pea file format specifications
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PeaZip is a free cross-platform file archiver that provides an unified portable GUI for many Open Source technologies like 7-Zip, FreeArc, PAQ, UPX...
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What is PEA file format


PEA file extension

PEA file format specifications

PEA file format specifications version 1.1

Pea (.pea file extension), acronym for Pack, Encrypt, Authenticate, designs a file format focused on data security, aiming to provide archiving, compression and multi volume file split (spanning) feature in a single passage, along with flexible schemes of optional integrity check and authenticated encryption (AES in EAX or HMAC mode, alternatively Twofish and Serpent in EAX mode); PEA file format specifications are released under public domain.

Pea compression is optional, at current level of implementation are defined only following levels: PCOMPRESS0 (store only, no compression), and PCOMPRESS1..3 based on deflate (reference zlib's compres/uncompres algorithm code), respectively at compression level 3, 6 and 9.

PEA format security model acts at 3 levels: objects (input files and folders sent to .pea archive), volumes (output archive file that can be spanned to user defined size) and streams (the actual output data stream that is formed by multiple input files and can be written written to multiple output volumes); each one of those levels can be omitted as needed by the user.
  • Object level integrity checking is performed to detect errors with object level granularity on raw input data and all associated data (name, size, attributes, date-time);
    • Current implementation allows: Checksum (Adler32, CRC32, CRC64), Hash (MD5, SHA1, RIPEMD-160, SHA256, SHA512, Whirlpool, , SHA3-256, SHA3-512)
  • Volume level integrity check is communication oriented and allow to discard single corrupted volumes in order to minimize, in case of error, the retransmission overhead;
    • Current implementation allows same Checksum and Hash algorithms featured by Object level check
  • Stream level check offers wide choice of algorithms up to authenticated encryption, protecting privacy and authenticity of a group of objects sharing same security needs, including tags generated by object level checks;
    • Current implementation allows same Checksum and Hash algorithms featured by Object and Volume levels, plus Authenticated encryption schemes: HMAC mode AES128, EAX mode AES128, AES256, Serpent128, Serpent256, Twofish128, Twofish 256.
Arbitrarily sized volume spanning allows the archive to be splitted in volumes of arbitrary size, with the only constrain of volumes being at least 10 byte bigger than volume control tag to allow passing (through archive's header) minimum needed information to the extraction application.

PEA file format standard, as defined in version 1 revision 1 specification, can store a single stream containing unlimited objects, each up to 2^64 byte in size; current Pea executable supports 1.1 file format specifications (practically, archives are memory and filesystem-limited rather than format limited) and is featured starting from PeaZip 6.0.1 release, previous PeaZip releases supporting PEA 1.0 format revision.

PEA 2.0 file format specifications extend the concepts behind PEA 1.x file format and can store an unlimited number of stream, but the format is not actually supported by current Pea archiving utility.

Here, a brief table of features and limitations applying to file format and to current implementation:


PEA file format

Current implementation


Max archive size

unlimited, no limit is set by the format design for maximum archive size, only filesystem size limitations applies

up to 999999 volumes of 2^64-1 byte each; using 128 bit block encryption it would be safe not to encrypt more than 2^64 byte with same key, better staying one or more orders of magnitude below

Stream number

1.1: single stream;

2.0 unlimited number of streams;

Single stream (1.1 file format)



Optional Authenticated Encryption, at stream level only. HMAC mode: AES128, EAX mode: AES 128 or 256bit, Serpent 128 / 256, Twofish 128 / 256.

Integrity check

AE tag (see security section) or hash or checksum at stream level, plus hash or checksum for input objects, and for output volumes.

Currently supported: Adler32, CRC32, CRC64 checksum algorithms; MD5, SHA1, RIPEMD-160, SHA-2 and SHA-3 families, and Whirlpool hash algorithms.

Error correction

No scheme featured at current level of development

Communication recovery

Independent volume control check allow to identify corrupted volumes (first volume may be needed to know volume check algorithm)

No specific tool developed; volume check is done during extraction and then, allowing to repeat download only of corrupted volumes

Data recovery

Stream control tags allow to recognize correct streams, if better granularity is needed object control tags allow to recognize correct objects; input object names and POD trigger allow to identify objects and stream between the archive data;

No specific tool developed to try error resistant data extraction, however object check errors are reported to identify corrupted and non corrupted data if the extraction is successful

Support for multi volume output

Native, requires a single pass. Raw file spanning compatible with Unix split command, and applications like HJSplit and 7-Zip.

Volume number


1..999999 (6 digit counter string in output file name, after .pea file extension)

Volume size

Volume tag size +1.. unlimited; first volume must contain at least 10 byte of data to allow parsing of the archive header, to allow unpacking application to  calculate volume tag size

Volume tag size +1.. 2^64-1 (qword variable) ; first volume must contain at least 10 byte of data


Native, requires single pass; schemes:

PCOMPRESS0: no compression; PCOMPRESS1..3 based on deflate using zlib's compres/uncompres, level 3, 6 and 9 respectively 

Solid archive

Not implemented compression modes featuring the possibility of creating solid archive


Input types

1.1: files and dirs;

2.0: files, dirs, metadata stored as messages triggers

Files and dirs (1.1)

Input objects number


Host system memory limited (input object list is stored in a dynamic array of strings)

Input object size (of single objects)



Input object qualified name size (size 0 mean that archive object is a trigger, no input object mapped to the archive object)


1..32K (exceeding needs, longer values are considered errors)


Objects attributes and last modification time, optionally comments and any kind of meta content using messages

Save object attributes and object last modification time. Restore only object attributes (on Microsoft Windows), nothing on *x

For a more complete explanation and discussion of the pea format specifications please see the documentation about Pea archive format design (.pdf).

when to use pea When it is recommended to use PEA format: it is a good choice when it is needed to guarantee confidentiality (data cannot be accessed without password), integrity, and autenticity - data can only be modified by recipient knowing the password, as data is subject to password-dependent, cryptographically strong verification.

what are pea files




Author: Giorgio Tani, 2006

SPEED encrypted file type
Average, due lightweight, quick Deflate-based compression algorithm, and efficient encryption and hashing algorithms.

COMPRESSION RATIO high compression ratio
Fast Deflate-based compression, comparable with compression ratios of GZ and classic ZIP format.

ADVANCED OPTIONS file encryption
Pea format lacks some features of competing formats, but offers advanced security focused characteristics, as AES-based authenticated encryption (can be optionally be replaced by Serpent or Twofish EAX mode authenticated encryption).




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