Kai Tanaka
KAI TANAKA
SSH, TLS and applied cryptography.
Kai Tanaka handles keys and certificates: SSH host and agent errors, mTLS handshake failures, certificate chain validation, and the OpenSSL 3 rejections that break configurations written for older versions.
Method: each fix is reproduced against a real client and server pair, and the handshake transcript or the exact OpenSSL error line is included. Anything touching a private key is tested with a throwaway key generated for the article.
Articles by Kai Tanaka
- error: gpg.ssh.allowedSignersFile needs to be configured · 13 October 2026
- Could not open a connection to your authentication agent · 05 October 2026
- dh key too small: OpenSSL 3 rejects 1024-bit DH params · 02 October 2026
- TLS hostname mismatch: "certificate is not valid for X" · 24 September 2026
- WARNING: UNPROTECTED PRIVATE KEY FILE! — SSH Fix · 21 September 2026
- tlsv13 alert certificate required: mTLS client cert fix · 17 September 2026
- self-signed certificate in certificate chain: Fix curl 60 · 11 September 2026
- WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED: Fix · 04 September 2026
- ssh_exchange_identification: Connection closed by host · 31 August 2026
- Nmap "requires root privileges" Error: Fix SYN Scan · 26 August 2026