In the digital age, mobile numbers are a key piece of personal data used in marketing, communication, authentication, and analytics. However, because mobile numbers are personally identifiable information (PII), protecting them is essential for privacy, security, and regulatory compliance. One of the most common methods businesses and organizations use to safeguard mobile numbers while still being able to analyze or share data is hashing.
But what exactly are hashed mobile numbers? How does hashing work? Why is it important? And what are its benefits and limitations? This article answers these questions in detail.
What Is Hashing?
Before understanding hashed mobile numbers, it’s important to grasp what hashing is.
Hashing is a cryptographic process that transforms input data (like a mobile number) into a fixed-length string of characters, called a hash value or digest. This transformation is one-way and irreversible, meaning you cannot easily retrieve the original mobile number from its hash.
Common hashing algorithms include:
MD5 (now considered insecure for some uses)
SHA-1 (also deprecated for security-critical applications)
SHA-256 (widely used and secure)
bcrypt, scrypt, Argon2 (for password hashing, involving salting and key stretching)
What Are Hashed Mobile Numbers?
Hashed mobile numbers are mobile phone numbers that have been processed through a hash function to produce anonymized versions of the original numbers.
Instead of storing or sharing the actual number:
Businesses store the hash value.
When needing to recent mobile phone number data match or compare mobile numbers, they hash the input number and compare the hashes.
Why Use Hashed Mobile Numbers?
1. Privacy Protection
Mobile numbers are sensitive personal data. If a data breach happens, exposing hashed mobile numbers is far safer than exposing raw phone numbers, because:
Hashing is one-way, so hackers cannot reverse-engineer the original number easily.
This reduces the risk of identity theft or misuse.
2. Data Security Compliance
Regulations such as GDPR (Europe), CCPA (California), and others require organizations to safeguard PII.
Hashing helps organizations why marketers should pay attention to rcs data pseudonymize mobile data, a key requirement for compliance.
It allows businesses to process or share data without exposing raw phone numbers.
3. Cross-System Matching Without Sharing Raw Data
Companies or advertisers often want to match customer data between systems or partners without revealing real phone numbers.
By exchanging hashed mobile numbers, they can find common users without exposing PII.
For example, an ad platform may hash user numbers and compare them with hashed numbers from a customer database to target ads securely.
How Does Hashing Mobile Numbers Work in Practice?
Step 1: Normalize the Mobile Number
Before hashing, mobile virgin islands mobile data numbers are standardized (e.g., E.164 format, removing spaces, dashes) to ensure consistency. For example, both “555-123-4567” and “+1 (555) 123-4567” become “+15551234567.”
Step 2: Hash the Number
A secure hash function (e.g., SHA-256) processes the normalized number to create a hash digest.
Step 3: Store or Share the Hash
The hashed value is stored in databases or sent to partners.
When needing to check if a user exists, the input number is hashed the same way and matched against the stored hash.
Salting: Increasing Security
A salt is a random string added to the mobile number before hashing to prevent attacks like rainbow table attacks, where attackers precompute hashes of common inputs.
1. Vulnerability to Brute Force Attacks
Because mobile numbers have a limited range of valid possibilities (especially within a country), attackers can try hashing all possible numbers (a brute force attack).
2. Inconsistent Hashing
If different parties use different formatting or salts, hashed numbers won’t match, defeating the purpose of data matching.