Add auth middleware

pkg/api/middleware/es256k.go

@@ -0,0 +1,91 @@
+package middleware
+
+// copied from https://gist.github.com/bnewbold/bc9b97c9b281295da1fa47c03b0b3c69
+
+import (
+	"crypto"
+	"errors"
+	"fmt"
+
+	atcrypto "github.com/bluesky-social/indigo/atproto/crypto"
+	"github.com/golang-jwt/jwt/v5"
+)
+
+var (
+	SigningMethodES256K *SigningMethodAtproto
+	SigningMethodES256  *SigningMethodAtproto
+)
+
+type SigningMethodAtproto struct {
+	alg      string
+	hash     crypto.Hash
+	toOutSig toOutSig
+	sigLen   int
+}
+
+type toOutSig func(sig []byte) []byte
+
+func init() {
+	SigningMethodES256K = &SigningMethodAtproto{
+		alg:      "ES256K",
+		hash:     crypto.SHA256,
+		toOutSig: toES256K,
+		sigLen:   64,
+	}
+	jwt.RegisterSigningMethod(SigningMethodES256K.Alg(), func() jwt.SigningMethod {
+		return SigningMethodES256K
+	})
+	SigningMethodES256 = &SigningMethodAtproto{
+		alg:      "ES256",
+		hash:     crypto.SHA256,
+		toOutSig: toES256,
+		sigLen:   64,
+	}
+	jwt.RegisterSigningMethod(SigningMethodES256.Alg(), func() jwt.SigningMethod {
+		return SigningMethodES256
+	})
+	fmt.Println("init Completed")
+}
+
+// Errors returned on different problems.
+var (
+	ErrWrongKeyFormat  = errors.New("wrong key type")
+	ErrBadSignature    = errors.New("bad signature")
+	ErrVerification    = errors.New("signature verification failed")
+	ErrFailedSigning   = errors.New("failed generating signature")
+	ErrHashUnavailable = errors.New("hasher unavailable")
+)
+
+func (sm *SigningMethodAtproto) Verify(signingString string, sig []byte, key any) error {
+	pub, ok := key.(atcrypto.PublicKey)
+	if !ok {
+		return ErrWrongKeyFormat
+	}
+
+	if !sm.hash.Available() {
+		return ErrHashUnavailable
+	}
+
+	if len(sig) != sm.sigLen {
+		return ErrBadSignature
+	}
+
+	return pub.HashAndVerifyLenient([]byte(signingString), sig)
+}
+
+func (sm *SigningMethodAtproto) Sign(signingString string, key any) ([]byte, error) {
+	// TODO: implement signatures
+	return nil, ErrFailedSigning
+}
+
+func (sm *SigningMethodAtproto) Alg() string {
+	return sm.alg
+}
+
+func toES256K(sig []byte) []byte {
+	return sig[:64]
+}
+
+func toES256(sig []byte) []byte {
+	return sig[:64]
+}