Hello, I'm trying to manually verify signature in some SignedData ASN.1 structures, which is used in most cases in signature - e.g. S/MIME, Timestamps, ... using x.509 certificates.
Lets see this example: -in file.tsr is Time Stamp reply - it contains SignedData structure (at byte 9 offset) which contains SignerInfo which contains signedAttributes. They are signed with private key of certificate cert.pem (it is the public part only). - lets get signedAttrs (that is what is signed) and the signature itself openssl asn1parse -inform der -in file.tsr -strparse 410 -out signedAttrs dd if=file.tsr of=sig bs=1 skip=697 In http://www.ietf.org/rfc/rfc2630.txt section 5.4 (site 11) says, that it must be changed the IMPLICIT [0] to SET -> I have changed the first byte of signedAttrs to 31h - if you parse it with asn1parse, it seems to be correct then. The corrected version is in file signedAttrs-with-SET -now remains to get digests: openssl dgst -sha256 -binary -out signedAttrs.sha256 signedAttrs openssl dgst -sha256 -binary -out signedAttrs-with-SET.sha256 signedAttrs-with-SET - and we can try to verify: openssl pkeyutl -verify -in signedAttrs.sha256 -sigfile sig -certin -inkey cert.pem openssl pkeyutl -verify -in signedAttrs-with-SET.sha256 -sigfile sig -certin -inkey cert.pem but both fails: "Signature Verification Failure" All files in attachment. Could someone find out, what I'm doing wrong. please ? --kapetr P.S. Some infos to parse: --------- see http://www.ietf.org/rfc/rfc2630.txt site 6 and following SignedData ::= SEQUENCE { version CMSVersion, digestAlgorithms DigestAlgorithmIdentifiers, encapContentInfo EncapsulatedContentInfo, certificates [0] IMPLICIT CertificateSet OPTIONAL, crls [1] IMPLICIT CertificateRevocationLists OPTIONAL, signerInfos SignerInfos } SignerInfos ::= SET OF SignerInfo SignerInfo ::= SEQUENCE { version CMSVersion, sid SignerIdentifier, digestAlgorithm DigestAlgorithmIdentifier, signedAttrs [0] IMPLICIT SignedAttributes OPTIONAL, signatureAlgorithm SignatureAlgorithmIdentifier, signature SignatureValue, unsignedAttrs [1] IMPLICIT UnsignedAttributes OPTIONAL }
test-sig.tgz
Description: application/compressed-tar
