Untangle algorithm: use uint64_t for count, move union into struct, use struct

more consistently, simplify macros a bit, redo finalization.  Also toybox
code is gplv2 so remove confusing output to the contrarary (in a main() that's
going to get yanked soon anyway, but just to be clear...)

diff --git a/toys/sha1.c b/toys/sha1.c
index 4180f39..b57805f 100644 (file)
--- a/toys/sha1.c
+++ b/toys/sha1.c
@@ -13,12 +13,15 @@
 
 struct sha1 {
        uint32_t state[5];
-       uint32_t count[2];
-       unsigned char buffer[64];
+       uint64_t count;
+       union {
+               unsigned char c[64];
+               uint32_t i[16];
+       } buffer;
 };
 
 void sha1_init(struct sha1 *this);
-void sha1_transform(unsigned int state[5], unsigned char buffer[64]);
+void sha1_transform(struct sha1 *this);
 void sha1_update(struct sha1 *this, unsigned char *data, unsigned int len);
 void sha1_final(struct sha1 *this, unsigned char digest[20]);
 
@@ -27,13 +30,13 @@ void sha1_final(struct sha1 *this, unsigned char digest[20]);
 /* blk0() and blk() perform the initial expand. */
 /* I got the idea of expanding during the round function from SSLeay */
 #ifdef LITTLE_ENDIAN
-#define blk0(i) (block->l[i] = (rol(block->l[i],24)&0xFF00FF00) \
-       |(rol(block->l[i],8)&0x00FF00FF))
+#define blk0(i) (block[i] = (rol(block[i],24)&0xFF00FF00) \
+       |(rol(block[i],8)&0x00FF00FF))
 #else
-#define blk0(i) block->l[i]
+#define blk0(i) block[i]
 #endif
-#define blk(i) (block->l[i&15] = rol(block->l[(i+13)&15]^block->l[(i+8)&15] \
-       ^block->l[(i+2)&15]^block->l[i&15],1))
+#define blk(i) (block[i&15] = rol(block[(i+13)&15]^block[(i+8)&15] \
+       ^block[(i+2)&15]^block[i&15],1))
 
 /* (R0+R1), R2, R3, R4 are the different operations used in SHA1 */
 #define R0(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk0(i)+0x5A827999+rol(v,5);w=rol(w,30);
@@ -52,25 +55,17 @@ void printy(unsigned char *this)
 
 /* Hash a single 512-bit block. This is the core of the algorithm. */
 
-void sha1_transform(unsigned int state[5], unsigned char buffer[64])
+void sha1_transform(struct sha1 *this)
 {
        unsigned int a, b, c, d, e;
-
-       typedef union {
-               unsigned char c[64];
-               unsigned int l[16];
-       } CHAR64LONG16;
-       CHAR64LONG16* block;
-       unsigned char workspace[64];
-       block = (CHAR64LONG16*)workspace;
-       memcpy(block, buffer, 64);
+       uint32_t *block = this->buffer.i;
 
        /* Copy context->state[] to working vars */
-       a = state[0];
-       b = state[1];
-       c = state[2];
-       d = state[3];
-       e = state[4];
+       a = this->state[0];
+       b = this->state[1];
+       c = this->state[2];
+       d = this->state[3];
+       e = this->state[4];
        /* 4 rounds of 20 operations each. Loop unrolled. */
        R0(a,b,c,d,e, 0); R0(e,a,b,c,d, 1); R0(d,e,a,b,c, 2); R0(c,d,e,a,b, 3);
        R0(b,c,d,e,a, 4); R0(a,b,c,d,e, 5); R0(e,a,b,c,d, 6); R0(d,e,a,b,c, 7);
@@ -93,12 +88,12 @@ void sha1_transform(unsigned int state[5], unsigned char buffer[64])
        R4(d,e,a,b,c,72); R4(c,d,e,a,b,73); R4(b,c,d,e,a,74); R4(a,b,c,d,e,75);
        R4(e,a,b,c,d,76); R4(d,e,a,b,c,77); R4(c,d,e,a,b,78); R4(b,c,d,e,a,79);
        /* Add the working vars back into context.state[] */
-       state[0] += a;
-       state[1] += b;
-       state[2] += c;
-       state[3] += d;
-       state[4] += e;
-
+       this->state[0] += a;
+       this->state[1] += b;
+       this->state[2] += c;
+       this->state[3] += d;
+       this->state[4] += e;
+printy(this->state);
        /* Wipe variables */
        a = b = c = d = e = 0;
 }
@@ -114,7 +109,7 @@ void sha1_init(struct sha1 *this)
        this->state[2] = 0x98BADCFE;
        this->state[3] = 0x10325476;
        this->state[4] = 0xC3D2E1F0;
-       this->count[0] = this->count[1] = 0;
+       this->count = 0;
 }
 
