Digital signatures in real life

Hi,
I've been trying to grok the concept for a while, not without a modicum of success. Yet the big picture escapes me. I'm interested primarily in electronic document workflow as a substitute for classic paper document workflow. There must be software frameworks serving the concept, protocols of higher level than gpg, industry standards - something like that. Links and keywords are extremely welcome. It's hard to start googling effectively without a keyword or two.

Maybe how citizenship smartcards work and are used in real life is of interest? Belgium eletronic identity cards and Portuguese citizenship cards support that.
The involved standarts are something like pkcs11, pkcs10, etc. If you understand the way private and public assimetric keys work you will understand the process at high level. From there it's all details on how to actually sign something how to and where get and store the keys, etc.
For example, the portuguese card has 2 pairs of private / public keys. One of them for authenticity purposes and the other pair for signing. It also contains the certificates that form the chain of trust and allow to verify the keys are still valid.
Having a smartcard reader and obviously one of those cards you can just plug it in the laptop, create a document, like a pdf file or even a word file in the office and choose to sign it. Now for example if you sign a pdf file, the person that receives it can just open and it magically says if the signature is valid or not. It does this by magic also .
Ok, not everything is magic. When you sign the document in the process yoru certificate file that contains your public key is attached to it, then when the document is opened it will check the cryptographic signature of the file. Aditional verifications will be done for example in adobe reader, like checking the signature timestamp with an online service and also checking the certificates chain of trust.
But i'm kind sleppy and may be saying something stupid. Someone else can correct me and add more information
Last edited by Diaz (2013-12-19 07:28:06)

Similar Messages

Excel 2013 crash - related to digital signature?

