feat: add cross-invocation passphrase caching via Linux keyring (v0.3.0)

Use keyctl (keyutils) to cache the master passphrase in the kernel keyring
with a configurable TTL (default 5 min). New unlock/lock subcommands for
manual cache control. keyctl is optional — silently skipped if not installed.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -10,6 +10,45 @@ authentication detection (bearer token or HTTP basic auth).
 
 ---
 
+## What Changed (Session 2026-03-01b)
+
+### Passphrase caching via Linux keyring (v0.3.0)
+
+Added cross-invocation master passphrase caching using the Linux kernel keyring
+(`keyctl` from `keyutils`). `keyctl` is an **optional** dependency — if not
+installed, behaviour is unchanged (prompt every time).
+
+**New functions** (Encryption helpers section):
+
+| Function | Purpose |
+| --- | --- |
+| `_keyring_available()` | Returns 0 if `keyctl` is installed |
+| `_keyring_get()` | Read cached passphrase from user keyring; return 1 if missing/expired |
+| `_keyring_set(pass, ttl)` | Store passphrase in keyring with TTL |
+| `_keyring_clear()` | Revoke the cached key |
+
+**New subcommands**:
+
+| Command | Purpose |
+| --- | --- |
+| `unlock` | Prompt for passphrase and cache in keyring (useful before scripting) |
+| `lock` | Clear cached passphrase from keyring immediately |
+
+**New global option**: `--cache-timeout <seconds>` (default 300 / 5 min).
+Also configurable via `CACHE_TIMEOUT=<seconds>` in `hubmanager.conf`.
+
+**New constants**: `HM_KEYRING_KEY`, `HM_KEYRING_DEFAULT_TIMEOUT`.
+**New global variable**: `HM_CACHE_TIMEOUT`.
+
+**Modified functions**:
+
+- `_prompt_master_pass()` — checks keyring before prompting; stores after prompt
+- `_prompt_set_master_pass()` — stores in keyring after confirmation
+
+**Version bump**: `0.2.1` → `0.3.0`
+
+---
+
 ## What Changed (Session 2026-03-01)
 
 ### Bug fixes and improvements (v0.2.1)
@@ -105,6 +144,8 @@ Both `load_config()` and `resolve_registry_alias()` detect the prefix and call
 | `delete` | Resolve tag → digest → `DELETE`; requires confirmation or `--yes` |
 | `copy` | Copy/retag within or across registries; blob mount for same-registry retag |
 | `prune` | Delete outdated tags sorted by image creation date |
+| `unlock` | Cache master passphrase in kernel keyring (requires `keyctl`) |
+| `lock` | Clear cached master passphrase from keyring |
 
 ### Supporting files
 
@@ -126,11 +167,12 @@ set -euo pipefail
 # --- Output / Formatting helpers ---
 # --- Dependency check ---
 # --- Encryption helpers ---   _encrypt_value(), _decrypt_value(), _prompt_master_pass()
+#                              _keyring_get(), _keyring_set(), _keyring_clear()
 # --- Config loading ---
 # --- HTTP helpers ---         raw_http(), get_response_header()
 # --- Authentication ---       probe_registry_auth(), get_bearer_token(), make_auth_header()
 # --- Registry request ---     registry_request()  ← main HTTP wrapper
-# --- Subcommands ---          cmd_login/list/tags/inspect/delete/copy/prune
+# --- Subcommands ---          cmd_login/unlock/lock/list/tags/inspect/delete/copy/prune
 # --- Global arg parsing ---   parse_global_args()
 # --- Main dispatcher ---      main()
 main "$@"
@@ -184,6 +226,14 @@ main "$@"
      `HM_MASTER_PASS`).
    - `openssl` is an optional dependency: not checked at startup, only on first `enc:` encounter.
 
+10. **Passphrase caching** (v0.3.0):
+    - Uses Linux kernel keyring (`keyctl` from `keyutils`) to cache the master passphrase
+      across invocations with a configurable TTL (default 300s / 5 min).
+    - `_prompt_master_pass()` checks keyring before prompting; stores after prompt.
+    - `keyctl` is optional: if not installed, each invocation prompts as before (no errors).
+    - `unlock` pre-caches the passphrase; `lock` clears it immediately.
+    - TTL configurable via `--cache-timeout <seconds>` flag or `CACHE_TIMEOUT` config key.
+
 ---
 
