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2023-01-08​

  • Generate EC KeyPair with node:crypto and fetch key data from DER export:
import { generateKeyPair, KeyObject } from "node:crypto";
import asn from "asn1.js";

generateKeyPair('ec', 
  {
    namedCurve: 'secp256k1',
    publicKeyEncoding: { type: 'spki', format: 'der' },
    privateKeyEncoding: { type: 'pkcs8', format: 'der' }
  },
  (err, publicKey, privateKey) => { // Callback function
    if(err) {
      console.log("Err is: ", err);
      return;
    }

    // See https://github.com/crypto-browserify/parse-asn1/blob/master/asn1.js

    var AlgorithmIdentifier = asn.define('AlgorithmIdentifier', function () {
      this.seq().obj(
        this.key('algorithm').objid(),
        this.key('none').null_().optional(),
        this.key('curve').objid().optional(),
        this.key('params').seq().obj(
          this.key('p').int(),
          this.key('q').int(),
          this.key('g').int()
        ).optional()
      )
    })

    var PrivateKeyInfo = asn.define('PrivateKeyInfo', function () {
      this.seq().obj(
        this.key('version').int(),
        this.key('algorithm').use(AlgorithmIdentifier),
        this.key('subjectPrivateKey').octstr()
      )
    })

    var ECPrivateKey = asn.define('ECPrivateKey', function () {
      this.seq().obj(
        this.key('version').int(),
        this.key('privateKey').octstr(),
        this.key('parameters').optional().explicit(0).use(ECParameters),
        this.key('publicKey').optional().explicit(1).bitstr()
      )
    });
    
    var ECParameters = asn.define('ECParameters', function () {
      this.choice({
        namedCurve: this.objid()
      })
    });

    var privateKeyInfo = PrivateKeyInfo.decode(Buffer.from(privateKey.toString('hex'), "hex"), 'der');
    var ecPrivateKey = ECPrivateKey.decode(privateKeyInfo.subjectPrivateKey, 'der');
    
    console.log(privateKeyInfo);
    console.log(ecPrivateKey);
    console.log(ecPrivateKey.privateKey.toString('hex'));
    console.log(ecPrivateKey.publicKey.data.toString('hex'));
  }
);
const getMethods = (obj) => {
  let properties = new Set()
  let currentObj = obj
  do {
    Object.getOwnPropertyNames(currentObj).map(item => properties.add(item))
  } while ((currentObj = Object.getPrototypeOf(currentObj)))
  return [...properties.keys()].filter(item => typeof obj[item] === 'function')
}

2022-12-02​

  • Capturing web traffic:

    • Packet Capture

      • tcpdump - Good for network package capture.
      • Takeaway: Largely a bad way to capture traffic unless you are doing network level inspection.

    • Proxy Capture

      • mitmproxy - Good for web traffic and asset capture. Not good for viewing.
        • mitmproxy -w <path> - To save flows to a file.
        • mitmproxy -r <path> - To read flows from a file.
        • Note: You can not read AND write from command line.
        • Best flow is to write interactively in app and then otherwise use -r on the command line.
      • Takeaway: Proxy capture can do a lot to capture assets and see inside the TLS session but it really comes down to offloading what a browser's developer tools would provide anyway.

    • Browser Extension Capture

      • Save WE - Browser Extension that saves a site as single HTML for offline viewing.
      • WebScrapBook - Browser Extensions that saves all tab assets for offline viewing.
        • Lots of options and different ways to archive page.
      • Takeaway: Capturing via extensions are probably the best option for archival purposes because you get the whole DOM to help assemble the various parts.
      • TODO: Still looking for that extension that automatically captures all assets on the first download and then assembles an archive of the site for all sites I visit as a user.

  • wttr.in is a neat terminal weather site.

2022-10-14​

  • Installed VirtualBox 7.

    sudo apt-get update
    sudo apt-get install build-essential linux-headers-`uname -r`
    # Insert VBox Additions Disc and Run the install
    sudo usermod -aG vboxsf $USER
    sudo shutdown -r now

  • VSCode: Open Local File In Remote Mode

    • Note: There is no support for adding local folder in remote mode. Instead, when using local VM, setup shared folders and mount local remotely (if appropriate).

