Pseudo RSA keys are generated using the hidden small exponent method proposed by Claude Crepeau and Alain Slakmon:
Let M := a STRENGTH*2 bit even constant fixed in the program.
REPEAT pick a random number P of STRENGTH bits UNTIL Rabin-Miller primality
test claims it is a prime
REPEAT pick a random number Q of STRENGTH bits UNTIL Rabin-Miller primality
test claims it is a prime
Let N:=P*Q, PHI:=(P-1)*(Q-1)
REPEAT
REPEAT
pick a random number D such that |D|<|N|/4
UNTIL gcd(D,PHI)=1
using the extended Euclidean algorithm find E such that D*E=1 mod PHI.
let E' := E + M mod N-1
UNTIL gcd(E',PHI)=1
using the extended Euclidean algorithm find D' such that D'*E'=1 mod PHI.
Output Private Key := (D',P,Q), Public Key := (E',N).
If you are the pseudo RSA algorithm implementer and know the secret constant, M, you can backdoor the encrypted message:
Given the public key (E',N), compute the related public key (E,N) where
E := E'-M mod N-1. Using the Wiener algorithm solve the instance (E,N) for the
corresponding D such that |D|<|N|/4, factor N as P,Q, given E,D.