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Most authorities would agree that one of the main challenges they face is from sophisticated fraudsters seeking to tamper with legitimate passports.
A variety of tools and techniques have been employed to address just this threat. However, criminals and other malicious forces remain as determined as they are ingenious.
To ensure the integrity of passports, the design of one particular component – commonly known as the data page hinge – plays a vital role.
The hinge is responsible for attaching the all-important passport data page, also known as the biographical or bio page, to the rest of the booklet.
So getting this aspect of passport construction right can create a huge obstacle for anyone hoping to insert a fake bio page or modify the existing one.
For this article, we slapped on our lab coats and decided to test everything.
- We reviewed 110+ passports.
- We anatomized 43.
In the end, we discovered three main factors that need to be taken into account when specifying a hinge.
We also looked at the potential issues raised by using polycarbonate data pages and the solutions adopted by countries.
Finally, we identified which of these approaches represents the most effective weapon in the on-going fight against passport fraud and forgery.
And in today's guide, we are going to show you everything we learned.
The data page or passport biometric page is tied to the booklet via the hinge.
Passport data page: what's the real story here?
Readers familiar with the 7th edition of ICAO 9303 will know that part two of the publication lists the main threats to machine-readable travel passports.
One of them is the removal and substitution of entire pages.
Naturally, the top target for fraudsters is always likely to be the data page, which contains the genuine holder's details.
Over the last decade, a growing number of countries have adopted passport bio pages constructed from polycarbonate. The new British passport, issued as of 2020, integrates a polycarbonate bio page, and the next generation of U.S. passports is said to incorporate that feature.
As we explained in this recent article on passport secure design, polycarbonate provides some significant security benefits.
However, given that the hinge (also known as the sleeve or flap) is the section that links the biographical page with the rest of the booklet, securing this aspect represents another vital part of passport security design.
But when it comes to creating the hinge, it is essential to remember that security is not the only factor that needs to be considered.
Flexibility and durability must also be taken into account.
Now let's consider passport flexibility.
- From the user's perspective, flexibility is crucial because it means that the booklet opens flat for easy checking at border control but closes completely to maintain privacy.
- For the manufacturer, flexibility is a significant concern because the hinge must integrate easily into the bookbinding process.
And what about passport durability?
Any passport booklet must pass ICAO minimum durability tests. This process includes the Physical Damage Evaluation Method, with mechanical stress applying a force of 60N (Newton) to tear the passport bio page.
After being subjected to these tests, no part of the passport data page should be missing, and more than 90% of the binding must be intact.
To demonstrate the durability level that can be achieved here, below is a member of our lab team suspended from a passport by nothing more than the hinge.
In this example, several hundred N are being applied.
Don't try this at home!
Now on to security
As far as the hinge is concerned, an obvious threat is removing the data page and the integration of another passport booklet.
Even more worrying is using the hinge as a potential entry point to attack the data page and replace genuine personal data with forged information.
There is a fourth factor: the ease of handling, specifically for document manufacturers, who integrate it into their manufacturing process.
It relates to the adaptability to various types of lamination processes (platen press or continuous roll) for ease of collation, suitability for multiple cycles of lamination, and ease of sewing into the passport booklet.
Passport hinge attacks: here's the battle scene.
One potential opportunity for fraudsters is to cut the hinge along with the original passport bio page and then paste in a falsified replacement.
Alternatively, they'll try to slice the data page to swap certain personal information with fraudulent details.
Conventional methods include using hairdryers or a scalpel to create a split, starting at the page's edges.
Sometimes attempts are made to weaken the data page first, using chemicals or extreme temperatures.
To counter this, any small initial cut in the hinge must not weaken the data page structure. The hinge must be constructed so that it does not allow the cut to spread easily, allowing the data page to become detached from the booklet.
Life can be tough for passports: scalpel, heat, acid, microwaves, or extreme cold.
So why does polycarbonate create a paradox?
Polycarbonate is a fused material. It becomes a monoblock after lamination. With printing and personalization on different layers inside the body and a tactile surface, it is highly resistant to splitting attacks.
The paradox lies in the fact that, while polycarbonate offers outstanding data page security, it is not flexible enough to act as the hinge as well.
Some polycarbonate data page construction approaches to address this by using a different type of plastic at its core. This material can then extend to form the hinge.
However, this means that the passport data page is no longer 100% polycarbonate and, therefore, not a single block of delaminable plastic.
The introduction of a second material introduces a vulnerability: the possibility of delaminating the bio page and accessing the personalization data it contains, as indicated below.
To avoid compromising security, non-polycarbonate material must only be used as part of the data page construction in a way that does not weaken the data page structure itself while remaining securely attached.
Lines of UV ink can be used to spot better any replacement of the booklet's passport bio page.
Best passport bio page hinge: what's the answer?
The three main approaches to constructing hinges for polycarbonate passport data pages:
Hinge attached to the side of the data page
Using this technique, the hinge is attached to the data page's side, either with mechanical elements such as pins and holes or using ultrasonic welding.
First, here's the good news.
