Re: Verify X.509 certificate, openssl verify returns bad signature
Nit: redundant leading 00 (or FF) in an INTEGER is VALID *B*ER but INVALID *D*ER. And signed things like certs are *D*ER for exactly this reason, so a reconstructed encoding is bit for bit identical and hashes and signatures etc. work. BER is already 'distinguished concerning the content octets of an INTEGER. X.690: 8 Basic encoding rules ... 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. Chapter 10 and 11 don't say anything about INTEGER. The length field in definite encoding may have redundant zeros though in BER DER: 10.1 Length forms The definite form of length encoding shall be used, encoded in the minimum number of octets. [Contrast with 8.1.3.2 b).] __ OpenSSL Project http://www.openssl.org User Support Mailing Listopenssl-users@openssl.org Automated List Manager majord...@openssl.org __ OpenSSL Project http://www.openssl.org User Support Mailing Listopenssl-users@openssl.org Automated List Manager majord...@openssl.org
Re: [openssl-dev] Re: Verify X.509 certificate, openssl verify returns bad signature
Hodie IV Kal. Sep. MMX, Mounir IDRASSI scripsit: [...] Specifically, Peter Gutmann in his X.509 Style Guide says this about this field : If you're writing certificate-handling code, just treat the serial number as a blob which happens to be an encoded integer. This is the kind of advice that pushes programmers to allocate fixed size fields in databases, and consider a certificate's serial number to always fit the size. This is also bad in practice. -- Erwann ABALEA erwann.aba...@keynectis.com Département RD KEYNECTIS __ OpenSSL Project http://www.openssl.org User Support Mailing Listopenssl-users@openssl.org Automated List Manager majord...@openssl.org
Re: Verify X.509 certificate, openssl verify returns bad signature
У нед, 29. 08 2010. у 04:17 +0200, Mounir IDRASSI пише: After some digging, I found that part of the problem is caused by the functions c2i_ASN1_INTEGER and d2i_ASN1_UINTEGER in file crypto\asn1\a_int.c. At lines 244 and 314, there is an if block that removes any leading zeros. Commenting out these blocks solves the DER encoding mismatch but the verification still fails because the computed digest is different from the recovered one. Thank you, I can confirm that your suggestion is working. Applying a patch that you described does solve a problem for me. The MUPCAGradjani certificate can be verified against the MUPCARoot, as well as certificates issued by the MUPCAGradjani, like the two personal certificates I have on my eID card. I had to reconvert DER to PEM with patched openssl to get PEM certificates with correct serial number encoding. I read the other messages in this thread, but I am not an expert in the field so I do not know if openssl should add a support for incorrect serial numbers. In RFC 3280 there is a note about Non-conforming CAs where section 4.1.2.2 Serial number is saying that certificate users SHOULD be prepared to gracefully handle such certificates. Maybe the note can apply in this case? What I do know is that without a patch openssl can not be used with certificates issued on a Serbian national eID card. At least one other Serbian CA is hit by the same problem (http://ca.pks.rs/certs/) where PKI solution was provided by a same company. I have published patched openssl package for Ubuntu GNU/Linux distribution in my Ubuntu PPA at: https://launchpad.net/~grakic/+archive/serbian-eid Kind regards, Goran Rakic __ OpenSSL Project http://www.openssl.org User Support Mailing Listopenssl-users@openssl.org Automated List Manager majord...@openssl.org
Re: [openssl-users] Re: Verify X.509 certificate, openssl verify returns bad signature
