Replace SecRandomCopyBytes with CCRandomGenerateBytes (#33)

Author: 05nelsonm

README.md

@@ -21,7 +21,7 @@
 ![badge-support-js-ir]
 ![badge-support-linux-arm]
 
-A Kotlin Multiplatform library for obtaining cryptographically secure random data.
+A Kotlin Multiplatform library for procuring cryptographically secure random data.
 
 The Linux/AndroidNative implementation was heavily inspired by [rust-random/getrandom][url-rust-random].
 

library/crypto-rand/src/commonMain/kotlin/org/kotlincrypto/random/CryptoRand.kt

@@ -49,9 +49,10 @@ public abstract class CryptoRand @DelicateCryptoRandApi protected constructor()
      *      - Node: [Crypto.randomFillSync()](https://nodejs.org/api/crypto.html#cryptorandomfillsyncbuffer-offset-size)
      *  - WasmWasi: [random_get](https://github.com/WebAssembly/WASI/blob/main/legacy/preview1/docs.md#random_get)
      *  - Native:
-     *      - Android Native targets: [getrandom(2)](https://www.man7.org/linux/man-pages/man2/getrandom.2.html). If unavailable, `/dev/urandom` is used.
-     *      - Linux targets: [getrandom(2)](https://www.man7.org/linux/man-pages/man2/getrandom.2.html). If unavailable, `/dev/urandom` is used.
-     *      - Apple targets: [SecRandomCopyBytes](https://developer.apple.com/documentation/security/1399291-secrandomcopybytes)
+     *      - Linux & Android Native targets: [getrandom(2)](https://www.man7.org/linux/man-pages/man2/getrandom.2.html)
+     *        when available (GLIBC 2.25+ & Android API 23+), with a fallback to reading from `/dev/urandom` after polling
+     *        `/dev/random` once (per process lifetime) to ensure appropriate levels of system entropy are had.
+     *      - Apple targets: [CCRandomGenerateBytes](https://github.com/apple-oss-distributions/CommonCrypto/blob/main/include/CommonRandom.h)
      *      - Windows targets: [BCryptGenRandom](https://learn.microsoft.com/en-us/windows/win32/api/bcrypt/nf-bcrypt-bcryptgenrandom)
      * */
     public companion object Default: CryptoRand() {

library/crypto-rand/src/commonTest/kotlin/org/kotlincrypto/random/CryptoRandUnitTest.kt

@@ -23,31 +23,33 @@ open class CryptoRandUnitTest {
 
     protected open val cryptoRand: CryptoRand = CryptoRand.Default
 
+    private companion object {
+        private const val LIMIT_LINUX = 256
+        private const val LIMIT_WEB = 65536
+    }
+
     // https://github.com/briansmith/ring/blob/main/tests/rand_tests.rs
     @Test
     fun givenArray_whenNextBytes_thenIsFilledWithData() {
-        val linuxLimit = 256
-        val webLimit = 65536
-
         listOf(
             1,
             2,
             3,
             96,
-            linuxLimit - 1,
-            linuxLimit,
-            linuxLimit + 1,
-            linuxLimit * 2,
+            LIMIT_LINUX - 1,
+            LIMIT_LINUX,
+            LIMIT_LINUX + 1,
+            LIMIT_LINUX * 2,
             511,
             512,
             513,
             4096,
-            webLimit - 1,
-            webLimit,
-            webLimit + 1,
-            webLimit * 2,
+            LIMIT_WEB - 1,
+            LIMIT_WEB,
+            LIMIT_WEB + 1,
+            LIMIT_WEB * 2,
             // To ensure remainder logic is working properly for JS/WasmJS
-            (webLimit * 2) + 6_000,
+            (LIMIT_WEB * 2) + 6_000,
         ).forEach { size ->
             val zeroCount = cryptoRand.nextBytes(buf = ByteArray(size)).count { it == 0.toByte() }
 

library/crypto-rand/src/darwinMain/kotlin/org/kotlincrypto/random/internal/DarwinPlatform.kt

@@ -18,18 +18,17 @@
 package org.kotlincrypto.random.internal
 
 import kotlinx.cinterop.*
-import platform.Security.SecRandomCopyBytes
-import platform.Security.kSecRandomDefault
 import org.kotlincrypto.random.RandomnessProcurementException
+import platform.CoreCrypto.CCRandomGenerateBytes
+import platform.CoreCrypto.kCCSuccess
 
 @Throws(RandomnessProcurementException::class)
 internal actual fun ByteArray.cryptoRandFill() {
     @OptIn(ExperimentalForeignApi::class, UnsafeNumber::class)
     val status = usePinned { pinned ->
-        // kSecRandomDefault is synonymous to NULL
-        SecRandomCopyBytes(kSecRandomDefault, size.toUInt().convert(), pinned.addressOf(0))
+        CCRandomGenerateBytes(pinned.addressOf(0), size.toUInt().convert())
     }
 
-    if (status == 0) return
-    throw RandomnessProcurementException("Failed to obtain bytes from [SecRandomCopyBytes]. Code: $status")
+    if (status == kCCSuccess) return
+    throw RandomnessProcurementException("Failed to obtain bytes from [CCRandomGenerateBytes]. kCCStatus: $status")
 }

library/crypto-rand/src/linuxAndroidMain/kotlin/org/kotlincrypto/random/internal/LinuxAndroidPlatform.kt

@@ -34,7 +34,7 @@ private inline fun getrandom2(buf: CPointer<ByteVar>, buflen: size_t, flags: u_i
     return syscall(SYS_getrandom.convert(), buf, buflen, flags).convert()
 }
 
-// getrandom(2) available on Linux LIBC 3.17+, and Android Native API 28+
+// getrandom(2) available for Linux Kernel 3.17+ (Android API 23+)
 @OptIn(ExperimentalForeignApi::class, UnsafeNumber::class)
 internal val HAS_GET_RANDOM: Boolean by lazy(LazyThreadSafetyMode.SYNCHRONIZED) {
     val buf = ByteArray(1)