"Key.fromPlainString" does not works as expected. about lazysodium-android HOT 2 CLOSED

Found a solution.

We must initialize LazySodium with ISO_8859_1 charset:

val lazySodium = LazySodiumAndroid(SodiumAndroid(), Charsets.ISO_8859_1)

then we must use the same charset for plain string methods

val cek = lazySodium.keygen(AEAD.Method.XCHACHA20_POLY1305_IETF)

val plainStringCek = cek.getAsPlainString(Charsets.ISO_8859_1)
val restoredCek = Key.fromPlainString(plainStringCek, Charsets.ISO_8859_1)

from lazysodium-android.

Using asPlainString and fromPlainString is pretty dangerous because it uses UTF-8 as an encoding. Generally you should encode using Hex (we have these in LS as Key.asHexString and Key.fromHexString) or Base64.

Converting raw bytes to a UTF-8 string can lead to inconsistent outputs as you have found out. In your case you can use:

val cek = lazySodium.keygen(AEAD.Method.XCHACHA20_POLY1305_IETF)

val hexStringCek = cek.asHexString
val restoredCek = Key.fromHexString(hexStringCek)

from lazysodium-android.