Hodie III Kal. Sep. MMX, Goran Rakic scripsit: [...] I read the other messages in this thread, but I am not an expert in the field so I do not know if openssl should add a support for incorrect serial numbers. In RFC 3280 there is a note about Non-conforming CAs where section 4.1.2.2 Serial number is saying that certificate users SHOULD be prepared to gracefully handle such certificates. Maybe the note can apply in this case? What I do know is that without a patch openssl can not be used with certificates issued on a Serbian national eID card. At least one other Serbian CA is hit by the same problem (http://ca.pks.rs/certs/) where PKI solution was provided by a same company. These are not X.509 certificates, since they're not correctly encoded (not DER, not even BER). The paragraph you're mentioning is about the value of the serial number (strictly positive, no more than 20 bytes), not about its encoding. A serial number can be negative, or larger than 20 bytes when encoded, if your only goal is to be X.509 compliant, and not RFC5280 compliant. Whence, non-conforming CAs here is to be understood as non-RFC5280-conforming CAs. Those certificates should have been rejected by any correct validator (human or machine) before going into production. The serial number is encoded using 4 bytes as its value, it should be 1 byte only. -- Erwann ABALEA erwann.aba...@keynectis.com Département RD KEYNECTIS __ OpenSSL Project http://www.openssl.org User Support Mailing Listopenssl-users@openssl.org Automated List Manager majord...@openssl.org
Re: Verify X.509 certificate, openssl verify returns bad signature
On Mon, Aug 30, 2010, Goran Rakic wrote:
?? ??, 29. 08 2010. ?? 04:17 +0200, Mounir IDRASSI :
After some digging, I found that part of the problem is caused by the
functions c2i_ASN1_INTEGER and d2i_ASN1_UINTEGER in file
crypto\asn1\a_int.c. At lines 244 and 314, there is an if block that
removes any leading zeros. Commenting out these blocks solves the DER
encoding mismatch but the verification still fails because the computed
digest is different from the recovered one.
Thank you, I can confirm that your suggestion is working.
Applying a patch that you described does solve a problem for me. The
MUPCAGradjani certificate can be verified against the MUPCARoot, as well
as certificates issued by the MUPCAGradjani, like the two personal
certificates I have on my eID card. I had to reconvert DER to PEM with
patched openssl to get PEM certificates with correct serial number
encoding.
I read the other messages in this thread, but I am not an expert in the
field so I do not know if openssl should add a support for incorrect
serial numbers. In RFC 3280 there is a note about Non-conforming CAs
where section 4.1.2.2 Serial number is saying that certificate users
SHOULD be prepared to gracefully handle such certificates. Maybe the
note can apply in this case?
What I do know is that without a patch openssl can not be used with
certificates issued on a Serbian national eID card. At least one other
Serbian CA is hit by the same problem (http://ca.pks.rs/certs/) where
PKI solution was provided by a same company.
I have published patched openssl package for Ubuntu GNU/Linux
distribution in my Ubuntu PPA at:
https://launchpad.net/~grakic/+archive/serbian-eid
I wouldn't advise changing the code in that way (FYI I wrote it). The normal
workaround in OpenSSL for broken encodings is to use the original encoding
by caching it. The attached three line patch adds this workaround for
certificates.
Steve.
--
Dr Stephen N. Henson. OpenSSL project core developer.
Commercial tech support now available see: http://www.openssl.org
Index: crypto/asn1/x_x509.c
===
RCS file: /v/openssl/cvs/openssl/crypto/asn1/x_x509.c,v
retrieving revision 1.29
diff -u -r1.29 x_x509.c
--- crypto/asn1/x_x509.c8 Aug 2008 15:35:27 - 1.29
+++ crypto/asn1/x_x509.c29 Aug 2010 23:08:35 -
@@ -63,7 +63,7 @@
#include openssl/x509.h
#include openssl/x509v3.h
-ASN1_SEQUENCE(X509_CINF) = {
+ASN1_SEQUENCE_enc(X509_CINF, enc, 0) = {
ASN1_EXP_OPT(X509_CINF, version, ASN1_INTEGER, 0),
ASN1_SIMPLE(X509_CINF, serialNumber, ASN1_INTEGER),
ASN1_SIMPLE(X509_CINF, signature, X509_ALGOR),
@@ -74,7 +74,7 @@
ASN1_IMP_OPT(X509_CINF, issuerUID, ASN1_BIT_STRING, 1),
ASN1_IMP_OPT(X509_CINF, subjectUID, ASN1_BIT_STRING, 2),
ASN1_EXP_SEQUENCE_OF_OPT(X509_CINF, extensions, X509_EXTENSION, 3)
-} ASN1_SEQUENCE_END(X509_CINF)
+} ASN1_SEQUENCE_END_enc(X509_CINF, X509_CINF)
IMPLEMENT_ASN1_FUNCTIONS(X509_CINF)
/* X509 top level structure needs a bit of customisation */
Index: crypto/x509/x509.h
===
RCS file: /v/openssl/cvs/openssl/crypto/x509/x509.h,v
retrieving revision 1.171
diff -u -r1.171 x509.h
--- crypto/x509/x509.h 14 Mar 2010 12:52:38 - 1.171
+++ crypto/x509/x509.h 29 Aug 2010 23:04:30 -
@@ -258,6 +258,7 @@
