Military apply the concept “security through obscurity” and the key length is important but it is not always the case, for example:
- Chiasmus cipher (secret German cipher leaked by reverse engineering) used 64-bit plaintext,160-bit key length, and ECB mode.
- Red pike block cipher uses 64-bit block size and 64-bit key length (leaked on Cypherpunk)
The industry tends to use standards mainly AES (highly respected as a strong cipher and received many public analyses) especially when cryptography is not their core business.
