139 lines
3.1 KiB
Go
139 lines
3.1 KiB
Go
package events
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import (
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"bytes"
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"encoding/hex"
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"fmt"
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"git.wisehodl.dev/jay/go-roots/errors"
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"github.com/btcsuite/btcd/btcec/v2/schnorr"
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)
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// Validate performs a complete event validation: structure, ID computation,
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// and signature verification. Returns the first error encountered.
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func Validate(e Event) error {
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if err := ValidateStructure(e); err != nil {
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return err
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}
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idBytes, err := checkIDMatch(e)
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if err != nil {
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return err
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}
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return validateSignatureBytes(idBytes, e.Sig, e.PubKey)
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}
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// ValidateStructure checks that all event fields conform to the protocol
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// specification: hex lengths, tag structure, and field formats.
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func ValidateStructure(e Event) error {
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if !IsValidKey(e.PubKey) {
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return errors.MalformedPubKey
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}
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if !IsValidID(e.ID) {
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return errors.MalformedID
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}
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if !IsValidSig(e.Sig) {
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return errors.MalformedSig
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}
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for _, tag := range e.Tags {
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if len(tag) < 2 {
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return errors.MalformedTag
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}
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}
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return nil
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}
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// ValidateID recomputes the event ID and verifies it matches the stored ID field.
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func ValidateID(e Event) error {
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_, err := checkIDMatch(e)
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return err
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}
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// ValidateSignature verifies the event signature is cryptographically valid
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// for the event ID and public key using Schnorr verification.
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func ValidateSignature(e Event) error {
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idBytes, err := hex.DecodeString(e.ID)
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if err != nil {
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return fmt.Errorf("invalid event id hex: %w", err)
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}
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return validateSignatureBytes(idBytes, e.Sig, e.PubKey)
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}
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// Value validators
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// IsValidKey verifies that a public or private key is properly formatted.
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func IsValidKey(value string) bool {
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return isLowerHex(value, 64)
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}
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// IsValidKey verifies that an event id is properly formatted.
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func IsValidID(value string) bool {
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return isLowerHex(value, 64)
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}
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// IsValidKey verifies that an event signature is properly formatted.
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func IsValidSig(value string) bool {
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return isLowerHex(value, 128)
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}
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// Helpers
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func checkIDMatch(e Event) ([]byte, error) {
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idHash := GetIDBytes(e)
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idBytes, err := hex.DecodeString(e.ID)
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if err != nil {
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return nil, errors.MalformedID
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}
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if !bytes.Equal(idBytes, idHash[:]) {
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return nil, fmt.Errorf(
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"event id %q does not match computed id %q",
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e.ID, hex.EncodeToString(idHash[:]))
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}
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return idBytes, nil
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}
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func validateSignatureBytes(idBytes []byte, sigHex, pkHex string) error {
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sigBytes, err := hex.DecodeString(sigHex)
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if err != nil {
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return fmt.Errorf("invalid event signature hex: %w", err)
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}
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pkBytes, err := hex.DecodeString(pkHex)
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if err != nil {
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return fmt.Errorf("invalid public key hex: %w", err)
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}
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signature, err := schnorr.ParseSignature(sigBytes)
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if err != nil {
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return fmt.Errorf("malformed signature: %w", err)
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}
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publicKey, err := schnorr.ParsePubKey(pkBytes)
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if err != nil {
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return fmt.Errorf("malformed public key: %w", err)
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}
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if signature.Verify(idBytes, publicKey) {
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return nil
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}
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return errors.InvalidSig
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}
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func isLowerHex(s string, n int) bool {
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if len(s) != n {
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return false
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}
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for i := 0; i < n; i++ {
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c := s[i]
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if (c < '0' || c > '9') && (c < 'a' || c > 'f') {
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return false
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}
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}
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return true
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}
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