dorsal/arxiv
View SchemaSome Attacks On Quantum-based Cryptographic Protocols
| Authors | Hoi-Kwong Lo, Tsz-Mei Ko |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0309127 |
| URL | https://arxiv.org/abs/quant-ph/0309127 |
| Journal | Quantum Information and Computation. Vol. 5, No.1 (2005) 40-47. |
Abstract
Quantum-based cryptographic protocols are often said to enjoy security guaranteed by the fundamental laws of physics. However, even carefully designed quantum-based cryptographic schemes may be susceptible to subtle attacks that are outside the original design. As an example, we give attacks against a recently proposed ``secure communication using mesoscopic coherent states'', which employs mesoscopic states, rather than single-photon states. Our attacks can be used either as a known-plaintext attack or in the case where the plaintext has not been randomized. One of our attacks requires beamsplitters and the replacement of a lossy channel by a lossless one. It is successful provided that the original loss in the channel is so big that Eve can obtain 2^k copies of what Bob receives, where k is the length of the seed key pre-shared by Alice and Bob. Substantial improvements over such an exhaustive key search attack can be made, whenever a key is reused. Furthermore, we remark that, under the same assumption of a known or non-random plaintext, Grover's exhaustive key search attack can be applied directly to "secure communication using mesoscopic coherent states", whenever the channel loss is more than 50 percent. Therefore, as far as information-theoretic security is concerned, optically amplified signals necessarily degrade the security of the proposed scheme, when the plaintext is known or non-random. Our attacks apply even if the mesoscopic scheme is used only for key generation with a subsequent use of the key for one-time-pad encryption.
{
"annotation_id": "59851022-4235-4653-b98f-76e4bf764e66",
"date_created": "2026-03-02T18:02:03.650000Z",
"date_modified": "2026-03-02T18:02:03.650000Z",
"file_hash": "411c67f6a4917fa5a72e355c806354f558d4bb91eb58ee0c55d5296e4bb26eef",
"private": false,
"record": {
"abstract": "Quantum-based cryptographic protocols are often said to enjoy security\nguaranteed by the fundamental laws of physics. However, even carefully designed\nquantum-based cryptographic schemes may be susceptible to subtle attacks that\nare outside the original design. As an example, we give attacks against a\nrecently proposed ``secure communication using mesoscopic coherent states\u0027\u0027,\nwhich employs mesoscopic states, rather than single-photon states. Our attacks\ncan be used either as a known-plaintext attack or in the case where the\nplaintext has not been randomized. One of our attacks requires beamsplitters\nand the replacement of a lossy channel by a lossless one. It is successful\nprovided that the original loss in the channel is so big that Eve can obtain\n2^k copies of what Bob receives, where k is the length of the seed key\npre-shared by Alice and Bob. Substantial improvements over such an exhaustive\nkey search attack can be made, whenever a key is reused. Furthermore, we remark\nthat, under the same assumption of a known or non-random plaintext, Grover\u0027s\nexhaustive key search attack can be applied directly to \"secure communication\nusing mesoscopic coherent states\", whenever the channel loss is more than 50\npercent. Therefore, as far as information-theoretic security is concerned,\noptically amplified signals necessarily degrade the security of the proposed\nscheme, when the plaintext is known or non-random. Our attacks apply even if\nthe mesoscopic scheme is used only for key generation with a subsequent use of\nthe key for one-time-pad encryption.",
"arxiv_id": "quant-ph/0309127",
"authors": [
"Hoi-Kwong Lo",
"Tsz-Mei Ko"
],
"categories": [
"quant-ph"
],
"journal_ref": "Quantum Information and Computation. Vol. 5, No.1 (2005) 40-47.",
"title": "Some Attacks On Quantum-based Cryptographic Protocols",
"url": "https://arxiv.org/abs/quant-ph/0309127"
},
"schema_id": "dorsal/arxiv",
"source": {
"execution_id": "12a6bebb-6d26-44b7-992d-a2a02ea92855",
"id": "arXiv Dataset IDs",
"type": "Model",
"variant": "snapshot-2026-03-01",
"version": "0.1.0"
},
"user_id": 1000002
}