CMS - PKCS #7 (#19)

CMS - PKCS #7

Author: richardschneider

.travis.yml

@@ -14,15 +14,11 @@ matrix:
 script:
   - npm run lint
   - npm run test
-  - npm run coverage
 
 before_script:
   - export DISPLAY=:99.0
   - sh -e /etc/init.d/xvfb start
 
-after_success:
-  - npm run coverage-publish
-
 addons:
   firefox: 'latest'
   apt:

README.md

@@ -65,8 +65,8 @@ A naming service for a key
 
 Cryptographically protected messages
 
-- `cms.createAnonymousEncryptedData (name, plain, callback)`
-- `cms.readData (cmsData, callback)`
+- `cms.encrypt (name, plain, callback)`
+- `cms.decrypt (cmsData, callback)`
 
 ### KeyInfo
 
@@ -105,6 +105,10 @@ const defaultOptions = {
 
 The actual physical storage of an encrypted key is left to implementations of [interface-datastore](https://github.com/ipfs/interface-datastore/).  A key benifit is that now the key chain can be used in browser with the [js-datastore-level](https://github.com/ipfs/js-datastore-level) implementation.
 
+### Cryptographic Message Syntax (CMS)
+
+CMS, aka [PKCS #7](https://en.wikipedia.org/wiki/PKCS) and [RFC 5652](https://tools.ietf.org/html/rfc5652), describes an encapsulation syntax for data protection. It is used to digitally sign, digest, authenticate, or encrypt arbitrary message content. Basically, `cms.encrypt` creates a DER message that can be only be read by someone holding the private key.
+
 ## Contribute
 
 Feel free to join in. All welcome. Open an [issue](https://github.com/libp2p/js-libp2p-crypto/issues)!

src/cms.js

@@ -0,0 +1,142 @@
+'use strict'
+
+const async = require('async')
+const forge = require('node-forge')
+const util = require('./util')
+
+/**
+ * Cryptographic Message Syntax (aka PKCS #7)
+ *
+ * CMS describes an encapsulation syntax for data protection. It
+ * is used to digitally sign, digest, authenticate, or encrypt
+ * arbitrary message content.
+ *
+ * See RFC 5652 for all the details.
+ */
+class CMS {
+  /**
+   * Creates a new instance with a keychain
+   *
+   * @param {Keychain} keychain - the available keys
+   */
+  constructor (keychain) {
+    if (!keychain) {
+      throw new Error('keychain is required')
+    }
+
+    this.keychain = keychain
+  }
+
+  /**
+   * Creates some protected data.
+   *
+   * The output Buffer contains the PKCS #7 message in DER.
+   *
+   * @param {string} name - The local key name.
+   * @param {Buffer} plain - The data to encrypt.
+   * @param {function(Error, Buffer)} callback
+   * @returns {undefined}
+   */
+  encrypt (name, plain, callback) {
+    const self = this
+    const done = (err, result) => async.setImmediate(() => callback(err, result))
+
+    if (!Buffer.isBuffer(plain)) {
+      return done(new Error('Plain data must be a Buffer'))
+    }
+
+    async.series([
+      (cb) => self.keychain.findKeyByName(name, cb),
+      (cb) => self.keychain._getPrivateKey(name, cb)
+    ], (err, results) => {
+      if (err) return done(err)
+
+      let key = results[0]
+      let pem = results[1]
+      try {
+        const privateKey = forge.pki.decryptRsaPrivateKey(pem, self.keychain._())
+        util.certificateForKey(key, privateKey, (err, certificate) => {
+          if (err) return callback(err)
+
+          // create a p7 enveloped message
+          const p7 = forge.pkcs7.createEnvelopedData()
+          p7.addRecipient(certificate)
+          p7.content = forge.util.createBuffer(plain)
+          p7.encrypt()
+
+          // convert message to DER
+          const der = forge.asn1.toDer(p7.toAsn1()).getBytes()
+          done(null, Buffer.from(der, 'binary'))
+        })
+      } catch (err) {
+        done(err)
+      }
+    })
+  }
+
+  /**
+   * Reads some protected data.
+   *
+   * The keychain must contain one of the keys used to encrypt the data.  If none of the keys
+   * exists, an Error is returned with the property 'missingKeys'.  It is array of key ids.
+   *
+   * @param {Buffer} cmsData - The CMS encrypted data to decrypt.
+   * @param {function(Error, Buffer)} callback
+   * @returns {undefined}
+   */
+  decrypt (cmsData, callback) {
+    const done = (err, result) => async.setImmediate(() => callback(err, result))
+
+    if (!Buffer.isBuffer(cmsData)) {
+      return done(new Error('CMS data is required'))
+    }
+
+    const self = this
+    let cms
+    try {
+      const buf = forge.util.createBuffer(cmsData.toString('binary'))
+      const obj = forge.asn1.fromDer(buf)
+      cms = forge.pkcs7.messageFromAsn1(obj)
+    } catch (err) {
+      return done(new Error('Invalid CMS: ' + err.message))
+    }
+
+    // Find a recipient whose key we hold. We only deal with recipient certs
+    // issued by ipfs (O=ipfs).
+    const recipients = cms.recipients
+      .filter(r => r.issuer.find(a => a.shortName === 'O' && a.value === 'ipfs'))
+      .filter(r => r.issuer.find(a => a.shortName === 'CN'))
+      .map(r => {
+        return {
+          recipient: r,
+          keyId: r.issuer.find(a => a.shortName === 'CN').value
+        }
+      })
+    async.detect(
+      recipients,
+      (r, cb) => self.keychain.findKeyById(r.keyId, (err, info) => cb(null, !err && info)),
+      (err, r) => {
+        if (err) return done(err)
+        if (!r) {
+          const missingKeys = recipients.map(r => r.keyId)
+          err = new Error('Decryption needs one of the key(s): ' + missingKeys.join(', '))
+          err.missingKeys = missingKeys
+          return done(err)
+        }
+
+        async.waterfall([
+          (cb) => self.keychain.findKeyById(r.keyId, cb),
+          (key, cb) => self.keychain._getPrivateKey(key.name, cb)
+        ], (err, pem) => {
+          if (err) return done(err)
+
+          const privateKey = forge.pki.decryptRsaPrivateKey(pem, self.keychain._())
+          cms.decrypt(r.recipient, privateKey)
+          done(null, Buffer.from(cms.content.getBytes(), 'binary'))
+        })
+      }
+    )
+  }
+}
+
+module.exports = CMS

