Content Distribution System with Public Key Watermarking
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Solution Overview
Problem
Existing content distribution systems cannot prevent transmission devices from performing unauthorized acts by disguising as reception devices, leading to potential copyright infringement.
Innovation Solution
A content distribution system that includes a transmission device with a key obtaining unit, watermark embedding unit, and encryption unit to embed different public key identifiers as electronic watermarks in identical content, and a reception device with a key storage unit, key transmission unit, and decryption unit to receive and decrypt encrypted contents, making it impossible for the transmission device to identify the source of the content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transmission device embeds electronic watermarks and encrypts contents using public keys, then the reception device can be identified from unauthorized copies, but the transmission device cannot prevent itself from performing unauthorized acts by disguising as a reception device
Solution Approach 1:
The patent inverts the traditional watermarking approach by embedding the transmission device's own public key identifier into the content. This allows any device (including the transmission device itself) to be identified as the source. The reception device then uses its private key to decrypt and obtain the content, creating a system where the ability to decrypt proves legitimate reception rather than transmission origin.
Solution Approach 2:
The patent introduces public key infrastructure as an intermediary mechanism. The public key identifier embedded in the content acts as a mediator that links the content to its source without revealing the source's identity to potential copyers. The private key held by the reception device serves as a mediator that proves legitimate receipt without exposing the reception device to the transmission device.
2Measurement precision
If the transmission device distributes encrypted contents with embedded public key identifiers, then source identification is enabled, but the transmission device can still generate pirated content by embedding false public key identifiers
Solution Approach 1:
The patent applies preliminary action by having the reception device request content using its public key identifier before the actual content transfer. This creates a pre-established link between the public key identifier and the legitimate reception device. When the transmission device embeds the public key identifier in the content, it is embedding an identifier that the reception device has already proven it legitimately possesses through the key exchange process.
Solution Approach 2:
The patent implements feedback through the decryption process. The reception device decrypts the content using its private key, and this successful decryption serves as feedback that confirms the public key identifier embedded in the content matches its own public key. This feedback mechanism prevents the transmission device from successfully embedding false identifiers, as only the legitimate reception device's private key can decrypt the content.
Data Source
AI summary
A content distribution system for transferring contents between transmission device and reception device. The transmission device includes: key obtaining unit that obtains, from reception device, public keys and public key identifiers; watermark embedding unit that embeds a different public key identifier, as electronic watermark, into each of contents that are identical in substance; an encryption unit that encrypts contents using public keys to generate encrypted contents; and transmission unit that transmits encrypted contents to reception device. The reception device includes: key storage unit storing public keys, public key identifiers, and a private key that makes a pair with one of the public keys; key transmission unit that transmits public keys and public key identifiers to the transmission device; content receiving unit that receives encrypted contents from transmission device; and decryption unit that obtains a content from the received encrypted contents, using the private key.