SHA-1 JavaScript

// The SHA-1 code in this section was copied from:
// A JavaScript implementation of the Secure Hash Algorithm, SHA-1, as defined in FIPS PUB 180-1
// Version 2.1a Copyright Paul Johnston 2000 - 2002.
// Other contributors: Greg Holt, Andrew Kepert, Ydnar, Lostinet
// Distributed under the BSD License
// See http://pajhome.org.uk/crypt/md5 for details.
function b64_sha1(s) {
    return binb2b64(core_sha1(str2binb(s), s.length * 8));
}

function b64_hmac_sha1(key, data) {
    return binb2b64(core_hmac_sha1(key, data));
}

// Calculate the SHA-1 of an array of big-endian words, and a bit length
function core_sha1(x, len) {
    x[len >> 5] |= 0x80 << (24 - len % 32); // append padding
    x[((len + 64 >> 9) << 4) + 15] = len;

    var w = Array(80);
    var a = 1732584193;
    var b = -271733879;
    var c = -1732584194;
    var d = 271733878;
    var e = -1009589776;

    for (var i = 0; i < x.length; i += 16) {
        var olda = a;
        var oldb = b;
        var oldc = c;
        var oldd = d;
        var olde = e;

        for (var j = 0; j < 80; j++) {
            if (j < 16) {
                w[j] = x[i + j];
            } else {
                w[j] = rol(w[j - 3] ^ w[j - 8] ^ w[j - 14] ^ w[j - 16], 1);
            }

            var t = safe_add(safe_add(rol(a, 5), sha1_ft(j, b, c, d)), safe_add(safe_add(e, w[j]), sha1_kt(j)));
            e = d;
            d = c;
            c = rol(b, 30);
            b = a;
            a = t;
        }

        a = safe_add(a, olda);
        b = safe_add(b, oldb);
        c = safe_add(c, oldc);
        d = safe_add(d, oldd);
        e = safe_add(e, olde);
    }

    return Array(a, b, c, d, e);
}

// Perform the appropriate triplet combination function for the current iteration
function sha1_ft(t, b, c, d) {
    if (t < 20) {
        return (b & c) | ((~b) & d);
    }

    if (t < 40) {
        return b ^ c ^ d;
    }

    if (t < 60) {
        return (b & c) | (b & d) | (c & d);
    }

    return b ^ c ^ d;
}

// Determine the appropriate additive constant for the current iteration
function sha1_kt(t) {
    return (t < 20) ? 1518500249 : (t < 40) ? 1859775393 : (t < 60) ? -1894007588 : -899497514;
}

// Calculate the HMAC-SHA1 of a key and some data
function core_hmac_sha1(key, data) {
    var bkey = str2binb(key);
    if (bkey.length > 16) {
        bkey = core_sha1(bkey, key.length * 8);
    }

    var ipad = Array(16),
            opad = Array(16);
    for (var i = 0; i < 16; i++) {
        ipad[i] = bkey[i] ^ 0x36363636;
        opad[i] = bkey[i] ^ 0x5C5C5C5C;
    }

    var hash = core_sha1(ipad.concat(str2binb(data)), 512 + data.length * 8);
    return core_sha1(opad.concat(hash), 512 + 160);
}

// Add integers, wrapping at 2^32. This uses 16-bit operations internally
// to work around bugs in some JS interpreters.
function safe_add(x, y) {
    var lsw = (x & 0xFFFF) + (y & 0xFFFF);
    var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
    return (msw << 16) | (lsw & 0xFFFF);
}

// Bitwise rotate a 32-bit number to the left.
function rol(num, cnt) {
    return (num << cnt) | (num >>> (32 - cnt));
}


// Convert an 8-bit string to an array of big-endian words
// Characters > 255 have their hi-byte silently ignored.
function str2binb(str) {
    var bin = Array();
    var mask = (1 << 8) - 1;
    for (var i = 0; i < str.length * 8; i += 8) {
        bin[i >> 5] |= (str.charCodeAt(i / 8) & mask) << (32 - 8 - i % 32);
    }

    return bin;
}

// Convert an array of big-endian words to a string
function binb2str(bin) {
    var str = "";
    var mask = (1 << 8) - 1;
    for (var i = 0; i < bin.length * 32; i += 8) {
        str += String.fromCharCode((bin[i >> 5] >>> (32 - 8 - i % 32)) & mask);
    }

    return str;
}

// Convert an array of big-endian words to a base-64 string
function binb2b64(binarray) {
    var tab = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
    var str = "";
    for (var i = 0; i < binarray.length * 4; i += 3) {
        var triplet = (((binarray[i >> 2] >> 8 * (3 - i % 4)) & 0xFF) << 16) | (((binarray[i + 1 >> 2] >> 8 * (3 - (i + 1) % 4)) & 0xFF) << 8) | ((binarray[i + 2 >> 2] >> 8 * (3 - (i + 2) % 4)) & 0xFF);

        for (var j = 0; j < 4; j++) {
            if (i * 8 + j * 6 > binarray.length * 32) {
                str += '=';
            } else {
                str += tab.charAt((triplet >> 6 * (3 - j)) & 0x3F);
            }
        }
    }

    return str;
}