# Token Prefix Security Recommendations

## Current Security Issues

### 1. Information Disclosure
- Prefixes like "KMS", "TEST", "PROD" expose system architecture
- Makes it easy for attackers to identify token origins and purposes
- Leaks information about internal applications and environments

### 2. Predictable Token Structure  
- Static tokens: `PREFIX + "T-" + token_data`
- User tokens: `PREFIX + "UT-" + jwt_token`
- Highly predictable format aids in token identification and potential attacks

### 3. Application Fingerprinting
- Trivial to map tokens to specific applications
- Easy to identify different environments (dev/staging/prod)
- Reveals system architecture from leaked tokens

## Recommended Security Improvements

### Option 1: Remove Custom Prefixes (Recommended)
```go
// Use a single, non-descriptive prefix for all tokens
const SecureTokenPrefix = "kms_"

// All tokens would be: kms_<random_data>
// No application or type information revealed
```

### Option 2: Opaque Application Identifiers
```go
// Use random/hashed identifiers instead of descriptive names
type Application struct {
    AppID       string `json:"app_id"`
    TokenPrefix string `json:"token_prefix"` // Random: "A7B2", "X9K5", etc.
}

// Generate random 4-character prefixes
func GenerateSecurePrefix() string {
    const charset = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
    result := make([]byte, 4)
    for i := range result {
        result[i] = charset[rand.Intn(len(charset))]
    }
    return string(result)
}
```

### Option 3: No Type Indicators
```go
// Remove "T-" and "UT-" type indicators
// Token type should be determined by validation, not structure
func GenerateToken(appPrefix string, tokenType string) string {
    token := appPrefix + randomTokenData  // No type suffix
    return token
}
```

### Option 4: Encrypted Token Metadata
```go
// Encrypt sensitive information within tokens
type TokenMetadata struct {
    AppID     string    `json:"app_id"`
    TokenType string    `json:"token_type"`
    IssuedAt  time.Time `json:"issued_at"`
}

func CreateSecureToken(metadata TokenMetadata, key []byte) string {
    // Encrypt metadata and embed in token
    encrypted := encrypt(metadata, key)
    return "kms_" + base64.URLEncoding.EncodeToString(encrypted)
}
```

## Implementation Priority

1. **Immediate**: Remove descriptive prefixes ("KMS", "TEST", "PROD")
2. **Short-term**: Remove type indicators ("T-", "UT-")  
3. **Long-term**: Implement encrypted token metadata

## Security Best Practices

### Token Storage
- Always hash tokens before database storage
- Use strong hashing algorithms (bcrypt, scrypt, Argon2)
- Never log or expose full tokens

### Token Validation
- Validate tokens by content, not by prefix patterns
- Use cryptographic verification for all tokens
- Implement proper token revocation mechanisms

### Monitoring
- Monitor for token enumeration attempts
- Alert on suspicious prefix-based attacks
- Log token validation failures for security analysis

## Code Changes Required

### 1. Update Token Generation
```go
// Before: Predictable structure
token := "TESTT-" + tokenData

// After: Opaque structure  
token := "kms_" + secureRandomToken()
```

### 2. Update Validation Logic
```go
// Before: Prefix-based type detection
if strings.HasPrefix(token, app.TokenPrefix + "UT-") {
    return TokenTypeUser
}

// After: Cryptographic validation
tokenType, err := validateAndExtractType(token, app.HMACKey)
```

### 3. Database Migration
```sql
-- Remove descriptive prefixes from existing tokens
UPDATE applications 
SET token_prefix = 'kms_' 
WHERE token_prefix IN ('KMS', 'TEST', 'PROD', 'DEV');
```

## Risk Assessment

**Current Risk Level**: HIGH
- Token structure reveals sensitive system information
- Easy application and environment fingerprinting
- Predictable token patterns aid in attacks

**Mitigated Risk Level**: LOW
- Opaque token structure prevents information leakage
- No application or environment identification possible
- Cryptographic validation ensures security