Encrypted communications could have an undetectable backdoor

Researchers warn that many 1024-bit keys used to secure communications on the internet today might be based on prime numbers that have been intentionally backdoored in an undetectable way.

Many public-key cryptography algorithms that are used to secure web, email, VPN, SSH and other types of connections on the internet derive their strength from the mathematical complexity of discrete logarithms. Computing discrete logarithms for groups of large prime numbers cannot be efficiently done using classical methods. This is what makes cracking strong encryption computationally impractical.

Most key-generation algorithms rely on prime parameters whose generation is supposed to be verifiably random. However, many parameters have been standardized and are being used in popular crypto algorithms like Diffie-Hellman and DSA without the seeds that were used to generate them ever being published. That makes it impossible to tell whether, for example, the primes were intentionally "backdoored" -- selected to simplify the computation that would normally be required to crack the encryption.

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