mirror of
https://github.com/unidoc/unipdf.git
synced 2025-04-29 13:48:54 +08:00
Address core golint recommendations in crypt, io
This commit is contained in:
Gunnsteinn Hall
parent
a9f70a16ac
commit
ad47c116aa
@ -18,10 +18,9 @@ import (
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"github.com/unidoc/unidoc/common"
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)
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/*
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* The PDF standard supports encryption of strings and streams.
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* Section 7.6.
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*/
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// PdfCrypt provides PDF encryption/decryption support.
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// The PDF standard supports encryption of strings and streams (Section 7.6).
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// TODO (v3): Consider unexporting.
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type PdfCrypt struct {
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Filter string
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Subfilter string
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@ -45,6 +44,7 @@ type PdfCrypt struct {
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parser *PdfParser
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}
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// AccessPermissions is a list of access permissions for a PDF file.
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type AccessPermissions struct {
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Printing bool
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Modify bool
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@ -66,21 +66,26 @@ const padding = "\x28\xBF\x4E\x5E\x4E\x75\x8A\x41\x64\x00\x4E\x56\xFF" +
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"\xFA\x01\x08\x2E\x2E\x00\xB6\xD0\x68\x3E\x80\x2F\x0C" +
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"\xA9\xFE\x64\x53\x69\x7A"
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// CryptFilter represents information from a CryptFilter dictionary.
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// TODO (v3): Unexport.
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type CryptFilter struct {
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Cfm string
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Length int
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}
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// CryptFilters is a map of crypt filter name and underlying CryptFilter info.
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// TODO (v3): Unexport.
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type CryptFilters map[string]CryptFilter
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// Load crypt filter information from the encryption dictionary (V4 only).
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func (this *PdfCrypt) LoadCryptFilters(ed *PdfObjectDictionary) error {
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this.CryptFilters = CryptFilters{}
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// LoadCryptFilters loads crypt filter information from the encryption dictionary (V4 only).
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// TODO (v3): Unexport.
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func (crypt *PdfCrypt) LoadCryptFilters(ed *PdfObjectDictionary) error {
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crypt.CryptFilters = CryptFilters{}
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obj := ed.Get("CF")
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obj = TraceToDirectObject(obj) // XXX may need to resolve reference...
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if ref, isRef := obj.(*PdfObjectReference); isRef {
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o, err := this.parser.LookupByReference(*ref)
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o, err := crypt.parser.LookupByReference(*ref)
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if err != nil {
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common.Log.Debug("Error looking up CF reference")
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return err
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@ -98,7 +103,7 @@ func (this *PdfCrypt) LoadCryptFilters(ed *PdfObjectDictionary) error {
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v := cf.Get(name)
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if ref, isRef := v.(*PdfObjectReference); isRef {
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o, err := this.parser.LookupByReference(*ref)
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o, err := crypt.parser.LookupByReference(*ref)
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if err != nil {
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common.Log.Debug("Error lookup up dictionary reference")
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return err
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@ -163,34 +168,34 @@ func (this *PdfCrypt) LoadCryptFilters(ed *PdfObjectDictionary) error {
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cf.Length = int(*length)
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}
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this.CryptFilters[string(name)] = cf
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crypt.CryptFilters[string(name)] = cf
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}
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// Cannot be overwritten.
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this.CryptFilters["Identity"] = CryptFilter{}
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crypt.CryptFilters["Identity"] = CryptFilter{}
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// StrF strings filter.
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this.StringFilter = "Identity"
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crypt.StringFilter = "Identity"
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if strf, ok := ed.Get("StrF").(*PdfObjectName); ok {
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if _, exists := this.CryptFilters[string(*strf)]; !exists {
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if _, exists := crypt.CryptFilters[string(*strf)]; !exists {
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return fmt.Errorf("Crypt filter for StrF not specified in CF dictionary (%s)", *strf)
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}
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this.StringFilter = string(*strf)
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crypt.StringFilter = string(*strf)
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}
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// StmF streams filter.
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this.StreamFilter = "Identity"
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crypt.StreamFilter = "Identity"
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if stmf, ok := ed.Get("StmF").(*PdfObjectName); ok {
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if _, exists := this.CryptFilters[string(*stmf)]; !exists {
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if _, exists := crypt.CryptFilters[string(*stmf)]; !exists {
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return fmt.Errorf("Crypt filter for StmF not specified in CF dictionary (%s)", *stmf)
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}
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this.StreamFilter = string(*stmf)
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crypt.StreamFilter = string(*stmf)
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}
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return nil
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}
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// Prepare the document crypt handler based on the encryption dictionary
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// and trailer dictionary.
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// PdfCryptMakeNew makes the document crypt handler based on the encryption dictionary
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// and trailer dictionary. Returns an error on failure to process.
