b,c,d,e,f);
+       ROUND(t+3, f,g,h,a,b,c,d,e);
+       ROUND(t+4, e,f,g,h,a,b,c,d);
+       ROUND(t+5, d,e,f,g,h,a,b,c);
+       ROUND(t+6, c,d,e,f,g,h,a,b);
+       ROUND(t+7, b,c,d,e,f,g,h,a);
+    }
+
+    s->h[0] += a; s->h[1] += b; s->h[2] += c; s->h[3] += d;
+    s->h[4] += e; s->h[5] += f; s->h[6] += g; s->h[7] += h;
+}
+
+/* ----------------------------------------------------------------------
+ * Outer SHA256 algorithm: take an arbitrary length byte string,
+ * convert it into 16-word blocks with the prescribed padding at
+ * the end, and pass those blocks to the core SHA256 algorithm.
+ */
+
+#define BLKSIZE 64
+
+void SHA256_Init(SHA256_State *s) {
+    SHA256_Core_Init(s);
+    s->blkused = 0;
+    s->lenhi = s->lenlo = 0;
+}
+
+void SHA256_Bytes(SHA256_State *s, const void *p, int len) {
+    unsigned char *q = (unsigned char *)p;
+    uint32 wordblock[16];
+    uint32 lenw = len;
+    int i;
+
+    /*
+     * Update the length field.
+     */
+    s->lenlo += lenw;
+    s->lenhi += (s->lenlo < lenw);
+
+    if (s->blkused && s->blkused+len < BLKSIZE) {
+        /*
+         * Trivial case: just add to the block.
+         */
+        memcpy(s->block + s->blkused, q, len);
+        s->blkused += len;
+    } else {
+        /*
+         * We must complete and process at least one block.
+         */
+        while (s->blkused + len >= BLKSIZE) {
+            memcpy(s->block + s->blkused, q, BLKSIZE - s->blkused);
+            q += BLKSIZE - s->blkused;
+            len -= BLKSIZE - s->blkused;
+            /* Now process the block. Gather bytes big-endian into words */
+            for (i = 0; i < 16; i++) {
+                wordblock[i] =
+                    ( ((uint32)s->block[i*4+0]) << 24 ) |
+                    ( ((uint32)s->block[i*4+1]) << 16 ) |
+                    ( ((uint32)s->block[i*4+2]) <<  8 ) |
+                    ( ((uint32)s->block[i*4+3]) <<  0 );
+            }
+            SHA256_Block(s, wordblock);
+            s->blkused = 0;
+        }
+        memcpy(s->block, q, len);
+        s->blkused = len;
+    }
+}
+
+void SHA256_Final(SHA256_State *s, unsigned char *digest) {
+    int i;
+    int pad;
+    unsigned char c[64];
+    uint32 lenhi, lenlo;
+
+    if (s->blkused >= 56)
+        pad = 56 + 64 - s->blkused;
+    else
+        pad = 56 - s->blkused;
+
+    lenhi = (s->lenhi << 3) | (s->lenlo >> (32-3));
+    lenlo = (s->lenlo << 3);
+
+    memset(c, 0, pad);
+    c[0] = 0x80;
+    SHA256_Bytes(s, &c, pad);
+
+    c[0] = (lenhi >> 24) & 0xFF;
+    c[1] = (lenhi >> 16) & 0xFF;
+    c[2] = (lenhi >>  8) & 0xFF;
+    c[3] = (lenhi >>  0) & 0xFF;
+    c[4] = (lenlo >> 24) & 0xFF;
+    c[5] = (lenlo >> 16) & 0xFF;
+    c[6] = (lenlo >>  8) & 0xFF;
+    c[7] = (lenlo >>  0) & 0xFF;
+
+    SHA256_Bytes(s, &c, 8);
+
+    for (i = 0; i < 8; i++) {
+       digest[i*4+0] = (s->h[i] >> 24) & 0xFF;
+       digest[i*4+1] = (s->h[i] >> 16) & 0xFF;
+       digest[i*4+2] = (s->h[i] >>  8) & 0xFF;
+       digest[i*4+3] = (s->h[i] >>  0) & 0xFF;
+    }
+}
+
+void SHA256_Simple(const void *p, int len, unsigned char *output) {
+    SHA256_State s;
+
+    SHA256_Init(&s);
+    SHA256_Bytes(&s, p, len);
+    SHA256_Final(&s, output);
+}
+
+/*
+ * Thin abstraction for things where hashes are pluggable.
+ */
+
+static void *sha256_init(void)
+{
+    SHA256_State *s;
+
+    s = snew(SHA256_State);
+    SHA256_Init(s);
+    return s;
+}
+
+static void sha256_bytes(void *handle, void *p, int len)
+{
+    SHA256_State *s = handle;
+
+    SHA256_Bytes(s, p, len);
+}
+
+static void sha256_final(void *handle, unsigned char *output)
+{
+    SHA256_State *s = handle;
+
+    SHA256_Final(s, output);
+    sfree(s);
+}
+
+const struct ssh_hash ssh_sha256 = {
+    sha256_init, sha256_bytes, sha256_final, 32
+};
+
+#ifdef TEST
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+
+int main(void) {
+    unsigned char digest[32];
+    int i, j, errors;
+
+    struct {
+       const char *teststring;
+       unsigned char digest[32];
+    } tests[] = {
+       { "abc", {
+           0xba, 0x78, 0x16, 0xbf, 0x8f, 0x01, 0xcf, 0xea,
+           0x41, 0x41, 0x40, 0xde, 0x5d, 0xae, 0x22, 0x23,
+           0xb0, 0x03, 0x61, 0xa3, 0x96, 0x17, 0x7a, 0x9c,
+           0xb4, 0x10, 0xff, 0x61, 0xf2, 0x00, 0x15, 0xad,
+       } },
+       { "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq", {
+           0x24, 0x8d, 0x6a, 0x61, 0xd2, 0x06, 0x38, 0xb8,
+           0xe5, 0xc0, 0x26, 0x93, 0x0c, 0x3e, 0x60, 0x39,
+           0xa3, 0x3c, 0xe4, 0x59, 0x64, 0xff, 0x21, 0x67,
+           0xf6, 0xec, 0xed, 0xd4, 0x19, 0xdb, 0x06, 0xc1,
+       } },
+    };
+
+    errors = 0;
+
+    for (i = 0; i < sizeof(tests) / sizeof(*tests); i++) {
+       SHA256_Simple(tests[i].teststring,
+                     strlen(tests[i].teststring), digest);
+       for (j = 0; j < 32; j++) {
+           if (digest[j] != tests[i].digest[j]) {
+               fprintf(stderr,
+                       "\"%s\" digest byte %d should be 0x%02x, is 0x%02x\n",
+                       tests[i].teststring, j, tests[i].digest[j], digest[j]);
+               errors++;
+           }
+       }
+    }
+
+    printf("%d errors\n", errors);
+
+    return 0;
+}
+
+#endif