This is a cross-posting of a thread originally started in Microsoft Answers (Office- Excel) forum, advised to post in this forum by MS support engineer Mohan Suryanarayan (link to other forum: here).
I have a VB macro in file A (which otherwise contains only several Excel Tables with named ranges). My digital signature (for signing code) is attached to file A.
As the macro executes, the Open file dialog is called up so that the User can select a secondary file to open (file B or C).
Files B and C contain several sheets with formulas and Excel Tables, and also their own extensive VB macros. My digital signature is also attached to files B & C.
The remainder of the macro in file A simply executes an update of the Excel Tables in the secondary file, before saving & closing it.
I have been finding that during execution of the file A macro, Excel crashes and closes all open Excel files.
If I remove the digital signature from the secondary files then the macro in file A executes with no problem.
The macro was written in Excel 2007 and on a different laptop, with different digital signature, and used to have no problem at all. When a new laptop was purchased a new digital signature was obtained and placed into all of the files.
Execution of file A is a critical process - I need help with stopping the crash, while maintaining a digital signature in the secondary files (so that their own macros can execute).
Event Viewer error shows the following:
Faulting application name: EXCEL.EXE, version: 15.0.4667.1000, time stamp: 0x543d366c
Faulting module name: mso.dll, version: 0.0.0.0, time stamp: 0x5447696f
Exception code: 0xc0000602
Fault offset: 0x011aafdd
Faulting process id: 0x2d58
Faulting application start time: 0x01d01e17eafcd0bb
Faulting application path: C:\Program Files\Microsoft Office 15\root\office15\EXCEL.EXE
Faulting module path: C:\Program Files (x86)\Common Files\Microsoft Shared\Office15\mso.dll
JL Latham replied:
Tom, all I can give you is relatively non-information. I haven't experienced that type of behavior even in Excel 2013 with digitally signed macros in multiple workbooks. But my digital signature is a commercial one from DigiCert, not
self-cert. I'm not even sure what piece of Excel or Office processes the digital signature (that is, whether it is mso.dll or not). But your whole process has more moving parts than most of mine involving multiple workbooks do - I quite often turn
off .EnableEvents when doing things like that just so event driven macros in the other workbook(s) do not execute.
Do the macros in the 'B files' have to execute during all of this processing in file A? If not, have you tried turning interrupts off:
Application.EnableEvents = False
before starting to work with the B-files? Maybe something in them, such as a Worksheet_Change() or other event triggered process is messing things up?
If you do use Application.EnableEvents=False, remember that you MUST re-enable that later in the code with Application.EnableEvents=True to get responses to things like button clicks, changes in a worksheet or other event driven processes
to run 'normally' again.
Have you looked at this discussion:
http://answers.microsoft.com/en-us/office/forum/office_2013_release-excel/excel-2013-crashing-immediately-when-attempting-to/ea2ab100-5525-4a0d-a3cf-6977319f954f
Sounds very similar to yours - original signature created in 2007, and crashing in 2013. Some suggestions were made, but whether they fixed the issue or not is unknown: OP never came back and said "fixed it" or "didn't fix it".
I replied:
In answer, the secondary B files don't execute any part of their macros during the A file process, and I hadn't included an EnableEvents = False within the file A code. However, I have just tried it to check if it made any difference and unfortunately it didn't.
I had read the thread you gave a link to before posting, and also the sub threads given within that one, but didn't see anything I thought of immediate parallel other than an Excel 2013 crash.
The way I read the linked thread was that a User added a signature in Excel 2007 and when they tried to open the file Excel (2007?) crashes, although other people using Excel 2013 can open it (not clear whether it means others can open the one with
the 2007 signature or without it).
Anyway, the differences in my situation are that:
(1) my B-files were originally created in Excel 2007 on a different laptop to current and had their own signature attached. I maintain a 'stock' of B-file versions, some of which have the old signature and some the new. If I run the A-file macro
on one of the B-files with the old signature then it executes ok;
(2) I am able to open the B-files ok, no matter whether the signature in them derives from the old laptop with Excel 2007 or the new laptop with Excel 2013;
(3) the macros within the B-files execute ok (this includes any versions of the B-files which still have an old signature attached, by removing the old signature and replacing with the new and executing on the new laptop);
(4) the offending operation which triggers the crash (when the B-files have the new signature attached) is a Resize of the Excel Tables within the B-file. I understand that I may eventually have to find a workaround for this operation but initially
I want to sort out the signature issue (I'm reasonably sure the signature issue is not a red herring where the Resize is the 'real' problem).
Regards, Tom

Hi,
According to your description, this issue occurred with some particular files that stored in SharePoint site. Did the user download the file to local disk to print?
Based on the event log >>Faulting module name: EXCEL.EXE<<, it does not show the root Faulting module. Thus, please try to follow this KB to do general troubleshooting:
https://support.microsoft.com/en-us/kb/2758592
Then, if you have used "printer status application", please go to Device settings -> Installable options -> Printer Status notification and select disable.
If this issue still exists, we may need to collect the App crash dump file:
https://technet.microsoft.com/en-us/sysinternals/dd996900.aspx
You can try to analyze dump by yourself if you would like to：
How to analyze app crash dump file:
http://blogs.technet.com/b/askperf/archive/2007/05/29/basic-debugging-of-an-application-crash.aspx
Regards,
George Zhao
TechNet Community Support
It's recommended to download and install
Configuration Analyzer Tool (OffCAT), which is developed by Microsoft Support teams. Once the tool is installed, you can run it at any time to scan for hundreds of known issues in Office
programs.
Please remember to mark the replies as answers if they help, and unmark the answers if they provide no help. If you have feedback for TechNet Support, contact [email protected]

Digital Signature Text is too big, how to make it take up less room?

