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PGP, NaCl, and PBKDF2 in node.js and the browser (hashing, random, encryption, decryption, signatures, conversions), used by TogaTech.org
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JavaScript
// OpenPGP.js - An OpenPGP implementation in javascript
// Copyright (C) 2018 ProtonTech AG
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 3.0 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
/**
* @fileoverview This module implements AES-OCB en/decryption.
* @requires crypto/cipher
* @requires util
* @module crypto/ocb
*/
import ciphers from './cipher';
import util from '../util';
const blockLength = 16;
const ivLength = 15;
// https://tools.ietf.org/html/draft-ietf-openpgp-rfc4880bis-04#section-5.16.2:
// While OCB [RFC7253] allows the authentication tag length to be of any
// number up to 128 bits long, this document requires a fixed
// authentication tag length of 128 bits (16 octets) for simplicity.
const tagLength = 16;
function ntz(n) {
let ntz = 0;
for (let i = 1; (n & i) === 0; i <<= 1) {
ntz++;
}
return ntz;
}
function xorMut(S, T) {
for (let i = 0; i < S.length; i++) {
S[i] ^= T[i];
}
return S;
}
function xor(S, T) {
return xorMut(S.slice(), T);
}
const zeroBlock = new Uint8Array(blockLength);
const one = new Uint8Array([1]);
/**
* Class to en/decrypt using OCB mode.
* @param {String} cipher The symmetric cipher algorithm to use e.g. 'aes128'
* @param {Uint8Array} key The encryption key
*/
async function OCB(cipher, key) {
let maxNtz = 0;
let encipher;
let decipher;
let mask;
constructKeyVariables(cipher, key);
function constructKeyVariables(cipher, key) {
const aes = new ciphers[cipher](key);
encipher = aes.encrypt.bind(aes);
decipher = aes.decrypt.bind(aes);
const mask_x = encipher(zeroBlock);
const mask_$ = util.double(mask_x);
mask = [];
mask[0] = util.double(mask_$);
mask.x = mask_x;
mask.$ = mask_$;
}
function extendKeyVariables(text, adata) {
const newMaxNtz = util.nbits(Math.max(text.length, adata.length) / blockLength | 0) - 1;
for (let i = maxNtz + 1; i <= newMaxNtz; i++) {
mask[i] = util.double(mask[i - 1]);
}
maxNtz = newMaxNtz;
}
function hash(adata) {
if (!adata.length) {
// Fast path
return zeroBlock;
}
//
// Consider A as a sequence of 128-bit blocks
//
const m = adata.length / blockLength | 0;
const offset = new Uint8Array(blockLength);
const sum = new Uint8Array(blockLength);
for (let i = 0; i < m; i++) {
xorMut(offset, mask[ntz(i + 1)]);
xorMut(sum, encipher(xor(offset, adata)));
adata = adata.subarray(blockLength);
}
//
// Process any final partial block; compute final hash value
//
if (adata.length) {
xorMut(offset, mask.x);
const cipherInput = new Uint8Array(blockLength);
cipherInput.set(adata, 0);
cipherInput[adata.length] = 0b10000000;
xorMut(cipherInput, offset);
xorMut(sum, encipher(cipherInput));
}
return sum;
}
/**
* Encrypt/decrypt data.
* @param {encipher|decipher} fn Encryption/decryption block cipher function
* @param {Uint8Array} text The cleartext or ciphertext (without tag) input
* @param {Uint8Array} nonce The nonce (15 bytes)
* @param {Uint8Array} adata Associated data to sign
* @returns {Promise<Uint8Array>} The ciphertext or plaintext output, with tag appended in both cases
*/
function crypt(fn, text, nonce, adata) {
//
// Consider P as a sequence of 128-bit blocks
//
const m = text.length / blockLength | 0;
//
// Key-dependent variables
//
extendKeyVariables(text, adata);
//
// Nonce-dependent and per-encryption variables
//
// Nonce = num2str(TAGLEN mod 128,7) || zeros(120-bitlen(N)) || 1 || N
// Note: We assume here that tagLength mod 16 == 0.
