What is the Verhoeff algorithm and why does UIDAI use it for Aadhaar?

The Verhoeff algorithm is a decimal check digit algorithm based on the dihedral group D5 of permutations. UIDAI chose the Verhoeff algorithm for 12-digit Aadhaar numbers because it detects all single-digit transcription errors and 100% of adjacent two-digit transposition errors, providing vastly superior error detection compared to Luhn (mod 10).

What is an Aadhaar Data Vault (ADV)?

An Aadhaar Data Vault (ADV) is a dedicated, logically and physically separated encrypted secure data repository mandated by UIDAI circulars. Any entity that stores Aadhaar numbers (such as AUAs, KUAs, and sub-AUAs) must never store raw Aadhaar numbers in business databases or application tables. Instead, the raw Aadhaar is stored exclusively inside the vault, and replaced in transactional systems by an internal surrogate token (Reference Key).

What is the legal mandate for Masked Aadhaar?

Under UIDAI regulations and RBI/IRDAI KYC circulars, entities that are not permitted to retain raw Aadhaar numbers must redact or mask the first 8 digits of the Aadhaar number, leaving only the last 4 digits visible (formatted as XXXX-XXXX-1234). Storing unmasked Aadhaar numbers on un-vaulted drives is a punishable offense under Section 42 of the Aadhaar Act, 2016.

What encryption standards are required for the Aadhaar Data Vault?

The Aadhaar Data Vault must employ AES-256 encryption with GCM or CBC mode, using cryptographic keys managed inside a FIPS 140-2 Level 3 validated Hardware Security Module (HSM). The vault database must reside in a restricted network zone (VLAN/DMZ) with no direct internet access.

Does Toolique store or transmit the Aadhaar numbers entered here?

Never. Toolique executes 100% client-side inside your browser sandbox. No Aadhaar numbers, hashes, or keystrokes are transmitted across any network or recorded in server logs, adhering strictly to zero-knowledge privacy standards.

UIDAI Aadhaar Data Vault & Verhoeff Checksum Validator

Validate Aadhaar numbers with the official Verhoeff D5 dihedral algorithm, generate masked Aadhaar (XXXX-XXXX-1234), and simulate Aadhaar Data Vault (ADV) tokenization with zero server retention.

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How to Use UIDAI Aadhaar Data Vault & Verhoeff Checksum Validator

Enter or paste a 12-digit Aadhaar number into the validator input.
The engine immediately runs the official Dihedral Group D5 Verhoeff checksum algorithm to verify structural and mathematical validity.
View the real-time Masked Aadhaar format (XXXX-XXXX-1234) required for public storage and display under UIDAI regulations.
Navigate to the "Aadhaar Data Vault (ADV)" tab to simulate surrogate token generation (UUIDv4 ADV Reference Key) and inspect vault encryption specifications.
Explore UIDAI compliance guidelines regarding Hardware Security Modules (HSM), AES-256 key management, and statutory audit readiness.

Mathematical Mechanics of the Verhoeff Dihedral D5 Algorithm

The Verhoeff algorithm operates over the symmetric group of permutations of order 10, using dihedral group D5 multiplication and permutation matrices. Every digit of the 12-digit Aadhaar number is transformed using a permutation index based on its reverse position modulo 8. If the cumulative product evaluates to zero, the Aadhaar number is mathematically valid.

UIDAI Aadhaar Data Vault (ADV) Architecture Guidelines

UIDAI circular No. 11020/205/2017-UIDAI mandated the Aadhaar Data Vault for all ecosystem partners. The vault functions as an isolated enclave: business applications send the raw Aadhaar to the vault over mutual TLS (mTLS), which encrypts the number using an HSM-backed master key, generates a non-deterministic surrogate reference token, and returns the token to the application.

Statutory Penalties under Section 42 of the Aadhaar Act, 2016

Unauthorized storage, transmission, or disclosure of raw identity information or Aadhaar numbers is an offense under Section 42 and 43 of the Aadhaar (Targeted Delivery of Financial and Other Subsidies, Benefits and Services) Act, 2016, carrying imprisonment up to 3 years and substantial financial penalties.

Masked Aadhaar Implementation for KYC Intermediaries

For offline KYC, e-KYC paperless verification, and document archives, entities must strictly mask the initial 8 digits of the physical or digital Aadhaar card. Both visual PDFs and OCR extraction databases must mask digits 1 through 8 prior to archival.

Frequently Asked Questions

What is the Verhoeff algorithm and why does UIDAI use it for Aadhaar?: The Verhoeff algorithm is a decimal check digit algorithm based on the dihedral group D5 of permutations. UIDAI chose the Verhoeff algorithm for 12-digit Aadhaar numbers because it detects all single-digit transcription errors and 100% of adjacent two-digit transposition errors, providing vastly superior error detection compared to Luhn (mod 10).
What is an Aadhaar Data Vault (ADV)?: An Aadhaar Data Vault (ADV) is a dedicated, logically and physically separated encrypted secure data repository mandated by UIDAI circulars. Any entity that stores Aadhaar numbers (such as AUAs, KUAs, and sub-AUAs) must never store raw Aadhaar numbers in business databases or application tables. Instead, the raw Aadhaar is stored exclusively inside the vault, and replaced in transactional systems by an internal surrogate token (Reference Key).
What is the legal mandate for Masked Aadhaar?: Under UIDAI regulations and RBI/IRDAI KYC circulars, entities that are not permitted to retain raw Aadhaar numbers must redact or mask the first 8 digits of the Aadhaar number, leaving only the last 4 digits visible (formatted as XXXX-XXXX-1234). Storing unmasked Aadhaar numbers on un-vaulted drives is a punishable offense under Section 42 of the Aadhaar Act, 2016.
What encryption standards are required for the Aadhaar Data Vault?: The Aadhaar Data Vault must employ AES-256 encryption with GCM or CBC mode, using cryptographic keys managed inside a FIPS 140-2 Level 3 validated Hardware Security Module (HSM). The vault database must reside in a restricted network zone (VLAN/DMZ) with no direct internet access.
Does Toolique store or transmit the Aadhaar numbers entered here?: Never. Toolique executes 100% client-side inside your browser sandbox. No Aadhaar numbers, hashes, or keystrokes are transmitted across any network or recorded in server logs, adhering strictly to zero-knowledge privacy standards.