Remove VerifyDetachedSignatureAndSaltedHash and SaltedHashSpecifier (#…

…196)

This commit removes the openpgp.VerifyDetachedSignatureAndSaltedHash function and the packet.SaltedHashSpecifier as they are not required anymore. They were introduced for verifying the headers in cleartext messages. However, in the latest crypto refresh specification, cleartext message headers were dropped.

openpgp/packet/signature.go

@@ -127,13 +127,6 @@ type VerifiableSignature struct {
 	Packet *Signature
 }
 
-// SaltedHashSpecifier specifies that the given salt and hash are
-// used by a v6 signature.
-type SaltedHashSpecifier struct {
-	Hash crypto.Hash
-	Salt []byte
-}
-
 // NewVerifiableSig returns a struct of type VerifiableSignature referencing the input signature.
 func NewVerifiableSig(signature *Signature) *VerifiableSignature {
 	return &VerifiableSignature{

openpgp/read.go

@@ -6,7 +6,6 @@
 package openpgp // import "github.com/ProtonMail/go-crypto/openpgp"
 
 import (
-	"bytes"
 	"crypto"
 	_ "crypto/sha256"
 	_ "crypto/sha512"
@@ -455,45 +454,32 @@ func (scr *signatureCheckReader) Read(buf []byte) (int, error) {
 // if any, and a possible signature verification error.
 // If the signer isn't known, ErrUnknownIssuer is returned.
 func VerifyDetachedSignature(keyring KeyRing, signed, signature io.Reader, config *packet.Config) (sig *packet.Signature, signer *Entity, err error) {
-	return verifyDetachedSignature(keyring, signed, signature, nil, nil, false, config)
+	return verifyDetachedSignature(keyring, signed, signature, nil, false, config)
 }
 
 // VerifyDetachedSignatureAndHash performs the same actions as
 // VerifyDetachedSignature and checks that the expected hash functions were used.
 func VerifyDetachedSignatureAndHash(keyring KeyRing, signed, signature io.Reader, expectedHashes []crypto.Hash, config *packet.Config) (sig *packet.Signature, signer *Entity, err error) {
-	return verifyDetachedSignature(keyring, signed, signature, expectedHashes, nil, true, config)
-}
-
-// VerifyDetachedSignatureAndSaltedHash performs the same actions as
-// VerifyDetachedSignature and checks that the expected hash functions and salts were used.
-func VerifyDetachedSignatureAndSaltedHash(keyring KeyRing, signed, signature io.Reader, expectedHashes []crypto.Hash, expectedSaltedHashes []*packet.SaltedHashSpecifier, config *packet.Config) (sig *packet.Signature, signer *Entity, err error) {
-	return verifyDetachedSignature(keyring, signed, signature, expectedHashes, expectedSaltedHashes, true, config)
+	return verifyDetachedSignature(keyring, signed, signature, expectedHashes, true, config)
 }
 
 // CheckDetachedSignature takes a signed file and a detached signature and
 // returns the entity the signature was signed by, if any, and a possible
 // signature verification error. If the signer isn't known,
 // ErrUnknownIssuer is returned.
 func CheckDetachedSignature(keyring KeyRing, signed, signature io.Reader, config *packet.Config) (signer *Entity, err error) {
-	_, signer, err = verifyDetachedSignature(keyring, signed, signature, nil, nil, false, config)
-	return
-}
-
-// CheckDetachedSignatureAndSaltedHash performs the same actions as
-// CheckDetachedSignature and checks that the expected hash functions or salted hash functions were used.
-func CheckDetachedSignatureAndSaltedHash(keyring KeyRing, signed, signature io.Reader, expectedHashes []crypto.Hash, expectedSaltedHashes []*packet.SaltedHashSpecifier, config *packet.Config) (signer *Entity, err error) {
-	_, signer, err = verifyDetachedSignature(keyring, signed, signature, expectedHashes, expectedSaltedHashes, true, config)
+	_, signer, err = verifyDetachedSignature(keyring, signed, signature, nil, false, config)
 	return
 }
 
 // CheckDetachedSignatureAndHash performs the same actions as
 // CheckDetachedSignature and checks that the expected hash functions were used.
 func CheckDetachedSignatureAndHash(keyring KeyRing, signed, signature io.Reader, expectedHashes []crypto.Hash, config *packet.Config) (signer *Entity, err error) {
-	_, signer, err = verifyDetachedSignature(keyring, signed, signature, expectedHashes, nil, true, config)
+	_, signer, err = verifyDetachedSignature(keyring, signed, signature, expectedHashes, true, config)
 	return
 }
 
-func verifyDetachedSignature(keyring KeyRing, signed, signature io.Reader, expectedHashes []crypto.Hash, expectedSaltedHashes []*packet.SaltedHashSpecifier, checkHashes bool, config *packet.Config) (sig *packet.Signature, signer *Entity, err error) {
+func verifyDetachedSignature(keyring KeyRing, signed, signature io.Reader, expectedHashes []crypto.Hash, checkHashes bool, config *packet.Config) (sig *packet.Signature, signer *Entity, err error) {
 	var issuerKeyId uint64
 	var hashFunc crypto.Hash
 	var sigType packet.SignatureType
@@ -523,22 +509,11 @@ func verifyDetachedSignature(keyring KeyRing, signed, signature io.Reader, expec
 		sigType = sig.SigType
 		if checkHashes {
 			matchFound := false
-			if sig.Version == 6 {
-				// check for salted hashes
-				for _, expectedSaltedHash := range expectedSaltedHashes {
-					if hashFunc == expectedSaltedHash.Hash && bytes.Equal(sig.Salt(), expectedSaltedHash.Salt) {
-						matchFound = true
-						break
-					}
-				}
-
-			} else {
-				// check for hashes
-				for _, expectedHash := range expectedHashes {
-					if hashFunc == expectedHash {
-						matchFound = true
-						break
-					}
+			// check for hashes
+			for _, expectedHash := range expectedHashes {
+				if hashFunc == expectedHash {
+					matchFound = true
+					break
 				}
 			}
 			if !matchFound {

openpgp/v2/read.go

@@ -669,8 +669,6 @@ func VerifyDetachedSignature(keyring KeyRing, signed, signature io.Reader, confi
 // Once all data is read from md.UnverifiedBody the detached signature is verified.
 // If a verification error occurs it is stored in md.SignatureError
 // If the signer isn't known, ErrUnknownIssuer is returned.
-// If expectedHashes or expectedSaltedHashes is not nil, the method checks
-// if they match the signatures metadata or else return an error
 func VerifyDetachedSignatureReader(keyring KeyRing, signed, signature io.Reader, config *packet.Config) (md *MessageDetails, err error) {
 	return verifyDetachedSignatureReader(keyring, signed, signature, config)
 }