fix: resolve critical security vulnerabilities in debug logging and command execution

- Remove sensitive data from debug logs (vault/secrets.go, secret/version.go)
- Add input validation for GPG key IDs and keychain item names
- Resolve GPG key IDs to full fingerprints before storing in metadata
- Add comprehensive test coverage for validation functions
- Add golangci-lint configuration with additional linters

Security improvements:
- Debug logs no longer expose decrypted secret values or private keys
- GPG and keychain commands now validate input to prevent injection attacks
- All validation uses precompiled regex patterns for performance

internal/secret/pgpunlocker.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"regexp"
 	"strings"
 	"time"
 
@@ -24,6 +25,19 @@ var (
 	// GPGDecryptFunc is the function used for GPG decryption
 	// Can be overridden in tests to provide a non-interactive implementation
 	GPGDecryptFunc = gpgDecryptDefault
+
+	// gpgKeyIDRegex validates GPG key IDs
+	// Allows either:
+	// 1. Email addresses (user@domain.tld format)
+	// 2. Short key IDs (8 hex characters)
+	// 3. Long key IDs (16 hex characters)
+	// 4. Full fingerprints (40 hex characters)
+	gpgKeyIDRegex = regexp.MustCompile(
+		`^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}$|` +
+			`^[A-Fa-f0-9]{8}$|` +
+			`^[A-Fa-f0-9]{16}$|` +
+			`^[A-Fa-f0-9]{40}$`,
+	)
 )
 
 // PGPUnlockerMetadata extends UnlockerMetadata with PGP-specific data
@@ -285,14 +299,20 @@ func CreatePGPUnlocker(fs afero.Fs, stateDir string, gpgKeyID string) (*PGPUnloc
 		return nil, fmt.Errorf("failed to write encrypted age private key: %w", err)
 	}
 
-	// Step 9: Create and write enhanced metadata
+	// Step 9: Resolve the GPG key ID to its full fingerprint
+	fingerprint, err := resolveGPGKeyFingerprint(gpgKeyID)
+	if err != nil {
+		return nil, fmt.Errorf("failed to resolve GPG key fingerprint: %w", err)
+	}
+
+	// Step 10: Create and write enhanced metadata with full fingerprint
 	pgpMetadata := PGPUnlockerMetadata{
 		UnlockerMetadata: UnlockerMetadata{
 			Type:      "pgp",
 			CreatedAt: time.Now(),
 			Flags:     []string{"gpg", "encrypted"},
 		},
-		GPGKeyID: gpgKeyID,
+		GPGKeyID: fingerprint,
 	}
 
 	metadataBytes, err := json.MarshalIndent(pgpMetadata, "", "  ")
@@ -311,6 +331,46 @@ func CreatePGPUnlocker(fs afero.Fs, stateDir string, gpgKeyID string) (*PGPUnloc
 	}, nil
 }
 
+// validateGPGKeyID validates that a GPG key ID is safe for command execution
+func validateGPGKeyID(keyID string) error {
+	if keyID == "" {
+		return fmt.Errorf("GPG key ID cannot be empty")
+	}
+
+	if !gpgKeyIDRegex.MatchString(keyID) {
+		return fmt.Errorf("invalid GPG key ID format: %s", keyID)
+	}
+
+	return nil
+}
+
+// resolveGPGKeyFingerprint resolves any GPG key identifier to its full fingerprint
+func resolveGPGKeyFingerprint(keyID string) (string, error) {
+	if err := validateGPGKeyID(keyID); err != nil {
+		return "", fmt.Errorf("invalid GPG key ID: %w", err)
+	}
+
+	// Use GPG to get the full fingerprint for the key
+	cmd := exec.Command("gpg", "--list-keys", "--with-colons", "--fingerprint", keyID)
+	output, err := cmd.Output()
+	if err != nil {
+		return "", fmt.Errorf("failed to resolve GPG key fingerprint: %w", err)
+	}
+
+	// Parse the output to extract the fingerprint
+	lines := strings.Split(string(output), "\n")
+	for _, line := range lines {
+		if strings.HasPrefix(line, "fpr:") {
+			fields := strings.Split(line, ":")
+			if len(fields) >= 10 && fields[9] != "" {
+				return fields[9], nil
+			}
+		}
+	}
+
+	return "", fmt.Errorf("could not find fingerprint for GPG key: %s", keyID)
+}
+
 // checkGPGAvailable verifies that GPG is available
 func checkGPGAvailable() error {
 	cmd := exec.Command("gpg", "--version")
@@ -322,6 +382,10 @@ func checkGPGAvailable() error {
 
 // gpgEncryptDefault is the default implementation of GPG encryption
 func gpgEncryptDefault(data []byte, keyID string) ([]byte, error) {
+	if err := validateGPGKeyID(keyID); err != nil {
+		return nil, fmt.Errorf("invalid GPG key ID: %w", err)
+	}
+
 	cmd := exec.Command("gpg", "--trust-model", "always", "--armor", "--encrypt", "-r", keyID)
 	cmd.Stdin = strings.NewReader(string(data))