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func PdfCryptMakeNew(parser *PdfParser, ed, trailer *PdfObjectDictionary) (PdfCrypt, error) {
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crypter := PdfCrypt{}
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crypter.DecryptedObjects = map[PdfObject]bool{}
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@ -306,10 +311,11 @@ func PdfCryptMakeNew(parser *PdfParser, ed, trailer *PdfObjectDictionary) (PdfCr
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return crypter, nil
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}
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func (this *PdfCrypt) GetAccessPermissions() AccessPermissions {
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// GetAccessPermissions returns the PDF access permissions as an AccessPermissions object.
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func (crypt *PdfCrypt) GetAccessPermissions() AccessPermissions {
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perms := AccessPermissions{}
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P := this.P
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P := crypt.P
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if P&(1<<2) > 0 {
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perms.Printing = true
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}
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@ -337,6 +343,7 @@ func (this *PdfCrypt) GetAccessPermissions() AccessPermissions {
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return perms
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}
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// GetP returns the P entry to be used in Encrypt dictionary based on AccessPermissions settings.
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func (perms AccessPermissions) GetP() int32 {
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var P int32 = 0
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@ -367,22 +374,21 @@ func (perms AccessPermissions) GetP() int32 {
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return P
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}
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// Check whether the specified password can be used to decrypt the
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// document.
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func (this *PdfCrypt) authenticate(password []byte) (bool, error) {
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// Check whether the specified password can be used to decrypt the document.
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func (crypt *PdfCrypt) authenticate(password []byte) (bool, error) {
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// Also build the encryption/decryption key.
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this.Authenticated = false
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crypt.Authenticated = false
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// Try user password.
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common.Log.Trace("Debugging authentication - user pass")
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authenticated, err := this.Alg6(password)
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authenticated, err := crypt.Alg6(password)
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if err != nil {
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return false, err
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}
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if authenticated {
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common.Log.Trace("this.Authenticated = True")
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this.Authenticated = true
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crypt.Authenticated = true
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return true, nil
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}
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@ -390,13 +396,13 @@ func (this *PdfCrypt) authenticate(password []byte) (bool, error) {
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// May not be necessary if only want to get all contents.
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// (user pass needs to be known or empty).
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common.Log.Trace("Debugging authentication - owner pass")
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authenticated, err = this.Alg7(password)
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authenticated, err = crypt.Alg7(password)
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if err != nil {
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return false, err
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}
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if authenticated {
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common.Log.Trace("this.Authenticated = True")
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this.Authenticated = true
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crypt.Authenticated = true
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return true, nil
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}
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@ -409,11 +415,11 @@ func (this *PdfCrypt) authenticate(password []byte) (bool, error) {
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// The bool flag indicates that the user can access and can view the file.
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// The AccessPermissions shows what access the user has for editing etc.
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// An error is returned if there was a problem performing the authentication.
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func (this *PdfCrypt) checkAccessRights(password []byte) (bool, AccessPermissions, error) {
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func (crypt *PdfCrypt) checkAccessRights(password []byte) (bool, AccessPermissions, error) {
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perms := AccessPermissions{}
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// Try owner password -> full rights.
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isOwner, err := this.Alg7(password)
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isOwner, err := crypt.Alg7(password)
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if err != nil {
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return false, perms, err
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}
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@ -431,20 +437,20 @@ func (this *PdfCrypt) checkAccessRights(password []byte) (bool, AccessPermission
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}
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// Try user password.
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isUser, err := this.Alg6(password)
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isUser, err := crypt.Alg6(password)
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if err != nil {
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return false, perms, err
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}
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if isUser {
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// User password specified correctly -> access granted with specified permissions.
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return true, this.GetAccessPermissions(), nil
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return true, crypt.GetAccessPermissions(), nil
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}
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// Cannot even view the file.
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return false, perms, nil
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}
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func (this *PdfCrypt) paddedPass(pass []byte) []byte {
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func (crypt *PdfCrypt) paddedPass(pass []byte) []byte {
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key := make([]byte, 32)
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if len(pass) >= 32 {
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for i := 0; i < 32; i++ {
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@ -463,8 +469,8 @@ func (this *PdfCrypt) paddedPass(pass []byte) []byte {
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// Generates a key for encrypting a specific object based on the
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// object and generation number, as well as the document encryption key.
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func (this *PdfCrypt) makeKey(filter string, objNum, genNum uint32, ekey []byte) ([]byte, error) {
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cf, ok := this.CryptFilters[filter]
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func (crypt *PdfCrypt) makeKey(filter string, objNum, genNum uint32, ekey []byte) ([]byte, error) {
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cf, ok := crypt.CryptFilters[filter]
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if !ok {
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common.Log.Debug("ERROR Unsupported crypt filter (%s)", filter)
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return nil, fmt.Errorf("Unsupported crypt filter (%s)", filter)
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@ -503,27 +509,27 @@ func (this *PdfCrypt) makeKey(filter string, objNum, genNum uint32, ekey []byte)
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if len(ekey)+5 < 16 {
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return hashb[0 : len(ekey)+5], nil
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} else {
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return hashb, nil
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}
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return hashb, nil
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}
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// Check if object has already been processed.
