70 lines
1.8 KiB
JavaScript
70 lines
1.8 KiB
JavaScript
export default class Crypto {
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constructor(key) {
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if(typeof key === 'string')
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this.key = sjcl.codec.base64.toBits(base64_key)
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else
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this.key = key
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this.aes = new sjcl.cipher.aes(this.key)
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}
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static generate_key() {
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return sjcl.random.randomWords(8)
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}
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static pass_to_key(pass, salt = null) {
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if(salt === null)
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salt = sjcl.random.randomWords(4) // 128 bits (16 bytes)
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let key = sjcl.misc.pbkdf2(pass, salt, 10000)
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return {
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salt,
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key,
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}
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}
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encrypt(plaintext_data_in_bits, counter, return_encoded = true) {
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// 8 bytes of random data, (1 word = 4 bytes) * 2
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// with 8 bytes of byte encoded counter is used as
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// IV to guarantee a non-repeated IV (which is a catastrophe).
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// Assumes counter value is kept unique. Counter is taken from
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// Postgres sequence.
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let random_bits = sjcl.random.randomWords(2)
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let iv_bytes = sjcl.codec.bytes.fromBits(random_bits)
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for (let i = 0; i < 8; ++i) {
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let mask = 0xffn << BigInt(i*8)
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let counter_i_byte = (counter & mask) >> BigInt(i*8)
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iv_bytes[15-i] = Number(counter_i_byte)
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}
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let iv = sjcl.codec.bytes.toBits(iv_bytes)
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let encrypted = sjcl.mode['ccm'].encrypt(
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this.aes,
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plaintext_data_in_bits,
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iv,
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)
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// Returning 16 bytes (4 words) IV + encrypted data.
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if(return_encoded)
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return sjcl.codec.base64.fromBits(
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iv.concat(encrypted)
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)
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else
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return iv.concat(encrypted)
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}
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decrypt(encrypted_base64_data) {
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try {
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let encoded = sjcl.codec.base64.toBits(encrypted_base64_data)
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let iv = encoded.slice(0, 4) // in words (4 bytes), not bytes
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let encrypted_data = encoded.slice(4)
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return sjcl.mode['ccm'].decrypt(this.aes, encrypted_data, iv)
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} catch(err) {
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if(err.message == `ccm: tag doesn't match`)
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throw('Decryption failed')
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else
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throw(err)
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}
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}
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}
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