fixed typos, added error prefix and added usage to README.md

README.md

@@ -1 +1,61 @@
-# jwt - a simple JSON Web Token library in Go
+# jwt - a simple JSON Web Token library written in Go
+
+## Usage
+
+```
+package main
+
+import (
+	"fmt"
+	"git.giftfish.de/ston1th/jwt"
+	"log"
+	"time"
+)
+
+func main() {
+	// create a new signing instance
+	JWT, err := jwt.New(time.Hour, jwt.NewMemBlacklist(), nil)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// create a new token
+	t := jwt.NewToken(jwt.Claims{
+		"username": "admin",
+	}, nil)
+
+	// sign the token
+	err = JWT.Sign(t)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// print the token string
+	token := t.String()
+	fmt.Println(token)
+
+	// decode the token string
+	newToken, err := jwt.DecodeToken(token)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// verify the decoded token
+	err = JWT.Verify(newToken)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// add the token to the blacklist
+	err = JWT.Invalidate(newToken)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// try to verify the blacklisted token, it should fail
+	err = JWT.Verify(newToken)
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+```

jwt.go

@@ -39,21 +39,23 @@ const (
 // DefaultSecretReader is the default secret key generator
 var DefaultSecretReader = rand.Reader
 
+const jwtErr = "jwt: "
+
 var (
-	ErrNoJWT               = errors.New("not a json web token")
+	ErrNoJWT               = errors.New(jwtErr + "not a json web token")
-	ErrEmptyToken          = errors.New("token is empty")
+	ErrEmptyToken          = errors.New(jwtErr + "token is empty")
-	ErrUnsupportedAlg      = errors.New("unsupported algorithm")
+	ErrUnsupportedAlg      = errors.New(jwtErr + "unsupported algorithm")
-	ErrInvalid             = errors.New("token validation failed")
+	ErrInvalid             = errors.New(jwtErr + "token validation failed")
-	ErrBlacklisted         = errors.New("token blacklisted")
+	ErrBlacklisted         = errors.New(jwtErr + "token blacklisted")
-	ErrBlacklistNotEnabled = errors.New("blacklisting is not enabled")
+	ErrBlacklistNotEnabled = errors.New(jwtErr + "blacklisting is not enabled")
-	ErrNbf                 = errors.New("token not valid yet")
+	ErrNbf                 = errors.New(jwtErr + "token not valid yet")
-	ErrExp                 = errors.New("token expired")
+	ErrExp                 = errors.New(jwtErr + "token expired")
-	ErrMissingNbf          = errors.New("missing nbf claim")
+	ErrMissingNbf          = errors.New(jwtErr + "missing nbf claim")
-	ErrMissingExp          = errors.New("missing exp claim")
+	ErrMissingExp          = errors.New(jwtErr + "missing exp claim")
-	ErrMissingTokenParts   = errors.New("missing token parts")
+	ErrMissingTokenParts   = errors.New(jwtErr + "missing token parts")
-	ErrEmptySignature      = errors.New("token signature is empty")
+	ErrEmptySignature      = errors.New(jwtErr + "token signature is empty")
-	ErrTokenIsNil          = errors.New("token is nil")
+	ErrTokenIsNil          = errors.New(jwtErr + "token is nil")
-	ErrInvalidKeySize      = errors.New("invalid secret key size")
+	ErrInvalidKeySize      = errors.New(jwtErr + "invalid secret key size")
 )
 
 // JWT represents the JSON Web Token signing and blacklisting infrastructure
@@ -83,7 +85,7 @@ func New(expiry time.Duration, blacklist Blacklist, secret io.Reader) (*JWT, err
 	key := make([]byte, KeySize)
 	i, err := secret.Read(key)
 	if err != nil {
-		return nil, errors.New("secret reader error: " + err.Error())
+		return nil, errors.New(jwtErr + "secret reader error: " + err.Error())
 	}
 	if i < KeySize {
 		return nil, ErrInvalidKeySize
@@ -250,7 +252,7 @@ func (jwt *JWT) Verify(t *Token) error {
 	return nil
 }
 
-// Stop will end the cleaner goroutinge execution
+// Stop will end the cleaner goroutine execution
 func (jwt *JWT) Stop() error {
 	if jwt.blacklist == nil {
 		return ErrBlacklistNotEnabled

token.go

@@ -8,7 +8,7 @@ import (
 	"strings"
 )
 
-// Token is the JWT token representation
+// Token represents a JWT token
 type Token struct {
 	raw          string
 	data         string
@@ -23,17 +23,17 @@ func (t *Token) String() string {
 	return t.raw
 }
 
-// Sig returns the Tokens URLEncoded signature
+// Sig returns the tokens URLEncoded signature
 func (t *Token) Sig() string {
 	return t.signature
 }
 
-// RawSig returns the Tokens raw signature
+// RawSig returns the tokens raw signature
 func (t *Token) RawSig() []byte {
 	return t.rawSignature
 }
 
-// Data returns the first two token fields
+// Data returns the first two URLEncoded token fields
 func (t *Token) Data() string {
 	return t.data
 }