  • Many vendors have developer portals, for example: DigiKey Developer Portal

2022-08-28​

  • YouTube: God-Tier Developer Roadmap

  • My personal tiered code iceberg:

    • Tier 1: Scratch, Basic - For those that have never coded before.
    • Tier 2: Powershell, VBScript, Batch Scripts, Simple Shell Scripting
    • Tier 3: Python, Javascript, Ruby
    • Tier 4: SQL, Lua, bash, pwsh, VisualBasic, HTML, CSS
    • Tier 5: Java, C#, Typescript, Go, Dart
    • Tier 6: C, C++, Rust
    • Tier 7: Assembler, VHDL, Verilog, Digital Logic Gates

  • HBOMax ... what a shit show right now! HBOMax in their infinite wisdom doesn't allow you to login and cancel your account from abroad (e.g. UK). To work around this:

    • Got CyberGhost VPN.
    • Cleared all HBOMax cookies from Chrome.
    • Accessed hbomax.com and canceled my subscription!
    • There was some DNS setting, reboots, and other frustrations to get this to work.
    • CyberGhost Private Browser
      • Doesn't show up as Chrome, so it was also blocked by hbomax.com
      • Triggered as virus by Windows Defender. A bit sus, but I overrode it in Defender.

2022-08-06​

  • We have arrived.

2022-05-27​

2022-05-26​

  • Environment variables of a running process on Unix?

  • echo -ne "VAR=val1 VAR2=val2" | (eval `cat`;exec ./printsecret SECRET)

  • Wipe node environment values or configuration values in memory after use

  • SSH key encryption with OpenSSL

    • Encrypt and decrypt a file using SSH keys

    • Encrypt

      openssl rand 32 | \
        tee >(openssl rsautl -encrypt -oaep -pubin -inkey <(ssh-keygen -e -f ~/.ssh/id_rsa.pub -m PKCS8) -out secret.key | \
        openssl enc -aes-256-cbc -base64 -in data.txt -out data.txt.enc -pass stdin

    • Decrypt

      openssl rsautl -decrypt -oaep -inkey ~/.ssh/id_rsa -in secret.key | \
        openssl enc -d -aes-256-cbc -base64 -in data.txt.enc -out data.txt.dec -pass stdin

    • Decrypt remotely and execute.

      (ssh -T -q [email protected] cat /path/to/key) | \
        openssl rsautl -decrypt -oaep -inkey ~/.ssh/id_rsa | \
        openssl enc -d -aes-256-cbc -base64 -in data.txt.enc -pass stdin | \
        (eval `cat`;exec ./printsecret ANOTHER)

2022-05-25​

2022-05-24​

  • Multi-call Pattern for Containers

    : ${TOP_WORKSPACE_DIRECTORY:-"$(pwd)"}
    docker run -ti --rm \
      -w /workspace/$(realpath --relative-to=${TOP_WORKSPACE_DIRECTORY} $(pwd)) \
      -v $(realpath ${TOP_WORKSPACE_DIRECTORY}):/workspace \
      container_name $(basename $0) "$@"

  • EMUX - Similar to firmadyne without the emphasis on scalability.

  • cppreference - mblen - Location of decent strlen_mb implementation.

    Code
    #include <string.h>
    #include <stdlib.h>
    #include <locale.h>
    #include <stdio.h>

    // the number of characters in a multibyte string is the sum of mblen()'s
    // note: the simpler approach is mbstowcs(NULL, str, sz)
    size_t strlen_mb(const char* ptr)
    {
        size_t result = 0;
        const char* end = ptr + strlen(ptr);
        mblen(NULL, 0); // reset the conversion state
        while(ptr < end) {
            int next = mblen(ptr, end - ptr);
            if(next == -1) {
              perror("strlen_mb");
              break;
            }
            ptr += next;
            ++result;
        }
        return result;
    }

