Re: CA generation/certificate serial number

Peter Sylvester Thu, 03 Apr 2008 06:44:33 -0700

openssl is VERY tolerant concerning the encoding/decoding of an INTEGER value.

Other decoders may not like such things as length 0 etc.


When converting such a beast from DER to PEM or the other way, you might
have a surprise.


From X.690:


8.3 Encoding of an integer value

8.3.1 The encoding of an integer value shall be primitive. The contents octets shall consist of one or more octets. 8.3.2 If the contents octets of an integer value encoding consist of more than one octet, then the bits of the first octet and bit 8 of the second octet:

a) shall not all be ones; and
b) shall not all be zero.

NOTE – These rules ensure that an integer value is always encoded in the smallest possible number of octets. 8.3.3 The contents octets shall be a two’s complement binary number equal to the integer value, and consisting of bits 8 to 1 of the first octet, followed by bits 8 to 1 of the second octet, followed by bits 8 to 1 of each octet in turn up to and including the last octet of the contents octets. NOTE – The value of a two’s complement binary number is derived by numbering the bits in the contents octets, starting with bit 1 of the last octet as bit zero and ending the numbering with bit 8 of the first octet. Each bit is assigned a numerical value of 2N, where N is its position in the above numbering sequence. The value of the two’s complement binary number is obtained by summing the numerical values assigned to each bit for those bits which are set to one, excluding bit 8 of the first octet, and then reducing this value by the numerical value assigned to bit 8 of the first octet if that bit is set to one.Giang Nguyen wrote:

nils

Frédéric Donnat wrote:

  Hi,
Sorry for the mistake (nothing to deal with openssl.cnf file). I was just looking for ca.txt file.
Is it normal behavior of openssl to be able to view a certificate without serial number using (without any error mentioned):
  openssl x509 -in some_cert_without_sn.pem -text
  But to be unable to verify it using:
  openssl verify -CAfile some_cert_without_sn.pem some_cert_without_sn.pem


  Sample: (attached self-sign cert name pipo-bad.pem)

hmm, the attached certificate as has a serial number it's 0x0


actually the attachment 
http://www.mail-archive.com/openssl-users@openssl.org/msg41447/pipo-bad.pem 
does not have a serial number; that field is has lenght of zero:

    0:d=0  hl=4 l= 546 cons: SEQUENCE
    4:d=1  hl=4 l= 395 cons: SEQUENCE
    8:d=2  hl=2 l=   3 cons: cont [ 0 ]
   10:d=3  hl=2 l=   1 prim: INTEGER           :02
   13:d=2  hl=2 l=   0 prim: INTEGER           :00
   15:d=2  hl=2 l=  13 cons: SEQUENCE
   17:d=3  hl=2 l=   9 prim: OBJECT            :md5WithRSAEncryption


similar to the certificate i posted in the "signature failure when certificate 
contains no serial number (ie, not one that equals zero)?" thread:

arch [apps]$ cat /tmp/no_serial.pem
-----BEGIN CERTIFICATE-----
MIIBCzCBtqADAgECAgAwDQYJKoZIhvcNAQEFBQAwDzENMAsGA1UEAxMEdGVzdDAe
Fw0wNDA3MjIxNzU3MTlaFw0xMzAxMjMxNTIxMzVaMA8xDTALBgNVBAMTBHRlc3Qw
XDANBgkqhkiG9w0BAQEFAANLADBIAkEAsUDN7wFJBTJC+/BtbDzomHvDA6xMAxpx
zy4pDdkKBH0Key8yCxJ8dH1c8vNwaRfC5QgMZDxBY+o2n2DvrGrL+QIDAQABMA0G
CSqGSIb3DQEBBQUAA0EAiWk2QM5lxijnjQE/D/tsoWf0LZvPIuPC7laTUFUrAIKr
JbkAQ9rrf33pf+7JIhiJIgFxVVgOv2PXYKPWC7duUA==
-----END CERTIFICATE-----


    0:d=0  hl=4 l= 267 cons: SEQUENCE
    4:d=1  hl=3 l= 182 cons: SEQUENCE
    7:d=2  hl=2 l=   3 cons: cont [ 0 ]
    9:d=3  hl=2 l=   1 prim: INTEGER           :02
   12:d=2  hl=2 l=   0 prim: INTEGER           :00
   14:d=2  hl=2 l=  13 cons: SEQUENCE
   16:d=3  hl=2 l=   9 prim: OBJECT            :sha1WithRSAEncryption

[EMAIL PROTECTED] simple]$ LD_LIBRARY_PATH=/usr/local/ossl-0.9.8/lib /usr/local/ossl-0.9.8/bin/openssl verify -verbose -CAfile pipo-bad.pem pipo-bad.pem
   pipo-bad.pem: /C=UK/CN=OpenSSL Group
   error 7 at 0 depth lookup:certificate signature failure
   18588:error:04077068:rsa routines:RSA_verify:bad signature:rsa_sign.c:218:
18588:error:0D0C5006:asn1 encoding routines:ASN1_item_verify:EVP lib:a_verify.c:168:
well the signature really seems to be wrong. How did you create
the certificate ?



as to how i generated the certificate with no serial number, i simply commented out the code and 
ran "./openssl req" without specifying "-set_serial":

arch [apps]$ diff -u req.c.BAK req.c
--- req.c.BAK   2007-12-29 12:26:41.000000000 -0800
+++ req.c       2007-12-29 12:39:11.000000000 -0800
@@ -937,16 +937,18 @@
                                {
                                if (!X509_set_serialNumber(x509ss, serial)) 
goto end;
                                }
-                       else
-                               {
-                               if (!rand_serial(NULL,
-                                       X509_get_serialNumber(x509ss)))
-                                               goto end;
-                               }

                        if (!X509_set_issuer_name(x509ss, 
X509_REQ_get_subject_name(req))) goto end;

again, this is not causing any problems for me, just curious.

thanks.

Cheers,
Nils


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--

To verify the signature, see http://edelpki.edelweb.fr/ Cela vous permet de charger le certificat de l'autorité; die Liste mit zurückgerufenen Zertifikaten finden Sie da auch.

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Description: S/MIME Cryptographic Signature

Re: CA generation/certificate serial number

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