Jostein Tveit <[EMAIL PROTECTED]> writes: > Anyone got a test key with a real and a forged signature to test > other implementations than OpenSSL?
There are actually two problems to consider... First, there is the situation by Bleichenbacher at Crypto 06 and explained in: http://www.imc.org/ietf-openpgp/mail-archive/msg14307.html That uses the fact that implementation doesn't check for data beyond the end of the ASN.1 structure. OpenSSL was vulnerable to this, GnuTLS was not, see my analysis for GnuTLS on this at: http://lists.gnupg.org/pipermail/gnutls-dev/2006-September/001202.html Eric already posted test vectors that trigger this problem. The second problem is that the "parameters" field can ALSO be used to store data that may be used to manipulate the signature value into being a cube. To my knowledge, this was discovered by Yutaka Oiwa, Kazukuni Kobara, Hajime Watanabe. I didn't attend Crypto 06, but as far as I understand from Hal's post, this aspect was not discussed. Their analysis isn't public yet, as far as I know. Both OpenSSL and GnuTLS were vulnerable to the second problem. My discussion of this for GnuTLS is in: http://lists.gnupg.org/pipermail/gnutls-dev/2006-September/001205.html When I read the OpenSSL advisory, I get the impression that it doesn't quite spell out the second problem clearly, but if you look at the patch to correct this: + /* Excess data can be used to create forgeries */ + if(p != s+i) + { + RSAerr(RSA_F_RSA_VERIFY,RSA_R_BAD_SIGNATURE); + goto err; + } + + /* Parameters to the signature algorithm can also be used to + create forgeries */ + if(sig->algor->parameter + && sig->algor->parameter->type != V_ASN1_NULL) + { + RSAerr(RSA_F_RSA_VERIFY,RSA_R_BAD_SIGNATURE); + goto err; + } + You'll notice that there are two added checks, one check per problem. Test vectors for this second problem are as below, created by Yutaka OIWA. [EMAIL PROTECTED]:~/src/gnutls/tests$ cat pkcs1-pad-ok.pem -----BEGIN CERTIFICATE----- MIICzTCCAjagAwIBAgIJAOSnzE4Qx2H/MA0GCSqGSIb3DQEBBQUAMDkxCzAJBgNV BAYTAkpQMRQwEgYDVQQKEwtDQSBURVNUIDEtNDEUMBIGA1UEAxMLQ0EgVEVTVCAx LTQwHhcNMDYwOTA3MTY0MDM3WhcNMDcwOTA3MTY0MDM3WjBPMQswCQYDVQQGEwJK UDEOMAwGA1UECBMFVG9reW8xFjAUBgNVBAoTDVRFU1QgMiBDTElFTlQxGDAWBgNV BAMTD3d3dzIuZXhhbXBsZS5qcDCBnzANBgkqhkiG9w0BAQEFAAOBjQAwgYkCgYEA vSpZ6ig9DpeKB60h7ii1RitNuvkn4INOfEXjCjPSFwmIbGJqnyWvKTiMKzguEYkG 6CZAbsx44t3kvsVDeUd5WZBRgMoeQd1tNJBU4BXxOA8bVzdwstzaPeeufQtZDvKf M4ej+fo/j9lYH9udCug1huaNybcCtijzGonkddX4JEUCAwEAAaOBxjCBwzAJBgNV HRMEAjAAMCwGCWCGSAGG+EIBDQQfFh1PcGVuU1NMIEdlbmVyYXRlZCBDZXJ0aWZp Y2F0ZTAdBgNVHQ4EFgQUK0DZtd8K1P2ij9gVKUNcHlx7uCIwaQYDVR0jBGIwYIAU 