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func (this *PdfCrypt) isDecrypted(obj PdfObject) bool {
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_, ok := this.DecryptedObjects[obj]
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func (crypt *PdfCrypt) isDecrypted(obj PdfObject) bool {
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_, ok := crypt.DecryptedObjects[obj]
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if ok {
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common.Log.Trace("Already decrypted")
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return true
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} else {
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common.Log.Trace("Not decrypted yet")
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return false
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}
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common.Log.Trace("Not decrypted yet")
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return false
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}
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// Decrypt a buffer with a selected crypt filter.
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func (this *PdfCrypt) decryptBytes(buf []byte, filter string, okey []byte) ([]byte, error) {
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func (crypt *PdfCrypt) decryptBytes(buf []byte, filter string, okey []byte) ([]byte, error) {
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common.Log.Trace("Decrypt bytes")
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cf, ok := this.CryptFilters[filter]
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cf, ok := crypt.CryptFilters[filter]
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if !ok {
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common.Log.Debug("ERROR Unsupported crypt filter (%s)", filter)
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return nil, fmt.Errorf("Unsupported crypt filter (%s)", filter)
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@ -609,20 +615,20 @@ func (this *PdfCrypt) decryptBytes(buf []byte, filter string, okey []byte) ([]by
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// Traverses through all the subobjects (recursive).
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//
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// Does not look up references.. That should be done prior to calling.
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func (this *PdfCrypt) Decrypt(obj PdfObject, parentObjNum, parentGenNum int64) error {
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if this.isDecrypted(obj) {
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func (crypt *PdfCrypt) Decrypt(obj PdfObject, parentObjNum, parentGenNum int64) error {
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if crypt.isDecrypted(obj) {
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return nil
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}
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if io, isIndirect := obj.(*PdfIndirectObject); isIndirect {
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this.DecryptedObjects[io] = true
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crypt.DecryptedObjects[io] = true
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common.Log.Trace("Decrypting indirect %d %d obj!", io.ObjectNumber, io.GenerationNumber)
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objNum := (*io).ObjectNumber
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genNum := (*io).GenerationNumber
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err := this.Decrypt(io.PdfObject, objNum, genNum)
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err := crypt.Decrypt(io.PdfObject, objNum, genNum)
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if err != nil {
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return err
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}
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@ -632,7 +638,7 @@ func (this *PdfCrypt) Decrypt(obj PdfObject, parentObjNum, parentGenNum int64) e
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if so, isStream := obj.(*PdfObjectStream); isStream {
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// Mark as decrypted first to avoid recursive issues.
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this.DecryptedObjects[so] = true
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crypt.DecryptedObjects[so] = true
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objNum := (*so).ObjectNumber
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genNum := (*so).GenerationNumber
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common.Log.Trace("Decrypting stream %d %d !", objNum, genNum)
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@ -643,9 +649,9 @@ func (this *PdfCrypt) Decrypt(obj PdfObject, parentObjNum, parentGenNum int64) e
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dict := so.PdfObjectDictionary
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streamFilter := "Default" // Default RC4.
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if this.V >= 4 {
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streamFilter = this.StreamFilter
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common.Log.Trace("this.StreamFilter = %s", this.StreamFilter)
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if crypt.V >= 4 {
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streamFilter = crypt.StreamFilter
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common.Log.Trace("this.StreamFilter = %s", crypt.StreamFilter)
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if filters, ok := dict.Get("Filter").(*PdfObjectArray); ok {
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// Crypt filter can only be the first entry.
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@ -658,7 +664,7 @@ func (this *PdfCrypt) Decrypt(obj PdfObject, parentObjNum, parentGenNum int64) e
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// Check if valid crypt filter specified in the decode params.
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if decodeParams, ok := dict.Get("DecodeParms").(*PdfObjectDictionary); ok {
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if filterName, ok := decodeParams.Get("Name").(*PdfObjectName); ok {
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if _, ok := this.CryptFilters[string(*filterName)]; ok {
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if _, ok := crypt.CryptFilters[string(*filterName)]; ok {
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common.Log.Trace("Using stream filter %s", *filterName)
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streamFilter = string(*filterName)
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}
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@ -675,17 +681,17 @@ func (this *PdfCrypt) Decrypt(obj PdfObject, parentObjNum, parentGenNum int64) e
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}
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}
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err := this.Decrypt(so.PdfObjectDictionary, objNum, genNum)
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err := crypt.Decrypt(so.PdfObjectDictionary, objNum, genNum)
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if err != nil {
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return err
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}
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okey, err := this.makeKey(streamFilter, uint32(objNum), uint32(genNum), this.EncryptionKey)
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okey, err := crypt.makeKey(streamFilter, uint32(objNum), uint32(genNum), crypt.EncryptionKey)
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if err != nil {
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return err
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}
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so.Stream, err = this.decryptBytes(so.Stream, streamFilter, okey)
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so.Stream, err = crypt.decryptBytes(so.Stream, streamFilter, okey)
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if err != nil {
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return err
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}
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@ -698,18 +704,18 @@ func (this *PdfCrypt) Decrypt(obj PdfObject, parentObjNum, parentGenNum int64) e
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common.Log.Trace("Decrypting string!")
