[rcore] Add ComputeSHA256() function (#5264)

* [rcore] Add `ComputeSHA256()` function

* adjust function signatures

* review issues

* fix repeating 0

* fix mistake

* fixed macro

* remove undefs

* review styling mismatches

* rename `A0,1` to `SHA256_A0,1`

---------

Co-authored-by: CrackedPixel <5776225+CrackedPixel@users.noreply.github.com>

src/raylib.h

@@ -1164,6 +1164,7 @@ RLAPI unsigned char *DecodeDataBase64(const char *text, int *outputSize);
 RLAPI unsigned int ComputeCRC32(unsigned char *data, int dataSize);       // Compute CRC32 hash code
 RLAPI unsigned int *ComputeMD5(unsigned char *data, int dataSize);        // Compute MD5 hash code, returns static int[4] (16 bytes)
 RLAPI unsigned int *ComputeSHA1(unsigned char *data, int dataSize);       // Compute SHA1 hash code, returns static int[5] (20 bytes)
+RLAPI unsigned int *ComputeSHA256(unsigned char *data, int dataSize);     // Compute SHA256 hash code, returns static int[8] (32 bytes)
 
 // Automation events functionality
 RLAPI AutomationEventList LoadAutomationEventList(const char *fileName); // Load automation events list from file, NULL for empty list, capacity = MAX_AUTOMATION_EVENTS

src/rcore.c

@@ -3078,6 +3078,108 @@ unsigned int *ComputeSHA1(unsigned char *data, int dataSize)
     return hash;
 }
 
+// Compute SHA-256 hash code
+// NOTE: Returns a static int[8] array (32 bytes)
+unsigned int *ComputeSHA256(unsigned char *data, int dataSize)
+{
+    #define ROTATE_RIGHT(x, c) ((x >> c) | (x << ((sizeof(unsigned int) * 8) - c)))
+    #define SHA256_A0(x) (ROTATE_RIGHT(x, 7) ^ ROTATE_RIGHT(x, 18) ^ (x >> 3))
+    #define SHA256_A1(x) (ROTATE_RIGHT(x, 17) ^ ROTATE_RIGHT(x, 19) ^ (x >> 10))
+
+    static 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
+    };
+
+    static unsigned int hash[8];
+    hash[0] = 0x6A09e667;
+    hash[1] = 0xbb67ae85;
+    hash[2] = 0x3c6ef372;
+    hash[3] = 0xa54ff53a;
+    hash[4] = 0x510e527f;
+    hash[5] = 0x9b05688c;
+    hash[6] = 0x1f83d9ab;
+    hash[7] = 0x5be0cd19;
+
+    const unsigned long long int bitLen = ((unsigned long long int)dataSize)*8;
+    unsigned long long int paddedSize = dataSize + sizeof(dataSize);
+    paddedSize += (64 - (paddedSize%64));
+    unsigned char *buffer = RL_CALLOC(paddedSize, sizeof(unsigned char));
+
+    memcpy(buffer, data, dataSize);
+    buffer[dataSize] = 0x80;
+    for (int i = 1; i <= sizeof(bitLen); i++)
+        buffer[(paddedSize - sizeof(bitLen)) + (i - 1)] = (bitLen >> (8*(sizeof(bitLen) - i))) & 0xFF;
+
+    for (unsigned long long int blockN = 0; blockN < paddedSize/64; blockN++)
+    {
+        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];
+
+        unsigned char *block = buffer + (blockN*64);
+        unsigned int w[64];
+        for (int i = 0; i < 16; i++)
+        {         
+            w[i] =
+                ((unsigned int)block[i*4 + 0] << 24) |
+                ((unsigned int)block[i*4 + 1] << 16) |
+                ((unsigned int)block[i*4 + 2] << 8)  |
+                ((unsigned int)block[i*4 + 3]);
+        }
+        for (int t = 16; t < 64; t++) w[t] = SHA256_A1(w[t - 2]) + w[t - 7] + SHA256_A0(w[t - 15]) + w[t - 16];
+
+        for (unsigned long long int t = 0; t < 64; t++)
+        {
+            unsigned int e1 = (ROTATE_RIGHT(e, 6) ^ ROTATE_RIGHT(e, 11) ^ ROTATE_RIGHT(e, 25));
+            unsigned int ch = ((e & f) ^ (~e & g));
+            unsigned int t1 = (h + e1 + ch + k[t] + w[t]);
+            unsigned int e0 = (ROTATE_RIGHT(a, 2) ^ ROTATE_RIGHT(a, 13) ^ ROTATE_RIGHT(a, 22));
+            unsigned int maj = ((a & b) ^ (a & c) ^ (b & c));
+            unsigned int t2 = e0 + maj;
+
+            h = g;
+            g = f;
+            f = e;
+            e = d + t1;
+            d = c;
+            c = b;
+            b = a;
+            a = t1 + t2;
+        }
+
+        hash[0] += a;
+        hash[1] += b;
+        hash[2] += c;
+        hash[3] += d;
+        hash[4] += e;
+        hash[5] += f;
+        hash[6] += g;
+        hash[7] += h;
+    }
+    RL_FREE(buffer);
+    return hash;
+}
+
 //----------------------------------------------------------------------------------
 // Module Functions Definition: Automation Events Recording and Playing
 //----------------------------------------------------------------------------------