2022-05-20​

  • Google Drive mount for Linux

    • Use rclone:
      • curl https://rclone.org/install.sh | sudo bash
      • Google API Console
        • (For OAuth Client ID) Create rclone consent
        • Create rclone desktop app credential (for client_id and secret)
      • rclone config - Recommended to setup from XWindows environment
      • rclone mount --daemon gdrive: /opt/gdrive
      • Win.
    • Note: There is no official client for Linux
    • https://github.com/odeke-em/drive - Developed by previous Google Drive Employee

  • Install Chrome from command line:

    • wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
    • sudo dpkg -i google-chrome-stable_current_amd64.deb

  • Building Expo (EAS) Gradle project locally.

    • Alpine is linked with musl.
    • Buster-slim (i.e. debian) is linked with glibc.
    • Android builds (e.g. gradle) downloads dependencies that require specific linkage, like glibc. This means that you can't build expo android apps with alpine, you must you a glibc linked distro.
    • Take away: dynamic-binary dependency downloader build-systems are an anti-pattern!

  • https://invertase.io/ - Company specializing in mobile dev tools.

2022-05-19​

  • Remove a path from $PATH:
    • export PATH=$(echo $PATH | sed 's/:/\n/g' | sed "/$1/d" | tr '\n' ':')

2022-05-17​

  • Remove SSH Host Fingerprint and SSH

    • ssh-keygen -f ${HOME}/.ssh/known_hosts -R "[127.0.0.1]:2222" && ssh -p 2222 [email protected]

  • Linux 3.2 headers_install will remove libc headers.

    • Must headers_install first or rsync from a stage directory.

  • Install linux headers from linux_build:

    • make ARCH=<arch> O=. -C <src-path> headers_install INSTALL_HDR_PATH=<out-path>

  • With regards to projects that don't explicitly support parallel builds (-jX).

    • Do not short cut make && make install with make install.

  • Linux 4.20 requires libssl-dev package.

    • Without it'll complain about missing openssl/bio.h when building vmlinux.

  • When dealing with environment variable changes, its good to open another shell.

    • On exit, the original PATH (and other variables) are restored.
    • You can add an indication of shell depth with:
      • INIT_DISTANCE=$(($(pstree -Acs $$ 2>&1 | sed 's/-.-/\n/g; s/[\`|]-/\n/g; s/ //g; /^$/d;" | wc -1) - 6))

2022-05-16​

  • When using openssl enc:
    • OpenSSL 1.1.0 implicitly uses -md md5
    • OpenSSL 1.1.1 implicitly uses -md sha256
    • Explicit Encrypt: openssl enc -aes-256-cbc -md md5 -in $1 -out $1.txt
    • Explicit Decrypt: openssl enc -d -aes-256-cbc -md md5 -in $1.txt -out $1

2022-05-12​

  • When emulating...
    • If you're only analyzing userspace, emulate with newest kernel for >= 2.6.0.
    • If you're building for older kernel, you only need the libc to support syscall interface.

2022-05-10​

  • Crosstools-NG 1.19.0

    • Use CT_CC_VERSION, CT_KERNEL_VERSION, CT_LIBC_VERSION
    • Update .config:
      • sed -i '/^CT_PREFIX_DIR/c CT_PREFIX_DIR="${CT_PREFIX}${CT_TARGET}"' ${WD_PREFIX}builds/${STAGER_TARGET_ALIAS}/.config
    • For mipsel-static-linux-gnu, disable native-gdb.

  • For Ubuntu Hardy (6.10)

    • Enable no password sudo with echo '%sudo ALL=NOPASSWD: ALL' >> /etc/sudoers

  • binutils 2.24 and building for MIPS.

    • Starting with version 2.24.51.20140728 MIPS binutils complain loudly about mixing soft-float and hard-float object files. patch
    • Instead of using the patch, consider using crosstools-ng 1.19.0
      • ct-ng 1.19.0 uses binutils 2.19.1a.
      • The lowest 1.24.0 can go is binutils 2.26.