Created
March 30, 2020 22:30
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Key encapsulation
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| const sodium = require('sodium-native') | |
| const assert = require('nanoassert') | |
| const priv = new WeakMap() | |
| class Key { | |
| static BYTES = sodium.crypto_secretbox_KEYBYTES | |
| static NONCEBYTES = crypto.crypto_aead_xchacha20poly1305_ietf_NPUBBYTES | |
| static TAGBYTES = sodium.crypto_aead_xchacha20poly1305_ietf_ABYTES | |
| static create () { | |
| const key = sodium.sodium_malloc(this.BYTES) | |
| sodium.randombytes_buf(key) | |
| return new this(key) | |
| } | |
| static import (key) { | |
| return new this(key) | |
| } | |
| constructor (key) { | |
| assert(key.byteLength === this.BYTES, 'key must be Key.BYTES long') | |
| assert(key.secure, 'key must be secure buffer') | |
| this.destroyed = false | |
| priv.set(this, key) | |
| } | |
| encrypt (plaintext, buf) { | |
| if (this.destroyed) throw new Error('Destroyed') | |
| assert(Buffer.isBuffer(plaintext), 'plaintext must be (secure) buffer') | |
| const outlen = this.encryptLength(plaintext) | |
| if (buf == null) buf = Buffer.alloc(outlen) | |
| assert(buf.byteLength === outlen, 'buf must be encryptLength(plaintext) long') | |
| const nonce = buf.subarray(0, Key.NONCEBYTES) | |
| const ciphertext = buf.subarray(Key.NONCEBYTES) | |
| sodium.randombytes_buf(nonce) | |
| sodium.crypto_aead_xchacha20poly1305_ietf_encrypt(ciphertext, plaintext, null, null, nonce, priv.get(this)) | |
| return buf | |
| } | |
| encryptLength (plaintext) { | |
| assert(Buffer.isBuffer(plaintext), 'plaintext must be (secure) buffer') | |
| return Key.NONCEBYTES + plaintext.byteLength + Key.TAGBYTES | |
| } | |
| decrypt (ciphertext, buf) { | |
| if (this.destroyed) throw new Error('Destroyed') | |
| assert(Buffer.isBuffer(ciphertext), 'ciphertext must be buffer') | |
| const outlen = this.decryptLength(ciphertext) | |
| if (buf == null) buf = sodium.sodium_malloc(outlen) | |
| assert(buf.byteLength === outlen, 'buf must be decryptLength(ciphertext) long') | |
| const nonce = buf.subarray(0, Key.NONCEBYTES) | |
| const aead = buf.subarray(Key.NONCEBYTES) | |
| sodium.crypto_aead_xchacha20poly1305_ietf_decrypt(buf, null, aead, null, nonce, priv.get(this)) | |
| return buf | |
| } | |
| decryptLength (ciphertext) { | |
| assert(Buffer.isBuffer(ciphertext), 'ciphertext must be buffer') | |
| return -Key.NONCEBYTES + ciphertext.byteLength - Key.TAGBYTES | |
| } | |
| export () { | |
| if (this.destroyed) throw new Error('Destroyed') | |
| return priv.get(this) | |
| } | |
| destroy () { | |
| const key = priv.get(this) | |
| sodium.sodium_memzero(key) | |
| priv.delete(key) | |
| this.destroyed = true | |
| } | |
| } |
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