src/keychain.js

@@ -6,6 +6,7 @@ const deepmerge = require('deepmerge')
 const crypto = require('libp2p-crypto')
 const DS = require('interface-datastore')
 const pull = require('pull-stream')
+const CMS = require('./cms')
 
 const keyPrefix = '/pkcs8/'
 const infoPrefix = '/info/'
@@ -21,7 +22,7 @@ const defaultOptions = {
   // See https://cryptosense.com/parametesr-choice-for-pbkdf2/
   dek: {
     keyLength: 512 / 8,
-    iterationCount: 1000,
+    iterationCount: 10000,
     salt: 'you should override this value with a crypto secure random number',
     hash: 'sha2-512'
   }
@@ -86,8 +87,8 @@ function DsInfoName (name) {
  * Manages the lifecycle of a key. Keys are encrypted at rest using PKCS #8.
  *
  * A key in the store has two entries
- * - '/info/key-name', contains the KeyInfo for the key
- * - '/pkcs8/key-name', contains the PKCS #8 for the key
+ * - '/info/*key-name*', contains the KeyInfo for the key
+ * - '/pkcs8/*key-name*', contains the PKCS #8 for the key
  *
  */
 class Keychain {
@@ -130,12 +131,17 @@ class Keychain {
   }
 
   /**
-   * The default options for a keychain.
+   * Gets an object that can encrypt/decrypt protected data
+   * using the Cryptographic Message Syntax (CMS).
    *
-   * @returns {object}
+   * CMS describes an encapsulation syntax for data protection. It
+   * is used to digitally sign, digest, authenticate, or encrypt
+   * arbitrary message content.
+   *
+   * @returns {CMS}
    */
-  static get options () {
-    return defaultOptions
+  get cms () {
+    return new CMS(this)
   }
 
   /**
@@ -150,6 +156,16 @@ class Keychain {
     return options
   }
 
+  /**
+   * Gets an object that can encrypt/decrypt protected data.
+   * The default options for a keychain.
+   *
+   * @returns {object}
+   */
+  static get options () {
+    return defaultOptions
+  }
+
   /**
    * Create a new key.
    *

