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How NFC Chip Verification of Passports and ID Cards Works

Regulation and standards

For: Engineer or compliance lead who wants to know what reading the chip of a passport or ID card involves and what the result proves

What is on the chip of a passport or ID card, how a reader opens it, which checks the ICAO standard defines, and what a successful chip read does and does not prove.

A vendor tells you that its product reads the chip of a passport. You want to know what that means in concrete terms: what is on the chip, how a reader gets in, which checks exist, and what a positive result does and does not prove. This article answers those questions from the standards themselves. It draws on Part 10, Part 11 and Part 12 of ICAO Doc 9303, the BSI Technical Guideline TR-03110, Council Regulation (EU) 2025/1208 with the judgment of the Court of Justice that preceded it, the identity proofing volume of the United States Digital Identity Guidelines, and the platform documentation of Android. Each section opens with a line that names the part, section or article it rests on. Where a paragraph is our own reading and not a statement of a source, it says so.

A document that carries a chip

Sources: ICAO Doc 9303 Part 11, section 1 and section 3; Part 10; Council Regulation (EU) 2025/1208, Article 2, Article 3, Article 5 and Article 16; Case C-61/22.

The specification for machine readable travel documents is ICAO Doc 9303, published by the International Civil Aviation Organization. Its eighth edition dates from 2021 and is split into parts. Three of them matter for chip reading: Part 10 defines the logical data structure of the chip, Part 11 defines the security mechanisms, and Part 12 defines the public key infrastructure. The copies read for this article carry amendment No. 1 of 14 June 2024 for Part 10 and for Part 12, and the amendments of 14 June 2024 and 23 February 2026 for Part 11.

Part 11 states its scope in four points (section 1). It specifies cryptographic protocols that prevent skimming of data from the contactless chip, prevent eavesdropping on the communication between chip and reader, authenticate the data stored on the chip using the public key infrastructure of Part 12, and authenticate the chip itself. A travel document with such a chip is an eMRTD, an electronic machine readable travel document.

Which protections a given eMRTD carries is decided by its issuing State or organization. The standard makes two of them required: authentication of the data stored on the chip, and a protocol that prevents skimming and eavesdropping. Implementation of the other protocols is optional.

In the European Union the chip is also a legal requirement for identity cards. The instrument that sets this requirement is Council Regulation (EU) 2025/1208 of 12 June 2025, published in the Official Journal on 20 June 2025. It entered into force on the twentieth day after publication (Article 16), which is 10 July 2025, and it is binding in its entirety and directly applicable in the Member States. Denmark is not bound by it, as recital 47 records, and Ireland takes part, as recital 48 records.

What the Regulation requires of the card

The Regulation applies to identity cards issued by Member States to their own nationals as referred to in Article 4(3) of Directive 2004/38/EC, and to the registration certificates, documents certifying permanent residence, residence cards and permanent residence cards issued under that Directive (Article 2). Article 3(5) says that identity cards shall include a highly secure storage medium which shall contain biometric data, namely a facial image of the holder of the card and two fingerprints, in interoperable digital formats. Article 3(6) adds that the data stored shall be accessible in contactless form. Article 3(1) requires the card to be produced in ID-1 format with a machine readable zone, based on the specifications and minimum security standards of ICAO Document 9303. The Regulation does not apply to identification documents issued on a provisional basis with a period of validity of six months or less (Article 2).

Article 3(7) sets out the exceptions to the fingerprint requirement. Children under the age of 12 years may be exempt. Children under the age of 6 years shall be exempt. Persons in respect of whom fingerprinting is physically impossible shall be exempt.

Phasing out of older cards

Article 5(1) says that identity cards which do not meet the requirements of Article 3 cease to be valid at their expiry or by 3 August 2031, whichever is earlier. Article 5(2) derogates from that for two groups. Cards that do not meet the minimum security standards set out in part 2 of ICAO Document 9303, or that do not include a functional machine readable zone, cease to be valid at their expiry or by 3 August 2026, whichever is earlier. Cards of persons aged 70 and above on 2 August 2021, which meet those minimum standards and have a functional machine readable zone, cease to be valid at their expiry. The date of 3 August 2026 has passed at the time of writing.

