putty

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Porting PuTTY to Windows on Arm
2 months ago
- Compiling PuTTY for Windows on Arm required the _ARM_WINAPI_PARTITION_DESKTOP_SDK_AVAILABLE macro and built smoothly.
- Using clang-cl for WoA builds needed disabling stack protection with /GS-.
- MSI installer issues were resolved by removing custom DLLs and setting InstallerVersion to 500 with platform Arm64.
- AES encryption was accelerated using NEON intrinsics vaeseq_u8 and vaesmcq_u8 for round operations.
- SHA-256 acceleration used NEON instructions vsha256su0/su1 for message schedule and vsha256h/h2 for hash update, with interleaved scheduling.
- SHA-1 acceleration used similar NEON approach with vsha1su0/su1 and vsha1c/m/p for rounds, managing a five-word state.
History of PuTTY's development
2 months ago
- PuTTY began as a personal project (STel) in 1996 to address poor terminal emulation in Windows Telnet clients.
- In 1998, it was converted into a multi-protocol client with SSH-1 support and renamed PuTTY.
- First public release in 1999 with a single executable and no installer, manual, or zip file.
- Key features were added through community contributions: SCP (1999), X11 forwarding (2001), TCP port forwarding (2001), and Unicode support (2001).
- A manual was finally written in 2002.
- In 2002, the terminal emulator was ported to Linux, creating pterm and a full Linux version of PuTTY.
- Later major features include serial port support (2007) and connection sharing (2015), both requiring significant code restructuring.
- A server-side SSH refactoring in 2019 was done as a development tool, not for production use.
- Development was driven by 'dogfooding' (using the software personally) and community contributions, with little long-term planning.
- Serial port support was an exception: written by the original author due to user demand, despite lacking personal need.
Implementing OpenSSH certificate support in PuTTY
2 months ago
- Certificate support in PuTTY required changes across almost all code areas except terminal emulation, making it a far-reaching feature.
- The implementation was done in parallel across subsystems, with frequent context-switching to avoid rework of completed parts.
- A new global configuration system was introduced for CA settings, as per-session configuration was insufficient for host key certificates.
- A custom Boolean expression syntax was designed for CA trust rules, allowing simple wildcards like '*.example.com' and compound expressions with '&&' and '||'.
- User certificates can be provided via modified PPK files, separate certificate files, or command-line options, supporting multiple certificates per key.
- Pageant's key storage was refactored into separate public and private key data structures to ensure related keys are encrypted/decrypted together.
- A rekey bug caused crashes after an hour due to oversight in testing; fixed before release.
- Pre-release builds were announced for the first time to gather user feedback, successfully catching bugs before the final release.
Iconography of the PuTTY tools
2 months ago
- PuTTY's original icon (late 1990s) featured two computers connected by a yellow lightning bolt, using a 16-color palette at 32x32 pixels.
- PSCP and PSFTP icons reused the same computer design with a document, while Pageant introduced a computer wearing a hat, adding a 16x16 size for the system tray.
- PuTTYgen's icon paired a computer with a key, and the configuration dialog added a spanner overlay, both for visual consistency.
- In 2007, a script was created to auto-generate icons at 48x48, 32x32, and 16x16 sizes, plus black-and-white versions, improving consistency and quality.
- Linux ports (pterm) reused the computer icon, and later true-color support allowed brown for the installer's cardboard box icon via halftoning.
- Recent SVG versions of the icons were created for scalability, though the original 1990s styling is intentionally preserved as 'reassuringly old-fashioned'.

putty

Porting PuTTY to Windows on Arm

History of PuTTY's development

Implementing OpenSSH certificate support in PuTTY

Iconography of the PuTTY tools