src/util.js

@@ -0,0 +1,70 @@
+'use strict'
+
+const forge = require('node-forge')
+const pki = forge.pki
+exports = module.exports
+
+/**
+ * Gets a self-signed X.509 certificate for the key.
+ *
+ * The output Buffer contains the PKCS #7 message in DER.
+ *
+ * TODO: move to libp2p-crypto package
+ *
+ * @param {KeyInfo} key - The id and name of the key
+ * @param {RsaPrivateKey} privateKey - The naked key
+ * @param {function(Error, Certificate)} callback
+ * @returns {undefined}
+ */
+exports.certificateForKey = (key, privateKey, callback) => {
+  const publicKey = pki.setRsaPublicKey(privateKey.n, privateKey.e)
+  const cert = pki.createCertificate()
+  cert.publicKey = publicKey
+  cert.serialNumber = '01'
+  cert.validity.notBefore = new Date()
+  cert.validity.notAfter = new Date()
+  cert.validity.notAfter.setFullYear(cert.validity.notBefore.getFullYear() + 10)
+  const attrs = [{
+    name: 'organizationName',
+    value: 'ipfs'
+  }, {
+    shortName: 'OU',
+    value: 'keystore'
+  }, {
+    name: 'commonName',
+    value: key.id
+  }]
+  cert.setSubject(attrs)
+  cert.setIssuer(attrs)
+  cert.setExtensions([{
+    name: 'basicConstraints',
+    cA: true
+  }, {
+    name: 'keyUsage',
+    keyCertSign: true,
+    digitalSignature: true,
+    nonRepudiation: true,
+    keyEncipherment: true,
+    dataEncipherment: true
+  }, {
+    name: 'extKeyUsage',
+    serverAuth: true,
+    clientAuth: true,
+    codeSigning: true,
+    emailProtection: true,
+    timeStamping: true
+  }, {
+    name: 'nsCertType',
+    client: true,
+    server: true,
+    email: true,
+    objsign: true,
+    sslCA: true,
+    emailCA: true,
+    objCA: true
+  }])
+  // self-sign certificate
+  cert.sign(privateKey)
+
+  return callback(null, cert)
+}

test/browser.js

@@ -23,5 +23,6 @@ describe('browser', () => {
   })
 
   require('./keychain.spec')(datastore1, datastore2)
+  require('./cms-interop')(datastore2)
   require('./peerid')
 })

test/cms-interop.js

@@ -0,0 +1,73 @@
+/* eslint max-nested-callbacks: ["error", 8] */
+/* eslint-env mocha */
+'use strict'
+
+const chai = require('chai')
+const dirtyChai = require('dirty-chai')
+const expect = chai.expect
+chai.use(dirtyChai)
+chai.use(require('chai-string'))
+const Keychain = require('..')
+
+module.exports = (datastore) => {
+  describe('cms interop', () => {
+    const passPhrase = 'this is not a secure phrase'
+    const aliceKeyName = 'cms-interop-alice'
+    let ks
+
+    before((done) => {
+      ks = new Keychain(datastore, { passPhrase: passPhrase })
+      done()
+    })
+
+    const plainData = Buffer.from('This is a message from Alice to Bob')
+
+    it('imports openssl key', function (done) {
+      this.timeout(10 * 1000)
+      const aliceKid = 'QmNzBqPwp42HZJccsLtc4ok6LjZAspckgs2du5tTmjPfFA'
+      const alice = `-----BEGIN ENCRYPTED PRIVATE KEY-----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+-----END ENCRYPTED PRIVATE KEY-----
+`
+      ks.importKey(aliceKeyName, alice, 'mypassword', (err, key) => {
+        expect(err).to.not.exist()
+        expect(key.name).to.equal(aliceKeyName)
+        expect(key.id).to.equal(aliceKid)
+        done()
+      })
+    })
+
+    it('decrypts node-forge example', (done) => {
+      const example = `
+MIIBcwYJKoZIhvcNAQcDoIIBZDCCAWACAQAxgfowgfcCAQAwYDBbMQ0wCwYDVQQK
+EwRpcGZzMREwDwYDVQQLEwhrZXlzdG9yZTE3MDUGA1UEAxMuUW1OekJxUHdwNDJI
+WkpjY3NMdGM0b2s2TGpaQXNwY2tnczJkdTV0VG1qUGZGQQIBATANBgkqhkiG9w0B
+AQEFAASBgLKXCZQYmMLuQ8m0Ex/rr3KNK+Q2+QG1zIbIQ9MFPUNQ7AOgGOHyL40k
+d1gr188EHuiwd90PafZoQF9VRSX9YtwGNqAE8+LD8VaITxCFbLGRTjAqeOUHR8cO
+knU1yykWGkdlbclCuu0NaAfmb8o0OX50CbEKZB7xmsv8tnqn0H0jMF4GCSqGSIb3
+DQEHATAdBglghkgBZQMEASoEEP/PW1JWehQx6/dsLkp/Mf+gMgQwFM9liLTqC56B
+nHILFmhac/+a/StQOKuf9dx5qXeGvt9LnwKuGGSfNX4g+dTkoa6N
+`
+      ks.cms.decrypt(Buffer.from(example, 'base64'), (err, plain) => {
+        expect(err).to.not.exist()
+        expect(plain).to.exist()
+        expect(plain.toString()).to.equal(plainData.toString())
+        done()
+      })
+    })
+  })
+}