ASN1_BIT_STRING *issuerUID; /* [ 1 ] optional in v2 */
ASN1_BIT_STRING *subjectUID;/* [ 2 ] optional in v2 */
STACK_OF(X509_EXTENSION) *extensions; /* [ 3 ] optional in v3 */
+ ASN1_ENCODING enc;
} X509_CINF;
/* This stuff is certificate auxiliary info
Re: Verify X.509 certificate, openssl verify returns bad signature
У пон, 30. 08 2010. у 20:38 +0200, Dr. Stephen Henson пише: I wouldn't advise changing the code in that way (FYI I wrote it). The normal workaround in OpenSSL for broken encodings is to use the original encoding by caching it. The attached three line patch adds this workaround for certificates. Thanks Stephen. This preprocessor black magic looks very interesting, I will spend some free time trying to understand it in the following days. I read your message on openssl-dev about the issue with a dirty cache. As a naive code reader, I am wondering could not the modified field in the cached data be set whenever certificate data is modified to invalidate the cache? Will this allow integrating this patch upstream? Kind regards, Goran Rakic __ OpenSSL Project http://www.openssl.org User Support Mailing Listopenssl-users@openssl.org Automated List Manager majord...@openssl.org
Re: Verify X.509 certificate, openssl verify returns bad signature
On Mon, Aug 30, 2010, Goran Rakic wrote: ?? ??, 30. 08 2010. ?? 20:38 +0200, Dr. Stephen Henson : I wouldn't advise changing the code in that way (FYI I wrote it). The normal workaround in OpenSSL for broken encodings is to use the original encoding by caching it. The attached three line patch adds this workaround for certificates. Thanks Stephen. This preprocessor black magic looks very interesting, I will spend some free time trying to understand it in the following days. Well it is buried in the ASN1 code. All it does is uses an extra structure to save the received encoding. Then when signatures are calculated that is used instead of re-encoding the parsed out structure. I read your message on openssl-dev about the issue with a dirty cache. As a naive code reader, I am wondering could not the modified field in the cached data be set whenever certificate data is modified to invalidate the cache? Will this allow integrating this patch upstream? It isn't possible to cover all cases where the certificate data is modified as some don't keep a reference to the parent certificate structure. However it is possible to always re-encode when a certificate is signed (this is done for CRLs) which should cover all cases except pathological ones where a certificate is modified and not re-signed to deliberately produce invalid signatures. Steve. -- Dr Stephen N. Henson. OpenSSL project core developer. Commercial tech support now available see: http://www.openssl.org __ OpenSSL Project http://www.openssl.org User Support Mailing Listopenssl-users@openssl.org Automated List Manager majord...@openssl.org
Re: Verify X.509 certificate, openssl verify returns bad signature
The encoding is invalid BER. The openssl is tolerant but also destructive in copy. whenever you use openssl x509 -in -out ... you remove one leading 0 octet. IMHO openssl should reject the cert because of invalid encoding. On 08/29/2010 04:17 AM, Mounir IDRASSI wrote: Hi, The problem you are encountering is partly caused by the way OpenSSL handles integers whose DER encoded value starts with one or more zeros : in this case, OpenSSL removes the leading zero when creating the corresponding ASN1_INTEGER structure thus leading to the fact that computed DER of this structure and the original one will be different!! In your case, the certificate you are trying to verify has a DER encoded serial number 00 00 65. So, OpenSSL will create an ASN1_INTEGER with a value of 00 65. And in the course of the certificate signature verification, this structure will be encoded to DER which will lead to a encoded value of 00 65. Thus, the generated DER of the CertInfo will be different from the original one, which explains why the signature verification fails. After some digging, I found that part of the problem is caused by the functions c2i_ASN1_INTEGER and d2i_ASN1_UINTEGER in file crypto\asn1\a_int.c. At lines 244 and 314, there is an if block that removes any leading zeros. Commenting out these blocks solves