AESCrypt File Format DescriptionItems in quotes are a literal string.  Words outside of quotesare a textual description of the contents.  Fixed-valued octets arewritten in hexidecimal form (e.g., 0x01).The AESCrypt version 2 file format is as follows.      3 Octets - 'AES'      1 Octet  - 0x02 (Version)      1 Octet  - Reserved     .... Start of repeating extension block section      2 Octet  - Length in octets (in network byte order) of an extension                 identifier and contents.  If 0x0000, then no further                 extensions exist and the next octet is the start of the                 Initialization Vector (IV).  Following an extension,                 this length indicator would appear again to indicate                 presence or absense of another extension and the size of                 any such extension.     nn Octets - Extension identifier.  This is either a URI or an                 identifier defined by the AES developer community and                 documented on the standard extensions page, either                 of which is terminated by a single 0x00 octet.  All                 extension identifiers are case sensitive.                   Examples of URIs:                      http://www.aescrypt.com/extensions/creator/                      urn:oid:1.3.6.1.4.1.17090.55.14                      urn:uuid:85519EA3-1DA6-45b9-9041-8CD368D8C086                   Note:                      A URI was used to allow anybody to define extension                      types, though we should strive to define a standard                      set of extensions.                   Examples of standard extension identifiers:                      CREATED-DATE                      CREATED-BY                 A special extension is defined that has no name, but is                 merely a "container" for extensions to be added after the                 AES file is initially created.  Such an extension avoids                 the need to read and re-write the entire file in order to                 add a small extension.  Software tools that create AES                 files should insert a 128-octet "container" extension,                 placing a 0x00 in the first octet of the extension                 identifier field.  Developers may then insert extensions                 into this "container" area and reduce the size of this                 "container" as necessary.  If larger extensions are added                 or the "container" area is filled entirely, then reading                 and re-writing the entire file would be necessary to add                 additional extensions.     nn Octets - The contents of the extension     .... End of repeating extension block section     16 Octets - Initialization Vector (IV) used for encrypting the                 IV and symmetric key that is actually used to encrypt                 the bulk of the plaintext file.     48 Octets - Encrypted IV and 256-bit AES key used to encrypt the                 bulk of the file                 16 octets - Initialization Vector                 32 octets - encryption key     32 Octets - HMAC     nn Octets - Encrypted message (2^64 octets max)      1 Octet  - File size modulo 16 in least significant bit positions     32 Octets - HMAC     Thus, the footprint of the file is at least 136 octets.The AESCrypt version 1 file format is as follows.      3 Octets - 'AES'      1 Octet  - 0x01 (Version)      1 Octet  - Reserved     16 Octets - Initialization Vector (IV) used for encrypting the                 IV and symmetric key that is actually used to encrypt                 the bulk of the plaintext file.     48 Octets - Encrypted IV and 256-bit AES key used to encrypt the                 bulk of the file                 16 octets - Initialization Vector                 32 octets - encryption key     32 Octets - HMAC     nn Octets - Encrypted message (2^64 octets max)      1 Octet  - File size modulo 16 in least significant bit positions     32 Octets - HMAC     Thus, the footprint of the file is at least 134 octets.The AESCrypt version 0 file format is as follows.      3 Octets - 'AES'      1 Octet  - 0x00 (Version)      1 Octet  - File size modulo 16 in least significant bit positions     16 Octets - Initialization Vector (IV)     nn Octets - Encrypted message (2^64 octets max)     32 Octets - HMAC     Thus, the footprint of the file is at least 53 octets.