OAuth & SSH Keygen

publicSshToPem.js

@@ -0,0 +1,103 @@
+/* eslint no-bitwise: 0 */
+
+function wrap(text, len) {
+    const length = len || 72;
+    let result = "";
+    for (let i = 0; i < text.length; i += length) {
+      result += text.slice(i, i + length);
+      result += "\n";
+    }
+    return result;
+  }
+  
+  function pemPublicKey(key) {
+    return `---- BEGIN RSA PUBLIC KEY ----\n${wrap(key, 65)}---- END RSA PUBLIC KEY ----`;
+  }
+  
+  function integerToOctet(n) {
+    const result = [];
+    for (let i = n; i > 0; i >>= 8) {
+      result.push(i & 0xff);
+    }
+    return result.reverse();
+  }
+  
+  function asnEncodeLen(n) {
+    let result = [];
+    if (n >> 7) {
+      result = integerToOctet(n);
+      result.unshift(0x80 + result.length);
+    } else {
+      result.push(n);
+    }
+    return result;
+  }
+  
+  function checkHighestBit(v) {
+    if (v[0] >> 7 === 1) {
+      v.unshift(0); // add leading zero if first bit is set
+    }
+    return v;
+  }
+  
+  function asn1Int(int) {
+    const v = checkHighestBit(int);
+    const len = asnEncodeLen(v.length);
+    return [0x02].concat(len, v); // int tag is 0x02
+  }
+  
+  function asn1Seq(seq) {
+    const len = asnEncodeLen(seq.length);
+    return [0x30].concat(len, seq); // seq tag is 0x30
+  }
+  
+  function arrayToPem(a) {
+    return window.btoa(a.map(c => String.fromCharCode(c)).join(""));
+  }
+  
+  function arrayToString(a) {
+    return String.fromCharCode.apply(null, a);
+  }
+  
+  function stringToArray(s) {
+    return s.split("").map(c => c.charCodeAt());
+  }
+  
+  function pemToArray(pem) {
+    return stringToArray(window.atob(pem));
+  }
+  
+  function arrayToLen(a) {
+    let result = 0;
+    for (let i = 0; i < a.length; i += 1) {
+      result = result * 256 + a[i];
+    }
+    return result;
+  }
+  
+  function decodePublicKey(s) {
+    const split = s.split(" ");
+    const prefix = split[0];
+    if (prefix !== "ssh-rsa") {
+      throw new Error(`Unknown prefix: ${prefix}`);
+    }
+    const buffer = pemToArray(split[1]);
+    const nameLen = arrayToLen(buffer.splice(0, 4));
+    const type = arrayToString(buffer.splice(0, nameLen));
+    if (type !== "ssh-rsa") {
+      throw new Error(`Unknown key type: ${type}`);
+    }
+    const exponentLen = arrayToLen(buffer.splice(0, 4));
+    const exponent = buffer.splice(0, exponentLen);
+    const keyLen = arrayToLen(buffer.splice(0, 4));
+    const key = buffer.splice(0, keyLen);
+    return { type, exponent, key, name: split[2] };
+  }
+  
+  function publicSshToPem(publicKey) {
+    const { key, exponent } = decodePublicKey(publicKey);
+    const seq = [key, exponent].map(asn1Int).reduce((acc, a) => acc.concat(a));
+    return pemPublicKey(arrayToPem(asn1Seq(seq)));
+  }
+  
+  module.exports = { publicSshToPem };