Page 9 - 新思维数学学生用书8 样章

1 Integers

It is much harder to carry out the inverse operation – that is, to find the two prime numbers that

multiply to a given product. This fact is the basis of a system used to encode messages sent across
the internet.
The RSA cryptosystem was invented by Ronald Rivest, Adi Shamir and Leonard Adleman in 1977.
It uses two large prime numbers with about 150 digits each. These numbers are kept secret, but

anybody can use their product, N, which has about 300 digits.
If someone sends their credit card number to a website, their computer does a calculation using N
to encode their credit card number. The computer that receives the coded number does another
calculation to decode it. Anyone who does not know the two factors of N will not be able to do this.

Your credit card number is protected.

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