I added a digital signature to a PDF and part of it is a real handwritten signature. The digital signature text was also added but it is taking up too much room on the signature line. I would like to make the real signature large and the text part of the digital signature smaller. I cannot seem to find oout how to make this happen. Is it possible? If so, can someone please supply the steps?

hi Axl....
I've got tiger in ok, running fine - bought family pack and have done 3 installs without problem, so that's the good news ....
I did a major reshuffle and toss-out of files before I installed - bought 80gb mobile external hard drive - and did install with 5+gb free, so after it had about 3gb free, then all of a sudden I went down to less than 1gb
I've been in a hunt for more files to throw out (a nice find were the old ipod updaters that were eating 500mb) ....
If I want to throw out most of the language files (for instance) ... where are they ? (I did search for danois and found nothing, so .... buried ?)
any other suggestions for things to throw away .... I've pretty much eliminated 90% of all things classic, for instance ....
and - do you have ideas for why space seems to disappear so fast .... I'm not doing anything special, but wham, 2gb flies away to ???
thanks

Multiple Digital Signatures (certificates) results in VERY slow PDF

I created a form in Lifecycle that typically has 8 signatures. As more signatures are added the form slows down significantly. Our director, who ultimately signs off on the document, has informed us that it took him 35+ minutes to approve 3 documents. The forms are on a network drive. I had read some old threads that mentioned this issue was being investigated and the newer versions of Acrobat should help speed up this process. We are currently running Acrobat X 10.1.4. Any suggestions as to what might be slowing things down? I know the digital signatures require validating and expect it to slow things down a bit but 11+ minutes is probably more than it should be. Thanks

Hi,
Just out of curiousity, if the form has been Reader Enabled, and, if the director could download the free Adobe Reader v11 from the Adobe web site, and he signs the file using version 11, is the signing process faster? It should be much faster in version 11 because we fixed the recursive validation issue that made dealing with multiple signatures so slow.
If you're interested in the nuts and bolts read on, but if not I'll understand...
The way signature validation use to work is Acrobat (and Reader as well because because the signature creation and validation mechanisms are the same in both) would start to validate signature number 8 right after the signature was created (it needs to do the validation so it knows whether or not to put the green check mark next to the signature). As part of the validation process it would need to re-validate each previous signature (and this is where things start to get weird). In order to validate signature 7 it has to also validate all previous signatures (6 thru 1) and every time it validates a new signature it has to do all of the previous signatures. Each signature would get validated as many times as it was part of the revision list. That is, signature 1 got validated eight times, signature 2 seven times and so on.
Begining with version 11 (or XI as it says in the product) we stopped all of the recursive validation and just do each signature once which makes the signature validation process much quicker. I'm always looking for real world examples, and if you can test it with Reader XI I'd appreciate knowing the results.
Thanks,
Steve

Digital signatures and combining PDFs in Acrobat X

I hope that one of you Acrobat gurus can help me out with one or more of these questions:
Is it possible to maintain digital signatures when inserting signed PDFs into another PDF?
Is it possible to remove a digital signature after a signature has been deleted from the page?
Is it possible to change the format of the date and time on a digital signature?

In the simplest sense a digital signature is a special checksum of all the bytes in the bytes in the PDF combined with all the bytes in the digital signature. If the document is changed in any way the checksum changes, so the signature becomes invalid. A valid signature ensures that the document hasn't changed since the signature was applied. That stuff that's shown on the signature field is irrelevant. It's just a pretty picture. The real stuff is going on inside the PDF where you can't see it.
Obviously it gets a lot more complext then this. The signature can be selectively applied so that the certain types of changes are allowed. A signature does not add real protection to a PDF, but Acrobat plays along with this scheme by trying to not allow changes that would invalidate the signature, and logging all modifications to the PDF.
1) There are ways to maintain the visual appearance of the signature on the page. If the permissions have been set to allow it the PDF can be flattened, which also partially removes much of the stuff that's going on internally. But this isn't always possible. I had to solve this problem once for a client, so I wrote a plug-in that strips the signature permissions from the PDF (I'll post this to www.pdfscripting.com sometime soon), after which the the PDF can be flattened, keeping the appearance. But of course, after this point the document has to be considered invalid. For example, if the document was a contract, the flattened version would be good for use in an analysis of say all contracts for a particular year, or for copying legal language to another contract, but it couldn't be used as the basis of a legal dispute.
2) I don't understand this one. Do you mean you're deleting the signature field and some of the internal digital signature stuff is still hanging around causing problems? If you own the signature (or the permissions allow), then a standard form reset will "Un-Sign" the PDF. Inserting PDF pages into another PDF will strip out all this info as well.
3) The stamp appearance is set at the time the stamp is applied, it cannot be changed after this point. It's a lot like a PDF stamp.
Thom Parker
The source for PDF Scripting Info
pdfscripting.com
The Acrobat JavaScript Reference, Use it Early and Often
http://www.adobe.com/devnet/acrobat/javascript.html
Then most important JavaScript Development tool in Acrobat
The Console Window (Video tutorial)
The Console Window(article)