The earlier regulation and the judgment

Regulation (EU) 2019/1157 first set the same kind of requirement. In its judgment of 21 March 2024 in Case C-61/22, the Court of Justice found that the obligation to include two complete fingerprints in the storage medium of identity cards, although it limits the rights to private life and to the protection of personal data, is not disproportionate. It nevertheless declared Regulation 2019/1157 invalid, because it had been adopted on the basis of Article 21(2) of the Treaty on the Functioning of the European Union and not Article 77(3). The Court maintained the effects of that regulation until the entry into force of a new regulation based on Article 77(3) intended to replace it, within a reasonable period that could not exceed two years from 1 January 2025. Regulation 2025/1208 is based on Article 77(3) and was adopted after the judgment.

The text read for this article is the Official Journal version of 20 June 2025. Implementing acts, later amendments and national law were not reviewed, and nothing here is a statement about the legal position of a particular Member State.

What the chip stores

Sources: ICAO Doc 9303 Part 10, section 4, section 4.6 and section 4.7.

Part 10 organizes the chip as a logical data structure. The mandatory application, called LDS1, consists of the data recorded by the issuing State in Data Groups 1 through 16, together with the Document Security Object.

Data Group 1 reflects the entire contents of the machine readable zone. Data Group 2 holds the face of the holder, and Part 10 calls it the globally interoperable biometric for machine assisted identity confirmation with machine readable travel documents. Data Group 1 and Data Group 2 are mandatory. Fingerprints are Data Group 3 and iris images are Data Group 4, and both are optional. This is the structure of an ICAO eMRTD chip. Beyond the mandatory groups, which optional groups a given document carries is the issuer's choice, and the conditional groups below are required where the mechanism they serve is implemented. Whether a particular identity card follows this structure is a matter for the issuer of that card.

Two data groups carry security information. Data Group 14 holds security options and is required if Chip Authentication or certain PACE mappings are supported. Data Group 15 holds the public key for Active Authentication and is required when that optional mechanism is implemented.

The Document Security Object is stored in a file called EF.SOD and is mandatory. It is digitally signed by the issuing State and contains hash values of the data groups.

The eighth edition also adds optional LDS2 applications for travel records, visa records and additional biometrics, written after issuance.

Data Group 2 holds the face image. It is the portrait of the holder as the issuer stored it, and not a photograph of a printed portrait. Part 10 describes it as the image of the face of the holder as an input to a face recognition system.

Step one: opening the chip

Sources: ICAO Doc 9303 Part 11, section 4, section 4.1, section 4.3 and section 4.4.

A chip without access control adds two attack possibilities, according to Part 11. The data could be read electronically without the holder authorizing it, which the standard calls skimming. And the unencrypted communication between chip and reader could be eavesdropped within a distance of several metres.

The standard therefore says that issuing States shall implement a chip access control mechanism. A protected chip denies access to its contents unless the reader proves knowledge of information derived from the physical document. That information has to be retrieved optically or visually from the document, for example from the machine readable zone, and it must also be possible for an inspector to type it in manually when machine reading fails. The standard states the reasoning as an assumption: if the information cannot be obtained from an unviewed document, for example because it is derived from the optically read machine readable zone, it is accepted that the eMRTD was knowingly handed over for inspection. Our reading: that knowledge is not proof that anyone looked at the document, that it is physically present, or that its holder agreed, so access control protects against skimming and eavesdropping and is not an identity check. Earlier editions of the standard allowed chips with no access control at all, called plain eMRTDs. The eighth edition deprecates them, and compliant inspection systems must still support them (section 4.1, first note).

Two mechanisms are defined. Basic Access Control, BAC, is based purely on symmetric cryptography. Password Authenticated Connection Establishment, PACE, employs asymmetric cryptography to provide higher entropy session keys.

Basic Access Control

BAC is a three-pass challenge-response protocol with 3DES as the block cipher. Part 11 states the limit of this design openly. The keys are generated from printed data with very limited randomness, so they have relatively low entropy and are cryptographically weak. For a travel document valid for ten years, the maximum strength is approximately 56 bits for a numeric document number and 73 bits for an alphanumeric one.

