parses asn1

bin/rasha.js

@@ -0,0 +1,76 @@
+#!/usr/bin/env node
+'use strict';
+var fs = require('fs');
+
+var infile = process.argv[2];
+
+var pem = fs.readFileSync(infile, 'ascii');
+var b64 = pem.split(/\n/).filter(function (line) {
+  // TODO test if RSA key
+  if (/^---/.test(line)) {
+    return false;
+  }
+  return true;
+}).join('');
+var buf = Buffer.from(b64, 'base64');
+
+function ASN1(buf, depth) {
+  console.log();
+  if (!depth) { depth = 0; }
+  if (depth >= 15) {
+    throw new Error("We got stuck in a loop (or this is actually more than 15 layers deep, which we never expected)");
+  }
+  var asn1 = {
+    type: buf[0]
+  , length: 0
+  , lengthLength: buf[1]
+  , totalLength: 0
+  , value: null
+  , children: []
+  };
+  console.log(depth, buf.byteLength, buf);
+  var index = 2;
+  var child;
+  var i = 0;
+  if (0x80 & asn1.lengthLength) {
+    asn1.lengthLength = 0x7f & asn1.lengthLength;
+    // to not worry about Endianness:
+    console.log('lenlen:', buf.slice(index, index + asn1.lengthLength).toString('hex'));
+    asn1.length = parseInt(buf.slice(index, index + asn1.lengthLength).toString('hex'), 16);
+    index += asn1.lengthLength;
+  } else {
+    asn1.length = asn1.lengthLength;
+    asn1.lengthLength = 0;
+  }
+  asn1.totalLength += asn1.lengthLength + 1;
+  console.log('asn1:'
+    , Buffer.from([asn1.type]).toString('hex')
+    , Buffer.from([asn1.totalLength])
+    , asn1.length
+    , asn1.type <= 0x06
+  );
+
+  // this is a primitive value type
+  if (asn1.type <= 0x06) {
+    i += 1;
+    asn1.value = buf.slice(index, index + asn1.length);
+    console.log("type is less than or equal to 0x06 and value size is", asn1.value.byteLength
+      , Buffer.from(asn1.value.slice(asn1.value.byteLength - 3)).toString('hex'));
+    return asn1;
+  }
+
+  while (i < 12 && index < buf.byteLength) {
+    child = ASN1(buf.slice(index), depth += 1);
+    index += 1 /*child.type.length*/ + child.totalLength + child.length;
+    console.log("New Index is:", index, "New buf.byteLength:", buf.byteLength);
+    asn1.children.push(child);
+  }
+
+  if (i >= 12) {
+    throw new Error("malformed ASN1: got stuck in a read loop (or there were actually 100+ elements in a sequence, which we never expected)");
+  }
+
+  return asn1;
+}
+
+console.log(ASN1(buf));

lib/rasha.js

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+'use strict';
+
+var RSA = module.exports;