Wait, they don't use hashes? Why???<p><pre><code> Image ID
Each layer is given an ID upon its creation. It is represented as a hexadecimal encoding of 256 bits, e.g., a9561eb1b190625c9adb5a9513e72c4dedafc1cb2d4c5236c9a6957ec7dfd5a9. Image IDs should be sufficiently random so as to be globally unique. 32 bytes read from /dev/urandom is sufficient for all practical purposes. Alternatively, an image ID may be derived as a cryptographic hash of image contents as the result is considered indistinguishable from random. The choice is left up to implementors.</code></pre>