Diff: SHA256.cpp

Revision:

0:772b6de3a841

Child:

2:1991439ea6b8

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SHA256.cpp	Mon Jun 20 00:23:22 2011 +0000
@@ -0,0 +1,158 @@
+// Author: Remco Bloemen
+// Based on:
+//   http://en.wikipedia.org/wiki/SHA-2
+//   http://www.iwar.org.uk/comsec/resources/cipher/sha256-384-512.pdf
+
+#include "SHA256.h"
+
+inline unsigned int byte_swap(unsigned int x)
+{
+    // unsigned int result;
+    // asm("REV %0, %1" : "=r"(result) : "r"(x));
+    // return result
+    return __rev(x);
+}
+
+inline unsigned int rotate_right(unsigned int x, int shift)
+{
+    return (x >> shift) | (x << (32 - shift));
+}
+
+const unsigned int k[64] = {
+    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
+};
+
+inline unsigned int s0(unsigned int x) {
+    return rotate_right(x, 7) ^ rotate_right(x, 18) ^ (x >> 3);
+}
+
+inline unsigned int s1(unsigned int x) {
+    return rotate_right(x, 17) ^ rotate_right(x, 19) ^ (x >> 10);
+}
+
+inline unsigned int s2(unsigned int x) {
+    return rotate_right(x, 2) ^ rotate_right(x, 13) ^ rotate_right(x, 22);
+}
+
+inline unsigned int s3(unsigned int x) {
+    return rotate_right(x, 6) ^ rotate_right(x, 11) ^ rotate_right(x, 25);
+}
+
+void SHA256::reset()
+{
+    hash[0] = 0x6A09E667;
+    hash[1] = 0xBB67AE85;
+    hash[2] = 0x3C6EF372;
+    hash[3] = 0xA54FF53A;
+    hash[4] = 0x510E527F;
+    hash[5] = 0x9B05688C;
+    hash[6] = 0x1F83D9AB;
+    hash[7] = 0x5BE0CD19;
+    length = 0;
+}
+
+void SHA256::append(const char* data, int size)
+{
+    const char* end = data + size;
+    char* buffer = reinterpret_cast<char*>(w);
+    
+    // TODO: operate in words
+    
+    int index = length % 64;
+    while(data != end) {
+        int word_index = index / 4;
+        int byte_index = index % 4;
+        buffer[4 * word_index + 3 - byte_index] = *data;
+        ++index;
+        ++data;
+        if(index == 64) {
+            process_chunk();
+            index = 0;
+        }
+    }
+    length += size;
+}
+
+void SHA256::finalize()
+{
+    int trailing = length % 64;
+    
+    // Append the bit '1' to the message
+    int last_block = trailing / 4;
+    unsigned int bit_in_block = 0x80 << (24 - (trailing % 4) * 8); 
+    w[last_block] |= bit_in_block;
+    w[last_block] &= ~(bit_in_block - 1);
+    
+    // Set all other bits to zero
+    for(int i = last_block + 1; i < 15; ++i)
+        w[i] = 0;
+    
+    // Make room for the length if necessary
+    if(trailing >= 56) {
+        process_chunk();
+        for(int i = 0; i <= last_block; ++i)
+            w[i] = 0;
+    }
+    
+    // Append the length in bits
+    w[14] = length >> (32 - 3);
+    w[15] = length << 3;
+    process_chunk();
+    
+    // Convert the result to big endian
+    for(int i = 0; i < 8; ++i)
+       hash[i] = byte_swap(hash[i]);
+}
+
+// Process a 512 bit chunk stored in w[1...15]
+void SHA256::process_chunk()
+{
+    // Extend the chunk to 64 x 32 bit
+    for(int i = 16; i < 64; ++i)
+        w[i] = w[i - 16] + s0(w[i - 15]) + w[i - 7] + s1(w[i - 2]);
+    
+    // Initialize using current hash
+    unsigned int a = hash[0];
+    unsigned int b = hash[1];
+    unsigned int c = hash[2];
+    unsigned int d = hash[3];
+    unsigned int e = hash[4];
+    unsigned int f = hash[5];
+    unsigned int g = hash[6];
+    unsigned int h = hash[7];
+    
+    // Main loop
+    for(int i = 0; i < 64; ++i) {
+        unsigned int maj = (a & b) ^ (a & c) ^ (b & c);
+        unsigned int ch = (e & f) ^ ((~e) & g);
+        unsigned int t1 = h + s3(e) + ch + k[i] + w[i];
+        unsigned int t2 = maj + s2(a);
+        h = g;
+        g = f;
+        f = e;
+        e = d + t1;
+        d = c;
+        c = b;
+        b = a;
+        a = t1 + t2;
+    }
+    
+    // Update hash
+    hash[0] += a;
+    hash[1] += b;
+    hash[2] += c;
+    hash[3] += d;
+    hash[4] += e;
+    hash[5] += f;
+    hash[6] += g;
+    hash[7] += h; 
+}
+
+