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Diffstat (limited to 'node_modules/browserify-aes/ghash.js')
-rw-r--r-- | node_modules/browserify-aes/ghash.js | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/node_modules/browserify-aes/ghash.js b/node_modules/browserify-aes/ghash.js new file mode 100644 index 000000000..0ca143cd7 --- /dev/null +++ b/node_modules/browserify-aes/ghash.js @@ -0,0 +1,98 @@ +var zeros = new Buffer(16) +zeros.fill(0) +module.exports = GHASH +function GHASH (key) { + this.h = key + this.state = new Buffer(16) + this.state.fill(0) + this.cache = new Buffer('') +} +// from http://bitwiseshiftleft.github.io/sjcl/doc/symbols/src/core_gcm.js.html +// by Juho Vähä-Herttua +GHASH.prototype.ghash = function (block) { + var i = -1 + while (++i < block.length) { + this.state[i] ^= block[i] + } + this._multiply() +} + +GHASH.prototype._multiply = function () { + var Vi = toArray(this.h) + var Zi = [0, 0, 0, 0] + var j, xi, lsb_Vi + var i = -1 + while (++i < 128) { + xi = (this.state[~~(i / 8)] & (1 << (7 - i % 8))) !== 0 + if (xi) { + // Z_i+1 = Z_i ^ V_i + Zi = xor(Zi, Vi) + } + + // Store the value of LSB(V_i) + lsb_Vi = (Vi[3] & 1) !== 0 + + // V_i+1 = V_i >> 1 + for (j = 3; j > 0; j--) { + Vi[j] = (Vi[j] >>> 1) | ((Vi[j - 1] & 1) << 31) + } + Vi[0] = Vi[0] >>> 1 + + // If LSB(V_i) is 1, V_i+1 = (V_i >> 1) ^ R + if (lsb_Vi) { + Vi[0] = Vi[0] ^ (0xe1 << 24) + } + } + this.state = fromArray(Zi) +} +GHASH.prototype.update = function (buf) { + this.cache = Buffer.concat([this.cache, buf]) + var chunk + while (this.cache.length >= 16) { + chunk = this.cache.slice(0, 16) + this.cache = this.cache.slice(16) + this.ghash(chunk) + } +} +GHASH.prototype.final = function (abl, bl) { + if (this.cache.length) { + this.ghash(Buffer.concat([this.cache, zeros], 16)) + } + this.ghash(fromArray([ + 0, abl, + 0, bl + ])) + return this.state +} + +function toArray (buf) { + return [ + buf.readUInt32BE(0), + buf.readUInt32BE(4), + buf.readUInt32BE(8), + buf.readUInt32BE(12) + ] +} +function fromArray (out) { + out = out.map(fixup_uint32) + var buf = new Buffer(16) + buf.writeUInt32BE(out[0], 0) + buf.writeUInt32BE(out[1], 4) + buf.writeUInt32BE(out[2], 8) + buf.writeUInt32BE(out[3], 12) + return buf +} +var uint_max = Math.pow(2, 32) +function fixup_uint32 (x) { + var ret, x_pos + ret = x > uint_max || x < 0 ? (x_pos = Math.abs(x) % uint_max, x < 0 ? uint_max - x_pos : x_pos) : x + return ret +} +function xor (a, b) { + return [ + a[0] ^ b[0], + a[1] ^ b[1], + a[2] ^ b[2], + a[3] ^ b[3] + ] +} |