PACE

PACE is a password authenticated Diffie-Hellman key agreement protocol. It establishes secure messaging based on weak, short passwords and provides strong session keys independent of the strength of the password. For globally interoperable travel documents the key derived from the machine readable zone is required, and a key derived from the card access number is optional. PACE also has a variant, the Chip Authentication Mapping, which integrates Chip Authentication into the protocol and is optional.

The timetable

Both protocols are allowed today, but PACE is replacing BAC on a schedule. Chips of eMRTDs issued as of 1 January 2027 shall implement PACE, either with BAC or alone. Chips of eMRTDs issued as of 1 January 2028 shall implement PACE only. All eMRTDs with BAC shall be out of circulation by 1 January 2038.

Step two: authenticating the data

Sources: ICAO Doc 9303 Part 11, section 3 and section 5.1; Part 12, section 6.1.

Opening the chip proves that the reader may talk to it. It says nothing yet about whether the data is genuine. That is the job of the Document Security Object.

Part 11 describes it as digitally signed by the issuing State or organization and containing hash representations of the contents of the logical data structure. A reader that holds the Document Signer public key of each State, or has read the Document Signer certificate from the eMRTD, can verify the Document Security Object and so authenticate the contents of the data groups. The verification needs no processing capability of the chip, which is why the standard calls it Passive Authentication.

The inspection process in Part 11, section 5.1.1, has five steps.

  • The reader reads the Document Security Object, which must contain the Document Signer certificate.
  • It builds and validates a certificate path from a trust anchor to the Document Signer certificate, as Part 12 describes.
  • It uses the verified Document Signer public key to verify the signature of the Document Security Object.
  • It may read the relevant data groups.
  • It ensures that the contents of each data group are authentic and unchanged by hashing them and comparing the result with the corresponding hash value in the Document Security Object.

Taken together, the steps make three checks: a validated certificate path from a trust anchor to the Document Signer certificate, a verified signature on the Document Security Object, and a hash comparison for every data group that was read. Our reading: a valid signature on the Document Security Object does not by itself show that the data groups in the reader's hands are the signed ones, and the hash comparison is the step that ties the two together.

Passive Authentication proves that the contents of the Document Security Object and the data groups are authentic and not changed. It does not prevent exact copying of the content of the chip or chip substitution, and the standard says it should be supported by an additional physical inspection of the document.

The infrastructure behind the signature

Sources: ICAO Doc 9303 Part 12, section 2, section 3.1, section 4.1.5, section 5.1 and section 5.3.

Part 12 defines the public key infrastructure for these signatures. It is much simpler than the general internet infrastructure: each issuing State establishes a single certificate authority that issues all certificates directly to end entities, including Document Signers. These authorities are called Country Signing CAs, CSCAs, and there are no other CAs in the infrastructure.

The standard recommends generating and storing the CSCA key pair in a highly protected, off-line infrastructure. The Document Signer certificate must be stored in the chip of each eMRTD that was signed with the corresponding private key, so the receiving State always has the certificate relevant to the document it reads.

Every CSCA must produce periodic revocation information in the form of a Certificate Revocation List. It must issue at least one list every 90 days, even if no certificate has been revoked since the previous list, and not more often than every 48 hours. If a certificate is revoked, a list that shows the revocation must be distributed within 48 hours.

The ICAO Public Key Directory, the PKD, is a central repository for exchanging the information required to authenticate eMRTDs such as ePassports, electronic ID cards and Visible Digital Seals. Part 12 describes the directory as a service that accepts certificates, revocation lists and master lists from participating States, stores them, and makes them accessible to all receiving States. A master list is an optional, signed list of CSCA certificates that supports the bilateral distribution of those certificates.

A failure along this chain is not a verdict on the document. Part 12 says that revocation of a certificate, failure of the certificate path validation, or failure of the signature verification does not on its own cause an eMRTD to be considered invalid. It means that the electronic verification of the integrity and authenticity of the data has failed, and that other, non-electronic mechanisms could then be used to make the determination.

Step three: authenticating the chip itself

Sources: ICAO Doc 9303 Part 11, section 3, section 6.1, section 6.2 and section 4.4.

Passive Authentication cannot tell a genuine chip from a copy of its content. An issuing State may therefore protect its documents against chip substitution, and Part 11 offers three mechanisms for this.

