symmetric key cipher (block or stream cipher) providing partial decryption of data at some points. Although the entire data is not been decrypted but the data decrypted to that specific point should be viewed or accessed.
The partial decryption keys can be inherited form the main symmetric key to do partial decryptions successfully.
Can anyone refer to me any good stuff or papers worked out in this area?
Symmetric key decryption needs the key, once you have the key you can decrypt.
Now, you are asking about local decryption (partial one) for this you need to derive "chunk" key and open only that key. You can start from a master key and derive a binary tree of keys E(k,0) and E(k,1) for the left and right side keys and keep on doing it to build a tree of keys, at the leaves are the chunk keys with which you encrypt/ decrypt the data. You can always derive the chunk key specifically and use it to decrypt the chunk (and nothing else) other keys are pseudorandomly independent.
I am not sure if you are after something like this, but this is one possible solution to partial decryption with partial key only. Note that chunk key derivation is logarithmic in the number of chunks. I assume that you can delegate the chunk keys or even complete subtree key (for a sequence of consecutive chunks).
Symmetric key decryption needs the key, once you have the key you can decrypt.
Now, you are asking about local decryption (partial one) for this you need to derive "chunk" key and open only that key. You can start from a master key and derive a binary tree of keys E(k,0) and E(k,1) for the left and right side keys and keep on doing it to build a tree of keys, at the leaves are the chunk keys with which you encrypt/ decrypt the data. You can always derive the chunk key specifically and use it to decrypt the chunk (and nothing else) other keys are pseudorandomly independent.
I am not sure if you are after something like this, but this is one possible solution to partial decryption with partial key only. Note that chunk key derivation is logarithmic in the number of chunks. I assume that you can delegate the chunk keys or even complete subtree key (for a sequence of consecutive chunks).
It is not the answer but, if we have two pseudo random sequences with a good cross-correlation, the stream cipher by the one is used for the partial decryption of the other's... ?
This is not what you exactly ask for, but XML Encryption supports partial encryption and decryption. Certain parts of XML documents can be encrypted with different keys and and each receiver can decrypt only the part for which they possess the key.
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