PHP: fileformat phar - Phar Signature format

Phar Signature format

Phars containing a signature always have the signature appended to the end of the Phar archive after the loader, manifest, and file contents. The two signature formats supported at this time are MD5 and SHA1.

**Signature format**
Length in bytes	Description
16 or 20 bytes	The actual signature, 20 bytes for an SHA1 signature, 16 bytes for an MD5 signature, 32 bytes for an SHA256 signature, and 64 bytes for an SHA512 signature.
4 bytes	Signature flags. 0x0001 is used to define an MD5 signature, 0x0002 is used to define an SHA1 signature, 0x0004 is used to define an SHA256 signature, and 0x0008 is used to define an SHA512 signature. The SHA256 and SHA512 signature support was introduced with API version 1.1.0.
4 bytes	Magic GBMB used to define the presence of a signature.