Digital Signatures in Adobe

Hi Experts
Plz suggest the materials for Getting Started in Adobe Digital Signatures.
I tried with in the Adobe life cycle designer after drag and drop of signature field and executed, i clicked the signature and there is no action..
Is there any version problem and any thing to be updated..
As of now we are using Adobe Life Cycle Designer 7.0, Acrobat Reader 7.0
Regards
Chandran S

Hi Experts
Plz suggest the materials for Getting Started in Adobe Digital Signatures.
I tried with in the Adobe life cycle designer after drag and drop of signature field and executed, i clicked the signature and there is no action..
Is there any version problem and any thing to be updated..
As of now we are using Adobe Life Cycle Designer 7.0, Acrobat Reader 7.0
Regards
Chandran S

Using the AutoText Feature: An easy way to generate Digital Signatures

One feature I find particularly useful is "AutoText".
Using this, you can assign a keystroke combination to effectively generate a word, phrase or sentence while typing messages on your blackberry.
This is a great tool, particularly for multiple digital signatures across several email addresses, text messages and also to use with apps like Facebook and Twitter.
To access the "AutoText" feature, begin a new email or text message, hit the "Menu" button and select "Edit AutoText".
A list of all the stored abbreviations is displayed.
Simply begin typing the set of keystrokes you want to associate with your digital signature (or any other word/ phrase/ sentence etc.) and you will see the current abbreviations associated with those keys.
Type in a unique set of keys you want to associate with a series of words and hit the "return" or "enter" key.
A new screen with the following display will appear:
"Replace:
With:
Using: SmartCase
Language: All Locales"
In the "Replace:" section, key in your own abbreviation and the associated word or words in the "With:" area.
Pick the options from the "Using:" and "Language:" drop down menus and you're done!!
Hit the "Back" key and select "Save" from the dialog box which appears.
Now, use the keystroke you just created while typing messages and see how much easier this wonderful feature makes your life!!
Trust this tip is valuable to you all. I'm not the best writer in the world so if anything here is not clear, please ask and I will clarify to the best of my ability.
Best.
G

Thanks for your write up. Indeed autotext is great way to simplify your signature or commonly used templates for SMS or emails.
tanzim
If your query is resolved then please click on “Accept as Solution”
Click on the LIKE on the bottom right if the post deserves credit

When trying to send a pdf for multiple digital signatures, it keeps erroring out. What are some reasons?

I am having trouble sending out a document for digital signatures for multiple people. I enter the signature fields and click on Distribute. It then allows me to choose the receiving parties. I click on <SEND> and it processes for a moment and then I receive the following two errors: "Failed to send" followed by "Form distribution is aborted". It was working for me earlier and isn't now. I am fairly new to Acrobat and especially Digital Signatures. What are some possible reasons I am getting this error?

I finally got the document to send out by unclicking the "Collect name & email from recipients to provide optimal tracking" button, however, the responses come in as anonymous, so it's not real helpful with tracking my responses. Plus, I don't know if I'll encounter problems with follow up. The normal tracking system allows me to resend a message to those who have not responded. Now I guess I would just resend the request to those I have determined have not signed. Still working through the bugs but I'll update what I know and figure out here. Perhaps I will come to a solid solution and give a better summary.
As of now, I am sending and receiving responses... but the recipients have to change the received file to save as it is coming to them as read-only. Seems like this should be a whole lot less complicated.

