| Yubico Forum https://forum.yubico.com/ |
|
| Invalid signature in attestation certificate https://forum.yubico.com/viewtopic.php?f=33&t=2526 |
Page 1 of 1 |
| Author: | robn [ Thu Jan 19, 2017 8:21 am ] |
| Post subject: | Invalid signature in attestation certificate |
I'm looking at an attestation certificate from a Yubikey Plus. The signature part (as shown by openssl asn1parse -dump) starts like this: Code: 268:d=1 hl=2 l= 11 cons: SEQUENCE 270:d=2 hl=2 l= 9 prim: OBJECT :sha256WithRSAEncryption 281:d=1 hl=4 l= 257 prim: BIT STRING 0000 - 03 76 0e 36 95 65 ef 88-e9 04 28 04 d8 8f fa 5f .v.6.e....(...._ 0010 - bd 5b 99 93 a3 12 46 8f-b1 74 96 12 96 a5 39 cc .[....F..t....9. ... In an ASN.1 BIT STRING, the first byte is the number of unused/padding bits at the end of the string. According to RFC3477 s8.2.1: "Output: an octet string of length k, where k is the length in octets of the RSA modulus n." Therefore, it is impossible to have a valid DER-encoded RSA PKCS#1 signature that has unused bits. Is this certificate completely broken? Can you advise an approach for parsing it? (for more info and the certificate in question, please see https://github.com/briansmith/webpki/pull/34). |
|
| Author: | robn [ Thu Jan 19, 2017 11:35 am ] |
| Post subject: | Re: Invalid signature in attestation certificate |
Never mind. I've been informed that there's a set of six attestation certs with broken signatures. Seems there's nothing here to see. |
|
| Page 1 of 1 | All times are UTC + 1 hour |
| Powered by phpBB® Forum Software © phpBB Group https://www.phpbb.com/ |
|