the DER encoding mismatch but the verification still fails because the computed digest is different from the recovered one. I will continue my investigation to find all the culprits. Meanwhile, the question remains why in the first place the removal of the leading zero from the parsed DER encoding was added since this clearly have the side effect of making the computed DER different from the original one. Cheers, -- Mounir IDRASSI IDRIX http://www.idrix.fr On 8/28/2010 10:43 PM, Goran Rakic wrote: Hi all, I have two X.509 certificates MUPCAGradjani.crt and MUPCARoot.crt downloaded from http://ca.mup.gov.rs/sertifikati-lat.html Certificate path is MUPCARoot MUPCAGradjani and I would like to validate MUPCAGradjani against the other. What I did is to convert both to PEM format and rename them by hash as efd6650d.0 (Gradjani) and fc5fe32d.0 (Root) using this script: #!/bin/bash hash=`openssl x509 -in $1 -inform DER -noout -hash` echo Saving $1 as $hash.0 openssl x509 -in $1 -inform DER -out $hash.0 -outform PEM Now I run: $ openssl verify -CApath . efd6650d.0 error 7 at 0 depth lookup:certificate signature failure 16206:error:04077068:rsa routines:RSA_verify:bad signature:rsa_sign.c:255: 16206:error:0D0C5006:asn1 encoding routines:ASN1_item_verify:EVP lib:a_verify.c:173:/pre Hm, that is not working. What am I doing wrong here? I am running OpenSSL 0.9.8k 25 Mar 2009 on Ubuntu 10.04 GNU/Linux. I also have my personal certificate issued by MUPCAGradjani that I would like to verify but it is failing with the same error (just one level down): $ openssl verify -CApath . qualified.pem qualified.pem: /CN=MUPCA Gradjani/O=MUP Republike Srbije/L=Beograd/C=Republika Srbija (RS) error 7 at 1 depth lookup:certificate signature failure 16258:error:04077068:rsa routines:RSA_verify:bad signature:rsa_sign.c:255: 16258:error:0D0C5006:asn1 encoding routines:ASN1_item_verify:EVP lib:a_verify.c:173:/pre When I install downloaded certificates in Windows using Internet Explorer and doubleclick on my personal certificate (qualified.cer) it looks valid. I am not sure, but I believe it is doing certificate chain validation so the certificates and paths should be valid. After all they are issued by a trustful CA. Output of openssl x509 -nameopt multiline,utf8,-esc_msb -noout -text -in $1 looks reasonable for both downloaded certificates and is the same before and after conversion to PEM (using -inform DER in the first case). My take on this is that I am not doing conversion properly or maybe the original certificates are in some other format requiring extra argument, but I can not find answer in the docs. How can I properly validate X.509 certificate from http://ca.mup.gov.rs/sertifikati-lat.html by certificate chain? Kind regards, Goran __ OpenSSL Project http://www.openssl.org User Support Mailing Listopenssl-users@openssl.org Automated List Manager majord...@openssl.org __ OpenSSL Project http://www.openssl.org Development Mailing List openssl-...@openssl.org Automated List Manager majord...@openssl.org __ OpenSSL Project http://www.openssl.org User Support Mailing Listopenssl-users@openssl.org Automated List
Re: Verify X.509 certificate, openssl verify returns bad signature
Hi Peter, Although the certificate's encoding of the serial number field breaks the BER specification about the minimal bytes representation, it is known that many CA's and libraries treat this field as a blob and usually encode it on a fixed length basis without caring about leading zeros. Specifically, Peter Gutmann in his X.509 Style Guide says this about this field : If you're writing certificate-handling code, just treat the serial number as a blob which happens to be an encoded integer. Moreover, major PKI libraries are tolerant vis-a-vis the encoding of the serial number field of a certificate and they verify successfully the certificate chain given by the original poster. For example, NSS, GnuTLS and CryptoAPI accept the given certificates and verify successfully their trust. Supporting or not specific broken implementations have always been the subject of heated debates. Concerning the specific issue here, it's clear that OpenSSL is too restrictive compared to other major libraries since this is a minor deviation from the BER