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stringFilter := "Default"
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if this.V >= 4 {
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if crypt.V >= 4 {
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// Currently only support Identity / RC4.
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common.Log.Trace("with %s filter", this.StringFilter)
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if this.StringFilter == "Identity" {
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common.Log.Trace("with %s filter", crypt.StringFilter)
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if crypt.StringFilter == "Identity" {
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// Identity: pass unchanged: No action.
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return nil
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} else {
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stringFilter = this.StringFilter
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stringFilter = crypt.StringFilter
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}
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}
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key, err := this.makeKey(stringFilter, uint32(parentObjNum), uint32(parentGenNum), this.EncryptionKey)
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key, err := crypt.makeKey(stringFilter, uint32(parentObjNum), uint32(parentGenNum), crypt.EncryptionKey)
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if err != nil {
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return err
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}
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@ -720,7 +726,7 @@ func (this *PdfCrypt) Decrypt(obj PdfObject, parentObjNum, parentGenNum int64) e
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decrypted[i] = (*s)[i]
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}
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common.Log.Trace("Decrypt string: %s : % x", decrypted, decrypted)
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decrypted, err = this.decryptBytes(decrypted, stringFilter, key)
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decrypted, err = crypt.decryptBytes(decrypted, stringFilter, key)
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if err != nil {
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return err
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}
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@ -731,7 +737,7 @@ func (this *PdfCrypt) Decrypt(obj PdfObject, parentObjNum, parentGenNum int64) e
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if a, isArray := obj.(*PdfObjectArray); isArray {
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for _, o := range *a {
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err := this.Decrypt(o, parentObjNum, parentGenNum)
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err := crypt.Decrypt(o, parentObjNum, parentGenNum)
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if err != nil {
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return err
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}
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@ -757,7 +763,7 @@ func (this *PdfCrypt) Decrypt(obj PdfObject, parentObjNum, parentGenNum int64) e
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}
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if string(keyidx) != "Parent" && string(keyidx) != "Prev" && string(keyidx) != "Last" { // Check not needed?
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err := this.Decrypt(o, parentObjNum, parentGenNum)
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err := crypt.Decrypt(o, parentObjNum, parentGenNum)
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if err != nil {
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return err
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}
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@ -770,21 +776,21 @@ func (this *PdfCrypt) Decrypt(obj PdfObject, parentObjNum, parentGenNum int64) e
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}
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// Check if object has already been processed.
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func (this *PdfCrypt) isEncrypted(obj PdfObject) bool {
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_, ok := this.EncryptedObjects[obj]
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func (crypt *PdfCrypt) isEncrypted(obj PdfObject) bool {
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_, ok := crypt.EncryptedObjects[obj]
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if ok {
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common.Log.Trace("Already encrypted")
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return true
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} else {
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common.Log.Trace("Not encrypted yet")
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return false
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}
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common.Log.Trace("Not encrypted yet")
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return false
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}
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// Encrypt a buffer with the specified crypt filter and key.
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func (this *PdfCrypt) encryptBytes(buf []byte, filter string, okey []byte) ([]byte, error) {
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func (crypt *PdfCrypt) encryptBytes(buf []byte, filter string, okey []byte) ([]byte, error) {
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common.Log.Trace("Encrypt bytes")
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cf, ok := this.CryptFilters[filter]
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cf, ok := crypt.CryptFilters[filter]
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if !ok {
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common.Log.Debug("ERROR Unsupported crypt filter (%s)", filter)
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return nil, fmt.Errorf("Unsupported crypt filter (%s)", filter)
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@ -857,20 +863,20 @@ func (this *PdfCrypt) encryptBytes(buf []byte, filter string, okey []byte) ([]by
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// Traverses through all the subobjects (recursive).
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//
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// Does not look up references.. That should be done prior to calling.