 ## Global Variables (key ones)
@@ -199,6 +249,7 @@ main "$@"
 | `HM_TOKEN_CACHE["registry\|scope"]` | Cached bearer token |
 | `HM_TOKEN_EXPIRY["registry\|scope"]` | Token expiry (epoch seconds) |
 | `HM_MASTER_PASS` | Master passphrase for `enc:` config values (session-cached) |
+| `HM_CACHE_TIMEOUT` | Keyring cache TTL in seconds (default 300) |
 | `HM_LAST_HTTP_CODE` | HTTP status of most recent request |
 | `HM_LAST_HEADERS_FILE` | Temp file path with response headers |
 | `HM_TMPFILES` | Array of temp files, cleaned up via `trap EXIT` |

README.md

@@ -8,6 +8,7 @@ A Bash CLI tool to manage Docker Registry images remotely. Supports Docker Hub a
 - **curl**
 - **jq**
 - **openssl** *(optional — required only when using encrypted config values)*
+- **keyctl** *(optional — from `keyutils`; enables passphrase caching across invocations)*
 
 ## Installation
 
@@ -107,6 +108,33 @@ The `enc:` prefix also works for named alias passwords (`REGISTRY_<ALIAS>_PASSWO
 On every command that reads the config, the master passphrase is prompted once and cached
 for the duration of the session.
 
+### Passphrase caching across invocations
+
+If `keyctl` (from the `keyutils` package) is installed, the master passphrase is
+automatically cached in the Linux kernel keyring for 5 minutes. Subsequent commands
+within that window will not re-prompt.
+
+```bash
+# First command prompts for passphrase, caches it for 5 min
+hubmanager list
+
+# Runs without prompting (within cache window)
+hubmanager tags myuser/myapp
+
+# Pre-cache before a scripted batch
+hubmanager unlock
+hubmanager list && hubmanager tags myuser/myapp && hubmanager inspect myuser/myapp:latest
+
+# Clear cache immediately
+hubmanager lock
+
+# Custom timeout (10 minutes)
+hubmanager unlock --cache-timeout 600
+```
+
+If `keyctl` is not installed, passphrase caching is silently skipped — each invocation
+prompts as before.
+
 ## Global Options
 
 ```text
@@ -117,6 +145,7 @@ hubmanager [OPTIONS] <command> [COMMAND OPTIONS]
   -u, --user <username>   Username (overrides config file)
   -p, --password <pass>   Password or token (overrides config file)
       --config <file>     Config file path (default: ~/.config/hubmanager.conf)
+      --cache-timeout <s> Passphrase cache TTL in seconds (default: 300)
       --json              Output raw JSON (pipe-friendly)
       --no-color          Disable ANSI color
   -v, --verbose           Show HTTP request details (with auth redacted)
@@ -147,6 +176,42 @@ hubmanager login --registry https://registry.example.com \
 
 ---
 
+### `unlock` — Cache master passphrase
+
+```text
+hubmanager unlock [--cache-timeout SECONDS]
+```
+
+Prompts for the master passphrase and stores it in the Linux kernel keyring
+for the configured timeout (default: 300 seconds / 5 minutes). Useful before
+running a batch of commands. Requires `keyctl` (keyutils package).
+
+```bash
+hubmanager unlock
+# hubmanager master passphrase: ****
+# Passphrase cached for 300s.
+
+# Custom timeout
+hubmanager unlock --cache-timeout 600
+```
+
+---
+
+### `lock` — Clear cached passphrase
+
+```text
+hubmanager lock
+```
+
+Immediately revokes the cached passphrase from the kernel keyring.
+
+```bash
+hubmanager lock
+# Passphrase cache cleared.
+```
+
+---
+
 ### `list` — List repositories
 
 ```text
@@ -442,6 +507,7 @@ hubmanager copy myuser/myapp:staging myuser/myapp:production
 | `REGISTRY` | Default registry URL |
 | `USERNAME` | Default username |
 | `PASSWORD` | Default password or token; prefix with `enc:` for encrypted values |
+| `CACHE_TIMEOUT` | Passphrase keyring cache TTL in seconds (default: 300) |
 | `REGISTRY_<ALIAS>_URL` | URL for a named registry alias |
 | `REGISTRY_<ALIAS>_USERNAME` | Username for a named alias |
 | `REGISTRY_<ALIAS>_PASSWORD` | Password for a named alias (supports `enc:` prefix) |

hubmanager

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 # hubmanager - Manage Docker Registry images remotely
-# Version: 0.2.1
+# Version: 0.3.0
 # Dependencies: curl, jq, bash 4+
 # Usage: hubmanager --help
 
