P.71 of Cryptography Engineeering states "Any weakness in CTR encryption mode immediately implies a chosen plaintext attack on the block cipher." It seems to me that "any weakness" is vague. I'm not quite getting what the author has in mind. Can someone please elaborate?
The purpose of the statement seems to be to highlight the relationship between the security of the block cipher and CTR mode - a break of CTR implies a break in the underlying block cipher (except information leakage and traffic analysis). I don't see how a break of CTR means the break in the block cipher is necessarily of the chosen plaintext variety.