rpm
4.9.1.3

5.1. More...
#include <rpmpgp.h>
Data Fields  
uint8_t  version 
pgpKeyID_t  keyid 
uint8_t  algo 
5.1.
PublicKey Encrypted Session Key Packets (Tag 1)
A PublicKey Encrypted Session Key packet holds the session key used to encrypt a message. Zero or more Encrypted Session Key packets (either PublicKey or SymmetricKey) may precede a Symmetrically Encrypted Data Packet, which holds an encrypted message. The message is encrypted with the session key, and the session key is itself encrypted and stored in the Encrypted Session Key packet(s). The Symmetrically Encrypted Data Packet is preceded by one PublicKey Encrypted Session Key packet for each OpenPGP key to which the message is encrypted. The recipient of the message finds a session key that is encrypted to their public key, decrypts the session key, and then uses the session key to decrypt the message.
The body of this packet consists of:
Algorithm Specific Fields for RSA encryption
Algorithm Specific Fields for Elgamal encryption:
uint8_t pgpPktPubkey_s::algo 
uint8_t pgpPktPubkey_s::version 