A hinge attached to the top part of the data page offers adequate security; it does not compromise the passport bio page's integrity.
This sort of attachment is more usually done with ultrasonic welding. This uses very high-frequency vibration to heat the polycarbonate and hence helps to embed the component within it.
Here's the catch.
The rigidity can be an issue.
This approach negatively impacts the flexibility of the data page, preventing proper opening and closing and posing problems in terms of manufacturing.
It can also create a point at which the data page can be cut out.
But these security concerns can be addressed.
Even if the official bio page is removed, attaching a new one is very difficult.
When combined with tamper-evident features (such as printing a particular pattern on the hinge in visible and invisible inks, embossed text, and laser engraved data), any attempt at replacement becomes readily apparent.
UV printing can also be employed to leave unmistakable traces of tampering when the document is shone under a UV light.
A personalized hinge further enhances the level of security.
At present, 16 countries are using a passport with a hinge attached to the data page's side.
Hinge integrated across the data page
With this approach, the hinge is not partially embedded into the document. Instead, it forms an entire layer of the document: either attached to the side or in the structure's middle.
Here's something important to think about.
Some integral hinge data page constructions use a different material as the core of the bio page, and this core then extends and forms the hinge.
The data page is no longer 100% polycarbonate with these construction types and, therefore, not a single block of undelaminable plastic.
This type of hinge usually lacks security because it weakens the data page structure and facilitates fraud. The position of the hinge creates a weak point that can allow the data page to be split.
Hinges attached across the data page lack security if the adhesion between the Polycarbonate and the hinge material is weak.
The second material should be crosslinked to improve thermal tampering resistance and designed to bond robustly with the Polycarbonate, making delamination very difficult.
Hinges attached to the side of the data page across its entire length can also make it possible to hide counterfeiting attacks. A fraudster could potentially remove the hinge, modify the personalized layers of the data page, and then hide it back inside the passport booklet.
There's no getting around it.
Because it is not 100% polycarbonate, this solution usually makes the slicing type of attack easier. Admittedly, some techniques do use polycarbonate and are milled. However, this does not correctly address the issues of hinge flexibility and durability. On the plus side, this approach can incorporate tamper-evident features.
At present, just six countries are using this method of passport construction.
Lately, we have seen some improvements in this construction type, with some crosslinked material, which rectifies some critical weaknesses in other integral hinge solutions as it is flexible and durable.
Hinge partially integrated inside the data page
Here the hinge is inserted into the data page but does not go across its full length. As a result, it does not create weaknesses in the structure or facilitates slicing.
In theory, compared to an external hinge, fraudsters may perceive an angle of attack. However, if appropriately fused, this technique does not open the door to slicing by weakening the structure. The use of feature holes in the hinge material will provide better adhesion of polycarbonate layers during lamination.
The potential benefits don't stop there.
Optimum tamper evidence is achieved when the hinge has a visible area between the data page and the stitching. Indeed, many of the passports that use this type of hinge incorporate tamper-evident features, including:
- UV printing and/or UV threads in the fabric
- Precisely aligned patterns
- Combination with offset printing which will be destroyed if the data page is removed
Currently, 21 countries deploy passports using this hinge design.
So what's the conclusion?
First, here's a quick reminder of the five critical qualities displayed by an effective hinge for polycarbonate data pages:
- Does not compromise the construction of the data page or the security elements within it
- It is made of a durable and flexible material that passes ICAO testing.
- Can be firmly and securely attached to the data page and booklet and backed by effective countermeasures
- It is near-impossible to manipulate without leaving visible marks.
- Includes features that make a replacement more visible
Finally, how do the three options compare?
From a security perspective, it has significant drawbacks.
This approach weakens the data page structure and can facilitate slicing.
Furthermore, it is not very flexible.
Finally, there are question marks over its durability since its structure usually features a lower percentage of polycarbonate.
All these concerns are reflected in a low rate of adoption in the passport market.
The hinge integrated across the whole data page usually has drawbacks from a security perspective since it weakens the data page structure and can facilitate slicing. It is not very flexible either, and durability is a question mark.
Lately, we have seen some significant improvements in this construction type, with some crosslinked material, which rectifies some critical weaknesses in other integral hinge solutions as it is flexible and durable.
It also bonds well with Polycarbonate, enabling making tampering with heat more difficult in addition to being flexible and durable. Used in conjunction with certain security elements on the hinge or the data page, tampering will be evident. This is a much better product.
It offers reasonably good security since it does not bring any weakness to the data page structure and usually features some tamper-evident elements. It enjoys strong levels of adoption by governments.
The top position, however, goes to the hinge partially integrated inside the data page.
Crucially, this approach does not create weakness in the structure or facilitate slicing.
Feature holes in the hinge material offer better adhesion of polycarbonate layers during lamination, and many applications include tamper-evident features.
It's time for us to take off our lab coats.
More on data page security can be found in our 7-step guide on passport security design.
More tips on secure passport design dedicated to "paper matters" are shared in our web dossier on high-security printing.
High security for passport and why paper still matters in 2021
Now it's over to you.
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