specs (i.e. minimal bytes representation) and thus hurts deployments of real-world certificates. -- Mounir IDRASSI IDRIX http://www.idrix.fr The encoding is invalid BER. The openssl is tolerant but also destructive in copy. whenever you use openssl x509 -in -out ... you remove one leading 0 octet. IMHO openssl should reject the cert because of invalid encoding. On 08/29/2010 04:17 AM, Mounir IDRASSI wrote: Hi, The problem you are encountering is partly caused by the way OpenSSL handles integers whose DER encoded value starts with one or more zeros : in this case, OpenSSL removes the leading zero when creating the corresponding ASN1_INTEGER structure thus leading to the fact that computed DER of this structure and the original one will be different!! In your case, the certificate you are trying to verify has a DER encoded serial number 00 00 65. So, OpenSSL will create an ASN1_INTEGER with a value of 00 65. And in the course of the certificate signature verification, this structure will be encoded to DER which will lead to a encoded value of 00 65. Thus, the generated DER of the CertInfo will be different from the original one, which explains why the signature verification fails. After some digging, I found that part of the problem is caused by the functions c2i_ASN1_INTEGER and d2i_ASN1_UINTEGER in file crypto\asn1\a_int.c. At lines 244 and 314, there is an if block that removes any leading zeros. Commenting out these blocks solves the DER encoding mismatch but the verification still fails because the computed digest is different from the recovered one. I will continue my investigation to find all the culprits. Meanwhile, the question remains why in the first place the removal of the leading zero from the parsed DER encoding was added since this clearly have the side effect of making the computed DER different from the original one. Cheers, -- Mounir IDRASSI IDRIX http://www.idrix.fr On 8/28/2010 10:43 PM, Goran Rakic wrote: Hi all, I have two X.509 certificates MUPCAGradjani.crt and MUPCARoot.crt downloaded from http://ca.mup.gov.rs/sertifikati-lat.html Certificate path is MUPCARoot MUPCAGradjani and I would like to validate MUPCAGradjani against the other. What I did is to convert both to PEM format and rename them by hash as efd6650d.0 (Gradjani) and fc5fe32d.0 (Root) using this script: #!/bin/bash hash=`openssl x509 -in $1 -inform DER -noout -hash` echo Saving $1 as $hash.0 openssl x509 -in $1 -inform DER -out $hash.0 -outform PEM Now I run: $ openssl verify -CApath . efd6650d.0 error 7 at 0 depth lookup:certificate signature failure 16206:error:04077068:rsa routines:RSA_verify:bad signature:rsa_sign.c:255: 16206:error:0D0C5006:asn1 encoding routines:ASN1_item_verify:EVP lib:a_verify.c:173:/pre Hm, that is not working. What am I doing wrong here? I am running OpenSSL 0.9.8k 25 Mar 2009 on Ubuntu 10.04 GNU/Linux. I also have my personal certificate issued by MUPCAGradjani that I would like to verify but it is failing with the same error (just one level down): $ openssl verify -CApath . qualified.pem qualified.pem: /CN=MUPCA Gradjani/O=MUP Republike Srbije/L=Beograd/C=Republika Srbija (RS) error 7 at 1 depth lookup:certificate signature failure 16258:error:04077068:rsa routines:RSA_verify:bad signature:rsa_sign.c:255: 16258:error:0D0C5006:asn1 encoding routines:ASN1_item_verify:EVP lib:a_verify.c:173:/pre When I install downloaded certificates in Windows using Internet Explorer and doubleclick on my personal certificate (qualified.cer) it looks valid. I am not sure, but I believe it is doing certificate chain validation so the certificates and paths should be valid. After all they are issued by a trustful CA. Output of openssl x509 -nameopt multiline,utf8,-esc_msb -noout -text -in $1 looks reasonable for
Re: Verify X.509 certificate, openssl verify returns bad signature
