63 lines
1.5 KiB
Go
63 lines
1.5 KiB
Go
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package pow
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import (
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"crypto/rand"
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"time"
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)
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// Generator handles creation of PoW challenges with HMAC signing
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type Generator struct {
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config *Config
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}
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// GenerateOption represents a functional option for challenge generation
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type generateOption func(*Challenge)
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// WithDifficulty sets custom difficulty for the challenge
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func WithDifficulty(difficulty int) generateOption {
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return func(c *Challenge) {
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c.Difficulty = difficulty
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}
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}
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// NewGenerator creates a new challenge generator
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func NewGenerator(config *Config) *Generator {
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return &Generator{
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config: config,
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}
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}
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// GenerateChallenge creates a new HMAC-signed PoW challenge
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func (g *Generator) GenerateChallenge(opts ...generateOption) (*Challenge, error) {
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// Create challenge with defaults (no random data yet)
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challenge := &Challenge{
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Timestamp: time.Now().Unix(),
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Difficulty: g.config.DefaultDifficulty,
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Resource: g.config.Resource,
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}
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// Apply options
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for _, opt := range opts {
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opt(challenge)
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}
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// Validate difficulty bounds
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if challenge.Difficulty < g.config.MinDifficulty || challenge.Difficulty > g.config.MaxDifficulty {
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return nil, ErrInvalidDifficulty
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}
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// Generate cryptographic random data
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challenge.Random = g.generateRandom(g.config.RandomBytes)
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// Sign the challenge with HMAC
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challenge.Sign(g.config.HMACSecret)
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return challenge, nil
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}
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// generateRandom creates cryptographic random bytes
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func (g *Generator) generateRandom(length int) []byte {
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bytes := make([]byte, length)
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rand.Read(bytes)
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return bytes
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}
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