@@ -9,10 +9,12 @@ set -euo pipefail
 # =============================================================================
 # --- Constants ---
 # =============================================================================
-readonly HM_VERSION="0.2.1"
+readonly HM_VERSION="0.3.0"
 readonly HM_DEFAULT_REGISTRY="https://registry-1.docker.io"
 readonly HM_DEFAULT_CONFIG="${HOME}/.config/hubmanager.conf"
 readonly HM_DOCKERHUB_API="https://hub.docker.com"
+readonly HM_KEYRING_KEY="hubmanager:master"
+readonly HM_KEYRING_DEFAULT_TIMEOUT=300   # seconds (5 minutes)
 
 # =============================================================================
 # --- Global state ---
@@ -35,6 +37,7 @@ declare -A HM_CONFIG_VARS=()  # raw config key/value pairs
 
 HM_HUB_TOKEN=""               # Docker Hub REST API token (JWT)
 HM_MASTER_PASS=""             # Master passphrase for encrypted config values (session-scoped)
+HM_CACHE_TIMEOUT="$HM_KEYRING_DEFAULT_TIMEOUT"  # Keyring cache TTL in seconds
 HM_TMPFILES=()
 HM_LAST_HTTP_CODE=""
 HM_LAST_HEADERS_FILE=""
@@ -111,14 +114,54 @@ _require_openssl() {
         die "openssl is required for encrypted config values. Install openssl and retry."
 }
 
-# Prompt once per session; result cached in HM_MASTER_PASS
+# --- Keyring helpers (optional; keyctl from keyutils) ---
+
+# Check if keyctl is available
+_keyring_available() { command -v keyctl &>/dev/null; }
+
+# Try to read the cached passphrase from the user session keyring.
+# Outputs the passphrase on stdout; returns 1 if not found or expired.
+_keyring_get() {
+    _keyring_available || return 1
+    local key_id
+    key_id=$(keyctl request user "$HM_KEYRING_KEY" 2>/dev/null) || return 1
+    keyctl pipe "$key_id" 2>/dev/null || return 1
+}
+
+# Store passphrase in the user session keyring with a TTL.
+# Args: <passphrase> [timeout_seconds]
+_keyring_set() {
+    _keyring_available || return 0
+    local pass="$1"
+    local ttl="${2:-$HM_CACHE_TIMEOUT}"
+    local key_id
+    key_id=$(keyctl add user "$HM_KEYRING_KEY" "$pass" @u 2>/dev/null) || return 0
+    keyctl timeout "$key_id" "$ttl" 2>/dev/null || true
+}
+
+# Revoke (clear) the cached passphrase from the keyring.
+_keyring_clear() {
+    _keyring_available || return 0
+    local key_id
+    key_id=$(keyctl request user "$HM_KEYRING_KEY" 2>/dev/null) || return 0
+    keyctl revoke "$key_id" 2>/dev/null || true
+}
+
+# Prompt once per session; result cached in HM_MASTER_PASS and keyring
 _prompt_master_pass() {
     [[ -n "$HM_MASTER_PASS" ]] && return 0
+    # Try keyring cache first
+    local cached
+    if cached=$(_keyring_get); then
+        HM_MASTER_PASS="$cached"
+        return 0
+    fi
     _require_openssl
     printf "hubmanager master passphrase: " >/dev/tty
     read -rs HM_MASTER_PASS </dev/tty
     printf "\n" >/dev/tty
     [[ -n "$HM_MASTER_PASS" ]] || die "Master passphrase cannot be empty."
+    _keyring_set "$HM_MASTER_PASS" "$HM_CACHE_TIMEOUT"
 }
 
 # Prompt and confirm a new master passphrase (used by login --encrypt)
@@ -132,6 +175,7 @@ _prompt_set_master_pass() {
     [[ "$pass1" == "$pass2" ]] || die "Passphrases do not match."
     [[ -n "$pass1" ]] || die "Master passphrase cannot be empty."
     HM_MASTER_PASS="$pass1"
+    _keyring_set "$HM_MASTER_PASS" "$HM_CACHE_TIMEOUT"
 }
 