On 08/29/2010 01:20 PM, Mounir IDRASSI wrote: Hi Peter, Although the certificate's encoding of the serial number field breaks the BER specification about the minimal bytes representation, it is known that many CA's and libraries treat this field as a blob and usually encode it on a fixed length basis without caring about leading zeros. Specifically, Peter Gutmann in his X.509 Style Guide says this about this field : If you're writing certificate-handling code, just treat the serial number as a blob which happens to be an encoded integer. You are citing out of context. There is a reference to negative integers which can happen 50%. A text written 10 years ago is not really an excuse for a certificate from this year. Moreover, major PKI libraries are tolerant vis-a-vis the encoding of the serial number field of a certificate and they verify successfully the certificate chain given by the original poster. So what. The certs are still wrong. For example, NSS, GnuTLS and CryptoAPI accept the given certificates and verify successfully their trust. hm, inserting the certs into Firefox says to me that the certs cannot be validated for unknown reasons. The decoders in NSS and GnuTLS accept all kinds of bad encodings, the BER/DER decoders being very tolerant. Supporting or not specific broken implementations have always been the subject of heated debates. X509 has been updated to decode and reencode a certificate, in this sense openssl's behaviour of silently dropping one octet is not very nice. But there are other potential minor deviations. Concerning the specific issue here, it's clear that OpenSSL is too restrictive compared to other major libraries since this is a minor deviation from the BER specs (i.e. minimal bytes representation) and thus hurts deployments of real-world certificates. Others are EXTREMLY permissive in decoding. This minor deviation results in ambiguous DER. Assumed two values 0001 or 01, are these the same serialnumber, or not? This is asking for real trouble. Even when taking as a blob, displaying will show 1 for both in major implementations. I'd rather see openssl be more restrictive and reject bad encodings (I am not talking about a negative number here). and what about version: 02060002 020601230002 some treat the second as a v3 __ OpenSSL Project http://www.openssl.org User Support Mailing Listopenssl-users@openssl.org Automated List Manager majord...@openssl.org
Re: Verify X.509 certificate, openssl verify returns bad signature
On 08/29/2010 07:38 PM, Mounir IDRASSI wrote: Hi Peter, Thank you for your comments. As I said, this kind of debates can be very heated and going down this road don't lead usually to any results. The debate may be whether and how something should be done in openssl, I admit I had started that one. I am the first one to wish that the PKI world out there is ideal and everyone uses correctly validated modules. Unfortunately, we constantly have to balance between correctness and practicalness. Some programs are not strict in verification, so be it. But that has nothing to do with the fact that the certs in question are not correctly encoded and may create unexpected behaviour... Concerning Firefox check, I have managed to load the chain and to validate it correctly using Firefox 3.6.8 under Windows and Ubuntu 10.04. I'm attaching screenshots. Try edit the trustsetting. Or: Try load them without setting any trust during loading and to set some later through the certificate management. __ OpenSSL Project http://www.openssl.org User Support Mailing Listopenssl-users@openssl.org Automated List Manager majord...@openssl.org
RE: Verify X.509 certificate, openssl verify returns bad signature
From: owner-openssl-us...@openssl.org On Behalf Of Peter Sylvester Sent: Sunday, 29 August, 2010 05:44 The encoding is invalid BER. The openssl is tolerant but also destructive in copy. whenever you use openssl x509 -in -out ... you remove one leading 0 octet. IMHO openssl should reject the cert because of invalid encoding. On 08/29/2010 04:17 AM, Mounir IDRASSI wrote: Hi, The problem you are encountering is partly caused by the way OpenSSL handles integers whose DER encoded value starts with one or more zeros : in this case, OpenSSL removes the leading zero when creating the corresponding ASN1_INTEGER structure thus leading to the fact that computed DER of this structure and the original one will be different!! Nit: redundant leading 00 (or FF) in an INTEGER is VALID *B*ER but INVALID *D*ER. And signed things like certs are *D*ER for exactly this reason, so a reconstructed encoding is bit for bit identical and hashes and signatures etc. work. __ OpenSSL Project http://www.openssl.org User Support Mailing Listopenssl-users@openssl.org Automated List Manager majord...@openssl.org
