56 lines
1.8 KiB
JavaScript
56 lines
1.8 KiB
JavaScript
const { createCipheriv, createDecipheriv, getCiphers } = require('crypto')
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const { KEYOBJECT } = require('../help/consts')
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const { JWEInvalid, JWEDecryptionFailed } = require('../errors')
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const { asInput } = require('../help/key_object')
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const checkInput = function (size, iv, tag) {
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if (iv.length !== 12) {
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throw new JWEInvalid('invalid iv')
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}
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if (arguments.length === 3) {
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if (tag.length !== 16) {
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throw new JWEInvalid('invalid tag')
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}
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}
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}
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const encrypt = (size, { [KEYOBJECT]: keyObject }, cleartext, { iv, aad = Buffer.alloc(0) }) => {
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const key = asInput(keyObject, false)
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checkInput(size, iv)
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const cipher = createCipheriv(`aes-${size}-gcm`, key, iv, { authTagLength: 16 })
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cipher.setAAD(aad)
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const ciphertext = Buffer.concat([cipher.update(cleartext), cipher.final()])
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const tag = cipher.getAuthTag()
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return { ciphertext, tag }
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}
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const decrypt = (size, { [KEYOBJECT]: keyObject }, ciphertext, { iv, tag = Buffer.alloc(0), aad = Buffer.alloc(0) }) => {
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const key = asInput(keyObject, false)
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checkInput(size, iv, tag)
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try {
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const cipher = createDecipheriv(`aes-${size}-gcm`, key, iv, { authTagLength: 16 })
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cipher.setAuthTag(tag)
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cipher.setAAD(aad)
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return Buffer.concat([cipher.update(ciphertext), cipher.final()])
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} catch (err) {
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throw new JWEDecryptionFailed()
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}
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}
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module.exports = (JWA, JWK) => {
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['A128GCM', 'A192GCM', 'A256GCM'].forEach((jwaAlg) => {
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const size = parseInt(jwaAlg.substr(1, 3), 10)
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if (getCiphers().includes(`aes-${size}-gcm`)) {
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JWA.encrypt.set(jwaAlg, encrypt.bind(undefined, size))
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JWA.decrypt.set(jwaAlg, decrypt.bind(undefined, size))
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JWK.oct.encrypt[jwaAlg] = JWK.oct.decrypt[jwaAlg] = key => (key.use === 'enc' || key.use === undefined) && key.length === size
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}
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})
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}
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