Appearance of Digital Signature/Common Name

Hi,
I'm using Adobe Professional 8.1.2 and I'm able to create a digital signature except that it's appearance is broken up. For instance if my name "Maryann Doe" it appears on documents as:
Marya
nn Doe
It's broken up and I can't find way to fix this. I also have another signature that uses my computer login name of "ABCDE" as my common name. I can't find a way to change that either to input my real name. Any suggestions would be greatly appreciated!
Thank you!

Hi,
For the first problem (word wrap). The problem you are encountering is if "Maryanne Doe" is too long to fit in half of the signature field, the text wraps to the next line. The signature appearance that is written into the signature field consists of two halves. The left half contains the graphic properties and the right half contains the text properties.
You need to lengthen the width of the area where the graphics portion of the signature is contained. You can do this one of two way. Either lengthen the physical dimensions of the signature field before you sign. Or, you could create a custom signature appearance where you turn off all of the text properties, which has the effect of giving the whole signature fields over to the graphics portion. To play with custom signature appearances:
Select the Edit > Preferences (Win) or the Acrobat > Preferences (Mac) menu item
Select Security from the Categories list box
Click the New button in the Appearance group box
If you select the No Graphic radio button you give all of the space to the text portion. If you deselect all of the checkboxes in the Configure Text area, you give all of the space to the graphics portion.
While you are in the Preferences dialog, select Identity from the Categories list box. Go ahead and fill in all of the editable fields. This is where the data is procured during the creation of a self-signed digital ID. I think that will fix the second issue you raised.
Steve

Digital Signature(s) Do I need Reader 10?

Hello all, we have Adobe Reader X here and I am having a problem regarding the digital signature that I think I'm creating, but nothing appears to be working for me. I don't think I'm missing a step (I've been viewing the instructions and just think Reader X is not the way).
So the real question is... is having Reader X hindering my digital signature escapades or am I really that dumb?
Thanks to all.

You don't "need" anything, but OS X 10.9 "Mavericks" incorporates significant performance improvements over earlier versions.
I don't want to use the GBs on my laptop.
I'm not sure what you mean by that. You will need a minimum of 8 GB free hard disk space to install it, but if you are concerned about that then you have bigger problems to address. After its installation is finished Mavericks will result in a negligible overall change to HD usage, including the amount of free space remaining.

Reader not allowing digital signatures

I used Adobe9 to create a form so our volunteers/interns can fill it out, sign it and send it back to us via email. I can get everything to work so that it works in Acrobat reader, EXCEPT allow signing. No matter how I've tried, (extending the form, creating a policy to allow filling in forms and signing), when I bring the form up in reader (ver 9.3), the document properties still say signing is not allowed. I've tried other reader versions, same result. This should be so much easier, but I cannot figure for the life of me what is wrong. Any idas?
Thanks
Ken

George,
That is what I thought too. So I did extend it, and it still won't work. Here is a copy of my security properties after
I extended it as you mentioned: ------>
I can now save data in the form, but the only thing that is NOT working is this %$#@ digital signature thing. Maybe I don't understand digital signatures enough, but in Acrobat9, when designing a form, I could create a digital signature in the fly. Can't users do that when they view a document in Reader? Is it a properties issue, or can't a user create a digital signature in Acrobat Reader at all? Seems like extending a form takes away the signing property.
Ken

Message level security: difference digital signature and certificate

Hi everybody,
could anybody please explain the difference between <b>digital signature</b> and <b>certificate</b>?
Thans
Regards Mario

