/*
- * SHA core transform algorithm, used here solely as a `stirring'
- * function for the PuTTY random number pool. Implemented directly
- * from the specification by Simon Tatham.
+ * SHA1 hash algorithm. Used in SSH2 as a MAC, and the transform is
+ * also used as a `stirring' function for the PuTTY random number
+ * pool. Implemented directly from the specification by Simon
+ * Tatham.
*/
#include "ssh.h"
-#define rol(x,y) ( ((x) << (y)) | (((word32)x) >> (32-y)) )
+typedef unsigned int uint32;
+
+/* ----------------------------------------------------------------------
+ * Core SHA algorithm: processes 16-word blocks into a message digest.
+ */
+
+#define rol(x,y) ( ((x) << (y)) | (((uint32)x) >> (32-y)) )
+
+void SHA_Core_Init(uint32 h[5]) {
+ h[0] = 0x67452301;
+ h[1] = 0xefcdab89;
+ h[2] = 0x98badcfe;
+ h[3] = 0x10325476;
+ h[4] = 0xc3d2e1f0;
+}
void SHATransform(word32 *digest, word32 *block) {
word32 w[80];
digest[3] += d;
digest[4] += e;
}
+
+/* ----------------------------------------------------------------------
+ * Outer SHA 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 SHA algorithm.
+ */
+
+void SHA_Init(SHA_State *s) {
+ SHA_Core_Init(s->h);
+ s->blkused = 0;
+ s->lenhi = s->lenlo = 0;
+}
+
+void SHA_Bytes(SHA_State *s, 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 < 64) {
+ /*
+ * 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 >= 64) {
+ memcpy(s->block + s->blkused, q, 64 - s->blkused);
+ q += 64 - s->blkused;
+ len -= 64 - 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 );
+ }
+ SHATransform(s->h, wordblock);
+ s->blkused = 0;
+ }
+ memcpy(s->block, q, len);
+ s->blkused = len;
+ }
+}
+
+void SHA_Final(SHA_State *s, unsigned char *output) {
+ 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;
+ SHA_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;
+
+ SHA_Bytes(s, &c, 8);
+
+ for (i = 0; i < 5; i++) {
+ output[i*4 ] = (s->h[i] >> 24) & 0xFF;
+ output[i*4+1] = (s->h[i] >> 16) & 0xFF;
+ output[i*4+2] = (s->h[i] >> 8) & 0xFF;
+ output[i*4+3] = (s->h[i] ) & 0xFF;
+ }
+}
+
+void SHA_Simple(void *p, int len, unsigned char *output) {
+ SHA_State s;
+
+ SHA_Init(&s);
+ SHA_Bytes(&s, p, len);
+ SHA_Final(&s, output);
+}
+
+/* ----------------------------------------------------------------------
+ * The above is the SHA-1 algorithm itself. Now we implement the
+ * HMAC wrapper on it.
+ */
+
+static SHA_State sha1_mac_s1, sha1_mac_s2;
+
+static void sha1_sesskey(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];
+ SHA_Init(&sha1_mac_s1);
+ SHA_Bytes(&sha1_mac_s1, foo, 64);
+
+ memset(foo, 0x5C, 64);
+ for (i = 0; i < len && i < 64; i++)
+ foo[i] ^= key[i];
+ SHA_Init(&sha1_mac_s2);
+ SHA_Bytes(&sha1_mac_s2, foo, 64);
+
+ memset(foo, 0, 64); /* burn the evidence */
+}
+
+static void sha1_do_hmac(unsigned char *blk, int len, unsigned long seq,
+ unsigned char *hmac) {
+ SHA_State s;
+ unsigned char intermediate[20];
+
+ 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 = sha1_mac_s1; /* structure copy */
+ SHA_Bytes(&s, intermediate, 4);
+ SHA_Bytes(&s, blk, len);
+ SHA_Final(&s, intermediate);
+ s = sha1_mac_s2; /* structure copy */
+ SHA_Bytes(&s, intermediate, 20);
+ SHA_Final(&s, hmac);
+}
+
+static void sha1_generate(unsigned char *blk, int len, unsigned long seq) {
+ sha1_do_hmac(blk, len, seq, blk+len);
+}
+
+static int sha1_verify(unsigned char *blk, int len, unsigned long seq) {
+ unsigned char correct[20];
+ sha1_do_hmac(blk, len, seq, correct);
+ return !memcmp(correct, blk+len, 20);
+}
+
+struct ssh_mac ssh_sha1 = {
+ sha1_sesskey,
+ sha1_generate,
+ sha1_verify,
+ "hmac-sha1",
+ 20
+};
projects / u / mdw / putty / blobdiff