java - Verify a signature with bouncy castle -

i inherited code using deprecated bouncycastle api. before updating new api wanted write test verify didn't change behaviour. however, cannot work out correct way verify signature generated. code changed is:

public static byte[] createsigneddata(byte[] content, x509certificate cert, privatekey key)         throws nosuchalgorithmexception, nosuchproviderexception, cmsexception, ioexception {      // set generator     cmssigneddatagenerator gen = new cmssigneddatagenerator();      gen.addsigner(key, cert, cmssignedgenerator.digest_sha1);      // create signed-data object     cmsprocessable data = new cmsprocessablebytearray(content);     cmssigneddata signed = gen.generate(data, bc_provider);      return signed.getencoded(); } 

what being returned code? detached signature? tried verify signature small piece of code this, returns false:

signature signer = signature.getinstance(                               "sha1withrsa",                                bouncycastleprovider.provider_name); signer.initverify(cert.getpublickey()); signer.update(data); return signer.verify(sig); 

it return detached signature if use:

gen.generate(data, false); 

otherwise return signed data encapsulated in signature. so, if signature detached (which not case) in order verify need create new cmssigneddata object signed data bytes or base64 enconded string , copy of original data in constructor.

i think you're not verifying signature right way, don't know bouncycastle library version using , provided code snippet vague analyze.

this did in order sign , verify signature using bcmail-jdk16-1.46.jar, bcprov-jdk16-1.46.jar , jdk1.6.0_45 (i'm assuming using java since never specified it, in question tags - .net version similar).

you can download keystore used in example at: https://dl.dropboxusercontent.com/u/15208254/keys/certificates.p12

also, if want check if signature verification working fine, can change certificate (since i'm verifying against own certificate doesn't make sense) changing line in signature verification process, line 84:

if (signer.verify(new jcasimplesignerinfoverifierbuilder().setprovider(bc_provider).build(certfromsigneddata))) { ... } 

and loading keystore certificate it. know, certificates.p12 file using, contains 2 certificates alias key1 , key2 can play around them signing content key1 , verifying signature key2 example.

e.g:

// load 'key2' certificate 'certificates.p12' @ place on class after 'ks' declaration x509certificate certfromkeystore2 = (x509certificate) ks.getcertificate("key2"); 

then replace line 84 this:

if (signer.verify(new jcasimplesignerinfoverifierbuilder().setprovider(bc_provider).build(certfromkeystore2))) { ... } 

notice certfromsigneddata changed certfromkeystore2 , signature verification fail because content signed key1.

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java code:

don't forget change keystore path in constants!

package com.example.main;  import java.io.fileinputstream; import java.security.key; import java.security.keystore; import java.security.privatekey; import java.security.security; import java.security.signature; import java.security.cert.x509certificate; import java.util.arraylist; import java.util.collection; import java.util.iterator; import java.util.list;  import org.bouncycastle.cert.x509certificateholder; import org.bouncycastle.cert.jcajce.jcacertstore; import org.bouncycastle.cert.jcajce.jcax509certificateconverter; import org.bouncycastle.cms.cmsprocessablebytearray; import org.bouncycastle.cms.cmssigneddata; import org.bouncycastle.cms.cmssigneddatagenerator; import org.bouncycastle.cms.cmstypeddata; import org.bouncycastle.cms.signerinformation; import org.bouncycastle.cms.signerinformationstore; import org.bouncycastle.cms.jcajce.jcasignerinfogeneratorbuilder; import org.bouncycastle.cms.jcajce.jcasimplesignerinfoverifierbuilder; import org.bouncycastle.jce.provider.bouncycastleprovider; import org.bouncycastle.operator.contentsigner; import org.bouncycastle.operator.jcajce.jcacontentsignerbuilder; import org.bouncycastle.operator.jcajce.jcadigestcalculatorproviderbuilder; import org.bouncycastle.util.store;  public class verifysignature {      static final string keystore_file = "keys/certificates.p12";     static final string keystore_instance = "pkcs12";     static final string keystore_pwd = "test";     static final string keystore_alias = "key1";      static final string digest_sha1 = "sha1withrsa";     static final string bc_provider = "bc";      @suppresswarnings({ "rawtypes", "unchecked" })     public static void main(string[] args) throws exception {          // content signed         string text = "my name oscar";          security.addprovider(new bouncycastleprovider());          // keystore         keystore ks = keystore.getinstance(keystore_instance);         ks.load(new fileinputstream(keystore_file), keystore_pwd.tochararray());         key key = ks.getkey(keystore_alias, keystore_pwd.tochararray());          // private key , sign         privatekey privkey = (privatekey) key;         signature signature = signature.getinstance(digest_sha1, bc_provider);         signature.initsign(privkey);         signature.update(text.getbytes());          // build cms         x509certificate certfromkeystore = (x509certificate) ks.getcertificate(keystore_alias);         list certlist = new arraylist();         cmstypeddata data = new cmsprocessablebytearray(signature.sign());         certlist.add(certfromkeystore);         store certs = new jcacertstore(certlist);         cmssigneddatagenerator gen = new cmssigneddatagenerator();         contentsigner sha1signer = new jcacontentsignerbuilder(digest_sha1).setprovider(bc_provider).build(privkey);         gen.addsignerinfogenerator(new jcasignerinfogeneratorbuilder(new jcadigestcalculatorproviderbuilder().setprovider(bc_provider).build()).build(sha1signer, certfromkeystore));         gen.addcertificates(certs);         cmssigneddata signeddata = gen.generate(data, true);          // verify signature         store store = signeddata.getcertificates();          signerinformationstore signers = signeddata.getsignerinfos();          collection c = signers.getsigners();          iterator = c.iterator();         while (it.hasnext()) {              signerinformation signer = (signerinformation) it.next();              collection certcollection = store.getmatches(signer.getsid());              iterator certit = certcollection.iterator();             x509certificateholder certholder = (x509certificateholder) certit.next();             x509certificate certfromsigneddata = new jcax509certificateconverter().setprovider(bc_provider).getcertificate(certholder);             if (signer.verify(new jcasimplesignerinfoverifierbuilder().setprovider(bc_provider).build(certfromsigneddata))) {                 system.out.println("signature verified");             } else {                 system.out.println("signature verification failed");             }         }     } }