90 |
in schemes like DSA or RSA. |
in schemes like DSA or RSA. |
91 |
|
|
92 |
One-time signature schemes [XXX] are based |
One-time signature schemes [XXX] are based |
93 |
on one-way functions [#]_. |
on one-way functions, i.e., functions `$y=f(x)$` such |
94 |
|
as block ciphers or cryptographic hashes so that |
95 |
|
that given `$y$` it is infeasible to find `$x$`. |
96 |
Given a one-way function f, the signer generates a set |
Given a one-way function f, the signer generates a set |
97 |
of (pseudo)random numbers and and publishes f(x) for each |
of (pseudo)random numbers and and publishes f(x) for each |
98 |
x in the set. This is the public key. To sign a message, |
x in the set. This is the public key. To sign a message, |
104 |
f(x) for each published number x against the values |
f(x) for each published number x against the values |
105 |
in the public key. |
in the public key. |
106 |
|
|
|
.. [#] A function f is one-way if it is infeasible, for |
|
|
a given y, to find x so that y=f(x). Common examples |
|
|
are block ciphers and cryptographic hash functions. |
|
|
|
|
107 |
To prevent an attacker from using a subset of the |
To prevent an attacker from using a subset of the |
108 |
published numbers to sign a different message, |
published numbers to sign a different message, |
109 |
the deterministic algorithm is chosen so that no set |
the deterministic algorithm is chosen so that no set |