Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Parse signature certificate arrays on signature validation #175

Merged
merged 1 commit into from
Sep 26, 2019
Merged

Parse signature certificate arrays on signature validation #175

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
36 changes: 28 additions & 8 deletions model/sighandler/sighandler_pkcs7.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@ import (
"crypto/rsa"
"crypto/x509"
"errors"
"fmt"

"github.com/gunnsth/pkcs7"

Expand Down Expand Up @@ -71,16 +72,35 @@ func (a *adobePKCS7Detached) InitSignature(sig *model.PdfSignature) error {
}

func (a *adobePKCS7Detached) getCertificate(sig *model.PdfSignature) (*x509.Certificate, error) {
certificate := a.certificate
if certificate == nil {
certData := sig.Cert.(*core.PdfObjectString).Bytes()
certs, err := x509.ParseCertificates(certData)
if err != nil {
return nil, err
if a.certificate != nil {
return a.certificate, nil
}

var certData []byte
switch certObj := sig.Cert.(type) {
case *core.PdfObjectString:
certData = certObj.Bytes()
case *core.PdfObjectArray:
if certObj.Len() == 0 {
return nil, errors.New("no signature certificates found")
}
certificate = certs[0]
for _, obj := range certObj.Elements() {
certStr, ok := core.GetString(obj)
if !ok {
return nil, fmt.Errorf("invalid certificate object type in signature certificate chain: %T", obj)
}
certData = append(certData, certStr.Bytes()...)
}
default:
return nil, fmt.Errorf("invalid signature certificate object type: %T", certObj)
}
return certificate, nil

certs, err := x509.ParseCertificates(certData)
if err != nil {
return nil, err
}

return certs[0], nil
}

// NewDigest creates a new digest.
Expand Down
50 changes: 31 additions & 19 deletions model/sighandler/sighandler_rsa_sha1.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@ import (
"crypto/x509"
"encoding/asn1"
"errors"
"fmt"
"hash"

"github.com/unidoc/unipdf/v3/core"
Expand Down Expand Up @@ -70,16 +71,35 @@ func getHashFromSignatureAlgorithm(sa x509.SignatureAlgorithm) (crypto.Hash, boo
}

func (a *adobeX509RSASHA1) getCertificate(sig *model.PdfSignature) (*x509.Certificate, error) {
certificate := a.certificate
if certificate == nil {
certData := sig.Cert.(*core.PdfObjectString).Bytes()
certs, err := x509.ParseCertificates(certData)
if err != nil {
return nil, err
if a.certificate != nil {
return a.certificate, nil
}

var certData []byte
switch certObj := sig.Cert.(type) {
case *core.PdfObjectString:
certData = certObj.Bytes()
case *core.PdfObjectArray:
if certObj.Len() == 0 {
return nil, errors.New("no signature certificates found")
}
certificate = certs[0]
for _, obj := range certObj.Elements() {
certStr, ok := core.GetString(obj)
if !ok {
return nil, fmt.Errorf("invalid certificate object type in signature certificate chain: %T", obj)
}
certData = append(certData, certStr.Bytes()...)
}
default:
return nil, fmt.Errorf("invalid signature certificate object type: %T", certObj)
}

certs, err := x509.ParseCertificates(certData)
if err != nil {
return nil, err
}
return certificate, nil

return certs[0], nil
}

// NewDigest creates a new digest.
Expand All @@ -94,15 +114,11 @@ func (a *adobeX509RSASHA1) NewDigest(sig *model.PdfSignature) (model.Hasher, err

// Validate validates PdfSignature.
func (a *adobeX509RSASHA1) Validate(sig *model.PdfSignature, digest model.Hasher) (model.SignatureValidationResult, error) {
certData := sig.Cert.(*core.PdfObjectString).Bytes()
certs, err := x509.ParseCertificates(certData)
certificate, err := a.getCertificate(sig)
if err != nil {
return model.SignatureValidationResult{}, err
}
if len(certs) == 0 {
return model.SignatureValidationResult{}, errors.New("certificate not found")
}
cert := certs[0]

signed := sig.Contents.Bytes()
var sigHash []byte
if _, err := asn1.Unmarshal(signed, &sigHash); err != nil {
Expand All @@ -112,12 +128,8 @@ func (a *adobeX509RSASHA1) Validate(sig *model.PdfSignature, digest model.Hasher
if !ok {
return model.SignatureValidationResult{}, errors.New("hash type error")
}
certificate, err := a.getCertificate(sig)
if err != nil {
return model.SignatureValidationResult{}, err
}
ha, _ := getHashFromSignatureAlgorithm(certificate.SignatureAlgorithm)
if err := rsa.VerifyPKCS1v15(cert.PublicKey.(*rsa.PublicKey), ha, h.Sum(nil), sigHash); err != nil {
if err := rsa.VerifyPKCS1v15(certificate.PublicKey.(*rsa.PublicKey), ha, h.Sum(nil), sigHash); err != nil {
return model.SignatureValidationResult{}, err
}
return model.SignatureValidationResult{IsSigned: true, IsVerified: true}, nil
Expand Down