Active Authentication

Active Authentication authenticates the chip by signing a challenge sent by the reader with a private key known only to the chip. A hash of Data Group 15, which holds the public key, is stored in the Document Security Object and is therefore authenticated by the issuer's digital signature. The mechanism requires processing capability in the chip.

The conclusion that chip and document belong together rests on more than the challenge and response. Section 6.1.6 lists three steps. First, the entire machine readable zone is read visually from the document and compared with the zone in Data Group 1, and because Passive Authentication has checked Data Group 1, a match shows that the visual zone is authentic and unchanged. Second, Passive Authentication has also proven the authenticity of Data Group 15, so the Active Authentication public key is authentic and unchanged. Third, the reader runs the challenge and response with the chip, which shows that the Document Security Object is not a copy. Only after a successful challenge and response, following the first two steps, does the standard say it is proven that the Document Security Object belongs to the physical document, that the chip is genuine, and that chip and document belong to each other.

Chip Authentication

Chip Authentication is an ephemeral-static Diffie-Hellman key agreement protocol that provides secure communication and unilateral authentication of the chip. The static key pair is stored on the chip, and support is indicated by security information in Data Group 14 or in the file EF.CardSecurity. Unlike Active Authentication, it prevents what the standard calls challenge semantics, because the transcripts it produces are non-transferable. The standard states that it proves that the chip has not been substituted.

PACE with Chip Authentication Mapping

The third route folds the chip authentication into the chip access step. Support is indicated in the file EF.CardAccess, and if the mapping was performed successfully, the reader can use the public key from EF.CardSecurity together with the data received during PACE to authenticate the chip. The standard marks all of these mechanisms as optional, except that Chip Authentication is required for LDS2.

Step four: protecting sensitive data

Sources: ICAO Doc 9303 Part 11, section 7.1; the BSI TR-03110 page; Council Regulation (EU) 2025/1208, Article 11(6) and Article 11(7).

Terminal Authentication is the mechanism that prevents unauthorized access to sensitive data. Part 11 marks it conditional and says its implementation is required for LDS2 applications (section 7.1). Part 11 says it may be used to protect secondary biometrics in the eMRTD application. It is a two-move challenge-response protocol in which the reader proves, with a certificate chain that starts at a certificate the chip can verify, that it is entitled to the data. The protocol is based on Extended Access Control as specified in BSI TR-03110.

The German Federal Office for Information Security describes TR-03110 as the technical basis for the German ID card and residence permit and for European passports and driving licences, and says it also provides additional mechanisms. It describes Extended Access Control as a mutual authentication mechanism between terminal and chip based on public key infrastructures, in which Terminal Authentication restricts access to data on the chip to authorized terminals and Chip Authentication authenticates the chip as genuine while enforcing strong encryption and integrity protection of the transmitted data.

The law adds its own limits for EU cards, and they differ for the two kinds of stored biometric data.

Article 11(6) of Regulation 2025/1208 covers the facial image. It shall only be accessed by duly authorised staff of competent national authorities, Union agencies and private entities, and in compliance with Union data protection law. The permitted purposes are verifying the authenticity of the identity card or residence document, and verifying the identity of the holder by means of directly available comparable features where the document is required to be produced by law. Access by private entities shall also require the consent of the holder, unless access regardless of consent is strictly necessary for those purposes and provided for by Union or national law in compliance with Union data protection law. The facial image accessed shall not be retained unless its further processing is necessary for those purposes and is provided for by Union or national law, in compliance with Union data protection law. It shall not be retained for longer than is necessary for those purposes. Otherwise it shall be deleted as soon as the verification has been completed, and it shall not be transferred to third countries or international organisations unless Union data protection law permits it.

Article 11(7) covers the two fingerprints. They shall only be accessed for the same purposes, in compliance with Union data protection law, by duly authorised staff of competent national authorities and Union agencies, and where the document is required to be produced by Union or national law. Fingerprints accessed in this way shall not be retained.

Our reading, separate from the text of the Regulation: whether a particular service falls within these provisions depends on its own legal position, so a service that is not a competent national authority should take legal advice before it uses stored biometric data from these cards.

