Initial commit: Touch ID Keychain CLI tool

- Touch ID authentication for all commands
- Secure password input (no echo)
- macOS Keychain storage with encryption

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

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+# keychain-fingerprint
+
+Touch ID 인증으로 macOS Keychain 비밀번호에 안전하고 편리하게 접근하는 CLI 도구
+
+## Why?
+
+macOS Keychain에 저장된 비밀번호에 접근할 때 두 가지 불편함이 있습니다:
+
+### 문제 1: 보안 vs 편의성 딜레마
+
+`security find-generic-password` 명령어로 비밀번호에 접근하면:
+
+```
+"security"가 키체인의 "myapp"에 저장된 기밀 정보를 사용하려고 합니다.
+[거부] [허용] [항상 허용]
+```
+
+- **"허용"**: 매번 Mac 비밀번호를 입력해야 함 → 번거로움
+- **"항상 허용"**: 이후 어떤 앱에서든 비밀번호 없이 접근 가능 → 보안 취약
+
+### 문제 2: 비밀번호 입력의 불편함
+
+Mac 비밀번호는 보통 길고 복잡해서 매번 입력하기 번거롭습니다.
+
+### 해결책: Touch ID
+
+이 도구는 **Touch ID**로 인증하여:
+- **빠르고 편리함**: 손가락 한 번으로 인증 (비밀번호 입력 불필요)
+- **보안 유지**: 다른 앱에서 접근 시 여전히 Mac 비밀번호 필요
+
+## Installation
+
+```bash
+# Clone
+git clone https://github.com/dss99911/keychain-fingerprint.git
+cd keychain-fingerprint
+
+# Compile
+swiftc -o keychain-fingerprint main.swift -framework LocalAuthentication -framework Security
+
+# Install (optional)
+sudo cp keychain-fingerprint /usr/local/bin/
+```
+
+## Usage
+
+```bash
+# Save password (Touch ID → secure input)
+keychain-fingerprint set myapp user@example.com
+
+# Get password (Touch ID → stdout)
+keychain-fingerprint get myapp user@example.com
+
+# List saved items (Touch ID)
+keychain-fingerprint list
+
+# Delete password (Touch ID)
+keychain-fingerprint delete myapp user@example.com
+```
+
+### Shell Variable (Recommended)
+
+```bash
+# Capture password in variable (not displayed on screen)
+PASSWORD=$(keychain-fingerprint get myapp user@example.com)
+
+# Use the password
+echo "Using password..."
+
+# Clear the variable when done
+unset PASSWORD
+```
+
+## Security
+
+| Access Method | Authentication Required |
+|---------------|------------------------|
+| This app | Touch ID |
+| Other apps / `security` command | Mac password |
+
+### How it works
+
+```
+┌─────────────────────────────────────────┐
+│         keychain-fingerprint            │
+├─────────────────────────────────────────┤
+│  1. Touch ID authentication             │
+│  2. Access Keychain (auto-authorized)   │
+└─────────────────────────────────────────┘
+
+┌─────────────────────────────────────────┐
+│         Other apps / terminal           │
+├─────────────────────────────────────────┤
+│  Keychain access → Mac password prompt  │
+└─────────────────────────────────────────┘
+```
+
+### Features
+
+- All commands require Touch ID
+- Passwords stored encrypted in macOS Keychain
+- Password input is hidden (no echo)
+- Passwords only output to stdout (for variable capture)
+- Device-only access (`kSecAttrAccessibleWhenUnlockedThisDeviceOnly`)
+
+## Requirements
+
+- macOS with Touch ID
+- Xcode Command Line Tools (`xcode-select --install`)
+
+## License
+
+MIT