Mario,
A digital signature is an electronic signature that can be used to authenticate the identity of the sender of a message or the signer of a document, and possibly to ensure that the original content of the message or document that has been sent is unchanged. Digital signatures are easily transportable, cannot be imitated by someone else, and can be automatically time-stamped. The ability to ensure that the original signed message arrived means that the sender cannot easily repudiate it later.
A digital signature can be used with any kind of message, whether it is encrypted or not, simply so that the receiver can be sure of the sender's identity and that the message arrived intact. A digital certificate contains the digital signature of the certificate-issuing authority so that anyone can verify that the certificate is real.
where as
A digital certificate is an electronic "credit card" that establishes your credentials when doing business or other transactions on the Web. It is issued by a certification authority (CA). It contains your name, a serial number, expiration dates, a copy of the certificate holder's public key (used for encrypting messages and digital signatures), and the digital signature of the certificate-issuing authority so that a recipient can verify that the certificate is real. Some digital certificates conform to a standard, X.509. Digital certificates can be kept in registries so that authenticating users can look up other users' public keys.
hope it helps u.
--Archana

What is the certification authority, the third party that can confirm the digital signature?

I created a nice electronic signature, that I now regularly use and add to every document. I was told that a signature needs to be issued by a verification authority, a third party that is able to verify the signature, certificate. I created a free certificate at CAcert.org and tried to combine it with the adobe signature certificate file, but it doesnt support .cer and .crt files. Is the Adobe the certification authority in this case since i created signature in the Adobe software? Its not a big deal, I just want everything to be correct since I use the signature in official documents now (instead of scanning a signed document) ... Thanks for any info, ideas or help.
Jacob

Each Digital Certificate has a pair of private and public keys used for encryption/decryption. The private key belongs to the certificate owner and should be kept secret. It is protected by a password. The public key can be used by anyone. Digital certificates come in two flavors: one that contains both private and public key and one that contains only public key.
When you create a digital signature the signing process uses the private key to encrypt the signed content digest and the public key is used to decrypt it. So, only you can encrypt signed content with your certificate that has both private and private keys and anyone can decrypt it to validate the signature using certificate that has only public key. Usually, this certificate with the public key only is embedded in the digital signature, so that anyone can use it for decryption.
The .cer certificate contains only public key. Certificates with both private and public keys usually have extensions .pfx or .p12. You need one of those to sign.
CAcert.org issues only public key certificates. so you cannot use its certificates for digital signing.
Adobe is not a general purpose certification authority. It issues some certificates for internal use only.
Acrobat has a feature that allows you to create so-called self-signed certificates with both private and public keys but these certificates can be used only in a limited way. They do not provide the means to authenticate the real certificate owner nor revoke a certificate if it is stolen.
Generally, a digital signature asserts three main features:
1. Document integrity (document has not been changes since it had been signed),
2. Authentication (the signer is indeed what the certificate says)
3. Non-repudiation (the signature author cannot deny that he signed it: this is achieved via certificate revocation mechanism).
A self-signed certificate (of the type that Acrobat produces) can be used only for #1. It cannot be used for ##2 and 3. The latter two come only when a certificate (with private key) is issued by a reputable Certificate Authority which is trusted (like VeriSign, Symantec, etc.).

Digital signature does not validate with the given key

We are switching our single-signon provider from openssl to Weblogic's SAML. I am trying to create a test application that will send mock SAML assertions to our test Weblogic SAML server before we begin integration with the client that will send real SAML assertions.
I have configured a Weblogic 10.3.5 instance to be a SAML Service Provider as well as created an application that creates test SAML assertions to post to the SAML server. I'm currently using a self-signed certificate to sign the SAML assertion. I've imported the self-signed cert into both the DemoIdentiy.jks and cacerts on the Weblogic SAML server.
The Weblogic SAML server is giving the following error when trying to validate the signature of the assertion:
<SAML2Assert: Start verify assertion signature>
<SAML2Assert: The assertion is signed.>
<SAML2Assert: Digital signature does not validate with the given key
org.opensaml.xml.validation.ValidationException: Digital signature does not validate with the given key
at org.opensaml.xml.signature.SignatureValidator.validate(SignatureValidator.java:68)
at com.bea.security.saml2.util.SAML2Utils.verifySamlObjectSignature(SAML2Utils.java:229)
at com.bea.security.saml2.providers.SAML2Assert.verifySignature(SAML2Assert.java:285)
>
I get this error when the SAML assertion includes both the cert and the public key, just the cert, just the public key or neither.
I'm pretty sure I've configured the SAML instance correctly since I followed the steps provided by another group who got this working with a different client. The only difference is they are using a real signed certificate (Verisign i believe) instead of a self signed cert.
I'm looking for any help to track down which step in the process I've missed or implemented incorrectly.
Thanks!
Edited by: 911967 on Feb 6, 2012 12:26 PM

