Blowfish encryption with different keys produces same ciphertext I have set up a test app with Blowfish encryption taken from someone else's library. I have been astonished to find that password "Test" gives the same encrypted text as password "TestTestTestTest". Is this normal behavior of the algorithm or is it a bug?
It looks like the library is treating the string as the key to Blowfish, which has a veriable key size; the way the keysetup is done (with a cyclical use of the key bytes, see more details on the Wikipedia page) implies that key $k$ of length $n$ and key $k||k$ of length $2n$ have the same expanded key and thus an equivalent encryption/decryption function. Your "Test" example also illustrates this. 

Usually from a string a key is "derived" using a KDF, which is then input to an algorithm that accepts keys of some fixed sizes like 128 bits etc. But Blowfish can accept 1 byte keys, and 300 byte keys too, so libraries often don't do this an accept the key input 'as is', without KDF being compulsory. Or they "pad" a string like 'Test' to 16 bytes with 0-bytes etc. Be sure you know what a library does before using it. Keys should be random and unpredictable, not dictionary words.