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Introduce CryptoService for simple cryptographic operations

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This commit is contained in:
ganfra 2023-10-17 18:28:07 +02:00
parent 85102e3793
commit 493d67c8ca
4 changed files with 96 additions and 72 deletions
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49
libraries/cryptography/impl/src/main/kotlin/io/element/android/libraries/cryptography/impl/KeyStoreCipherFactory.kt → libraries/cryptography/impl/src/main/kotlin/io/element/android/libraries/cryptography/impl/DefaultCryptoService.kt
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@ -19,7 +19,8 @@ package io.element.android.libraries.cryptography.impl
import android.security.keystore.KeyGenParameterSpec
import android.security.keystore.KeyProperties
import com.squareup.anvil.annotations.ContributesBinding
import io.element.android.libraries.cryptography.api.CipherFactory
import io.element.android.libraries.cryptography.api.CryptoService
import io.element.android.libraries.cryptography.api.EncryptionResult
import io.element.android.libraries.di.AppScope
import java.security.KeyStore
import javax.crypto.Cipher
@ -34,28 +35,10 @@ private const val ENCRYPTION_PADDING = KeyProperties.ENCRYPTION_PADDING_NONE
private const val ENCRYPTION_ALGORITHM = KeyProperties.KEY_ALGORITHM_AES
private const val ENCRYPTION_AES_TRANSFORMATION = "$ENCRYPTION_ALGORITHM/$ENCRYPTION_BLOCK_MODE/$ENCRYPTION_PADDING"
/**
* Implementation of [CipherFactory] that uses the Android Keystore to store the keys.
*/
@ContributesBinding(AppScope::class)
class KeyStoreCipherFactory @Inject constructor() : CipherFactory {
class DefaultCryptoService @Inject constructor() : CryptoService {
override fun createEncryptionCipher(alias: String): Cipher {
val cipher = Cipher.getInstance(ENCRYPTION_AES_TRANSFORMATION)
val secretKey = getOrGenerateKeyForAlias(alias)
cipher.init(Cipher.ENCRYPT_MODE, secretKey)
return cipher
}
override fun createDecryptionCipher(alias: String, initializationVector: ByteArray): Cipher {
val cipher = Cipher.getInstance(ENCRYPTION_AES_TRANSFORMATION)
val secretKey = getOrGenerateKeyForAlias(alias)
val spec = GCMParameterSpec(128, initializationVector)
cipher.init(Cipher.DECRYPT_MODE, secretKey, spec)
return cipher
}
private fun getOrGenerateKeyForAlias(alias: String): SecretKey {
override fun getOrCreateSecretKey(alias: String): SecretKey {
val keyStore = KeyStore.getInstance(ANDROID_KEYSTORE)
val secretKeyEntry = (keyStore.getEntry(alias, null) as? KeyStore.SecretKeyEntry)
?.secretKey
@ -73,4 +56,28 @@ class KeyStoreCipherFactory @Inject constructor() : CipherFactory {
generator.generateKey()
} else secretKeyEntry
}
override fun createEncryptionCipher(key: SecretKey): Cipher {
return Cipher.getInstance(ENCRYPTION_AES_TRANSFORMATION).apply {
init(Cipher.ENCRYPT_MODE, key)
}
}
override fun createDecryptionCipher(key: SecretKey, initializationVector: ByteArray): Cipher {
val spec = GCMParameterSpec(128, initializationVector)
return Cipher.getInstance(ENCRYPTION_AES_TRANSFORMATION).apply {
init(Cipher.DECRYPT_MODE, key, spec)
}
}
override fun encrypt(key: SecretKey, input: ByteArray): EncryptionResult {
val cipher = createEncryptionCipher(key)
val encryptedData = cipher.doFinal(input)
return EncryptionResult(encryptedData, cipher.iv)
}
override fun decrypt(key: SecretKey, encryptionResult: EncryptionResult): ByteArray {
val cipher = createDecryptionCipher(key, encryptionResult.initializationVector)
return cipher.doFinal(encryptionResult.encryptedByteArray)
}
}