So I found my own answer to the issue. The error was being caused by an the following xml in the assertion:
<ds:Reference URI="">
The value of URI attribute must have a '#' followed by the same value of the ID attribute in the parent 'Assertion' element (in our case a random string):
<saml:Assertion xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" ID="a5k42vnhsywezqzyufq15c4bb9xuzeozrmbppj38xe" IssueInstant="2012-03-12T14:33:25.986Z" Version="2.0">
<saml:Issuer>ISSUER_NAME</saml:Issuer>
<ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
<ds:SignedInfo>
<ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
<ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
*<ds:Reference URI="#a5k42vnhsywezqzyufq15c4bb9xuzeozrmbppj38xe">*
How this is related to the digital signature is beyond me, though I admit I'm very new to saml and digital signing. However I spent a great deal of time investigating my certs and how I was creating the signature, which it seems is unrelated to the actual issue. I also wasn't able to find any docs specifying that this attribute was required, though I might have just missed it.

Usb2 in specs but 12 Mbps in real life ??

Hello,
I own a 2004 iMac flat panel (20", 1.25 GHz G4, Mac OS 10.3.9).
In the specs, it's supposed to be equipped with three usb2 connectors.
If I go to the system information, 2 buses are said to be limited to 12 Mbps, and a third one is said "high speed", but never shows any device.
The mac is connected to :
1. a Canon Pixma MP110 printer (officially usb2 High Speed, but 12 Mbps in the sys info)
2. a usb hubb (leading to Apple keyboard and logitech wireless mouse)
3. occasionnally to a digital camera or a iPod nano (and hopefully, if this problem is solved, to a usb2 camcorder in the future). All appear in the "normal" 12 Mbps usb listing in sys info.
How to get the advertised 480 Mbps usb2 ?
Thanks,
iMac G4 1.25 MHz 20" Mac OS X (10.3.9)

USB doesn't encrypt data.
USB 2 (High Speed USB is Apple System Profiler) is designed at 480Mbits per second which is 60MB per second. This real life this turns out to be a burst speed that the design of the protocol cannot sustain for long periods. There are overheads in the form of digital coding that will reduce this theoretical maximum too
USB1.1 (The type built in to older Macs) is designed at 12Mbits per second which is 1.5MB per second. Again overheads will be seen on this protocol. The USB Developers reckon upon you getting about 0.9MB of bandwidth.
(click to enlarge)
The first image shows how ASP lists that I have 4 USB connections only one of which is High Speed. The second image shows the USB2 (green dots) devices I have connected and the Red bars show the physical USB2 connections I've made.
In conclusion ASP is not an accurate list of the true USB hierarchy. This is probably due to their being spare USB buses in the iMac for Airport, bluetooth and modem data connections (not sure which though).
I'm not sure why your printer isn't listed as USB2 (mine says 480Mbps) but other than that all is normal - you aren't been shortchanged. All actual USB2 devices will be listed under the one High-Speed USB heading when they are in use.
I would recommend getting a Firewire connected DV Camcorder if possible as Firewire is a better protocol from Digital Video and Firewire plays nicer with iMovie (which is what I suspect you want).
regards
mrtotes

Digital signatures in real life

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