Right now, but people who work with this stuff are worried about
what quantum computers can do with it.
On Mon, 29 Dec 2025 07:31:06 -0700, Peter Flass wrote:
Right now, but people who work with this stuff are worried about
what quantum computers can do with it.
Those kinds of ?quantum computers? don?t exist. They can?t even
demonstrate a basic number-theoretic operation like factorizing an
integer, let alone implementing the fabled Shor?s algorithm.
Shor?s algorithm came out about 30 years ago. The progress towards implementing it since then has been ... zero.
If you know something ABOUT 'the pad' - like how
many letters/numbers and how it's used - that may
offer some attack options, at least narrow things
down at bit.
According to c186282 <c186282@nnada.net>:
If you know something ABOUT 'the pad' - like how
many letters/numbers and how it's used - that may
offer some attack options, at least narrow things
down at bit.
No, a real OTP is unbreakable. The problem is that for every byte of
message you need a byte of key, so distributing the keys and using
them correctly is a logistical nightmare.
According to c186282 <c186282@nnada.net>:
If you know something ABOUT 'the pad' - like how
many letters/numbers and how it's used - that may
offer some attack options, at least narrow things
down at bit.
No, a real OTP is unbreakable. The problem is that for every byte
of message you need a byte of key, so distributing the keys and
using them correctly is a logistical nightmare.
Venona decrpted Soviet messages that used OTPs because
sone of the putative OTPs in fact were used more than once
which was enough to let the US crack them.
John Levine <johnl@taugh.com> writes:
According to c186282 <c186282@nnada.net>:
If you know something ABOUT 'the pad' - like how
many letters/numbers and how it's used - that may
offer some attack options, at least narrow things
down at bit.
No, a real OTP is unbreakable. The problem is that for every byte of
message you need a byte of key, so distributing the keys and using
them correctly is a logistical nightmare.
OTPs are broken in the sense that they are malleable. It?s easy for an attacker to modify the encrypted message, if they know anything about
its expected structure.
For example, an encrypted financial transaction is likely to have the
amount of money to be sent at a predictable offset, so all the attacker
needs to do is flip one of the higher bits in that field and the victim spends a great deal more money than they intended. If the pad is applied using XOR (a natural approach today) then they can achieve that by
flipping the corresponding bit in the ciphertext.
The need for symmetric encryption systems to include a MAC to prevent
this kind of issue has been understood for a long time.
The need for symmetric encryption systems to include a MAC to
prevent this kind of issue has been understood for a long time.
Richard Kettlewell wrote:
The need for symmetric encryption systems to include a MAC to
prevent this kind of issue has been understood for a long time.
??
Just want to point out you used the term ?symmetric? in the sense in
which I think it *should* be used: to refer to encryption systems
where the encryption and decryption algorithms are one and the same.
Too often the term is used to refer to systems where the same key is
used for encryption and decryption -- I think these should more
properly be called ?secret-key? systems.
Lawrence D?Oliveiro <ldo@nz.invalid> writes:
Richard Kettlewell wrote:
The need for symmetric encryption systems to include a MAC to
prevent this kind of issue has been understood for a long time.
??
Just want to point out you used the term ?symmetric? in the sense in
which I think it *should* be used: to refer to encryption systems
where the encryption and decryption algorithms are one and the same.
Too often the term is used to refer to systems where the same key is
used for encryption and decryption -- I think these should more
properly be called ?secret-key? systems.
Please stop trolling.
(For anyone in doubt, symmetric encryption refers to single-key
encryption schemes, not encryption schemes were encryption and
decryption are the same operation.)
On 02/01/2026 21:17, Richard Kettlewell wrote:
Lawrence D?Oliveiro <ldo@nz.invalid> writes:I am surprised you didn't kf him years ago.
Richard Kettlewell wrote:Please stop trolling.
The need for symmetric encryption systems to include a MAC to
prevent this kind of issue has been understood for a long time.
??
Just want to point out you used the term ?symmetric? in the sense in
which I think it *should* be used: to refer to encryption systems
where the encryption and decryption algorithms are one and the same.
Too often the term is used to refer to systems where the same key is
used for encryption and decryption -- I think these should more
properly be called ?secret-key? systems.
(For anyone in doubt, symmetric encryption refers to single-key
encryption schemes, not encryption schemes were encryption and
decryption are the same operation.)
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