Re: Verify X.509 certificate, openssl verify returns bad signature
Hi, The problem you are encountering is partly caused by the way OpenSSL handles integers whose DER encoded value starts with one or more zeros : in this case, OpenSSL removes the leading zero when creating the corresponding ASN1_INTEGER structure thus leading to the fact that computed DER of this structure and the original one will be different!! In your case, the certificate you are trying to verify has a DER encoded serial number 00 00 65. So, OpenSSL will create an ASN1_INTEGER with a value of 00 65. And in the course of the certificate signature verification, this structure will be encoded to DER which will lead to a encoded value of 00 65. Thus, the generated DER of the CertInfo will be different from the original one, which explains why the signature verification fails. After some digging, I found that part of the problem is caused by the functions c2i_ASN1_INTEGER and d2i_ASN1_UINTEGER in file crypto\asn1\a_int.c. At lines 244 and 314, there is an if block that removes any leading zeros. Commenting out these blocks solves the DER encoding mismatch but the verification still fails because the computed digest is different from the recovered one. I will continue my investigation to find all the culprits. Meanwhile, the question remains why in the first place the removal of the leading zero from the parsed DER encoding was added since this clearly have the side effect of making the computed DER different from the original one. Cheers, -- Mounir IDRASSI IDRIX http://www.idrix.fr On 8/28/2010 10:43 PM, Goran Rakic wrote: Hi all, I have two X.509 certificates MUPCAGradjani.crt and MUPCARoot.crt downloaded from http://ca.mup.gov.rs/sertifikati-lat.html Certificate path is MUPCARoot MUPCAGradjani and I would like to validate MUPCAGradjani against the other. What I did is to convert both to PEM format and rename them by hash as efd6650d.0 (Gradjani) and fc5fe32d.0 (Root) using this script: #!/bin/bash hash=`openssl x509 -in $1 -inform DER -noout -hash` echo Saving $1 as $hash.0 openssl x509 -in $1 -inform DER -out $hash.0 -outform PEM Now I run: $ openssl verify -CApath . efd6650d.0 error 7 at 0 depth lookup:certificate signature failure 16206:error:04077068:rsa routines:RSA_verify:bad signature:rsa_sign.c:255: 16206:error:0D0C5006:asn1 encoding routines:ASN1_item_verify:EVP lib:a_verify.c:173:/pre Hm, that is not working. What am I doing wrong here? I am running OpenSSL 0.9.8k 25 Mar 2009 on Ubuntu 10.04 GNU/Linux. I also have my personal certificate issued by MUPCAGradjani that I would like to verify but it is failing with the same error (just one level down): $ openssl verify -CApath . qualified.pem qualified.pem: /CN=MUPCA Gradjani/O=MUP Republike Srbije/L=Beograd/C=Republika Srbija (RS) error 7 at 1 depth lookup:certificate signature failure 16258:error:04077068:rsa routines:RSA_verify:bad signature:rsa_sign.c:255: 16258:error:0D0C5006:asn1 encoding routines:ASN1_item_verify:EVP lib:a_verify.c:173:/pre When I install downloaded certificates in Windows using Internet Explorer and doubleclick on my personal certificate (qualified.cer) it looks valid. I am not sure, but I believe it is doing certificate chain validation so the certificates and paths should be valid. After all they are issued by a trustful CA. Output of openssl x509 -nameopt multiline,utf8,-esc_msb -noout -text -in $1 looks reasonable for both downloaded certificates and is the same before and after conversion to PEM (using -inform DER in the first case). My take on this is that I am not doing conversion properly or maybe the original certificates are in some other format requiring extra argument, but I can not find answer in the docs. How can I properly validate X.509 certificate from http://ca.mup.gov.rs/sertifikati-lat.html by certificate chain? Kind regards, Goran __ OpenSSL Project http://www.openssl.org User Support Mailing Listopenssl-users@openssl.org Automated List Manager majord...@openssl.org __ OpenSSL Project http://www.openssl.org User Support Mailing Listopenssl-users@openssl.org Automated List Manager majord...@openssl.org