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func (this *PdfCrypt) Encrypt(obj PdfObject, parentObjNum, parentGenNum int64) error {
|
||||
if this.isEncrypted(obj) {
|
||||
func (crypt *PdfCrypt) Encrypt(obj PdfObject, parentObjNum, parentGenNum int64) error {
|
||||
if crypt.isEncrypted(obj) {
|
||||
return nil
|
||||
}
|
||||
|
||||
if io, isIndirect := obj.(*PdfIndirectObject); isIndirect {
|
||||
this.EncryptedObjects[io] = true
|
||||
crypt.EncryptedObjects[io] = true
|
||||
|
||||
common.Log.Trace("Encrypting indirect %d %d obj!", io.ObjectNumber, io.GenerationNumber)
|
||||
|
||||
objNum := (*io).ObjectNumber
|
||||
genNum := (*io).GenerationNumber
|
||||
|
||||
err := this.Encrypt(io.PdfObject, objNum, genNum)
|
||||
err := crypt.Encrypt(io.PdfObject, objNum, genNum)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
@ -879,7 +885,7 @@ func (this *PdfCrypt) Encrypt(obj PdfObject, parentObjNum, parentGenNum int64) e
|
||||
}
|
||||
|
||||
if so, isStream := obj.(*PdfObjectStream); isStream {
|
||||
this.EncryptedObjects[so] = true
|
||||
crypt.EncryptedObjects[so] = true
|
||||
objNum := (*so).ObjectNumber
|
||||
genNum := (*so).GenerationNumber
|
||||
common.Log.Trace("Encrypting stream %d %d !", objNum, genNum)
|
||||
@ -890,11 +896,11 @@ func (this *PdfCrypt) Encrypt(obj PdfObject, parentObjNum, parentGenNum int64) e
|
||||
dict := so.PdfObjectDictionary
|
||||
|
||||
streamFilter := "Default" // Default RC4.
|
||||
if this.V >= 4 {
|
||||
if crypt.V >= 4 {
|
||||
// For now. Need to change when we add support for more than
|
||||
// Identity / RC4.
|
||||
streamFilter = this.StreamFilter
|
||||
common.Log.Trace("this.StreamFilter = %s", this.StreamFilter)
|
||||
streamFilter = crypt.StreamFilter
|
||||
common.Log.Trace("this.StreamFilter = %s", crypt.StreamFilter)
|
||||
|
||||
if filters, ok := dict.Get("Filter").(*PdfObjectArray); ok {
|
||||
// Crypt filter can only be the first entry.
|
||||
@ -907,7 +913,7 @@ func (this *PdfCrypt) Encrypt(obj PdfObject, parentObjNum, parentGenNum int64) e
|
||||
// Check if valid crypt filter specified in the decode params.
|
||||
if decodeParams, ok := dict.Get("DecodeParms").(*PdfObjectDictionary); ok {
|
||||
if filterName, ok := decodeParams.Get("Name").(*PdfObjectName); ok {
|
||||
if _, ok := this.CryptFilters[string(*filterName)]; ok {
|
||||
if _, ok := crypt.CryptFilters[string(*filterName)]; ok {
|
||||
common.Log.Trace("Using stream filter %s", *filterName)
|
||||
streamFilter = string(*filterName)
|
||||
}
|
||||
@ -924,17 +930,17 @@ func (this *PdfCrypt) Encrypt(obj PdfObject, parentObjNum, parentGenNum int64) e
|
||||
}
|
||||
}
|
||||
|
||||
err := this.Encrypt(so.PdfObjectDictionary, objNum, genNum)
|
||||
err := crypt.Encrypt(so.PdfObjectDictionary, objNum, genNum)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
|
||||
okey, err := this.makeKey(streamFilter, uint32(objNum), uint32(genNum), this.EncryptionKey)
|
||||
okey, err := crypt.makeKey(streamFilter, uint32(objNum), uint32(genNum), crypt.EncryptionKey)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
|
||||
so.Stream, err = this.encryptBytes(so.Stream, streamFilter, okey)
|
||||
so.Stream, err = crypt.encryptBytes(so.Stream, streamFilter, okey)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
@ -947,17 +953,17 @@ func (this *PdfCrypt) Encrypt(obj PdfObject, parentObjNum, parentGenNum int64) e
|
||||
common.Log.Trace("Encrypting string!")
|
||||
|
||||
stringFilter := "Default"
|
||||
if this.V >= 4 {
|
||||
common.Log.Trace("with %s filter", this.StringFilter)
|
||||
if this.StringFilter == "Identity" {
|
||||
if crypt.V >= 4 {
|
||||
common.Log.Trace("with %s filter", crypt.StringFilter)
|
||||
if crypt.StringFilter == "Identity" {
|
||||
// Identity: pass unchanged: No action.
|
||||
return nil
|
||||
} else {
|
||||
stringFilter = this.StringFilter
|
||||
stringFilter = crypt.StringFilter
|
||||
}
|
||||
}
|
||||
|
||||
key, err := this.makeKey(stringFilter, uint32(parentObjNum), uint32(parentGenNum), this.EncryptionKey)
|
||||
key, err := crypt.makeKey(stringFilter, uint32(parentObjNum), uint32(parentGenNum), crypt.EncryptionKey)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
@ -967,7 +973,7 @@ func (this *PdfCrypt) Encrypt(obj PdfObject, parentObjNum, parentGenNum int64) e
|
||||
encrypted[i] = (*s)[i]
|
||||
}
|
||||
common.Log.Trace("Encrypt string: %s : % x", encrypted, encrypted)
|
||||
encrypted, err = this.encryptBytes(encrypted, stringFilter, key)
|
||||
encrypted, err = crypt.encryptBytes(encrypted, stringFilter, key)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
@ -978,7 +984,7 @@ func (this *PdfCrypt) Encrypt(obj PdfObject, parentObjNum, parentGenNum int64) e
|
||||
|
||||
if a, isArray := obj.(*PdfObjectArray); isArray {
|
||||
for _, o := range *a {
|
||||
err := this.Encrypt(o, parentObjNum, parentGenNum)
|
||||
err := crypt.Encrypt(o, parentObjNum, parentGenNum)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
@ -1004,7 +1010,7 @@ func (this *PdfCrypt) Encrypt(obj PdfObject, parentObjNum, parentGenNum int64) e
|
||||
continue
|
||||
}
|
||||
if string(keyidx) != "Parent" && string(keyidx) != "Prev" && string(keyidx) != "Last" { // Check not needed?