 /* Run your data through this function. */
@@ -123,49 +118,52 @@ void sha1_update(struct sha1 *this, unsigned char *data, unsigned int len)
 {
        unsigned int i, j;
 
-       j = (this->count[0] >> 3) & 63;
-       if ((this->count[0] += len << 3) < (len << 3)) this->count[1]++;
-       this->count[1] += (len >> 29);
+       j = this->count & 63;
+       this->count += len;
+
+       // Enough data to process a frame?
        if ((j + len) > 63) {
-               memcpy(this->buffer + j, data, (i = 64-j));
-               sha1_transform(this->state, this->buffer);
-               for ( ; i + 63 < len; i += 64)
-                       sha1_transform(this->state, data + i);
+               i = 64-j;
+               memcpy(this->buffer.c + j, data, i);
+               sha1_transform(this);
+               for ( ; i + 63 < len; i += 64) {
+                       memcpy(this->buffer.c, data + i, 64);
+                       sha1_transform(this);
+               }
                j = 0;
-       }
-       else i = 0;
-       memcpy(this->buffer + j, data + i, len - i);
+       } else i = 0;
+       // Grab remaining chunk
+       memcpy(this->buffer.c + j, data + i, len - i);
 }
 
-
 /* Add padding and return the message digest. */
 
 void sha1_final(struct sha1 *this, unsigned char digest[20])
 {
-       unsigned int i, j;
-       unsigned char finalcount[8];
+       uint64_t count = this->count << 3;
+       unsigned int i;
+       unsigned char buf;
+
+       // End the message by appending a "1" bit to the data, ending with the
+       // message size (in bits, big endian), and adding enough zero bits in
+       // between to pad to the end of the next 64-byte frame.  Since our input
+       // up to now has been in whole bytes, we can deal with bytes here too.
+
+       buf = 0x80;
+       do {
+               sha1_update(this, &buf, 1);
+               buf = 0;
+       } while ((this->count & 63) != 56);
+       for (i = 0; i < 8; i++)
+         this->buffer.c[56+i] = count >> (8*(7-i));
+       sha1_transform(this);
 
-       for (i = 0; i < 8; i++) {
-               finalcount[i] = (unsigned char)((this->count[(i >= 4 ? 0 : 1)]
-                >> ((3-(i & 3)) * 8) ) & 255);  /* Endian independent */
-       }
-       sha1_update(this, (unsigned char *)"\200", 1);
-       while ((this->count[0] & 504) != 448) {
-               sha1_update(this, (unsigned char *)"\0", 1);
-       }
-       sha1_update(this, finalcount, 8);  /* Should cause a SHA1Transform() */
        for (i = 0; i < 20; i++) {
                digest[i] = (unsigned char)
                 ((this->state[i>>2] >> ((3-(i & 3)) * 8) ) & 255);
        }
        /* Wipe variables */
-       i = j = 0;
-       memset(this->buffer, 0, 64);
-       memset(this->state, 0, 20);
-       memset(this->count, 0, 8);
-       memset(finalcount, 0, 8);
-       /* make SHA1Transform overwrite it's own static vars */
-       sha1_transform(this->state, this->buffer);
+       i = 0;
 }
 
 
@@ -179,11 +177,6 @@ int main(int argc, char** argv)
        unsigned char digest[20], buffer[16384];
        FILE* file;
 
-       if (argc > 2) {
-               puts("Public domain SHA-1 implementation - by Steve Reid <steve@edmweb.com>");
-               puts("Produces the SHA-1 hash of a file, or stdin if no file is specified.");
-               exit(0);
-       }
        if (argc < 2) {
                file = stdin;
        }