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Export function to verify individual signature #1334

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merged 1 commit into from
Jan 18, 2022
Merged

Export function to verify individual signature #1334

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99 changes: 52 additions & 47 deletions pkg/cosign/verify.go
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Original file line number Diff line number Diff line change
Expand Up @@ -321,53 +321,9 @@ func verifySignatures(ctx context.Context, sigs oci.Signatures, h v1.Hash, co *C
validationErrs := []string{}

for _, sig := range sl {
if err := func(sig oci.Signature) error {
verifier := co.SigVerifier
if verifier == nil {
// If we don't have a public key to check against, we can try a root cert.
cert, err := sig.Cert()
if err != nil {
return err
}
if cert == nil {
return errors.New("no certificate found on signature")
}
verifier, err = ValidateAndUnpackCert(cert, co)
if err != nil {
return err
}
}

if err := verifyOCISignature(ctx, verifier, sig); err != nil {
return err
}

// We can't check annotations without claims, both require unmarshalling the payload.
if co.ClaimVerifier != nil {
if err := co.ClaimVerifier(sig, h, co.Annotations); err != nil {
return err
}
}

verified, err := VerifyBundle(ctx, sig)
if err != nil && co.RekorClient == nil {
return errors.Wrap(err, "unable to verify bundle")
}
bundleVerified = bundleVerified || verified

if !verified && co.RekorClient != nil {
if co.SigVerifier != nil {
pub, err := co.SigVerifier.PublicKey(co.PKOpts...)
if err != nil {
return err
}
return tlogValidatePublicKey(ctx, co.RekorClient, pub, sig)
}

return tlogValidateCertificate(ctx, co.RekorClient, sig)
}
return nil
}(sig); err != nil {
verified, err := VerifyImageSignature(ctx, sig, h, co)
bundleVerified = bundleVerified || verified
if err != nil {
validationErrs = append(validationErrs, err.Error())
continue
}
Expand All @@ -381,6 +337,55 @@ func verifySignatures(ctx context.Context, sigs oci.Signatures, h v1.Hash, co *C
return checkedSignatures, bundleVerified, nil
}

// VerifyImageSignature verifies a signature
func VerifyImageSignature(ctx context.Context, sig oci.Signature, h v1.Hash, co *CheckOpts) (bundleVerified bool, err error) {
verifier := co.SigVerifier
if verifier == nil {
// If we don't have a public key to check against, we can try a root cert.
cert, err := sig.Cert()
if err != nil {
return bundleVerified, err
}
if cert == nil {
return bundleVerified, errors.New("no certificate found on signature")
}
verifier, err = ValidateAndUnpackCert(cert, co)
if err != nil {
return bundleVerified, err
}
}

if err := verifyOCISignature(ctx, verifier, sig); err != nil {
return bundleVerified, err
}

// We can't check annotations without claims, both require unmarshalling the payload.
if co.ClaimVerifier != nil {
if err := co.ClaimVerifier(sig, h, co.Annotations); err != nil {
return bundleVerified, err
}
}

bundleVerified, err = VerifyBundle(ctx, sig)
if err != nil && co.RekorClient == nil {
return false, errors.Wrap(err, "unable to verify bundle")
}

if !bundleVerified && co.RekorClient != nil {
if co.SigVerifier != nil {
pub, err := co.SigVerifier.PublicKey(co.PKOpts...)
if err != nil {
return bundleVerified, err
}
return bundleVerified, tlogValidatePublicKey(ctx, co.RekorClient, pub, sig)
}

return bundleVerified, tlogValidateCertificate(ctx, co.RekorClient, sig)
}

return bundleVerified, nil
}

func loadSignatureFromFile(sigRef string, signedImgRef name.Reference, co *CheckOpts) (oci.Signatures, error) {
var b64sig string
targetSig, err := blob.LoadFileOrURL(sigRef)
Expand Down