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Simplify nonce verify

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This commit is contained in:
Mikołaj Pich 2023-09-24 21:04:23 +02:00
parent fff27cf91b
commit bd59a06e49
3 changed files with 4 additions and 45 deletions
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7
src/main/kotlin/io/github/wulkanowy/schools/integrity/GenerateRandom.kt
View file

@ -1,7 +0,0 @@
package io.github.wulkanowy.schools.integrity
const val RANDOM_BYTE_COUNT = 16
fun ByteArray.toHexString(): String = joinToString(separator = "") {
currentByte -> "%02x".format(currentByte) }

4
src/main/kotlin/io/github/wulkanowy/schools/integrity/TokenDecrypt.kt
View file

@ -8,7 +8,6 @@ import com.google.auth.http.HttpCredentialsAdapter
import com.google.auth.oauth2.GoogleCredentials
import com.google.common.collect.Lists
import kotlinx.serialization.json.Json
import java.util.logging.Logger
fun decryptToken(tokenString: String, playIntegrity: PlayIntegrity = getPlayIntegrity()): IntegrityVerdictPayload {
val decodeTokenRequest = DecodeIntegrityTokenRequest().setIntegrityToken(tokenString)
@ -17,9 +16,6 @@ fun decryptToken(tokenString: String, playIntegrity: PlayIntegrity = getPlayInte
.execute()
.toPrettyString()
val log = Logger.getLogger("decryptToken")
log.info("Decrypted token: $returnString")
return Json.decodeFromString(returnString)
}

38
src/main/kotlin/io/github/wulkanowy/schools/integrity/ValidateCommand.kt
View file

@ -1,7 +1,5 @@
package io.github.wulkanowy.schools.integrity
import java.security.MessageDigest
import java.util.*
import java.util.logging.Logger
// Package name of the client application
@ -15,28 +13,15 @@ const val VERDICT_VAL_MEETS_VIRTUAL_INTEGRITY = "MEETS_VIRTUAL_INTEGRITY"
const val VERDICT_VAL_VERSION_UNRECOGNIZED = "UNRECOGNIZED_VERSION"
const val VERDICT_VAL_VERSION_RECOGNIZED = "PLAY_RECOGNIZED"
const val VERDICT_VAL_LICENSED = "LICENSED"
const val VERDICT_VAL_UNLICENSED = "UNLICENSED"
fun validateCommand(originalNonce: String, integrityVerdict: IntegrityVerdict): ValidateResult {
if (integrityVerdict.requestDetails.nonce != null) {
var nonceString: String = integrityVerdict.requestDetails.nonce
// Server might re-pad base64 with unicode '=', trim any that exist to
// match our web-safe original
val utfEqualRegex = "\\u003d$".toRegex()
nonceString = utfEqualRegex.replace(nonceString, "")
// The nonce string contains two parts, the random number previously generated,
// and the SHA256 hash of the command string, we need to separate them
// The values were written out as hex values, so they are base64 compatible, but
// we don't actually base64 decode them.
val randomString = nonceString.slice(IntRange(0, (RANDOM_BYTE_COUNT * 2) - 1))
val hashString = nonceString.slice(IntRange(RANDOM_BYTE_COUNT * 2, nonceString.lastIndex))
val decryptedNonce = integrityVerdict.requestDetails.nonce
val log = Logger.getLogger("validateCommand")
log.info("Raw nonce: $nonceString")
log.info("Random nonce segment: $randomString")
log.info("Hash nonce segment: $hashString")
log.info("Original nonce: $originalNonce")
log.info("Decrypted nonce: $decryptedNonce")
return if (validateHash(originalNonce, hashString)) {
return if (originalNonce == decryptedNonce) {
if (validateVerdict(integrityVerdict)) {
ValidateResult.VALIDATE_SUCCESS
} else {
@ -49,21 +34,6 @@ fun validateCommand(originalNonce: String, integrityVerdict: IntegrityVerdict):
return ValidateResult.VALIDATE_NONCE_NOT_FOUND
}
fun validateHash(commandString: String, hashString: String): Boolean {
val messageDigest = MessageDigest.getInstance("SHA-256")
val commandHashBytes = messageDigest.digest(commandString.toByteArray(Charsets.UTF_8))
val commandHashString = commandHashBytes.toHexString()
val hashMatch = hashString.contentEquals(commandHashString)
val log = Logger.getLogger("validateHash")
log.info("Command string: $commandString")
log.info("token hash string: $hashString")
log.info("command hash string: $commandHashString")
log.info("hashMatch: $hashMatch")
return hashMatch
}
fun validateVerdict(integrityVerdict: IntegrityVerdict): Boolean {
// Process the integrity verdict and 'validate' the command if the following positive
// signals exist: