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Code Issues Releases Wiki Activity

SSLSocketFactory: import newer settings from DAVDroid.

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This commit is contained in:
Tom Hacohen 2019-01-05 16:52:15 +00:00
parent 1901cf1bb1
commit f46bccab8e
1 changed files with 64 additions and 67 deletions
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97
app/src/main/java/com/etesync/syncadapter/SSLSocketFactoryCompat.kt
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@ -8,17 +8,12 @@
package com.etesync.syncadapter
import android.text.TextUtils
import android.os.Build
import java.io.IOException
import java.net.InetAddress
import java.net.Socket
import java.security.GeneralSecurityException
import java.util.Arrays
import java.util.HashSet
import java.util.LinkedList
import java.util.Locale
import java.util.*
import javax.net.ssl.SSLContext
import javax.net.ssl.SSLSocket
import javax.net.ssl.SSLSocketFactory
@ -97,75 +92,77 @@ class SSLSocketFactoryCompat(trustManager: X509TrustManager) : SSLSocketFactory(
}
companion object {
// Android 5.0+ (API level21) provides reasonable default settings
// Android 5.0+ (API level 21) provides reasonable default settings
// but it still allows SSLv3
// https://developer.android.com/reference/javax/net/ssl/SSLSocket.html
internal var protocols: Array<String>? = null
internal var cipherSuites: Array<String>? = null
var protocols: Array<String>? = null
var cipherSuites: Array<String>? = null
init {
if (Build.VERSION.SDK_INT >= 23) {
// Since Android 6.0 (API level 23),
// - TLSv1.1 and TLSv1.2 is enabled by default
// - SSLv3 is disabled by default
// - all modern ciphers are activated by default
protocols = null
cipherSuites = null
App.log.fine("Using device default TLS protocols/ciphers")
} else {
(SSLSocketFactory.getDefault().createSocket() as? SSLSocket)?.use { socket ->
try {
val socket = SSLSocketFactory.getDefault().createSocket() as SSLSocket
if (socket != null) {
/* set reasonable protocol versions */
// - enable all supported protocols (enables TLSv1.1 and TLSv1.2 on Android <5.0)
// - remove all SSL versions (especially SSLv3) because they're insecure now
val protocols = LinkedList<String>()
for (protocol in socket.supportedProtocols)
if (!protocol.toUpperCase(Locale.US).contains("SSL"))
protocols.add(protocol)
App.log.info("Setting allowed TLS protocols: " + TextUtils.join(", ", protocols))
SSLSocketFactoryCompat.protocols = protocols.toTypedArray()
val whichProtocols = LinkedList<String>()
for (protocol in socket.supportedProtocols.filterNot { it.contains("SSL", true) })
whichProtocols += protocol
App.log.info("Enabling (only) these TLS protocols: ${whichProtocols.joinToString(", ")}")
protocols = whichProtocols.toTypedArray()
/* set up reasonable cipher suites */
// choose known secure cipher suites
val allowedCiphers = Arrays.asList(
// first priority
"TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384",
"TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384",
"TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256",
"TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256",
"TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256",
"TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256",
"TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384",
"TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384",
// second priority
"TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384",
"TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384",
val knownCiphers = arrayOf(
// TLS 1.2
"TLS_RSA_WITH_AES_256_GCM_SHA384",
"TLS_RSA_WITH_AES_128_GCM_SHA256",
"TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256",
"TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256",
"TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384",
"TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256",
// compat
"TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA",
"TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256",
// maximum interoperability
"TLS_RSA_WITH_3DES_EDE_CBC_SHA",
"SSL_RSA_WITH_3DES_EDE_CBC_SHA",
"TLS_RSA_WITH_AES_128_CBC_SHA",
// additionally
"TLS_RSA_WITH_AES_256_CBC_SHA",
"TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA",
"TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA",
"TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA",
"TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA",
"TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA"
)
val availableCiphers = Arrays.asList(*socket.supportedCipherSuites)
App.log.info("Available cipher suites: " + TextUtils.join(", ", availableCiphers))
val availableCiphers = socket.supportedCipherSuites
App.log.info("Available cipher suites: ${availableCiphers.joinToString(", ")}")
/* For maximum security, preferredCiphers should *replace* enabled ciphers (thus
* disabling ciphers which are enabled by default, but have become unsecure), but for
* the security level of DAVdroid and maximum compatibility, disabling of insecure
* the security level of DAVx5 and maximum compatibility, disabling of insecure
* ciphers should be a server-side task */
// for the final set of enabled ciphers, take the ciphers enabled by default, ...
val enabledCiphers = HashSet(Arrays.asList(*socket.enabledCipherSuites))
App.log.info("Cipher suites enabled by default: " + TextUtils.join(", ", enabledCiphers))
val whichCiphers = LinkedList<String>()
whichCiphers.addAll(socket.enabledCipherSuites)
App.log.fine("Cipher suites enabled by default: ${whichCiphers.joinToString(", ")}")
// ... add explicitly allowed ciphers ...
enabledCiphers.addAll(allowedCiphers)
whichCiphers.addAll(knownCiphers)
// ... and keep only those which are actually available
enabledCiphers.retainAll(availableCiphers)
whichCiphers.retainAll(availableCiphers)
App.log.info("Enabling (only) those TLS ciphers: " + TextUtils.join(", ", enabledCiphers))
SSLSocketFactoryCompat.cipherSuites = enabledCiphers.toTypedArray()
socket.close()
}
App.log.info("Enabling (only) these TLS ciphers: " + whichCiphers.joinToString(", "))
cipherSuites = whichCiphers.toTypedArray()
} catch (e: IOException) {
App.log.severe("Couldn't determine default TLS settings")
}
}
}
}
}
}