340JbeYcg6V9zi8aozy48aIhtfihPaQ7MDkxCzAJBgNVBAYTAkpQMRQwEgYDVQQK EwtDQSBURVNUIDEtNDEUMBIGA1UEAxMLQ0EgVEVTVCAxLTSCCQDkp8xOEMdh/jAN BgkqhkiG9w0BAQUFAAOBgQCkGhwCDLRwWbDnDFReXkIZ1/9OhfiR8yL1idP9iYVU cSoWxSHPBWkv6LORFS03APcXCSzDPJ9pxTjFjGGFSI91fNrzkKdHU/+0WCF2uTh7 Dz2blqtcmnJqMSn1xHxxfM/9e6M3XwFUMf7SGiKRAbDfsauPafEPTn83vSeKj1lg Dw== -----END CERTIFICATE----- -----BEGIN CERTIFICATE----- MIICijCCAfOgAwIBAgIJAOSnzE4Qx2H+MA0GCSqGSIb3DQEBBQUAMDkxCzAJBgNV BAYTAkpQMRQwEgYDVQQKEwtDQSBURVNUIDEtNDEUMBIGA1UEAxMLQ0EgVEVTVCAx LTQwHhcNMDYwOTA3MTYzMzE4WhcNMDYxMDA3MTYzMzE4WjA5MQswCQYDVQQGEwJK UDEUMBIGA1UEChMLQ0EgVEVTVCAxLTQxFDASBgNVBAMTC0NBIFRFU1QgMS00MIGd MA0GCSqGSIb3DQEBAQUAA4GLADCBhwKBgQDZfFjkPDZeorxWqk7/DKM2d/9Nao28 dM6T5sb5L41hD5C1kXV6MJev5ALASSxtI6OVOmZO4gfubnsvcj0NTZO4SeF1yL1r VDPdx7juQI1cbDiG/EwIMW29UIdj9h052JTmEbpT0RuP/4JWmAWrdO5UE40xua7S z2/6+DB2ZklFoQIBA6OBmzCBmDAdBgNVHQ4EFgQU340JbeYcg6V9zi8aozy48aIh tfgwaQYDVR0jBGIwYIAU340JbeYcg6V9zi8aozy48aIhtfihPaQ7MDkxCzAJBgNV BAYTAkpQMRQwEgYDVQQKEwtDQSBURVNUIDEtNDEUMBIGA1UEAxMLQ0EgVEVTVCAx LTSCCQDkp8xOEMdh/jAMBgNVHRMEBTADAQH/MA0GCSqGSIb3DQEBBQUAA4GBABsH aJ/c/3cGHssi8IvVRci/aavqj607y7l22nKDtG1p4KAjnfNhBMOhRhFv00nJnokK y0uc4DIegAW1bxQjqcMNNEmGbzAeixH/cRCot8C1LobEQmxNWCY2DJLWoI3wwqr8 uUSnI1CDZ5402etkCiNXsDy/eYDrF+2KonkIWRrr -----END CERTIFICATE----- [EMAIL PROTECTED]:~/src/gnutls/tests$ ../src/certtool -e < pkcs1-pad-ok.pem Certificate[0]: C=JP,ST=Tokyo,O=TEST 2 CLIENT,CN=www2.example.jp Issued by: C=JP,O=CA TEST 1-4,CN=CA TEST 1-4 Verifying against certificate[1]. Verification output: Verified. Certificate[1]: C=JP,O=CA TEST 1-4,CN=CA TEST 1-4 Issued by: C=JP,O=CA TEST 1-4,CN=CA TEST 1-4 Verification output: Verified. [EMAIL PROTECTED]:~/src/gnutls/tests$ cat pkcs1-pad-broken.pem -----BEGIN CERTIFICATE----- MIICzTCCAjagAwIBAgIJAOSnzE4Qx2H/MA0GCSqGSIb3DQEBBQUAMDkxCzAJBgNV BAYTAkpQMRQwEgYDVQQKEwtDQSBURVNUIDEtNDEUMBIGA1UEAxMLQ0EgVEVTVCAx LTQwHhcNMDYwOTA3MTY0MDM3WhcNMDcwOTA3MTY0MDM3WjBPMQswCQYDVQQGEwJK UDEOMAwGA1UECBMFVG9reW8xFjAUBgNVBAoTDVRFU1QgMiBDTElFTlQxGDAWBgNV BAMTD3d3dzIuZXhhbXBsZS5qcDCBnzANBgkqhkiG9w0BAQEFAAOBjQAwgYkCgYEA vSpZ6ig9DpeKB60h7ii1RitNuvkn4INOfEXjCjPSFwmIbGJqnyWvKTiMKzguEYkG 6CZAbsx44t3kvsVDeUd5WZBRgMoeQd1tNJBU4BXxOA8bVzdwstzaPeeufQtZDvKf M4ej+fo/j9lYH9udCug1huaNybcCtijzGonkddX4JEUCAwEAAaOBxjCBwzAJBgNV HRMEAjAAMCwGCWCGSAGG+EIBDQQfFh1PcGVuU1NMIEdlbmVyYXRlZCBDZXJ0aWZp Y2F0ZTAdBgNVHQ4EFgQUK0DZtd8K1P2ij9gVKUNcHlx7uCIwaQYDVR0jBGIwYIAU 340JbeYcg6V9zi8aozy48aIhtfihPaQ7MDkxCzAJBgNVBAYTAkpQMRQwEgYDVQQK EwtDQSBURVNUIDEtNDEUMBIGA1UEAxMLQ0EgVEVTVCAxLTSCCQDkp8xOEMdh/jAN