const paddedNonce = util.concatUint8Array([zeroBlock.subarray(0, ivLength - nonce.length), one, nonce]);
// bottom = str2num(Nonce[123..128])
const bottom = paddedNonce[blockLength - 1] & 0b111111;
// Ktop = ENCIPHER(K, Nonce[1..122] || zeros(6))
paddedNonce[blockLength - 1] &= 0b11000000;
const kTop = encipher(paddedNonce);
// Stretch = Ktop || (Ktop[1..64] xor Ktop[9..72])
const stretched = util.concatUint8Array([kTop, xor(kTop.subarray(0, 8), kTop.subarray(1, 9))]);
// Offset_0 = Stretch[1+bottom..128+bottom]
const offset = util.shiftRight(stretched.subarray(0 + (bottom >> 3), 17 + (bottom >> 3)), 8 - (bottom & 7)).subarray(1);
// Checksum_0 = zeros(128)
const checksum = new Uint8Array(blockLength);
const ct = new Uint8Array(text.length + tagLength);
//
// Process any whole blocks
//
let i;
let pos = 0;
for (i = 0; i < m; i++) {
// Offset_i = Offset_{i-1} xor L_{ntz(i)}
xorMut(offset, mask[ntz(i + 1)]);
// C_i = Offset_i xor ENCIPHER(K, P_i xor Offset_i)
// P_i = Offset_i xor DECIPHER(K, C_i xor Offset_i)
ct.set(xorMut(fn(xor(offset, text)), offset), pos);
// Checksum_i = Checksum_{i-1} xor P_i
xorMut(checksum, fn === encipher ? text : ct.subarray(pos));
text = text.subarray(blockLength);
pos += blockLength;
}
//
// Process any final partial block and compute raw tag
//
if (text.length) {
// Offset_* = Offset_m xor L_*
xorMut(offset, mask.x);
// Pad = ENCIPHER(K, Offset_*)
const padding = encipher(offset);
// C_* = P_* xor Pad[1..bitlen(P_*)]
ct.set(xor(text, padding), pos);
// Checksum_* = Checksum_m xor (P_* || 1 || new Uint8Array(127-bitlen(P_*)))
const xorInput = new Uint8Array(blockLength);
xorInput.set(fn === encipher ? text : ct.subarray(pos, -tagLength), 0);
xorInput[text.length] = 0b10000000;
xorMut(checksum, xorInput);
pos += text.length;
}
// Tag = ENCIPHER(K, Checksum_* xor Offset_* xor L_$) xor HASH(K,A)
const tag = xorMut(encipher(xorMut(xorMut(checksum, offset), mask.$)), hash(adata));
//
// Assemble ciphertext
//
// C = C_1 || C_2 || ... || C_m || C_* || Tag[1..TAGLEN]
ct.set(tag, pos);
return ct;
}
return {
/**
* Encrypt plaintext input.
* @param {Uint8Array} plaintext The cleartext input to be encrypted
* @param {Uint8Array} nonce The nonce (15 bytes)
* @param {Uint8Array} adata Associated data to sign
* @returns {Promise<Uint8Array>} The ciphertext output
*/
encrypt: async function(plaintext, nonce, adata) {
return crypt(encipher, plaintext, nonce, adata);
},
/**
* Decrypt ciphertext input.
* @param {Uint8Array} ciphertext The ciphertext input to be decrypted
* @param {Uint8Array} nonce The nonce (15 bytes)
* @param {Uint8Array} adata Associated data to sign
* @returns {Promise<Uint8Array>} The ciphertext output
*/
decrypt: async function(ciphertext, nonce, adata) {
if (ciphertext.length < tagLength) throw new Error('Invalid OCB ciphertext');
const tag = ciphertext.subarray(-tagLength);
ciphertext = ciphertext.subarray(0, -tagLength);
const crypted = crypt(decipher, ciphertext, nonce, adata);
// if (Tag[1..TAGLEN] == T)
if (util.equalsUint8Array(tag, crypted.subarray(-tagLength))) {
return crypted.subarray(0, -tagLength);
}
throw new Error('Authentication tag mismatch');
}
};
}
/**
* Get OCB nonce as defined by {@link https://tools.ietf.org/html/draft-ietf-openpgp-rfc4880bis-04#section-5.16.2|RFC4880bis-04, section 5.16.2}.
* @param {Uint8Array} iv The initialization vector (15 bytes)
* @param {Uint8Array} chunkIndex The chunk index (8 bytes)
*/
OCB.getNonce = function(iv, chunkIndex) {
const nonce = iv.slice();
for (let i = 0; i < chunkIndex.length; i++) {
nonce[7 + i] ^= chunkIndex[i];
}
return nonce;
};
OCB.blockLength = blockLength;
OCB.ivLength = ivLength;
OCB.tagLength = tagLength;
export default OCB;