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Password reuse

As explained in Real-World Cryptography

Password reuse is the practice of using the same password for multiple accounts or services.

Password reuse means using the same password for multiple accounts or services. It is tempting because people prefer passwords that are easy to remember, but one stolen or weak password can affect many accounts. section 11.2

Remembering a different password for every website sounds safer, yet the mental load is impractical for many users. Two common responses move the burden away from repeated human memory: single sign-on and password managers. section 11.2.1

The main alternatives work in different ways:

  • Single sign-on (SSO) lets a user prove ownership of one account to access multiple services, reducing the number of passwords to remember. section 11.2.1
  • Password managers generate or suggest complex passwords for new sites, remember separate passwords, and protect access behind one master password. section 11.2.1
  • SSO depends on participating services, while password managers address broader web use through the client rather than changing every server. section 11.2.1

Connect without another password

A user with a Facebook or Google account can connect to a new service such as Airbnb through SSO instead of creating another password.

How Real-World Cryptography covers it

How deep it goes
Explains the motivation and compares two remedies, but stops short of implementation details or password-recovery procedures.
Examples
Uses Facebook, Google, and Airbnb to illustrate SSO, alongside browser-generated and stored passwords.
What it assumes
Assumes only familiarity with websites, accounts, and passwords, while explaining the reuse problem from the beginning.
What you can do after
Apply password managers or SSO to avoid remembering one reused password across many services.
How it connects
Connects password reuse with user authentication, single sign-on, password managers, SAML, OIDC, and OAuth 2.0.
Cover of Real-World Cryptography
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Related concepts

This explainer was generated by Manning's knowledge graph from the text of Real-World Cryptography. The section links point to the parts of the book it draws on.