go/src/crypto/tls/auth.go

// verifyHandshakeSignature verifies a signature against pre-hashed
// (if required) handshake contents.
func verifyHandshakeSignature(sigType uint8, pubkey crypto.PublicKey, hashFunc crypto.Hash, signed, sig []byte) error { … }

const serverSignatureContext …

const clientSignatureContext …

var signaturePadding …

// signedMessage returns the pre-hashed (if necessary) message to be signed by
// certificate keys in TLS 1.3. See RFC 8446, Section 4.4.3.
func signedMessage(sigHash crypto.Hash, context string, transcript hash.Hash) []byte { … }

// typeAndHashFromSignatureScheme returns the corresponding signature type and
// crypto.Hash for a given TLS SignatureScheme.
func typeAndHashFromSignatureScheme(signatureAlgorithm SignatureScheme) (sigType uint8, hash crypto.Hash, err error) { … }

// legacyTypeAndHashFromPublicKey returns the fixed signature type and crypto.Hash for
// a given public key used with TLS 1.0 and 1.1, before the introduction of
// signature algorithm negotiation.
func legacyTypeAndHashFromPublicKey(pub crypto.PublicKey) (sigType uint8, hash crypto.Hash, err error) { … }

var rsaSignatureSchemes …

// signatureSchemesForCertificate returns the list of supported SignatureSchemes
// for a given certificate, based on the public key and the protocol version,
// and optionally filtered by its explicit SupportedSignatureAlgorithms.
//
// This function must be kept in sync with supportedSignatureAlgorithms.
// FIPS filtering is applied in the caller, selectSignatureScheme.
func signatureSchemesForCertificate(version uint16, cert *Certificate) []SignatureScheme { … }

// selectSignatureScheme picks a SignatureScheme from the peer's preference list
// that works with the selected certificate. It's only called for protocol
// versions that support signature algorithms, so TLS 1.2 and 1.3.
func selectSignatureScheme(vers uint16, c *Certificate, peerAlgs []SignatureScheme) (SignatureScheme, error) { … }

// unsupportedCertificateError returns a helpful error for certificates with
// an unsupported private key.
func unsupportedCertificateError(cert *Certificate) error { … }