Questions tagged [cbc]

Cipher Block Chaining (CBC) is a block cipher mode of operation.

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Are ECB and CBC modes of operation generally insecure?

In some Java code that I'm reading, I stumbled over the following encryption algorithms passed to the Cipher.getInstance(...) method: AES/CBC/PKCS5Padding DESede/ECB/PKCS5Padding RSA/ECB/PKCS1Padding ...
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0answers
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How does one implement chunked CBC encryption safely; is this implementation flawed?

UPDATE: Upon further research, I discovered a library that appears to meet my needs, especially with regard to the chunked aspect. Rather than "roll my own", I would be better served to use this well-...
0
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1answer
79 views

What if the attacker tamper the IV used in the block cipher CBC mode?

I am a newbie to block cipher and when learning the CBC mode, I start to understand that an IV is being used in this mode and also will be transferred to the message receiver. So here is my question,...
55
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2answers
10k views

Why does SSL Labs now consider CBC suites weak?

Why does SSL labs now mark CBC 256 suites as weak, although equivalent GCM and ChaCha20 are considered strong? Until a few months ago, it was unmarked in reports (neither explicitly as weak or strong),...
1
vote
1answer
570 views

Decrypting AES-128-CBC leads to first block being correct, the rest corrupt

I'm currently investigating a piece of software which encrypts it's files with AES-128-CBC. From disassembly it is truly known that the algorithm used is correct (log messages plus calls to the ...
0
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1answer
151 views

Why is authentication impossible with CBC mode?

Suppose I have a protocol where fixed-length messages (1280 bytes, no padding) are encrypted with AES in CBC mode. I want to put some data in the message body to verify that the message is authentic. ...
16
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2answers
2k views

What is the impact of the reported weak IV in 7 Zip?

It has been reported that 7 Zip generates IVs in a weak manner. What is the actual impact of this? I'm asking about historical Zip files that I've sent. I've no plans to use 7 Zip going forward until ...