|
||||
err := this.Encrypt(o, parentObjNum, parentGenNum)
|
||||
err := crypt.Encrypt(o, parentObjNum, parentGenNum)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
@ -1016,19 +1022,20 @@ func (this *PdfCrypt) Encrypt(obj PdfObject, parentObjNum, parentGenNum int64) e
|
||||
return nil
|
||||
}
|
||||
|
||||
// Algorithm 2: Computing an encryption key.
|
||||
func (this *PdfCrypt) Alg2(pass []byte) []byte {
|
||||
// Alg2 computes an encryption key.
|
||||
// TODO (v3): Unexport.
|
||||
func (crypt *PdfCrypt) Alg2(pass []byte) []byte {
|
||||
common.Log.Trace("Alg2")
|
||||
key := this.paddedPass(pass)
|
||||
key := crypt.paddedPass(pass)
|
||||
|
||||
h := md5.New()
|
||||
h.Write(key)
|
||||
|
||||
// Pass O.
|
||||
h.Write(this.O)
|
||||
h.Write(crypt.O)
|
||||
|
||||
// Pass P (Lower order byte first).
|
||||
var p uint32 = uint32(this.P)
|
||||
var p uint32 = uint32(crypt.P)
|
||||
var pb = []byte{}
|
||||
for i := 0; i < 4; i++ {
|
||||
pb = append(pb, byte(((p >> uint(8*i)) & 0xff)))
|
||||
@ -1037,36 +1044,36 @@ func (this *PdfCrypt) Alg2(pass []byte) []byte {
|
||||
common.Log.Trace("go P: % x", pb)
|
||||
|
||||
// Pass ID[0] from the trailer
|
||||
h.Write([]byte(this.Id0))
|
||||
h.Write([]byte(crypt.Id0))
|
||||
|
||||
common.Log.Trace("this.R = %d encryptMetadata %v", this.R, this.EncryptMetadata)
|
||||
if (this.R >= 4) && !this.EncryptMetadata {
|
||||
common.Log.Trace("this.R = %d encryptMetadata %v", crypt.R, crypt.EncryptMetadata)
|
||||
if (crypt.R >= 4) && !crypt.EncryptMetadata {
|
||||
h.Write([]byte{0xff, 0xff, 0xff, 0xff})
|
||||
}
|
||||
hashb := h.Sum(nil)
|
||||
|
||||
if this.R >= 3 {
|
||||
if crypt.R >= 3 {
|
||||
for i := 0; i < 50; i++ {
|
||||
h = md5.New()
|
||||
h.Write(hashb[0 : this.Length/8])
|
||||
h.Write(hashb[0 : crypt.Length/8])
|
||||
hashb = h.Sum(nil)
|
||||
}
|
||||
}
|
||||
|
||||
if this.R >= 3 {
|
||||
return hashb[0 : this.Length/8]
|
||||
if crypt.R >= 3 {
|
||||
return hashb[0 : crypt.Length/8]
|
||||
}
|
||||
|
||||
return hashb[0:5]
|
||||
}
|
||||
|
||||
// Create the RC4 encryption key.
|
||||
func (this *PdfCrypt) alg3_key(pass []byte) []byte {
|
||||
func (crypt *PdfCrypt) alg3Key(pass []byte) []byte {
|
||||
h := md5.New()
|
||||
okey := this.paddedPass(pass)
|
||||
okey := crypt.paddedPass(pass)
|
||||
h.Write(okey)
|
||||
|
||||
if this.R >= 3 {
|
||||
if crypt.R >= 3 {
|
||||
for i := 0; i < 50; i++ {
|
||||
hashb := h.Sum(nil)
|
||||
h = md5.New()
|
||||
@ -1075,25 +1082,25 @@ func (this *PdfCrypt) alg3_key(pass []byte) []byte {
|
||||
}
|
||||
|
||||
encKey := h.Sum(nil)
|
||||
if this.R == 2 {
|
||||
if crypt.R == 2 {
|
||||
encKey = encKey[0:5]
|
||||
} else {
|
||||
encKey = encKey[0 : this.Length/8]
|
||||
encKey = encKey[0 : crypt.Length/8]
|
||||
}
|
||||
return encKey
|
||||
}
|
||||
|
||||
// Algorithm 3: Computing the encryption dictionary’s O
|
||||
// (owner password) value.
