Update docs.

Author: atholbro

README.md

@@ -77,7 +77,7 @@ data class TaintedClaimFooter internal constructor(
  * @receiver A [PasetoFooter] instance to turn taint.
  * @return A [TaintedPasetoFooter] representation of the given [PasetoFooter].
  */
-fun PasetoFooter.taint(): TaintedPasetoFooter? = when (this) {
+fun PasetoFooter.taint(): TaintedPasetoFooter = when (this) {
     is ClaimFooter -> TaintedClaimFooter(keyId, wrappedKey, claims)
     is StringFooter -> TaintedStringFooter(value)
 }

paseto/src/main/kotlin/net/aholbrook/paseto/Footer.kt

@@ -92,7 +92,7 @@ sealed interface TokenService {
      * @param [token] paseto token to decode the footer of.
      * @return [TaintedPasetoFooter] with the decoded footer contents.
      */
-    fun insecureGetFooter(token: String): TaintedPasetoFooter?
+    fun insecureGetFooter(token: String): TaintedPasetoFooter
 }
 
 internal class LocalTokenService internal constructor(
@@ -113,7 +113,7 @@ internal class LocalTokenService internal constructor(
         return paseto.encrypt(
             m = encoded.toByteArray(Charsets.UTF_8),
             key = keyProvider(),
-            footer = encodedFooter ?: "",
+            footer = encodedFooter,
             implicitAssertion = implicitAssertion,
         )
     }
@@ -136,7 +136,7 @@ internal class LocalTokenService internal constructor(
         return decoded
     }
 
-    override fun insecureGetFooter(token: String): TaintedPasetoFooter? =
+    override fun insecureGetFooter(token: String): TaintedPasetoFooter =
         json.decodeFooter(footerOptions, extractFooter(token)).taint()
 }
 
@@ -163,7 +163,7 @@ internal class PublicTokenService internal constructor(
         return paseto.sign(
             m = encoded.toByteArray(Charsets.UTF_8),
             secretKey = keyPair.secretKey,
-            footer = encodedFooter ?: "",
+            footer = encodedFooter,
             implicitAssertion = implicitAssertion,
         )
     }
@@ -187,6 +187,6 @@ internal class PublicTokenService internal constructor(
         return decoded
     }
 
-    override fun insecureGetFooter(token: String): TaintedPasetoFooter? =
+    override fun insecureGetFooter(token: String): TaintedPasetoFooter =
         json.decodeFooter(footerOptions, extractFooter(token)).taint()
 }

paseto/src/main/kotlin/net/aholbrook/paseto/TokenService.kt

@@ -15,7 +15,7 @@ import java.nio.charset.Charset
  * @param expected The expected byte array.
  * @return true if the arrays are equal, false if not.
  */
-internal fun ByteArray.constantTimeEquals(expected: ByteArray): Boolean {
+fun ByteArray.constantTimeEquals(expected: ByteArray): Boolean {
     if (size != expected.size) {
         var result = 0
         for (i in indices) {
@@ -44,5 +44,5 @@ internal fun ByteArray.constantTimeEquals(expected: ByteArray): Boolean {
  * @param expected The expected byte array.
  * @return true if the arrays are equal, false if not.
  */
-internal fun String.constantTimeEquals(expected: String, charset: Charset = Charsets.UTF_8): Boolean =
+fun String.constantTimeEquals(expected: String, charset: Charset = Charsets.UTF_8): Boolean =
     toByteArray(charset).constantTimeEquals(expected.toByteArray(charset))

paseto/src/main/kotlin/net/aholbrook/paseto/crypto/ConstantTimeEquals.kt

@@ -62,6 +62,8 @@ class AsymmetricSecretKey private constructor(material: ByteArray, val version:
             else -> material
         }
     }
+    
+    fun copy(): AsymmetricSecretKey = AsymmetricSecretKey(material.copyOf(), version)
 
     fun toHex(): String {
         if (cleared) throw KeyReuseException()

paseto/src/main/kotlin/net/aholbrook/paseto/protocol/key/AsymmetricSecretKey.kt

@@ -11,6 +11,7 @@ import net.aholbrook.paseto.protocol.Version
 import java.io.FileInputStream
 import java.io.FileNotFoundException
 import java.io.IOException
+import java.security.Key
 import java.security.KeyStore
 import java.security.KeyStoreException
 import java.security.NoSuchAlgorithmException
@@ -33,6 +34,8 @@ class KeyPair(val secretKey: AsymmetricSecretKey?, val publicKey: AsymmetricPubl
 
     val version: Version = publicKey.version
 
+    fun copy(): KeyPair = KeyPair(secretKey?.copy(), publicKey)
+
     override fun equals(other: Any?): Boolean {
         if (this === other) {
             return true

paseto/src/main/kotlin/net/aholbrook/paseto/protocol/key/KeyPair.kt

@@ -20,6 +20,8 @@ class SymmetricKey private constructor(private val material: ByteArray, val vers
         }
     }
 
+    fun copy(): SymmetricKey = SymmetricKey(material.copyOf(), version)
+
     fun toHex(): String {
         if (cleared) throw KeyReuseException()
         return Hex.toHexString(material)