What an Android phone contributes

Sources: the Android IsoDep reference and Advanced NFC overview; ICAO Doc 9303 Part 11, section 4.2 and section 9.8.

This section is limited to Android readers that use the IsoDep class, the one platform whose documentation was read for this article. Other phone platforms have their own interfaces, and nothing here says that they offer the same facilities. The Android developer documentation describes the IsoDep class as providing access to properties and input and output operations of a tag, with transceive as the primary operation, and it says that applications must implement their own protocol stack on top of that operation. For a chip with access control, Part 11 requires that all communication after chip access is protected by secure messaging; inspection systems must also support chips without access control (section 4.1). Taken together, our reading for an Android reader that uses IsoDep: the IsoDep class gives the application a raw channel to the chip, and the application needs an implementation of the eMRTD protocols of Part 10 and Part 11 on top of it, covering selecting the application, running BAC or PACE where the chip enforces access control, wrapping the following commands in secure messaging on such a chip, and reading the data groups. That implementation may come from a library or be written by the application's developer.

What a successful read proves, and what it does not

Sources: ICAO Doc 9303 Part 11, section 2, section 3 and section 5.1; Part 12, section 2 and section 6.1.

A read that passes Passive Authentication supports two statements. The data groups read are the ones the Document Signer signed. And the signing certificate chains to the trust anchor of the issuing State, so the signature is the State's.

It does not support three others. It does not show that the person at the screen is the holder: Data Group 2 is an input to a face recognition system, and the comparison with a live face is a separate step. It does not show that the chip is the original and not a copy of its content, which is what Active Authentication and Chip Authentication address where the issuer implemented them. And it does not turn a chip check into the sole measure, because the standard itself says otherwise. Part 11 assumes that the use of such a technique is not the sole measure for determining authenticity, and says that it should not be relied upon as a single determining factor. It adds that if the chip data cannot be used, for instance after a certificate revocation or an invalid signature, or if the chip was left intentionally blank, the document is not necessarily invalidated, and a receiving State may rely on other document security features.

Documents without a chip remain a reality, and for them the image still has to carry the weight. Our companion article on reading the security features of an ID document covers what a photograph can and cannot show.

Chip evidence in identity proofing guidance

Sources: Special Publication 800-63A-4; ICAO Doc 9303 Part 11, section 5.1; Part 12, section 6.1.

The United States guideline on identity proofing, Special Publication 800-63A-4, classifies identity evidence by strength. To reach the top strength class, identity evidence has to meet all of a list of requirements. One of them is that the evidence contains attributes and data objects that are cryptographically protected and can be validated using approved cryptography through verification of a digital signature applied by the issuing source. Our article on that guideline covers the rest of it.

Our reading of the two documents together: where a provider wants chip data to count as cryptographically validated evidence, the guideline and the ICAO standard meet at the signature check and the trust chain. Those are the steps the guideline names, and they are the steps Part 11 and Part 12 define.

Questions to put to any chip-reading service

The standards raise a short list of questions that separate a chip read from a chip verification. They are our own reading, and they apply to every provider, including us.

  • Which documents and issuing States are read, and from which trust anchors is the signature validated?
  • Is Passive Authentication performed, with a certificate path built to a CSCA certificate?
  • How are revocation lists handled, and how current are they?
  • Which of Active Authentication, Chip Authentication and PACE with Chip Authentication Mapping are performed where the document supports them?
  • Is PACE used where the chip offers it, and when does the reader fall back to BAC?
  • What happens when a read fails, and is the fallback visible in the result?

How NeuroVision fits

NeuroVision reads the NFC chip of identity documents. The data comes from the chip, not from a photo of the document. The platform has other capabilities of its own, described on their own pages and not part of the chip reading. Its document step reads printed and handwritten text and the machine readable zone with its checksum, and its anti-fraud step covers screen photos, photocopies, printouts, glued photos, drawn-on elements, erasures, edited images and logical data errors. Its face match step compares the selfie with the portrait on the document, and its liveness step is active: the person moves the face closer through two ovals. The questions above are the right ones for any provider, and we are glad to go through them for your documents and markets. Read the NFC chip reading page, or contact the team.

Sources

All sources were read on 27 October 2026.

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