Which innovative security feature was first implemented by Spotify in 2019 to protect user accounts from credential stuffing attacks?

As music streaming dominates the industry, cybersecurity has become crucial for protecting artists' intellectual property and users' personal data. Major streaming platforms process millions of credit card transactions, store personal listening habits, and manage valuable content libraries. How well do you understand the security measures that keep the music flowing securely to our devices?

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Password-free login system using one-time SMS codes
Automatic detection and reset of compromised credentials
Mandatory two-factor authentication for all accounts
Biometric verification through device fingerprinting