Merge pull request gchq#1695 from Kalkran/master

Add Caret/M-decode Operation
t03857785 · Feb 13, 2024 · 14ee3f0 · 14ee3f0
2 parents 26fa5f3 + dc68b7d
commit 14ee3f0
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diff --git a/src/core/config/Categories.json b/src/core/config/Categories.json
@@ -70,6 +70,7 @@
             "Avro to JSON",
             "CBOR Encode",
             "CBOR Decode",
+            "Caret/M-decode",
             "Rison Encode",
             "Rison Decode"
         ]

diff --git a/src/core/operations/CaretMdecode.mjs b/src/core/operations/CaretMdecode.mjs
@@ -0,0 +1,98 @@
+/**
+ * @author tedk [tedk@ted.do]
+ * @copyright Crown Copyright 2024
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation.mjs";
+
+/**
+ * Caret/M-decode operation
+ *
+ * https://gist.githubusercontent.com/JaHIY/3c91bbf7bea5661e6abfbd1349ee81a2/raw/c7b480e9ff24bcb8f5287a8a8a2dcb9bf5628506/decode_m_notation.cpp
+ */
+class CaretMdecode extends Operation {
+
+    /**
+     * CaretMdecode constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Caret/M-decode";
+        this.module = "Default";
+        this.description = "Decodes caret or M-encoded strings, i.e. ^M turns into a newline, M-^] turns into 0x9d. Sources such as `cat -v`.\n\nPlease be aware that when using `cat -v` ^_ (caret-underscore) will not be encoded, but represents a valid encoding (namely that of 0x1f).";
+        this.infoURL = "https://en.wikipedia.org/wiki/Caret_notation";
+        this.inputType = "string";
+        this.outputType = "byteArray";
+        this.args = [];
+    }
+
+    /**
+     * @param {string} input
+     * @param {Object[]} args
+     * @returns {byteArray}
+     */
+    run(input, args) {
+
+        const bytes = [];
+
+        let prev = "";
+
+        for (let i = 0; i < input.length; i++) {
+
+            const charCode = input.charCodeAt(i);
+            const curChar = input.charAt(i);
+
+            if (prev === "M-^") {
+                if (charCode > 63 && charCode <= 95) {
+                    bytes.push(charCode + 64);
+                } else if (charCode === 63) {
+                    bytes.push(255);
+                } else {
+                    bytes.push(77, 45, 94, charCode);
+                }
+                prev = "";
+            } else if (prev === "M-") {
+                if (curChar === "^") {
+                    prev = prev + "^";
+                } else if (charCode >= 32 && charCode <= 126) {
+                    bytes.push(charCode + 128);
+                    prev = "";
+                } else {
+                    bytes.push(77, 45, charCode);
+                    prev = "";
+                }
+            } else if (prev === "M") {
+                if (curChar === "-") {
+                    prev = prev + "-";
+                } else {
+                    bytes.push(77, charCode);
+                    prev = "";
+                }
+            } else if (prev === "^") {
+                if (charCode > 63 && charCode <= 126) {
+                    bytes.push(charCode - 64);
+                } else if (charCode === 63) {
+                    bytes.push(127);
+                } else {
+                    bytes.push(94, charCode);
+                }
+                prev = "";
+            } else {
+                if (curChar === "M") {
+                    prev = "M";
+                } else if (curChar === "^") {
+                    prev = "^";
+                } else {
+                    bytes.push(charCode);
+                }
+            }
+
+        }
+        return bytes;
+    }
+
+}
+
+export default CaretMdecode;
diff --git a/tests/operations/index.mjs b/tests/operations/index.mjs
@@ -34,6 +34,7 @@ import "./tests/Bombe.mjs";
 import "./tests/BSON.mjs";
 import "./tests/ByteRepr.mjs";
 import "./tests/CaesarBoxCipher.mjs";
+import "./tests/CaretMdecode.mjs";
 import "./tests/CartesianProduct.mjs";
 import "./tests/CBORDecode.mjs";
 import "./tests/CBOREncode.mjs";

diff --git a/tests/operations/tests/CaretMdecode.mjs b/tests/operations/tests/CaretMdecode.mjs
@@ -0,0 +1,39 @@
+/**
+ * Caesar Box Cipher tests.
+ *
+ * @author tedk [tedk@ted.do]
+ *
+ * @copyright Crown Copyright 2020
+ * @license Apache-2.0
+ */
+import TestRegister from "../../lib/TestRegister.mjs";
+
+TestRegister.addTests([
+    {
+        name: "Caret/M-decode: nothing",
+        input: "",
+        expectedOutput: "",
+        recipeConfig: [
+            {
+                op: "Caret/M-decode",
+                args: [],
+            },
+        ],
+    },
+    {
+        /*
+         * Tests the full range.
+         * Everything except "^_" (\x5e\x5f) will decode correctly.
+         */
+        name: "Caret/M-decode: Full set",
+        input: "^@^A^B^C^D^E^F^G^H^I^J^K^L^M^N^O^P^Q^R^S^T^U^V^W^X^Y^Z^[^\\^]^^^_ !\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~^?M-^@M-^AM-^BM-^CM-^DM-^EM-^FM-^GM-^HM-^IM-^JM-^KM-^LM-^MM-^NM-^OM-^PM-^QM-^RM-^SM-^TM-^UM-^VM-^WM-^XM-^YM-^ZM-^[M-^\\M-^]M-^^M-^_M- M-!M-\"M-#M-$M-%M-&M-'M-(M-)M-*M-+M-,M--M-.M-/M-0M-1M-2M-3M-4M-5M-6M-7M-8M-9M-:M-;M-<M-=M->M-?M-@M-AM-BM-CM-DM-EM-FM-GM-HM-IM-JM-KM-LM-MM-NM-OM-PM-QM-RM-SM-TM-UM-VM-WM-XM-YM-ZM-[M-\\M-]M-^M-_M-`M-aM-bM-cM-dM-eM-fM-gM-hM-iM-jM-kM-lM-mM-nM-oM-pM-qM-rM-sM-tM-uM-vM-wM-xM-yM-zM-{M-|M-}M-~M-^?",
+        expectedOutput: "\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\x20\x21\x22\x23\x24\x25\x26\x27\x28\x29\x2a\x2b\x2c\x2d\x2e\x2f\x30\x31\x32\x33\x34\x35\x36\x37\x38\x39\x3a\x3b\x3c\x3d\x3e\x3f\x40\x41\x42\x43\x44\x45\x46\x47\x48\x49\x4a\x4b\x4c\x4d\x4e\x4f\x50\x51\x52\x53\x54\x55\x56\x57\x58\x59\x5a\x5b\x5c\x5d\x1f\x60\x61\x62\x63\x64\x65\x66\x67\x68\x69\x6a\x6b\x6c\x6d\x6e\x6f\x70\x71\x72\x73\x74\x75\x76\x77\x78\x79\x7a\x7b\x7c\x7d\x7e\x7f\x80\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f\xa0\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\x8d\x2d\x5f\xe0\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff",
+        recipeConfig: [
+            {
+                op: "Caret/M-decode",
+                args: [],
+            },
+        ],
+    },
+]);
+