|
||||
func (this *PdfCrypt) Alg3(upass, opass []byte) (PdfObjectString, error) {
|
||||
// Alg3 computes the encryption dictionary’s O (owner password) value.
|
||||
// TODO (v3): Unexport.
|
||||
func (crypt *PdfCrypt) Alg3(upass, opass []byte) (PdfObjectString, error) {
|
||||
// Return O string val.
|
||||
O := PdfObjectString("")
|
||||
|
||||
var encKey []byte
|
||||
if len(opass) > 0 {
|
||||
encKey = this.alg3_key(opass)
|
||||
encKey = crypt.alg3Key(opass)
|
||||
} else {
|
||||
encKey = this.alg3_key(upass)
|
||||
encKey = crypt.alg3Key(upass)
|
||||
}
|
||||
|
||||
ociph, err := rc4.NewCipher(encKey)
|
||||
@ -1101,11 +1108,11 @@ func (this *PdfCrypt) Alg3(upass, opass []byte) (PdfObjectString, error) {
|
||||
return O, errors.New("Failed rc4 ciph")
|
||||
}
|
||||
|
||||
ukey := this.paddedPass(upass)
|
||||
ukey := crypt.paddedPass(upass)
|
||||
encrypted := make([]byte, len(ukey))
|
||||
ociph.XORKeyStream(encrypted, ukey)
|
||||
|
||||
if this.R >= 3 {
|
||||
if crypt.R >= 3 {
|
||||
encKey2 := make([]byte, len(encKey))
|
||||
for i := 0; i < 19; i++ {
|
||||
for j := 0; j < len(encKey); j++ {
|
||||
@ -1123,12 +1130,12 @@ func (this *PdfCrypt) Alg3(upass, opass []byte) (PdfObjectString, error) {
|
||||
return O, nil
|
||||
}
|
||||
|
||||
// Algorithm 4: Computing the encryption dictionary’s U (user password)
|
||||
// value (Security handlers of revision 2).
|
||||
func (this *PdfCrypt) Alg4(upass []byte) (PdfObjectString, []byte, error) {
|
||||
// Alg4 computes the encryption dictionary’s U (user password) value (Security handlers of revision 2).
|
||||
// TODO (v3): Unexport.
|
||||
func (crypt *PdfCrypt) Alg4(upass []byte) (PdfObjectString, []byte, error) {
|
||||
U := PdfObjectString("")
|
||||
|
||||
ekey := this.Alg2(upass)
|
||||
ekey := crypt.Alg2(upass)
|
||||
ciph, err := rc4.NewCipher(ekey)
|
||||
if err != nil {
|
||||
return U, ekey, errors.New("Failed rc4 ciph")
|
||||
@ -1142,21 +1149,21 @@ func (this *PdfCrypt) Alg4(upass []byte) (PdfObjectString, []byte, error) {
|
||||
return U, ekey, nil
|
||||
}
|
||||
|
||||
// Algorithm 5: Computing the encryption dictionary’s U (user password)
|
||||
// value (Security handlers of revision 3 or greater).
|
||||
func (this *PdfCrypt) Alg5(upass []byte) (PdfObjectString, []byte, error) {
|
||||
// Alg5 computes the encryption dictionary’s U (user password) value (Security handlers of revision 3 or greater).
|
||||
// TODO (v3): Unexport.
|
||||
func (crypt *PdfCrypt) Alg5(upass []byte) (PdfObjectString, []byte, error) {
|
||||
U := PdfObjectString("")
|
||||
|
||||
ekey := this.Alg2(upass)
|
||||
ekey := crypt.Alg2(upass)
|
||||
|
||||
h := md5.New()
|
||||
h.Write([]byte(padding))
|
||||
h.Write([]byte(this.Id0))
|
||||
h.Write([]byte(crypt.Id0))
|
||||
hash := h.Sum(nil)
|
||||
|
||||
common.Log.Trace("Alg5")
|
||||
common.Log.Trace("ekey: % x", ekey)
|
||||
common.Log.Trace("ID: % x", this.Id0)
|
||||
common.Log.Trace("ID: % x", crypt.Id0)
|
||||
|
||||
if len(hash) != 16 {
|
||||
return U, ekey, errors.New("Hash length not 16 bytes")
|
||||
@ -1206,15 +1213,16 @@ func (this *PdfCrypt) Alg5(upass []byte) (PdfObjectString, []byte, error) {
|
||||
return U, ekey, nil
|
||||
}
|
||||
|
||||
// Algorithm 6: Authenticating the user password
|
||||
func (this *PdfCrypt) Alg6(upass []byte) (bool, error) {
|
||||
// Alg6 authenticates the user password.
|
||||
// TODO (v3): Unexport.