 # Encrypt PLAINTEXT using AES-256-CBC; outputs base64 ciphertext (no newlines)
@@ -208,6 +252,10 @@ load_config() {
             HM_PASSWORD="$pw"
         fi
     fi
+    # Cache timeout (only override if not set via CLI)
+    if [[ "$HM_CACHE_TIMEOUT" == "$HM_KEYRING_DEFAULT_TIMEOUT" && -v 'HM_CONFIG_VARS[CACHE_TIMEOUT]' ]]; then
+        HM_CACHE_TIMEOUT="${HM_CONFIG_VARS[CACHE_TIMEOUT]}"
+    fi
 }
 
 resolve_registry_alias() {
@@ -607,6 +655,7 @@ ${C_BOLD}Options:${C_RESET}
   -u, --user <username>   Username
   -p, --password <pass>   Password or token
       --config <file>     Config file (default: ~/.config/hubmanager.conf)
+      --cache-timeout <s> Passphrase cache TTL in seconds (default: 300)
       --json              Output raw JSON
       --no-color          Disable color output
   -v, --verbose           Verbose mode
@@ -622,6 +671,8 @@ ${C_BOLD}Commands:${C_RESET}
   copy    <src> <dst>     Copy/retag an image
   prune   <image>         Delete outdated tags for an image
   login                   Test credentials and optionally save to config (--save [--encrypt])
+  unlock                  Cache master passphrase in kernel keyring (requires keyctl)
+  lock                    Clear cached master passphrase
 
 Run ${C_BOLD}hubmanager <command> --help${C_RESET} for command-specific options.
 EOF
@@ -634,6 +685,50 @@ cmd_help() { show_usage; }
 # =============================================================================
 cmd_version() { echo "hubmanager $HM_VERSION"; }
 
+# =============================================================================
+# --- Subcommand: unlock ---
+# =============================================================================
+cmd_unlock() {
+    if [[ "${1:-}" == "--help" ]]; then
+        cat <<EOF
+${C_BOLD}Usage:${C_RESET} hubmanager unlock [--timeout <seconds>]
+
+Cache the master passphrase in the Linux kernel keyring so subsequent
+commands do not re-prompt. Requires ${C_BOLD}keyctl${C_RESET} (keyutils package).
+
+  --timeout <sec>   Cache duration (default: ${HM_KEYRING_DEFAULT_TIMEOUT}s / 5 min)
+EOF
+        return 0
+    fi
+    _keyring_available || die "keyctl (keyutils) is required for passphrase caching. Install keyutils and retry."
+    _require_openssl
+    # Force a fresh prompt even if already cached
+    HM_MASTER_PASS=""
+    printf "hubmanager master passphrase: " >/dev/tty
+    read -rs HM_MASTER_PASS </dev/tty
+    printf "\n" >/dev/tty
+    [[ -n "$HM_MASTER_PASS" ]] || die "Master passphrase cannot be empty."
+    _keyring_set "$HM_MASTER_PASS" "$HM_CACHE_TIMEOUT"
+    info "Passphrase cached for ${HM_CACHE_TIMEOUT}s."
+}
+
+# =============================================================================
+# --- Subcommand: lock ---
+# =============================================================================
+cmd_lock() {
+    if [[ "${1:-}" == "--help" ]]; then
+        cat <<EOF
+${C_BOLD}Usage:${C_RESET} hubmanager lock
+
+Clear the cached master passphrase from the Linux kernel keyring.
+EOF
+        return 0
+    fi
+    _keyring_clear
+    HM_MASTER_PASS=""
+    info "Passphrase cache cleared."
+}
+
 # =============================================================================
 # --- Subcommand: login ---
 # =============================================================================
@@ -1593,8 +1688,9 @@ parse_global_args() {
             -r|--registry) HM_REGISTRY="$2"; shift 2 ;;
             -u|--user)     HM_USERNAME="$2"; shift 2 ;;
             -p|--password) HM_PASSWORD="$2"; shift 2 ;;
-            --config)      HM_CONFIG_FILE="$2"; shift 2 ;;
+            --config)        HM_CONFIG_FILE="$2"; shift 2 ;;
-            --json)        HM_OPT_JSON=true; shift ;;
+            --cache-timeout) HM_CACHE_TIMEOUT="$2"; shift 2 ;;
+            --json)          HM_OPT_JSON=true; shift ;;
             --no-color)    HM_OPT_NO_COLOR=true; shift ;;
             -v|--verbose)  HM_OPT_VERBOSE=true; shift ;;
             -q|--quiet)    HM_OPT_QUIET=true; shift ;;
@@ -1635,6 +1731,8 @@ main() {
         copy)    cmd_copy    "$@" ;;
         prune)   cmd_prune   "$@" ;;
         login)   cmd_login   "$@" ;;
+        unlock)  cmd_unlock  "$@" ;;
+        lock)    cmd_lock    "$@" ;;
         help|-h|--help)     cmd_help ;;
         version|--version)  cmd_version ;;
         *)