BgkqhkiG9w0BAQUFAAOBgQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAUKJ+eFJYSvXwGF2wxzDXj+x5YCItrHFmrEy4AXXAW+H0NgJVNvqRY/O Kw== -----END CERTIFICATE----- -----BEGIN CERTIFICATE----- MIICijCCAfOgAwIBAgIJAOSnzE4Qx2H+MA0GCSqGSIb3DQEBBQUAMDkxCzAJBgNV BAYTAkpQMRQwEgYDVQQKEwtDQSBURVNUIDEtNDEUMBIGA1UEAxMLQ0EgVEVTVCAx LTQwHhcNMDYwOTA3MTYzMzE4WhcNMDYxMDA3MTYzMzE4WjA5MQswCQYDVQQGEwJK UDEUMBIGA1UEChMLQ0EgVEVTVCAxLTQxFDASBgNVBAMTC0NBIFRFU1QgMS00MIGd MA0GCSqGSIb3DQEBAQUAA4GLADCBhwKBgQDZfFjkPDZeorxWqk7/DKM2d/9Nao28 dM6T5sb5L41hD5C1kXV6MJev5ALASSxtI6OVOmZO4gfubnsvcj0NTZO4SeF1yL1r VDPdx7juQI1cbDiG/EwIMW29UIdj9h052JTmEbpT0RuP/4JWmAWrdO5UE40xua7S z2/6+DB2ZklFoQIBA6OBmzCBmDAdBgNVHQ4EFgQU340JbeYcg6V9zi8aozy48aIh tfgwaQYDVR0jBGIwYIAU340JbeYcg6V9zi8aozy48aIhtfihPaQ7MDkxCzAJBgNV BAYTAkpQMRQwEgYDVQQKEwtDQSBURVNUIDEtNDEUMBIGA1UEAxMLQ0EgVEVTVCAx LTSCCQDkp8xOEMdh/jAMBgNVHRMEBTADAQH/MA0GCSqGSIb3DQEBBQUAA4GBABsH aJ/c/3cGHssi8IvVRci/aavqj607y7l22nKDtG1p4KAjnfNhBMOhRhFv00nJnokK y0uc4DIegAW1bxQjqcMNNEmGbzAeixH/cRCot8C1LobEQmxNWCY2DJLWoI3wwqr8 uUSnI1CDZ5402etkCiNXsDy/eYDrF+2KonkIWRrr -----END CERTIFICATE----- [EMAIL PROTECTED]:~/src/gnutls/tests$ ../src/certtool -e < pkcs1-pad-broken.pem Certificate[0]: C=JP,ST=Tokyo,O=TEST 2 CLIENT,CN=www2.example.jp Issued by: C=JP,O=CA TEST 1-4,CN=CA TEST 1-4 Verifying against certificate[1]. Verification output: Not verified. Certificate[1]: C=JP,O=CA TEST 1-4,CN=CA TEST 1-4 Issued by: C=JP,O=CA TEST 1-4,CN=CA TEST 1-4 Verification output: Verified. [EMAIL PROTECTED]:~/src/gnutls/tests$ If the above commands were used with an older GnuTLS 'certtool', they would claim that the chain in pkcs1-pad-broken.pem is valid. For reference, the certificate key: -----BEGIN RSA PRIVATE KEY----- MIICXQIBAAKBgQC9KlnqKD0Ol4oHrSHuKLVGK026+Sfgg058ReMKM9IXCYhsYmqf Ja8pOIwrOC4RiQboJkBuzHji3eS+xUN5R3lZkFGAyh5B3W00kFTgFfE4DxtXN3Cy 3No95659C1kO8p8zh6P5+j+P2Vgf250K6DWG5o3JtwK2KPMaieR11fgkRQIDAQAB AoGBAJCYvwJun713uNsFTNpv46EvmMtDiWfk9ymnglVaJ03Uy6ON11Kvy6UGxJ6E 4zIkPFNYaghH5GAGncP1pg4exHKRGJTNcQbMf9iOsCTOuvKSWbBZpnJcFllKyESK PTt72D6x/cuzDXVTeWvQMoOILa09szW7aqFNIdxae4Vq7a4BAkEA6MoehuRtZ4N9 Jtc9cIpSKOOatZ1UajWEFV2yVHaDED2kkWxKjppPzRn06LzX8LWm1RT0qe3Zyasi iXCXlno/+QJBANAGvY+k/+OvzWnv1yTKO8OmrMqkSzh3KAhFbiVWdQaqMSCWtKYk GoOKnq0PB73ExhdbTFmxC4KBPHTC2guOca0CQCD78pNebnoKUYNdYCFAGCAfD97H 6hwadRqp6gi5uhxk/5pzY6UNDF2dXexURayfsIHktD4Xq5I9o2kiAPibXdECQQDC KihwlL9K02JVSMl0y1XxDfclxSd4cq9o2PUv4HymVeA43LGMiRI+SPpF6Ut+ctW6 IzsmVDu7+chl6yD9vFyZAkA3Auv9UxKL3kPtvu5G/lrCVmwzVfAzuwtnmSfp1+M5 yTYBz+VFSsYrdlDZ3jdLnFzVOMiIm9pZca/L93QjmXJ+ -----END RSA PRIVATE KEY----- /Simon --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]