|
||||
func (crypt *PdfCrypt) Alg6(upass []byte) (bool, error) {
|
||||
var uo PdfObjectString
|
||||
var err error
|
||||
var key []byte
|
||||
if this.R == 2 {
|
||||
uo, key, err = this.Alg4(upass)
|
||||
} else if this.R >= 3 {
|
||||
uo, key, err = this.Alg5(upass)
|
||||
if crypt.R == 2 {
|
||||
uo, key, err = crypt.Alg4(upass)
|
||||
} else if crypt.R >= 3 {
|
||||
uo, key, err = crypt.Alg5(upass)
|
||||
} else {
|
||||
return false, errors.New("invalid R")
|
||||
}
|
||||
@ -1223,11 +1231,11 @@ func (this *PdfCrypt) Alg6(upass []byte) (bool, error) {
|
||||
return false, err
|
||||
}
|
||||
|
||||
common.Log.Trace("check: % x == % x ?", string(uo), string(this.U))
|
||||
common.Log.Trace("check: % x == % x ?", string(uo), string(crypt.U))
|
||||
|
||||
uGen := string(uo) // Generated U from specified pass.
|
||||
uDoc := string(this.U) // U from the document.
|
||||
if this.R >= 3 {
|
||||
uGen := string(uo) // Generated U from specified pass.
|
||||
uDoc := string(crypt.U) // U from the document.
|
||||
if crypt.R >= 3 {
|
||||
// comparing on the first 16 bytes in the case of security
|
||||
// handlers of revision 3 or greater),
|
||||
if len(uGen) > 16 {
|
||||
@ -1237,27 +1245,29 @@ func (this *PdfCrypt) Alg6(upass []byte) (bool, error) {
|
||||
uDoc = uDoc[0:16]
|
||||
}
|
||||
}
|
||||
|
||||
if uGen == uDoc {
|
||||
this.EncryptionKey = key
|
||||
crypt.EncryptionKey = key
|
||||
return true, nil
|
||||
} else {
|
||||
return false, nil
|
||||
}
|
||||
|
||||
return false, nil
|
||||
}
|
||||
|
||||
// Algorithm 7: Authenticating the owner password.
|
||||
func (this *PdfCrypt) Alg7(opass []byte) (bool, error) {
|
||||
encKey := this.alg3_key(opass)
|
||||
// Alg7 authenticates the owner password.
|
||||
// TODO (v3): Unexport.
|
||||
func (crypt *PdfCrypt) Alg7(opass []byte) (bool, error) {
|
||||
encKey := crypt.alg3Key(opass)
|
||||
|
||||
decrypted := make([]byte, len(this.O))
|
||||
if this.R == 2 {
|
||||
decrypted := make([]byte, len(crypt.O))
|
||||
if crypt.R == 2 {
|
||||
ciph, err := rc4.NewCipher(encKey)
|
||||
if err != nil {
|
||||
return false, errors.New("Failed cipher")
|
||||
}
|
||||
ciph.XORKeyStream(decrypted, this.O)
|
||||
} else if this.R >= 3 {
|
||||
s := append([]byte{}, this.O...)
|
||||
ciph.XORKeyStream(decrypted, crypt.O)
|
||||
} else if crypt.R >= 3 {
|
||||
s := append([]byte{}, crypt.O...)
|
||||
for i := 0; i < 20; i++ {
|
||||
//newKey := encKey
|
||||
newKey := append([]byte{}, encKey...)
|
||||
@ -1275,7 +1285,7 @@ func (this *PdfCrypt) Alg7(opass []byte) (bool, error) {
|
||||
return false, errors.New("invalid R")
|
||||
}
|
||||
|
||||
auth, err := this.Alg6(decrypted)
|
||||
auth, err := crypt.Alg6(decrypted)
|
||||
if err != nil {
|
||||
return false, nil
|
||||
}
|
||||
|
||||
@ -15,6 +15,7 @@ import (
|
||||
|
||||
// ReadAtLeast reads at least n bytes into slice p.
|
||||
// Returns the number of bytes read (should always be == n), and an error on failure.
|
||||
// TODO (v3): Unexport.
|
||||
func (this *PdfParser) ReadAtLeast(p []byte, n int) (int, error) {
|
||||
remaining := n
|
||||
start := 0
|
||||
@ -33,6 +34,7 @@ func (this *PdfParser) ReadAtLeast(p []byte, n int) (int, error) {
|
||||
}
|
||||
|
||||
// Get the current file offset, accounting for buffered position.
|
||||
// TODO (v3): Unexport.
|
||||
func (this *PdfParser) GetFileOffset() int64 {
|
||||
offset, _ := this.rs.Seek(0, os.SEEK_CUR)
|
||||
offset -= int64(this.reader.Buffered())
|
||||
@ -40,6 +42,7 @@ func (this *PdfParser) GetFileOffset() int64 {
|
||||
}
|
||||
|
||||
// Seek the file to an offset position.
|
||||
// TODO (v3): Unexport.
|
||||
func (this *PdfParser) SetFileOffset(offset int64) {
|
||||
this.rs.Seek(offset, os.SEEK_SET)
|
||||
this.reader = bufio.NewReader(this.rs)
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user