| crypto/sha256 | Package sha256 implements the SHA224 and SHA256 hash algorithms as defined in FIPS 180-4. |
| crypto/sha512 | Package sha512 implements the SHA-384, SHA-512, SHA-512/224, and SHA-512/256 hash algorithms as defined in FIPS 180-4. |
| flag | Package flag implements command-line flag parsing. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| github.com/docker/distribution/version | |
| github.com/opencontainers/go-digest | Package digest provides a generalized type to opaquely represent message digests and their operations within the registry. |
| io | Package io provides basic interfaces to I/O primitives. |
| log | Package log implements a simple logging package. |
| os | Package os provides a platform-independent interface to operating system functionality. |