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jdenticon-js/src/common/sha1.js

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+/**
+ * Jdenticon
+ * https://github.com/dmester/jdenticon
+ * Copyright © Daniel Mester Pirttijärvi
+ */
+
+/**
+ * Computes a SHA1 hash for any value and returns it as a hexadecimal string.
+ * 
+ * This function is optimized for minimal code size and rather short messages.
+ * 
+ * @param {string} message 
+ */
+export function sha1(message) {
+    const HASH_SIZE_HALF_BYTES = 40;
+    const BLOCK_SIZE_WORDS = 16;
+
+    // Variables
+    // `var` is used to be able to minimize the number of `var` keywords.
+    var i = 0,
+        f = 0,
+    
+        // Use `encodeURI` to UTF8 encode the message without any additional libraries
+        // We could use `unescape` + `encodeURI` to minimize the code, but that would be slightly risky
+        // since `unescape` is deprecated.
+        urlEncodedMessage = encodeURI(message) + "%80", // trailing '1' bit padding
+        
+        // This can be changed to a preallocated Uint32Array array for greater performance and larger code size
+        data = [],
+        dataSize,
+        
+        hashBuffer = [],
+
+        a = 0x67452301,
+        b = 0xefcdab89,
+        c = ~a,
+        d = ~b,
+        e = 0xc3d2e1f0,
+        hash = [a, b, c, d, e],
+
+        blockStartIndex = 0,
+        hexHash = "";
+
+    /**
+     * Rotates the value a specified number of bits to the left.
+     * @param {number} value  Value to rotate
+     * @param {number} shift  Bit count to shift.
+     */
+    function rotl(value, shift) {
+        return (value << shift) | (value >>> (32 - shift));
+    }
+
+    // Message data
+    for ( ; i < urlEncodedMessage.length; f++) {
+        data[f >> 2] = data[f >> 2] |
+            (
+                (
+                    urlEncodedMessage[i] == "%"
+                        // Percent encoded byte
+                        ? parseInt(urlEncodedMessage.substring(i + 1, i += 3), 16)
+                        // Unencoded byte
+                        : urlEncodedMessage.charCodeAt(i++)
+                )
+
+                // Read bytes in reverse order (big endian words)
+                << ((3 - (f & 3)) * 8)
+            );
+    }
+
+    // f is now the length of the utf8 encoded message
+    // 7 = 8 bytes (64 bit) for message size, -1 to round down
+    // >> 6 = integer division with block size
+    dataSize = (((f + 7) >> 6) + 1) * BLOCK_SIZE_WORDS;
+
+    // Message size in bits.
+    // SHA1 uses a 64 bit integer to represent the size, but since we only support short messages only the least
+    // significant 32 bits are set. -8 is for the '1' bit padding byte.
+    data[dataSize - 1] = f * 8 - 8;
+    
+    // Compute hash
+    for ( ; blockStartIndex < dataSize; blockStartIndex += BLOCK_SIZE_WORDS) {
+        for (i = 0; i < 80; i++) {
+            f = rotl(a, 5) + e + (
+                    // Ch
+                    i < 20 ? ((b & c) ^ ((~b) & d)) + 0x5a827999 :
+                    
+                    // Parity
+                    i < 40 ? (b ^ c ^ d) + 0x6ed9eba1 :
+                    
+                    // Maj
+                    i < 60 ? ((b & c) ^ (b & d) ^ (c & d)) + 0x8f1bbcdc :
+                    
+                    // Parity
+                    (b ^ c ^ d) + 0xca62c1d6
+                ) + ( 
+                    hashBuffer[i] = i < BLOCK_SIZE_WORDS
+                        // Bitwise OR is used to coerse `undefined` to 0
+                        ? (data[blockStartIndex + i] | 0)
+                        : rotl(hashBuffer[i - 3] ^ hashBuffer[i - 8] ^ hashBuffer[i - 14] ^ hashBuffer[i - 16], 1)
+                );
+
+            e = d;
+            d = c;
+            c = rotl(b, 30);
+            b = a;
+            a = f;
+        }
+
+        hash[0] = a = ((hash[0] + a) | 0);
+        hash[1] = b = ((hash[1] + b) | 0);
+        hash[2] = c = ((hash[2] + c) | 0);
+        hash[3] = d = ((hash[3] + d) | 0);
+        hash[4] = e = ((hash[4] + e) | 0);
+    }
+
+    // Format hex hash
+    for (i = 0; i < HASH_SIZE_HALF_BYTES; i++) {
+        hexHash += (
+            (
+                // Get word (2^3 half-bytes per word)
+                hash[i >> 3] >>>
+
+                // Append half-bytes in reverse order
+                ((7 - (i & 7)) * 4)
+            ) 
+            // Clamp to half-byte
+            & 0xf
+        ).toString(16);
+    }
+
+    return hexHash;
+}