Signature classification field (see below). Length of following material that is implicitly included RSA public-key-encrypted packet that contains the conventional key.ĬTB for secret-key-encrypted (signed) packet The conventionally-encrypted ciphertext packet begins right after the RSA-encrypted integer, encrypted conventional key packet. May affect rest of fields that follow.Īlgorithm byte for RSA (=1 for RSA). In bytes of the rest of the packet, not counting the CTB and the packet length The 8-, 16-, or 32-bit packet length field after the CTB gives the length No length field follows CTB, unknown packet length. Other CTB packet types are unimplemented. User ID packet, associated with public or secret key Raw literal plaintext data, with filename and mode The CTBīit fields have the following meaning (bit 0 is the LSB, bit 7 is theĬTB type field, specifies type of packet that follows Which specifies the type of data structure that follows it. Many of these data structures begin with a Cipher Type Byte (CTB), This is the standardįormat used by Unix timestamps. Number of seconds elapsed since 1970 Jan 1 00:00:00 GMT. Some packets contain a timestamp, which is a 32-bit unsigned integer of the Unlike a C string, the user ID has a length byte at theīeginning that has a byte count of the rest of the string. Some packets contain a "user ID", which is an ASCII string that contains The key ID is the least significant 64īits of the RSA public modulus that was involved in creating the packet.įor all practical purposes it unique to each RSA public key. For example, the integer value 5 would be stored as these three bytes:Īn MPI with a value of zero is simply stored with the 16-bit bitcount prefixįield containing a 0, with no value bytes following it. The bitcount always specifies the exact number of significantīits. Usual byte order, with the MSB padded with zero bits if the bitcount is notĪ multiple of 8. The integer that follows this bitcount field is stored in the With a 16-bit prefix that gives the number of significant bits in the integer PGP externally stores a multiprecision integer (MPI) RSA arithmetic involves a lot of multiprecision integers, often having hundreds The MSB-first byte order for external packet representation was chosen onlyīecause many other crypto standards use it. ThisĬovers multiprecision RSA integers, bit count prefix fields, byte count prefixįields, checksums, key IDs, and timestamps. This is for cross-compatibility of messages and keys between hosts. Just like a binary file described here, but with an extra layer of encodingĪdded, framing lines, and a checksum at the end.]Īll integer data used by PGP is externally stored most significant byte (MSB)įirst, regardless of the byte order used internally by the host CPU architecture.
[To be included: a description of ASCII armor. Or trying to implement other PGP- compatible cryptography products, or anyone
#Dmg vs pgp signature meaning software#
Includes software engineers trying to port PGP to other hardware environments (PGP), the RSA public key cryptography application. This appendix describes the file formats used externally by Pretty Good Privacy Literal data packet, with filename and mode.Conventional Data Encryption Key (DEK) "packet".
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