Port secrets exercise

config.json

@@ -55,6 +55,15 @@
           "basics"
         ],
         "status": "wip"
+      },
+      {
+        "slug": "secrets",
+        "name": "secrets",
+        "uuid": "eeb45ce0-2caa-4283-b374-f086a9627da2",
+        "concepts": [
+          "bitwise-operations"
+        ],
+        "prerequisites": []
       }
     ],
     "practice": [
@@ -1196,15 +1205,15 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 6,
+        "status": "deprecated",
         "topics": [
           "conditionals",
           "games",
           "integers",
           "lists",
           "matrices",
           "strings"
-        ],
-        "status": "deprecated"
+        ]
       },
       {
         "slug": "rail-fence-cipher",

exercises/concept/secrets/.docs/hints.md

@@ -0,0 +1,18 @@
+# Hints
+
+## 1. Shift back the bits
+
+- There are two operators for shifting to the right, but only one will always insert a 0.
+
+## 2. Set some bits
+
+- One of the bit wise operators will always set a bit to 1 where the bits in both values are 1.
+
+## 3. Flip specific bits
+
+- There is an bit operation that will flip a bit where the mask is 1.
+
+## 4. Clear specific bits
+
+- One of the bit operations clears bits where the bit in the mask is 0.
+- But you may need to combine it with another operator to clear bits where the mask is 1.

exercises/concept/secrets/.docs/instructions.md

@@ -0,0 +1,58 @@
+# Instructions
+
+Your friend has just sent you a message with an important secret.
+Not wanting to make it easy for others to read it, the message was encrypted by performing a series of bit manipulations.
+You will need to write the functions to help decrypt the message.
+
+## 1. Shift back the bits
+
+The first step in decrypting the message is to undo the shifting from the encryption process by shifting the bits back to the right.
+There will be further steps in the decryption process that assume 0s are inserted from the left hand side.
+
+Implement the `shiftBack` function that takes a value and the number of places to shift and performs the shift.
+
+```kotlin
+shiftBack(0b1001, 2)
+# => 0b0010
+```
+
+## 2. Set some bits
+
+Next, there are some bits that need to be set to 1.
+
+Implement the `setBits` function that takes a value and a mask and returns the result of setting the bits in value to 1.
+A bit from value should be set to 1 where the bit in the mask is also 1.
+All other bits should be kept unchanged.
+
+```kotlin
+setBits(0b0110, 0b0101);
+# => 0b0111
+```
+
+## 3. Flip specific bits
+
+Some bits are flipped during encryption.
+They will need to be flipped back to decrypt the message.
+
+Implement the `flipBits` function that takes a value and the mask.
+The mask indicates which bits in the value to flip.
+If the bit is 1 in mask, the bit is flipped in the value.
+All other bits are kept unchanged.
+
+```java
+flipBits(0b1100, 0b0101);
+# => 0b1001
+```
+
+## 4. Clear specific bits
+
+Lastly, there are also certain bits that always decrypt to 0.
+
+Implement the `clearBits` function that takes a value and a mask.
+The bits in the `value` should be set to 0 where the bit in the mask is 1.
+All other bits should be kept unchanged.
+
+```java
+clearBits(0b0110, 0b0101);
+# => 0b0010
+```

exercises/concept/secrets/.meta/config.json

@@ -0,0 +1,21 @@
+{
+  "authors": [
+    "kahgoh"
+  ],
+  "files": {
+    "solution": [
+      "src/main/kotlin/Secrets.kt"
+    ],
+    "test": [
+      "src/test/kotlin/SecretsTest.kt"
+    ],
+    "exemplar": [
+      ".meta/src/reference/kotlin/Secrets.kt"
+    ]
+  },
+  "forked_from": [
+    "crystal/secrets"
+  ],
+  "icon": "secrets",
+  "blurb": "Learn about bit manipulation by writing a program to decrypt a message."
+}

exercises/concept/secrets/.meta/src/reference/kotlin/Secrets.kt

@@ -0,0 +1,15 @@
+fun shiftBack(value: Int, amount: Int): Int {
+    return value ushr amount
+}
+
+fun setBits(value: Int, mask: Int): Int {
+    return value or mask
+}
+
+fun flipBits(value: Int, mask: Int): Int {
+    return value xor mask
+}
+
+fun clearBits(value: Int, mask: Int): Int {
+    return value and mask.inv()
+}

exercises/concept/secrets/build.gradle.kts

@@ -0,0 +1,23 @@
+import org.gradle.api.tasks.testing.logging.TestExceptionFormat
+
+plugins {
+    kotlin("jvm")
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    implementation(kotlin("stdlib-jdk8"))
+
+    testImplementation("junit:junit:4.13.2")
+    testImplementation(kotlin("test-junit"))
+}
+
+tasks.withType<Test> {
+    testLogging {
+        exceptionFormat = TestExceptionFormat.FULL
+        events("passed", "failed", "skipped")
+    }
+}

exercises/concept/secrets/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.4-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists