In some applications, a short private exponent
d is chosen to improve the decryption or signing process for RSA public key cryptosystem. However, in a typical RSA, if the private exponent
d is selected first, the public exponent
e should be of the same order of magnitude as
φ(
N). Sun et al. devised three RSA variants using unbalanced prime factors
p and
q to lower the computational cost. Unfortunately, Durfee & Nguyen broke the illustrated instances of the first and third variants by solving small roots to trivariate modular polynomial equations. They also indicated that the instances with unbalanced primes
p and
q are more insecure than the instances with balanced
p and
q. This investigation focuses on designing a new RSA variant with balanced
p and
q, and short exponents
d and
e, to improve the security of an RSA variant against the Durfee & Nguyen's attack, and the other existing attacks. Furthermore, the proposed variant (Scheme A) is also extended to another RSA variant (Scheme B) in which
p and
q are balanced, and a trade-off between the lengths of
d and
e is enable. In addition, we provide the security analysis and feasibility analysis of the proposed schemes.
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