first commit

internal/token/token.go

@@ -0,0 +1,60 @@
+package token
+
+import (
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"fmt"
+	"strings"
+)
+
+const TokenLength = 32 // 32 bytes = 256 bits per token
+
+// Tokens holds the 3 authentication tokens
+type Tokens struct {
+	Token1 string `json:"token1"`
+	Token2 string `json:"token2"`
+	Token3 string `json:"token3"`
+}
+
+// Generate creates 3 cryptographically random tokens
+func Generate() (*Tokens, error) {
+	t := &Tokens{}
+	var err error
+
+	t.Token1, err = randomToken()
+	if err != nil {
+		return nil, fmt.Errorf("generating token 1: %w", err)
+	}
+	t.Token2, err = randomToken()
+	if err != nil {
+		return nil, fmt.Errorf("generating token 2: %w", err)
+	}
+	t.Token3, err = randomToken()
+	if err != nil {
+		return nil, fmt.Errorf("generating token 3: %w", err)
+	}
+
+	return t, nil
+}
+
+// Hash computes the SHA256 hash of the 3 tokens combined
+func (t *Tokens) Hash() string {
+	combined := strings.Join([]string{t.Token1, t.Token2, t.Token3}, ":")
+	sum := sha256.Sum256([]byte(combined))
+	return fmt.Sprintf("%x", sum)
+}
+
+// HashFromString computes the hash from a pre-combined token string
+func HashFromTokens(token1, token2, token3 string) string {
+	t := &Tokens{Token1: token1, Token2: token2, Token3: token3}
+	return t.Hash()
+}
+
+func randomToken() (string, error) {
+	b := make([]byte, TokenLength)
+	if _, err := rand.Read(b); err != nil {
+		return "", err
+	}
+	return base64.URLEncoding.EncodeToString(b), nil
+}