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The symmetric cryptosystem one-time pad (OTP) seems to be very beautiful since it is perfectly secret according to Shannon. Many books, however, point out the main drawback: one must create a secret key the same length as the plaintext. For this reason, the concept of perfect secrecy has these days been abandoned, and we prefer other cryptosystems.

Now, for example, suppose I want to encode my text message with the ASCII scheme, and moreover suppose that this plaintext is 10 gigabytes long, therefore (using a OTP) the key must be the same length, 10 gigabytes. I think, however, this is a ''sustainable price'' because I'm sure that the ciphertext can't be attacked.

Practically, I don't understand why having such long keys with a OTP is a big disadvantage if we reach "the dream"-- namely, perfect secrecy. Nowadays the storage of information is very easy, so what is the real problem? I can, for example, share the "long key" in person.

The symmetric cryptosystem one-time pad (OTP) seems to be very beautiful since it is perfectly secret according to Shannon. Many books, however, point out the main drawback: one must create a secret key the same length as the plaintext. For this reason, the concept of perfect secrecy has these days been abandoned, and we prefer other cryptosystems.

Now, for example, suppose I want to encode my text message with the ASCII scheme, and moreover suppose that this plaintext is 10 gigabytes long, therefore (using an OTP) the key must be the same length, 10 gigabytes. I think, however, this is a ''sustainable price'' because I'm sure that the ciphertext can't be attacked.

Practically, I don't understand why having such long keys with an OTP is a big disadvantage if we reach "the dream"-- namely, perfect secrecy. Nowadays the storage of information is very easy, so what is the real problem? I can, for example, share the "long key" in person.

The symmetric cryptosystem one-time pad (OTP) seems to be very beautiful since it is perfectly secret according to Shannon. Many books, however, point out the main drawback: one must create a secret key the same length as the plaintext. For this reason, the concept of perfect secrecy has these days been abandoned, and we prefer other cryptosystems.

Now, for example, suppose I want to encode my text message with the ASCII scheme, and moreover suppose that this plaintext is 10 gigabytes long, therefore (using a OTP) the key must be the same length, 10 gigabytes. I think, however, this is a ''sustainable price'' because I'm sure that the ciphertext can't be attacked.

Practically, I don't understand why having such long keys with a OTP is a big disadvantage if we reach "the dream"-- namely, perfect secrecy. Nowadays the storage of information is very easy, so what is the real problem? I can, for example, share the "long key" in person.

Thanks in advance

The symmetric cryptosystem one-time pad (OTP) seems to be very beautiful since it is perfectly secret according to Shannon. Many books, however, point out the main drawback: one must create a secret key the same length as the plaintext. For this reason, the concept of perfect secrecy has these days been abandoned, and we prefer other cryptosystems.

Now, for example, suppose I want to encode my text message with the ASCII scheme, and moreover suppose that this plaintext is 10 gigabytes long, therefore (using a OTP) the key must be the same length, 10 gigabytes. I think, however, this is a ''sustainable price'' because I'm sure that the ciphertext can't be attacked.

Practically, I don't understand why having such long keys with a OTP is a big disadvantage if we reach "the dream"-- namely, perfect secrecy. Nowadays the storage of information is very easy, so what is the real problem? I can, for example, share the "long key" in person.

The symmetric cryptosystem One time pad (OTP) seems to be very beautiful since it is perfectly secret according to Shannon. Many books, however, point out that the main drawback is that one must create a secret key of length as the plaintext. For this reason the concept of perfect secrecy is nowadays abandoned, and we prefer other types of cryptosystems.

Now for example suppose I want to encode my text message with the ASCII scheme, and moreover suppose that this plaintext occupies 10 gigabytes, thus (using OTP) also the key occupies 10 gigabytes. I think however this is a ''sustainable price'' because on the other hand I'm sure that the ciphertext is can't be attacked.

Practically, I don't understand why having such long keys with OTP is a big disavantage even if we reach "the dream" namely the perfect secrecy  . Nowadays the storage of informations is very easy, so where is really the problem? I can for example share the "long key" with a physical meeting!

Thanks in advance

The symmetric cryptosystem one-time pad (OTP) seems to be very beautiful since it is perfectly secret according to Shannon. Many books, however, point out the main drawback: one must create a secret key the same length as the plaintext. For this reason, the concept of perfect secrecy has these days been abandoned, and we prefer other cryptosystems.

Now, for example, suppose I want to encode my text message with the ASCII scheme, and moreover suppose that this plaintext is 10 gigabytes long, therefore (using a OTP) the key must be the same length, 10 gigabytes. I think, however, this is a ''sustainable price'' because I'm sure that the ciphertext can't be attacked.

Practically, I don't understand why having such long keys with a OTP is a big disadvantage if we reach "the dream"-- namely, perfect secrecy. Nowadays the storage of information is very easy, so what is the real problem? I can, for example, share the "long key" in person.

Thanks in advance